Oregano (Origanum vulgare)

Traditional Indications

Oregano (Origanum vulgare L.). is an important Mediterranean aromatic plant of great value in traditional phytotherapy, next to its widespread dietary uses. Uses of oregano in ethnomedicine have been linked to stomachic, carminative, expectorant, and emmenagogue properties. It has been indicated as tinctures or teas in respiratory and digestive disorders, but also as ointments to treat wounds. Its traditional uses include indigestions, diarrhoea, cough, and bronchitis. It has also been used as a remedy against pruritus, headaches, and depression. Particular uses have been mentioned for different parts of the plant: while the aerial parts have been used in pain, cough, or sexual dysfunction, the seeds were used in urinary tract infections or menstrual disorders and the flowering branches were used externally by rubbing in place of fractures or to treat toothaches. An ethnobotanical study showed that tea made from Origanum vulgare herb was traditionally used in Transylvania to treat sore throat. In Turkey, the flowering branches and the leaves were prepared as infusions and used for cold, flu, headache, or toothache (1).

Pharmacognosy

Essential oils of oregano are widely recognised for their antimicrobial activity, as well as their antiviral and antifungal properties. Carvacrol and thymol, monoterpenes found in oregano have demonstrated effective antimicrobial activity in Staphylococcus aureus and Staphylococcus epidermidis biofilms (2). The cold extract of oregano showed pronounced antibacterial effect against the strains of P. aeruginosa and K. pneumoniae and C. albicans (3).

RBD comparisons of the structures of three CoVs have shown that there is a high affinity between human MERS-CoV receptor dipeptidyl peptidase 4 (DPP4) and the spike RBD of SARS-CoV-2, thus DPP4 is also recognised as a candidate binding target of the SARS-CoV-2 S protein (4). DPP4 acts as a CoV coreceptor, having a mechanism similar to the host cell entry of SARS-CoV-2 and is another potential therapeutic target. DPP4 inhibitors known as gliptins are widely used in diabetes patients and whilst the role of DPP4 inhibitors in SARS-CoV-2 infection remains to be clarified, evidence suggests that DPP4 inhibitors modulate inflammation and exert anti-fibrotic activity and that these properties may useful to stop the progression of the hyperinflammatory state associated with severe COVID-19 disease (5). The phytochemical flavonoids luteolin, apigenin and flavone are potent DPP4 inhibitors (6). Oregano contains the highest sources of luteolin (7). Apigenin is also found in significant amounts in oregano (8).

1. Lombrea A, Antal D, Ardelean F, Avram S, Pavel IZ, Vlaia L, et al. A Recent Insight Regarding the Phytochemistry and Bioactivity of Origanum vulgare L. Essential Oil. Int J Mol Sci. 2020;21(24).
2. Nostro A, Sudano Roccaro A, Bisignano G, Marino A, Cannatelli MA, Pizzimenti FC, et al. Effects of oregano, carvacrol and thymol on Staphylococcus aureus and Staphylococcus epidermidis biofilms. Journal of medical microbiology. 2007;56(Pt 4):519-23.
3. Bankova R, Popova, Teodora P. Antimicrobial Activity in vitro of Aqueous Extracts of Oregano (Origanum vulgare L.) and Thyme (Thymus vulgaris L.). Int J Curr Microbiol App Sci. 2017;6(3):1-12.
4. Li Y, Zhang Z, Yang L, Lian X, Xie Y, Li S, et al. The MERS-CoV Receptor DPP4 as a Candidate Binding Target of the SARS-CoV-2 Spike. iScience. 2020;23(6):101160.
5. Strollo R, Pozzilli P. DPP4 inhibition: Preventing SARS-CoV-2 infection and/or progression of COVID-19? Diabetes Metab Res Rev. 2020;36(8):e3330.
6. Singla RK, Kumar R, Khan S, Mohit, Kumari K, Garg A. Natural Products: Potential Source of DPP-IV Inhibitors. Current protein & peptide science. 2019;20(12):1218-25.
7. Saleem H, Anwar S, Alafnan A, Ahemad N. Chapter 22 - Luteolin. In: Mushtaq M, Anwar F, editors. A Centum of Valuable Plant Bioactives: Academic Press; 2021. p. 509-23.
8. Salehi B, Venditti A, Sharifi-Rad M, Kręgiel D, Sharifi-Rad J, Durazzo A, et al. The Therapeutic Potential of Apigenin. Int J Mol Sci. 2019;20(6).