A 2018 comprehensive review "Carvacrol and human health" published in Phytother Res. by Mehdi Sharifi-Rad, Elena Maria Varoni, Marcello Iriti, Miquel Martorell, William N Setzer, María Del Mar Contreras, Bahare Salehi, Azam Soltani-Nejad, Sadegh Rajabi, Mercedeh Tajbakhsh, Javad Sharifi-Rad, carvacrol is a phenolic monoterpenoid found in essential oils of Marjoram (Origanum majorana), Oregano (Origanum vulgare), Thyme (Thymus vulgaris), Pepperwort (Lepidium flavum), Wild Bergamot (Citrus aurantium bergamia), and other plants. Carvacrol possesses a wide range of bioactivities putatively useful for clinical applications such antimicrobial, antioxidant, and anticancer activities. Carvacrol antimicrobial activity is higher than that of other volatile compounds present in essential oils due to the presence of the free hydroxyl group, hydrophobicity, and the phenol moiety. The present review illustrates the state-of-the-art studies on the antimicrobial, antioxidant, and anticancer properties of carvacrol. It is particularly effective against food-borne pathogens, including Escherichia coli, Salmonella, and Bacillus cereus. Carvacrol has high antioxidant activity and has been successfully used, mainly associated with thymol, as dietary phytoadditive to improve animal antioxidant status. The anticancer properties of carvacrol have been reported in preclinical models of breast, liver, and lung carcinomas, acting on proapoptotic processes. Besides the interesting properties of carvacrol and the toxicological profile becoming definite, to date, human trials on carvacrol are still lacking, and this largely impedes any conclusions of clinical relevance.

A 2007 study "Marjoram increases basal gastric acid and pepsin secretions in rat" published by Rafsanjani F N et al., shows the Marjoram contains some components that activate chief and parietal cells and increase basal acid and pepsin secretion.

A 2018 study "Antispasmodic and Myorelaxant Activity of Organic Fractions from Origanum majorana L. on Intestinal Smooth Muscle of Rodents" in European Journal of Medicinal Plants by Hanane Makrane, Mohammed Aziz, Hassane Mekhfi, Abderrahim Ziyyat, Mohamed Bnouham, Abdelkhaleq Legssyer, Bernard Gressier and Bruno Eto, evaluated the pharmacodynamic effects of Origanum majorana on isolated smooth muscles preparations of guinea pig's ileum and rat's colon. Results showed significant antispasmodic effect with a potential benefit for the treatment of colic in gastrointestinal disorders. Study confirmed the antispasmodic and myorelaxant activity of organic fractions of Origanum majorana in rat and rabbit jejunum. Results showed that adrenergic receptors, guanylate cyclase or muscarinic receptor pathways were not involved in relaxation induced by DFOM suggesting the antispasmodic effect on intestinal smooth muscle was non-competitive antaganism towards voltage-dependent calcium channels.

A 2009 study "Protective Effect of Origanum majorana L. Marjoram on various models of gastric mucosal injury in rats" published in Am J Chin Med. by Tawfeq Al-Howiriny, Abdulmalik Alsheikh, Saleh Alqasoumi, Mohammed Al-Yahya, Kamal ElTahir, Syed Rafatullah, evaluated the antiulcerogenic activity of the ethanol extract in hypothermic restraint stress-, indomethacin-, necrotizing agents- (80% ethanol, 25% NaCl and 0.2 M NaOH) induced ulcers and basal gastric acid secretion using pylorus ligated Shay rat-model. Marjoram at doses of 250 and 500 mg/kg of body weight, significantly decreased the incidence of ulcers, basal gastric secretion and acid output. Furthermore, the extract replenished the ethanol-induced depleted gastric wall mucus and nonprotein sulfhydryls (NP-SH) contents and significantly lowered the increase in the concentration of malondialdehyde (MDA). Ulcer preventing potential was further confirmed by histopathological assessment. An acute toxicity test showed a large margin of safety of the extract in mice. The phytochemical screening of aerial parts of Marjoram revealed the presence of volatile oil, flavonoids, tannins, sterols and/or triterpenes.

A study of six herbs revealed that Marjoram fought against Clostridium perfringens, a common foodborne pathogen. In addition, a rat study noted that its extract protected against stomach ulcers. Still, human studies are needed.

A 2009 animal study "Protective Effect of Origanum majorana L. 'Marjoram' on various models of gastric mucosal injury in rats" published in The American Journal of Chinese Medicine evaluated Marjoram’s ability to prevent and treat gastric ulcers. The study found that at doses of 250 and 500 mg per kilogram of body weight, it significantly decreased the incidence of ulcers, basal gastric secretion and acid output. Furthermore, the extract was found to replenish depleted mucus of the gastric wall, which plays a key part in the healing of ulcers and lowered the increase in malondialdehyde. Study evaluated the antiulcerogenic activity of ethanol extract in hypothermic restrained-stress-, indomethacin-, necrotizing agents-induced ulcers and basal gastric acid secretion in pylorus ligated Shay rat model. Marjoram not only prevented and treated ulcers, but it was also proved to have a large margin of safety. The aerial (above ground) parts of Marjoram were also shown to contain volatile oils, flavonoids, tannins, sterols and/or triterpenes. While research remains preliminary, Marjoram use for stomach health is promising.

A 2019 study "Origanum majorana L. extract exhibit positive cooperative effects on the main mechanisms involved in acute infectious diarrhea" published in Journal Ethnopharmacol. by Hanane Makrane, Mohammed Aziz, Hassane Mekhfi, Abderrahim Ziyyat, Abdelkhaleq Legssyer, Ahmed Melhaoui, Mohamed Berrabah, Mohamed Bnouham, Chakib Alem, Ferdinand Kouoh Elombo, Bernard Gressier, Jehan-François Desjeux, Bruno Eto, was to see if aqueous extract of Origanum majorana L. may exhibit an effect on those deleterious mechanisms. The effect of aqueous extract of Origanum majorana on electrogenic Cl^- secretion and Na⁺ absorption, the two main mechanisms underlying water movement in the intestine, was assessed on intestinal pieces of mice intestine mounted, in vitro, in Ussing chambers. aqueous extract of Origanum majorana effect on muscle relaxation was measured on rat intestinal smooth muscle mounted in an isotonic transducer.

1. Aqueous extract of Origanum majorana placed on the serosal (i.e. blood) side of the piece of jejunum entirely inhibited in a concentration-dependent manner the Forskolin-induced electrogenic chloride secretion, with an IC50 = 654 ± 8 µg/mL
2. Aqueous extract of Origanum majorana placed on the mucosal (i.e. luminal) side stimulated in a concentration-dependent manner an electrogenic Na⁺ absorption, with an IC₅₀ = 476.9 ± 1 µg/mL.
3. Aqueous extract of Origanum majorana (1 mg/mL) inhibition of Forskolin-induced electrogenic secretion was almost entirely prevented by prior exposure to Ca⁺⁺ channels or neurotransmitters inhibitors.
4. Aqueous extract of Origanum majorana (1 mg/mL) proabsorptive effect was greater in the ileum and progressively declined in the jejunum, distal colon and proximal colon (minimal).
5. Aqueous extract of Origanum majorana inhibited in a concentration-dependent manner smooth muscle Carbachol or KCl induced contraction, with an IC₅₀ = 1.64 ± 0.2 mg/mL or 1.92 ± 0.8 mg/mL, respectively. The present results indicate that aqueous extract of Origanum majorana L. exhibit positive cooperative effects on the main mechanisms that are involved in acute infectious diarrhea.

An animal study published in Cardiovascular Toxicology found that sweet Marjoram extract worked as an antioxidant and inhibited the production of nitric oxide and lipid peroxidation in myocardial infarcted (heart attack) rats. By simply smelling the plant, you can decrease your "fight-or-flight" response (sympathetic nervous system) and increase your “rest and digest system” (parasympathetic nervous system), which lessens the strain on your entire cardiovascular system, not to mention your whole body.

A 2015 study "Modulatory effect of Origanum majorana extract against cisplatin-induced dyslipidemia in rats" published in International Journal of Current Research in Life Sciences, Vol 4, No 6 by Amany Ahmed Sayed, Shreen Desouky, Mohamed Marzouk, Amel M Soliman, evaluated the curative effect of Origanum majorana ethanolic extract on the lipid profile abnormalities induced by cisplatin in a male Wistar rat model. There was a decrease in total lipid, triglycerides, and LDL cholesterol together with an increase in HDL. Results showed a hypolipidemic potential against cisplatin induced dyslipidemia and suggests that Origanum majorana might serve as a novel adjuvant therapy with cisplatin.

A 2021 study "Origanum majorana L. Extract Protects Against Isoproterenol-Induced Cardiotoxicity in Rats" published in Cardiovasc Toxicol. by Abeer M Rababa'h, Miya A Alzoubi, evidence from the literature has demonstrated that Origanum majorana L. (Marjoram) acts as an antioxidant, anti-inflammatory, antiplatelet, and assists in hormonal regulation. However, there is limited scientific evidence describing the signaling pathways associated with the Marjoram's positive effect on cardiac injury. Therefore, we aimed to understand the mechanistic protective effects of Marjoram on isoproterenol (ISO)-induced myocardial injury in rats. Sprague Dawley rats were randomly assigned into six groups. Marjoram was administrated by oral gavage and isoproterenol was administrated subcutaneously (ISO; 85 mg/kg). Heart weight, cardiac enzymes, inflammatory, and oxidative stress biomarkers were measured. The ISO-induced cardiac injury was confirmed by the significant increase in the levels of cardiac enzymes (P value < 0.05), whereas pre-treatment with Marjoram normalized these cardiac injury parameters. We also determined that Marjoram had a protective effect against ISO-induced increase in C-reactive protein (CRP), IL-6, IL-13, and TNF-α. Additionally, Marjoram significantly decreased cardiac thiobarbituric acid reactive substances (TBARS) levels (P value < 0.05) and protected against ISO-induced oxidative stress. We have demonstrated that Marjoram decreased both cardiac oxidative stress and inflammation, thus establishing the beneficial effects of Marjoram on ISO-induced cardiac injury in rats.

A 2023 study "Microbiological Studies on the Influence of Essential Oils from Several Origanum Species on Respiratory Pathogens" published in Molecules, by Bartłomiej Piasecki, Viktória L Balázs, Anna Kieltyka-Dadasiewicz, Péter Szabó, Béla Kocsis, Györgyi Horváth, Agnieszka Ludwiczuk, evaluate the antimicrobial activity of essential oils obtained from several samples of Origanum vulgare, Origanum syriacum, and Origanum majorana cultivated in Poland. essential oils were analyzed by GC-MS and tested against four bacterial strains: Staphylococcus aureus (MRSA), Haemophilus influenzae, Haemophilus parainfluenzae, and Pseudomonas aeruginosa. Chemical analyses showed that the Eos were characterized by a high diversity in composition. Based on the chemical data, four chemotypes of Origanum essential oils were confirmed. These were carvacrol, terpineol/sabinene hydrate, caryophyllene oxide, and thymol chemotypes. Thin-layer chromatography-bioautography confirmed the presence of biologically active antibacterial components in all tested essential oils. The highest number of active spots were found among essential oils with cis-sabinene hydrate as the major compound. On the other hand, the largest spots of inhibition were characteristic to essential oils of the carvacrol chemotype. Minimal inhibitory concentrations (MICs) were evaluated for the most active essential oils: O. vulgare 'Hirtum', O. vulgare 'Margarita', O. vulgare 'Hot & Spicy', O. majorana, and O. syriacum (I) and (II); it was shown that both Haemophilus strains were the most sensitive with an MIC value of 0.15 mg/mL for all essential oils. O. majorana essential oil was also the most active in the MIC assay and had the highest inhibitory rate in the anti-biofilm assay against all strains. The most characteristic components present in this essential oil were the trans-sabinene hydrate and terpinen-4-ol. The strain with the least sensitivity was the MRSA with an MIC of 0.6 mg/mL for all essential oils except for O. majorana, where the MIC value reached 0.3 mg/mL. Scanning electron microscopy performed on the Haemophilus influenzae and Haemophilus parainfluenzae biofilms showed a visible decrease in the appearance of bacterial clusters under the influence of O. majorana essential oil.

A 2016 study "In Vitro Cytotoxic Effect of Aqueous Extract of Origanum marjorana on AMN-3 Cell Line" published in Journal of Natural Sciences Research by Fayhaa M. Khaleel Areej SH. Hameed Taghreed U. Mohammd, evaluated the potential anticancer activity of Origanum majorana aqueous extract from air-dried plant materials on cancer cell lines AMN-3. Results showed growth inhibition of AMN-3 cell line that increased with plant extract concentration. The aqueous extract showed significant cytotoxic effect (p<0.05) with 66% at 100 mg/mL, 53,3% at 50 mg/mL, 40% at 25 mg/mL and decreasing to 0.8% at 0.04 mg/mL concentration.

A 2016 study "Origanum majorana Attenuates Nephrotoxicity of Cisplatin Anticancer Drug through Ameliorating Oxidative Stress" published in Nutrients by Amel M Soliman, Shreen Desouky, Mohamed Marzouk, Amany A Sayed, evaluated the effect of Originum majorana ethanolic extract (OMEE) on cisplatin-induced nephrotoxicity. Eighteen male rats were divided into three groups as follows: a control group, a group treated with cisplatin (3 mg/kg body weight), and a group that received both cisplatin and OMEE (500 mg/kg body weight) for 14 days. Cisplatin induced a significant increase in creatinine, urea, uric acid, blood urea nitrogen, malondialdehyde, and nitric oxide levels. However, glutathione, superoxide dismutase, and catalase levels were significantly diminished. Conversely, OMEE significantly modulated the renal and oxidative markers negatively impacted by cisplatin. OMEE significantly reduced the effects of cisplatin-induced changes in renal and oxidative markers, possibly through its free radical scavenging activity. Thus, OMEE may be combined with cisplatin to alleviate nephrotoxicity in cancer chemotherapy.

A 2010 study "The apoptotic and anti-proliferative activity of Origanum majorana extracts on human leukemic cell line" published in Leuk Res. by Roula M Abdel-Massih, Rida Fares, Samer Bazzi, Nisrine El-Chami, Elias Baydoun, scientists are constantly searching for phytochemicals and compounds with anti-cancer and antioxidant activity. In this study, the anti-proliferative activity of plant extracts from Origanum majorana was tested on human lymphoblastic leukemia cell line Jurkat. Cytotoxicity was examined using non-radioactive cytotoxicity assay and the IC(50) was calculated. At non-cytotoxic concentrations, the viability of cells decreased with increase of concentration of plant extract. The anti-proliferative effect was also found to be dose-dependent. Analysis via flow cytometry shows that Marjoram extracts stimulated apoptosis. Induction of apoptosis was caused by an up-regulation of p53 protein levels and down-regulation of Bcl-2alpha. Marjoram exhibited a strong scavenging activity (SC(50)=0.03mg dry weight). The conclusions from this study suggest that Marjoram extracts exhibit anti-proliferative effect and high antioxidant activity. For that it merits further investigation as a potential therapeutic agent.

Yusra Al Dhaheri, Samir Attoub, Kholoud Arafat, Synan AbuQamar, Jean Viallet, Alaaeldin Saleh, Hala Al Agha, Ali Eid, Rabah Iratni, in a study "Anti-Metastatic and Anti-Tumor Growth Effects of Origanum majorana on Highly Metastatic Human Breast Cancer Cells: Inhibition of NFκB Signaling and Reduction of Nitric Oxide Production" have reported the anticancer activity of Origanum majorana by promoting cell cycle arrest and apoptosis of metastatic MDA-MB-231 breast cancer cell line. This study demonstrated that non-cytotoxic concentrations of O. majorana significantly inhibited the migration and invasion of MDA-MB-231 cells as shown by wound healing and matrigel invasion assay. On chick embryo tumor growth assay, Origanum majorana was shown to promote inhibition of tumor growth and metastasis in vivo. Findings suggest a promising chemopreventive and therapeutic candidate that modulate breast cancer growth and metastasis.

A 2020 study "Origanum majorana Essential Oil Triggers p38 MAPK-Mediated Protective Autophagy, Apoptosis, and Caspase-Dependent Cleavage of P70S6K in Colorectal Cancer Cells" published in Biomolecules by Khawlah Athamneh, Aysha Alneyadi, Halima Alsamri, Asma Alrashedi, Abdulrasheed Palakott, Khaled A El-Tarabily, Ali H Eid, Yusra Al Dhaheri, Rabah Iratni, investigated the anti-colon cancer potential of Origanum majorana essential oil and its underlying mechanisms of action. We showed that Origanum majorana essential oil significantly inhibited the cellular viability and colony growth of human HT-29 colorectal cancer cells. Origanum majorana essential oil induced protective autophagy, associated with downregulation of the mTOR/p70S6K pathway, and activated caspase-8 and caspase-9-dependent apoptosis. Blockade of autophagy with 3-methyladenine (3-MA) and chloroquine (CQ), two autophagy inhibitors, potentiated the Origanum majorana essential oil-induced apoptotic cell death. Inversely, inhibition of apoptosis with the pan-caspase inhibitor, Z-VAD-FMK, significantly reduced cell death, suggesting that apoptosis represents the main mechanism of Origanum majorana essential oil-induced cell death. Mechanistically, we found that Origanum majorana essential oil induces protective autophagy and apoptotic cells death via the activation of the p38 MAPK signaling pathway. Pharmacological inhibition of p38 MAPK by the p38 inhibitors SB 202190 and SB 203580 not only significantly decreased apoptotic cell death, but also reduced the autophagy level in Origanum majorana essential oil treated HT-29 cells. Strikingly, we found that Origanum majorana essential oil also induces p38 MAPK-mediated caspase-dependent cleavage of p70S6K, a protein reported to be overexpressed in colon cancer and associated with drug resistance. Our findings suggest that Origanum majorana essential oil inhibits colon cancer through p38 MAPK-mediated protective autophagy and apoptosis associated with caspase-dependent cleavage of p70S6K. To the best of our knowledge, this study is the first to report on the implications of the p38 MAPK signaling pathway in targeting p70S6K to caspase cleavage.

A 2015 study published in Master of Science in Molecular Biology and Biotechnology by Nedaa Faisal Al Tamimi from United Arab Emirates University evaluated a Origanum majorana plant extract for anti-cancer effect on in vitro proliferation and DNA damage on human colon cancer HT-29 cell line. Results showed O. majorana inhibited growth of DT-29 cells by affecting cell viability. Extract also showed ability to cause DNA damage, cell cycle arrest and apoptotic death through activation of caspase 8 and 3 pathways. Results showed it is an effective inhibitor of colon cancer progression.

A 2012 study on “Thymus mastichina: chemical constituents and their anti-cancer activity" published in Universidade Nova de Lisboa, Portugal concludes that the cytotoxicity-guided study of the dichloromethane and ethanol extracts of Thymus mastichina, commonly known as Spanish Marjoram, using the HCT colon cancer cell line allowed the identification of nine compounds, sakuranetin, sterubin, oleanolic acid, ursolic acid, lutein, beta-sitosterol, rosmarinic acid, 6-hydroxyluteolin-7-O-beta-glucopyranoside, and 6-hydroxyapigenin-7-O-beta-glucopyranoside.

A 2022 study "Origanum majorana essential oil decreases lung tumor growth and metastasis in vitro and in vivo" published in Biomed Pharmacother. by Kholoud Arafat, Shahrazad Sulaiman, Aya Mudhafar Al-Azawi, Javed Yasin, Subi Sugathan, Abderrahim Nemmar, Sherif Karam, Samir Attoub, in this pre-clinical study and using two major human NSCLC, namely A549 and LNM35, we demonstrated that Origanum majorana Essential Oil significantly decreases the viability of these cells and the growth of their pre-formed colonies in vitro in a concentration-dependent manner and partly via the induction of caspase 3/7-dependent cell death and downregulation of survivin. Moreover, Origanum majorana Essential Oil significantly slow down the growth of A549 and LNM35 tumor xenografts in the CAM and in nude mice models in vivo. Furthermore, Origanum majorana Essential Oil significantly reduces in vitro A549 and LNM35 cancer cell migration and invasion, and the incidence and growth of lymph nodes metastasis in vivo in nude mice xenografted subcutaneously with the highly metastatic LNM35 cells. Three months of treatment of mice with Origanum majorana Essential Oil did not affect blood, kidney, and liver functions. Our study demonstrates that Origanum majorana Essential Oil is a safe and robust anticancer option.

A 2018 study "Use of Origanum majorana oil in lung cancer therapy" as a Experimental-Molecular Therapeutics, Pharmacogenomics Drug Discovery - Drug Design in ESMD Open Cancer Horizons, Vol 3, Issue Suppl 2 by S Attoub, S Shahrazad, A Kholoud, evaluated the use of Origanum Majorana 100% pure essential oil in lung cancer therapy using two major human cancer cell, i.e., A549 and LNM35. Results showed concentration and time-dependent decrease in viability of lung cancer cells and their related colonies growth in vitro. Treatment also significantly decreased the growth on LNM35 and A549 xenografts in chick embryo and in nude mice models in vivo without significant side effects. Study showed major oil constituents that mediate anti-cancer effects.

A 2013 study "A comparative study of cytotoxic, membrane and DNA damaging effects of Origanum majorana’s essential oil and its oxygenated monoterpene component linalool on parental and epirubicin-resistant H1299 cells" published in Biologia, Vol 68, Issue 4 by Ayse Erdogan, Aysun Ozkan, of essential oil from Origanum majorana and its oxygenated monoterpene component linalool was tested on parental and epirubicin-resistant (drug resistant) human lung cancer cell lines (H1299). Results showed Origanum majorana essential oil and linalool exhibited cytotoxic, membrane and DNA damaging effects. Results suggest further studies for its potential therapeutic application for human lung cancer.

A 2016 study "The antiproliferative effect of Origanum majorana on human hepatocarcinoma cell line: suppression of NF-κB" published in Cell Mol Biol (Noisy-le-grand) by S A Fathy, M A Emam, S H Abo Agwa, F A Abu Zahra, F S Youssef, R M Sami, aimed to investigate the antiproliferative effect of aqueous and ethanol extracts of Origanum majorana leaf on human hepatocellular carcinoma (HepG2) cell line through incubation of various concentrations of origanum majorana extracts with HepG2 and at different time intervals. The effects of aqueous and ethanol extracts of Origanum majorana L. on HepG2 cell viability, nuclear factor kappa B (NF-kB) gene expression were examined. The results of the cell viability assays showed that aqueous and ethanol extracts exhibited a highly significant inhibitory effect on HepG2 cell proliferation which was evidenced by a reduction in viable cell count. The results were confirmed by microscopical examination of cell morphology. Furthermore, the Origanum majorana L. extracts suppressed the activity of NF-kB gene expression of HepG2 cells compared to the control.The conclusions from this study suggest that Marjoram extracts exhibit anti-proliferative effect against HCC through suppressing the activity of NF-kB gene expression and high antioxidant activity.

According to researchers, increased urination may also help reduce fat and lower blood pressure. People who take Marjoram to increase urination should increase their water intake in order to prevent dehydration. Regular urination can help.

A 2019 study "Antibacterial and Biofilm Inhibitory Activity of Medicinal Plant Essential Oils Against Escherichia coli Isolated from UTI Patients" published in Molecules by Rihab Lagha, Fethi Ben Abdallah, Badriah Osama Al-Sarhan, Yassin Al-Sodany, investigated the antibacterial activity of five medicinal plant essential oils against UTIs caused by E. coli using disc diffusion and minimal inhibition concentration (MIC) methods. In addition, biofilm inhibitory action of oils was realized by crystal violet. Gas chromatography⁻mass spectrometry (GC⁻MS) analysis showed a variability between oils in terms of compound numbers as well as their percentages. Antibacterial activity was observed only in cases of Origanum majorana, Thymus zygis and Rosmarinus officinalis, while Juniperus communis and Zingiber officinale did not showed any effect towards E. coli isolates. T. zygis essential oil demonstrated the highest antibacterial activity against E. coli isolates, followed by Origanum majorana and Rosmarinus officinalis. Further, oils showed high biofilm inhibitory action with a percentage of inhibition that ranged from 14.94% to 94.75%. Rosmarinus officinalis oil had the highest antibiofilm activity followed by T. zygis and Origanum majorana. Accordingly, tested oils showed very effective antibacterial and antibiofilm activities against E. coli UTIs and can be considered as good alternative for antibiotics substitution.

A study "Potential chemopreventitive activity of doash, (origanum majorana L.), a Saudi Arabian herbal tea" published in an e-theses Online Service by Khan, Jehan A., evaluated the potential of Doash (Origanum majorana) leaf water extracts for antimutagenic and anticarcinogenic effects against known classes of mutagens. Results showed the tea extract can affect the mutagenicity of various structurally diverse promutagens including food borne carcinogen by decreasing P450-mediated activation. Daily intake of doash tea may protect against the conversion of promutagene to mutagene and scavenging carcinogen from environmental contact.

A 2011 study "Comparative Study of Sedative, Pre-Anesthetic and Anti-Anxiety Effect of Origanum majorana Extract with Diazepam on Rats" published in Research Journal of Biological Sciences by Ali Rezaie, Behboud Jafari, Ghafour Mousavi, Mehrdad Nazeri, Amirreza Ebadi, Changiz Ahmadeh, and Elmira Habibi, evaluated the sedative, pre-anesthetic, and anti-anxiety effects of Origanum majorana with diazepam in different groups of male Wistar rats. Results showed sedative and anti-anxiety effects possibly due to the flavonoids present in the extract with its effect on benzodiazepine receptor binding to GABA-A receptors. Origanum majorana extract at dose of 200 mg/kbw was significant compared to diazepam at does of 1.2 mg/kg.

A 2020 study "Subacute Assessment of the Toxicity and Antidepressant-Like Effects of Origanum majorana L. Polyphenols in Swiss Albino Mice" published in Molecules by Amal Amaghnouje, Hamza Mechchate, Imane Es-Safi, Smahane Boukhira, Ali S Aliqahtani, Omar M Noman, Fahd A Nasr, Raffaele Conte, Anna Calarco, Dalila Bousta, aims to evaluate the antidepressant-like effect of the Origanum majorana L. polyphenols (OMP) obtained from the aerial parts using two different depression model tests: The forced swimming test (FST) and the tail suspension test (TST) in Swiss albino mice. The experiments were performed on days 1, 7, 14, and 21 with daily administration of different treatments. Two different doses were chosen for this study (50 and 100 mg/kg), and paroxetine was used as a positive control. Immobility as a consequence of the depression state was significantly reduced following the treatment with OMP, indicating an antidepressant effect. A subacute toxicity study was also performed following the Organization for Economic Co-operation and Development (OECD) Guidelines (407), showing no sign of toxicity for the studied doses. The phytochemical screening revealed the presence of 12 components, all belonging to polyphenols: Arbutin, rosmarinic acid, ursolic acid, quercetin-3-O-glucoside, quercetin-7-O-glucuronic acid, luteolin-7-O-glucoside, kaempferol-3-0-glucuronic acid, Kaempferol-3-0-pentose, caffeic acid, catechin, quercetin, and rutin. These findings suggest that Origanum majorana has interesting antidepressant-like properties, which deserve further investigation.

A 2001 study "Inhibitory effect of ursolic acid purified from Origanum majorana L on the acetylcholinesterase" by Chung YK, Heo HJ, Kim EK, Kim HK, Huh TL, Lim Y, Kim SK, Shin DH, screened 139 herbal spices in search of acetylcholinesterase (AChE) inhibition. Acetylcholinesterase inhibitors, which enhance cholinergic transmission through reduction of enzymatic degradation of ACh, are the only compounds approved for the treatment of Alzheimer's diseases. Of the edible plants and spices, an ethanol extract of Origanum majorana showed the highest inhibitory effect on AChE in vitro. The urosolic acid of Origanum majorana inhibited AChE activity in a dose dependent and competitive/non-competitive type. Results demonstrated the urosolic acid of Origanum majorana is a potent AChE inhibitor in Alzheimer's disease.

A 2021 randomized controlled pilot study "The effect of Origanum majorana tea on motor and non-motor symptoms in patients with idiopathic Parkinson's disease" published in Parkinsonism Relat Disord. by Chbili Chahra, Hassine Anis, Douma Bissene, Selmi Mejda, Maatoug Jihène, Naija Salma, Nouira Manel, Ben Amor Sana, Khairi Hedi, Ben Fredj Maha, was investigated in patients with idiopathic Parkinson's disease, measured by validated tools. 60 patients with idiopathic Parkinson's disease and under conventional medication were enrolled voluntarily in the study. All participants were randomized on double-blind to placebo or Origanum majorana. Clinical assessment with validated tools (UPDRSIII, NMSS, and BDI) was done before Origanum majorana or placebo consumption (Day 0) and at the end of the experiment (Day 30). The treatment groups were similar at baseline on demographic and clinical variables. During the course of study, nine participants withdrew for reasons of noncompliance and inability to follow-up. 51 participants completed the study. Upon completion of 30 days of treatment, Origanum majorana tea consumption did not decrease the UPDRSIII score ([UPDRSIII] D0 = 18.76 ± 8.58, D30 = 16.52 ± 7.96, p = 0.069) at the p value was 0.07. However, a statistically significant improvement was noted in NMSS and BDI scores (p < 0.0001 and p < 0.0001, respectively). Assessment of the UPDRSIII, NMSS and BDI scores of the patients did not reflect any improvement with placebo. No side effect was detected during the study. These findings show improvement of depressive and non-motor signs in patients with Parkinson's disease in the group that consumed Origanum majorana tea in combination with conventional therapy. Improvement of motor signs may need an extended treatment period. However, more research with a large number of participants and lasting longer than 1 month is needed to argue these findings.

A 2012 randomized Controlled double-blind clinical trial "Pain relief assessment by aromatic essential oil massage on outpatients with primary dysmenorrhea" published in Journal Obstet Gynaecol Res. by Ming-Chiu Ou, Tsung-Fu Hsu, Andrew C Lai, Yu-Ting Lin, Chia-Ching Lin, assessed the effectiveness of blended essential oils on menstrual cramps for outpatients with primary dysmenorrhea and explored the analgesic ingredients in the essential oils. A randomized, double-blind clinical trial was conducted. 48 outpatients were diagnosed with primary dysmenorrhea by a gynecologist and had 10-point numeric rating scales that were more than 5. The patients were randomly assigned to an essential oil group (n = 24) and a synthetic fragrance group (n = 24). Essential oils blended with Lavender (Lavandula officinalis), Clary Sage (Salvia sclarea) and Marjoram (Origanum majorana) in a 2:1:1 ratio was diluted in unscented cream at 3% concentration for the essential oil group. All outpatients used the cream daily to massage their lower abdomen from the end of the last menstruation continuing to the beginning of the next menstruation. Both the numeric rating scale and the verbal rating scale significantly decreased (P < 0.001) after one menstrual cycle intervention in the two groups. The duration of pain was significantly reduced from 2.4 to 1.8 days after aromatherapy intervention in the essential oil group. Aromatic oil massage provided relief for outpatients with primary dysmenorrhea and reduced the duration of menstrual pain in the essential oil group. The blended essential oils contain four key analgesic components that amount to as much as 79.29%; these analgesic constitutes are linalyl acetate, linalool, eucalyptol, and β-caryophyllene. This study suggests that this blended formula can serve as a reference for alternative and complementary medicine on primary dysmenorrhea.

A 2016 A randomized, double-blind, placebo- controlled clinical trial "The effect of Marjoram (Origanum majorana) tea on the hormonal profile of women with polycystic ovary syndrome" published in Journal of Human Nutrition and Dietetics by I Hai-Husein, S Tukan, F Alkazaleh, evaluated the effect of Marjoram tea on hormonal profile of women with polycystic ovary syndrome measuring parameters of FSH, LH, progesterone, estradiol, total testosterone, DHEA-S, fasting insulin and glucose, and homeostasis model assessment for insulin resistance (NOMA-IR) and glucose to insulin ratio. Results showed beneficial effects of majoram tea on hormonal profile of PCOS women as suggested by improved insulin sensitivity and reduced levels of adrenal androgens. Study evaluated the effects of Marjoram tea on the hormonal profile of women with PCOS in a randomized, double-blind, placebo controlled trial. Results showed beneficial effects of Marjoram tea on the hormonal profile of PCOS women evidenced by improvement in insulin sensitivity and reduction of levels of adrenal androgens. The study’s results revealed the positive effects of the tea on the hormonal profile of PCOS women. The tea improved insulin sensitivity and reduced the levels of adrenal androgens in these women. This is very significant since an excess of androgens is at the root of hormone imbalance for many women of reproductive age.  The study’s results revealed the positive effects of the tea on the hormonal profile of PCOS women.

A 2015 randomised controlled pilot trial "The effect of Marjoram (Origanum majorana) tea on the hormonal profile of women with polycystic ovary syndrome" published in Journal Hum Nutr Diet. by Haj-Husein, S Tukan, F Alkazaleh, 25 patients were assigned to receive Marjoram tea or a placebo tea twice daily for 1 month (intervention group: n = 14; placebo group: n = 11). The hormonal and metabolic parameters measured at baseline, as well as after the intervention, were: follicle-stimulating hormone, luteinising hormone, progesterone, oestradiol, total testosterone, dehydroepiandrosterone-sulphate (DHEA-S), fasting insulin and glucose, homeostasis model assessment for insulin resistance (HOMA-IR) and glucose to insulin ratio. Marjoram tea significantly reduced DHEA-S and fasting insulin levels (P < 0.05) by a mean (SD) of 1.4 (0.5) μmol L(-1) and 1.9 (0.8) μU mL(-1) , respectively. In comparison to the placebo group, the change was only significant for DHEA-S (P = 0.05) but not for insulin (P = 0.08). HOMA-IR was not reduced significantly in the intervention group (P = 0.06), although the change was significant compared to the placebo group (P < 0.05). The results obtained in the present study show the beneficial effects of Marjoram tea on the hormonal profile of PCOS women because it was found to improve insulin sensitivity and reduce the levels of adrenal androgens. Further research is needed to confirm these results and to investigate the active components and mechanisms contributing to such potential beneficial effects of Marjoram herb.

A 2023 study "Essential Oils from Apiaceae, Asteraceae, Cupressaceae and Lamiaceae Families Grown in Serbia: Comparative Chemical Profiling with In Vitro Antioxidant Activity" published in Plants (Basel), by Nevena Gladikostić, Bojana Ikonić, Nemanja Teslić, Zoran Zeković, Danica Božović, Predrag Putnik, Danijela Bursać Kovačević, Branimir Pavlić, investigate the chemical profile and antioxidant activity of essential oils obtained from the most commonly grown plant species in Serbia. Aromatic and medicinal plants from Lamiaceae (Mentha x Piperita, Ocimum basilicum, Origanum majorana, Origanum vulgare, Salvia officinalis, Satureja hortensis, Satureja montana and Thymus vulgaris), Asteraceae (Ehinacea purpurea and Matricaria chamomilla), Apiaceae (Anethum graveolens, Carum carvi, Foeniculum vulgare, Petroselinum crispum and Pimpinella anisum) and Cupressaceae (Juniperus comunis) were selected as raw material for essential oils (EOs)' isolation. Hydrodistillation (HD) was used for the isolation of EOs while they were evaluated in terms of yield and terpenoid profiles by GC-MS. In vitro radical scavenging DPPH and ABTS⁺ radical activities were carried out for all EOs. Finally, a principal component analysis (PCA) was performed with the experimental results of the composition and antioxidant activity of the EOs, which showed a clear distinction between the selected plant species for the aforementioned responses. This work represents a screening tool for the selection of other EO candidates for further processing by emerging extraction techniques and the use of EOs as natural additives for meat products.

A 2022 review "Chemical Composition, Enantiomeric Distribution, Antimicrobial and Antioxidant Activities of Origanum majorana L. Essential Oil from Nepal" published in Molecules by Prem Narayan Paudel, Prabodh Satyal, Rakesh Satyal, William N Setzer, Rajendra Gyawali, was conducted to examine the chemical constituents of Origanum majorana L. essential oils that originate in Nepal, as well as their biological activities, antioxidant properties, and enantiomeric compositions. The essential oils were extracted by the hydro-distillation method using a Clevenger-type apparatus and their chemical compositions were determined through gas chromatography and mass spectrometry (GC-MS). Chiral GC-MS was used to evaluate the enantiomeric compositions of essential oils. The minimum inhibitory concentrations (MICs) of the essential oils were determined by the micro-broth dilution method, and the antioxidant activity was evaluated by the 2,2-diphenyl-1-picrylhydrazyl scavenging assay and ferric-reducing antioxidant power (FRAP). GC-MS analysis showed the presence of 50 and 41 compounds in the essential oil samples, (S₁) and (S₂), respectively, representing the Kathmandu and Bhaktapur districts. The oxygenated monoterpenoids, along with terpinen-4-ol, were predominant constituents in both essential oil samples. However, the essential oils from two locations showed some variations in their major components. The chiral terpenoids for two essential oil samples of Marjoram have also been reported in this study in an elaborative way for the first time in accordance with the literature review. A hierarchical cluster analysis based on the compositions of essential oils with 50 compositions reported in the literature revealed at least 5 different chemotypes of Marjoram oil. The antioxidant activity for the sample (S₂) was found to be relatively moderate, with an IC₅₀ value of 225.61 ± 0.05 μg/mL and an EC₅₀ value of 372.72 ± 0.84 µg/mL, as compared to the standard used. Furthermore, with an MIC value of 78.1 µg/mL, the essential oil from sample (S₂) demonstrated effective antifungal activity against Aspergillus niger and Candida albicans. Moreover, both samples displayed considerable antimicrobial activity. The results suggest that essential oils of Origanum majorana possess some noteworthy antimicrobial properties as well as antioxidant activity, and hence can be used as a natural preservative ingredient in the food and pharmaceutical industries.

A 2019 study "Antioxidant potency and GC-MS composition of Origanum majorana Linn" published in Pak J Pharm Sci. by Nyayiru Kannaian Udaya Prakash, Nannu Shankar Sripriya, Dinakaran Divakar Raj, Santhanakrishnan Deepa, Srinivasan Bhuvaneswari, the methanolic extract of the leaves of Origanum majorana L., was screened for its antioxidant potential and chemical composition. Apart from high total phenolic, flavonoid and antioxidant contents, significant free radical scavenging ability was observed as assessed by the free radical scavenging assays viz., 2,2-Diphenyl-1-picryl hydrazyl, Ferric thiocyanate, Thiobarbituric acid, Ferric reducing antioxidant power and ABTS assays. The GC-MS analysis of the methanolic extract detected the presence of seven compounds - 5H-Cyclopropa [3,4] benz [1,2-e]azulen-5-one, 3,9,9a-tris (acetyloxy) - 3 - [(acetyloxy) methyl] - 2 - chloro - 1, 1a, 1b, 2, 3, 4, 4a, 7a, 7b, 8, 9, 9a-dodecahydro-4a,7b-dihydroxy - 1, 1, 6, 8-tetrame - thyl -, [1aR (1aa,1ba, 2a, 3a, 4aa, 7aa, 7ba, 8a, 9a, 9aa)]-; Pentacosanoic acid, methyl ester; 10-Octadecenoic acid, methyl ester; 1, 2, 4-Trioxolane-2-octanoic acid, 5-Octyl-, methyl ester; Oleoyl chloride; Docosanedioic acid, dimethyl ester and Ethyl iso-allocholate.

A 2018 study "Antineurodegenerative, antioxidant and antibacterial activities and phenolic components of Origanum majorana extracts" published in Journal of Applied Botany and Food Quality by Sonja Duletić-Laušević, Ana Alimpić Aradski, Stoimir Kolarević, Branka Vuković-Gačić, Mariana Oalđe, Jelena Živković, Katarina Šavikin, Petar D. Marin, showed high amount of rosmarinic acid, especially in the ethanolic extract. In this study, the water and ethanolic extract showed promising natural sources of bioactive compounds. The aqueous extract showed better antioxidant, antimicrobial, and antineurodegenerative activity than ethanolic extracts.
 

A 2015 study published in Indian Journal of Natural Products and Resources by Prernaa and Neeru Vasudeva, of ethanol extract of leaves showed antioxidant and marked free radical-scavenging activity using DPPH assay. Ethanol extracts of both stem and root showed in vitro antioxidant activity using DPPH, H2O2 free radical scavenging assay, metal chelating, and ferric reducing power assay. IC50s were comparable to ascorbic acid.

Another 2014 study published in American Journal of Drug Discovery and Development by Neeru Vasudeva, Prerna Singla, Sneha Das, and Surendra Kumar Sharma, investigated ethanol extracts of stem and root of Origanum majorana for antigout and antioxidant activity in rat models. Both ethanol extracts showed potent antioxidant activity in all models (DPPH, H2O2 radical scavenging, metal chelating). In vitro xanthine oxidase inhibitory activity was significant for both stem and root extracts with IC50s of 59.21 and 148 µg/ml, respectively. The extracts showed significant decrease in uric acid, creatinine, ESR, and MDA in the gouty rats. Results showed significant antigout activity associated with both antioxidant and anti-inflammatory effects which may be due to the presence of flavonoids, phenolics, saponins, and triterpenoidal compounds.

A 2011 study "Free radical scavenging and antiacetylcholinesterase activities of Origanum majorana L. essential oil" published in Hum Exp Toxicol. by A T H Mossa, G A M Nawwar, Origanum majorana L. essential oil (EO) was analyzed by gas chromatography-mass spectrometry (GC-MS) and evaluated for free radical scavenging and anticholinesterase activities. GC-MS analysis revealed the presence of 4-terpineol (29.97%), γ-terpinene (15.40%), trans-sabinene hydrate (10.93), α-terpinene (6.86%), 3-cycolohexene-1-1 methanal,a,a4-trimethyl-,(S)-(CAS) (6.54%), and sabinene (3.91%) as main constituents. Origanum majorana L. essential oil exhibited concentration-dependent inhibitory effects on 2,2'-diphenylpicrylhydrazyl (DPPH(•)), hydroxyl radical, hydrogen peroxide, reducing power, and lipid peroxidation with IC(50) values of 58.67, 67.11, 91.25, 78.67, and 68.75 µg/mL, respectively; while the IC(50) values for the standard trolox were noted to be 23.95, 44.97, 51.30, 42.22, and 52.72 µg/mL, respectively. Interestingly, cholinesterase inhibitory activity was also found with IC(50) values of 36.40 µg/mL. We can conclude that the Marjoram essential oil has a significant potential to be used as a natural antioxidant and anti-AChE.

A study published in Complementary Therapies in Medicine indicates that when Sweet Marjoram aromatherapy was used by nurses as part of patient care, it was able to reduce pain.

In a collective study of over 10,000 hospital admissions, Marjoram essential oil use reduced pain the most of any essential oils and also significantly reduced anxiety. A blend of essential oils including Marjoram was able to reduce menstrual pain and reduce the need for pain medications. In a nursing home setting, use of a blend of essential oils, including Marjoram, dramatically reduced pain and symptoms of depression in people with arthritis.

A 2019 study "Origanum majorana Essential Oil Inhalation during Neurofeedback Training Reduces Saliva Myeloperoxidase Activity at Session-1 in Bruxistic Patients" published in Journal of Clinical Medicine by José Joaquín Merino, José María Parmigiani-Izquierdo, María Elvira López-Oliva and María Eugenia Cabaña-Muñoz, evaluated whether Saliva myeloperoxidase activity could be reduced after 21 neurofeedback training sessions in bruxistic Origanum majorana-treated patients. Results showed that activity could predict stress level in bruxistic patients and repeated neurofeedback training reduced their stress level. Origanum majorana essential oil enhanced these anxiolytic effects.

A 2017 study "Origanum majorana L. as an Herbal Medicine for the Treatment of Apical Abscess: A Case Report and Literature Review" published in Galen Medical Journal by Maryam Mosaffa-Jahromi, Maryam Firouzmandi, Mehdi Pasalar, reports on a 28-year old female who presented with a preapical abscess which resolved after two days of an herbal preparation of Origanum majorana, without surgical intervention or post-treatment complication. Results suggest potential for a complementary or alternative non-invasive treatment for dental problems.

A 2013 study "Antimutagenic effect of Origanum majorana L. essential oil against prallethrin-induced genotoxic damage in rat bone marrow cells" published in Journal Med Food by Abdel-Tawab H Mossa, Amel A Refaie, Amal Ramadan, Jalloul Bouajila, aimed to investigate the genotoxic and cytotoxic potential of prallethrin in rat bone marrow cells and the protective effect of Origanum majorana L. essential oil. Our results demonstrated that prallethrin at dose 64.0 mg/kg body weight (b.wt.) (1/10 LD50), has a clastogenic/genotoxic potential as shown by the high percentage of chromosomal aberration (CA) and micronucleus (MN) in the bone marrow cells of male rats, whereas the combined treatment of prallethrin and Origanum majorana essential oil resulted in the reduction of the CA (54.54%). The combined treatment also reduced the micronuclei formation significantly. In conclusion, prallethrin can be considered clastogenic/genotoxic and may carry a risk to human health. The study revealed the antigenotoxic and anticytotoxic potential of Origanum majorana essential oil against prallethrin-induced genotoxic and cytotoxic effects in rat bone marrow cells.

A 2012 study "Comparative antihyperglycaemic and antihyperlipidemic effect of Origanum majorana extracts in NIDDM rats" pubslihed in Pharm Exp Med by B. P. Pimple, P. V. Kadam, M. J. Patil, in streptozotocin-induced diabetic rats showed the volatile oil and methanolic extract of leaves of Origanum majorana could be beneficial in the management of NIDDM and its associated lipid imbalance.

Another in Evidence-Based Complementary and Alternative Medicine, Volume 2012 published study "Inhibition of Advanced Glycation End-Product Formation by Origanum majorana L. In Vitro and in Streptozotocin-Induced Diabetic Rats" by Rosa Martha Perez Gutierrez, about the development of AGE (advanced glycation end products) inhibitors is considered to have therapeutic potential in diabetic patients. Study investigated the effect of methanoic extract of leaves of O. majorana on AGEs formation. Treatment of STZ-induced diabetic mice with OM and glibenclamide for 28 days showed beneficial effects on renal metabolic abnormalities including glucose level and AGEs formation. OM alleviated oxidative stress under diabetic conditions through inhibition of lipid peroxidation, preventing and/or delaying the onset of renal damage. Specifically, researchers found that commercial dried varieties of this plant, along with Mexican Oregano and Rosemary, act as a superior inhibitor of the enzyme known as protein tyrosine phosphatase 1B (PTP1B). In addition, greenhouse-grown Marjoram, Mexican oregano and rosemary extracts were the best inhibitors of dipeptidyl peptidase IV (DPP-IV). This is an awesome finding since the reduction or elimination of PTP1B and DPP-IV helps improve insulin signaling and tolerance. Both fresh and dried Marjoram can help improve the body’s ability to properly manage blood sugar.

A 2021 study "Productive Performance, Ovarian Follicular Development, Lipid Peroxidation, Antioxidative Status, and Egg Quality in Laying Hens Fed Diets Supplemented with Salvia officinalis and Origanum majorana Powder Levels" published in Animals (Basel) by Ahmed A Saleh, Shimaa Hamed, Aziza M Hassan, Khairy Amber, Wael Awad, Mohammed H Alzawqari, Mustafa Shukry, aimed to assess the effect of dietary supplementation with different levels of Salvia officinalis and/or Origanum majorana on productive performance, ovarian follicular development, lipid peroxidation, antioxidative status, and egg quality in laying hens. Two hundred and ninety-four 45-week-old Bovans brown hens were allocated into seven groups, with seven replicates of six hens each. The first group was fed with the basal considered as a control (A); the second (B) and third (C) groups were provided with the same control diet further supplemented with 0.5 and 1 kg/ton Salvia officinalis, respectively; the fourth (D) and fifth (E) groups received the control diet further supplemented with 0.5 and 1 kg/ton Origanum majorana, respectively; while the sixth (F) and the seventh (G) groups were offered a diet supplemented with 0.5 kg/ton Salvia officinalis and 0.5 kg/ton Origanum majorana and 1 kg/ton Salvia officinalis and 1 kg/ton Origanum majorana, respectively. No significant effects were observed in the final body weight (BW) and feed intake (FI) of the laying hens. In the diets supplemented with Salvia officinalis and Origanum majorana, the egg weights for groups C, F, and G had significantly higher values only compared to group D. The supplementation of the diets with Salvia officinalis and/or Origanum majorana significantly (p < 0.05) increased the Follicle stimulating hormone (FSH), luteinizing hormone (LH), and estradiol estrogenic hormone concentration, except for Origanum majorana at both levels with regard to estradiol. The dietary utilization of Salvia officinalis and Origanum majorana did not significantly alter the plasma glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT), total protein, albumin, globulin, and High density lipoprotein (HDL) parameters. Cholesterol, glucose, triglyceride, and Low density lipoprotein (LDL) were decreased (p < 0.05) in the birds fed with Salvia officinalis and/or Origanum majorana supplemented diets. Moreover, at both doses, the dietary supplementation with Salvia officinalis and Origanum majorana decreased (p < 0.05) the yolk cholesterol and liver Malondialdehyde (MDA) levels. In addition, the dietary enrichment with Salvia officinalis and/or Origanum majorana decreased (p < 0.05) the palmitoleic and stearic fatty acids' egg yolk concentration. In contrast, the yolk linoleic fatty acid concentration was significantly increased by Salvia officinalis and/or Origanum majorana. In conclusion, dietary supplementation with Salvia officinalis and/or Origanum positively affected productive performance, ovarian follicular development, antioxidant activity, hormonal status, and steroidogenesis in Bovans brown laying hens.

A 2021 study "Anticoccidial effect of Origanum majoranum aqueous extract on Eimeria tenella-infected chicken" published in Trop Biomed by E R A Mohamed, M F Elazab, N El-Habashi, N Elhawary, A A Mokhbatly, Avian coccidiosis, an important protozoal disease of chicken triggered by coccidian protozoa of genus Eimeria, causes considerable economic losses to broiler producers. The study was designed to assess the efficiency of Origanum majoranum aqueous extract on E. tenella-infected broiler chicken. Birds were divided into four groups including: positive control (PC, challenged with 5×104 sporulated oocysts of E. tenella at the 12th day of age), PC+Origanum majoranum aqueous extract (challenged with E. tenella oocysts at the 12th day of age and received Origanum majoranum aqueous extract (125 mg/kg BW) orally, started at the 7th day of age, and continued for 14 consecutive days), Origanum majoranum aqueous extract (received Origanum majoranum aqueous extract (125 mg/kg BW) orally, at the 7th day of age, for 14 consecutive days), and negative control (received basal diet only). Anticoccidial efficacy of Origanum majoranum aqueous extract was evaluated by complete blood picture, serum chemistry, serum protein electrophoresis, antioxidants markers, cecal oocysts count, and cecal lesions score. Briefly, collected data indicated that supplementation of OMAE could increase antioxidants concentrations and improve changes in hematobiochemical parameters and serum protein fractions, as well as decrease cecal oocysts count and reduce cecal lesion scores in E. tenella-infected birds. In conclusion, Origanum majoranum aqueous extract restores oxidant-antioxidant balance, and its supplementation in broiler chicken can alleviate E. tenella-infection and reduce its severity.

In a 2013 study "Amelioration of Prallethrin-Induced Oxidative Stress and Hepatotoxicity in Rat by the Administration of Origanum majorana Essential Oil" published in BioMed Research International by Abdel-Tawab H. Mossa, Amel A. Refaie, Amal Ramadan, and Jalloul Bouajila, synthetic pyrethroids are a new major class of broad-spectrum insecticides. Pyrethroid insecticides are acute neutoxicants and prallethrein is the most popular Type 1 synthetic pyrethroid used for household insect pests such as mosquitoes, houseflies, and cockroaches. Prallethrin has been shown to cause oxidative damage and liver injury in male rats. Study evaluated the protective role of Origanum majorana essential oil against the adverse effects of exposure to prallethrine on oxidant/antioxidant status and liver dysfunction biomarkers in a rat model. Results showed co-administration of essential oil attenuated the toxic effect of prallethrin.

A 2020 study "Evaluation of larvicidal potential against larvae of Aedes aegypti (Linnaeus, 1762) and of the antimicrobial activity of essential oil obtained from the leaves of Origanum majorana L" published in PLoS One by Renata do Socorro Barbosa Chaves, Rosany Lopes Martins, Alex Bruno Lobato Rodrigues, Érica de Menezes Rabelo, Ana Luzia Ferreira Farias, Lethicia Barreto Brandão, Lizandra Lima Santos, Allan Kardec Ribeiro Galardo, Sheylla Susan Moreira da Silva de Almeida, evaluated the larvicidal activity of Origanum majorana Linnaeus essential oil, identified the chemical composition, evaluated the antimicrobial, cytotoxic and antioxidant potential. The larvicidal activity was evaluated against larvae of the third stage of Aedes aegypti Linaeus, whereas the chemical composition was identified by gas chromatography coupled to mass spectrometer, the antimicrobial activity was carried out against the bacteria Pseudomonas aeruginosa, Escherichia coli and Staphylococcus auereus, the antioxidant activity was evaluated from of 2.2-diphenyl-1-picryl-hydrazila sequestration and Artemia salina Leach cytotoxicity. Regarding to the results, the larvicidal activity showed that O. majorana L. essential oil caused high mortality in A. aegypti L. larvae. In the chromatographic analysis, the main component found in O. majorana L. essential oil was pulegone (57.05%), followed by the other components verbenone (16.92%), trans-p-menthan-2-one (8.57%), iso-menthone (5.58%), piperitone (2.83%), 3-octanol (2.35%) and isopulegol (1.47%). The antimicrobial activity showed that E. coli and P. aeruginosa bacteria were more sensitive to oil than S. aureus, which was resistant at all concentrations. Essential oil did not present antioxidant activity, but it has high cytotoxic activity against A. salina L.

A 2014 study "Insecticidal activities of sweet marjoram (Origanum majorana L.) against Pediculus humanuscapitis (Anoplura: Pediculidae)" published in International Journal of Current Microbiology and Applied Sciences by Gehad T. El- Sherbini, Eman T. El-Sherbini and Nancy Osman Hanykamel, evaluated the in vitro insecticidal activity of various sweet marjoram extracts against head lice, Pediculus humanus capitis. On the basis of LT50s, marjoram oils were more toxic than either &phenothrin and pyrethrum. In fumigation tests, marjoram oils were more effective in closed containers than in open ones, suggesting the effect was the result of action in the vapor phase. Neither &phenothrin nor pyrethrum exhibited fumigant toxicity.

Another 2004 study "Insecticidal activity of plant essential oils against Pediculus humanus capitis (Anoplura: Pediculidae)" published in Journal Med Entomol. by Yang YC, Lee HS, Clark JM, Ahn YJ., evaluated the insecticidal activity of 54 plant essential oils against female Pediculus humanus capitis using direct contact and fumigation methods, compared with two commonly used pediculicides delta-phenothrin and pyrethrum. In fumigation tests at 0.25 mg/cm2, marjoram, together with three other herbs, were more effective in closed containers. Neither delta-phenothrin nor pyrethrum exhibited fumigant toxicity.