Antiprotozoal Activity of Turkish Origanum onites Essential Oil and Its Components

Molecules. 2019 Dec 3;24(23):4421. doi: 10.3390/molecules24234421.


Essential oil of Origanum species is well known for antimicrobial activity, but only a few have been evaluated in narrow spectrum antiprotozoal assays. Herein, we assessed the antiprotozoal potential of Turkish Origanum onites L. oil and its major constituents against a panel of parasitic protozoa. The essential oil was obtained by hydrodistillation from the dried herbal parts of O. onites and analyzed by Gas Chromatography-Flame Ionization Detector (GC-FID) and Gas Chromatography coupled with Mass Spectrometry (GC-MS). The in vitro activity of the oil and its major components were evaluated against Trypanosoma brucei rhodesiense, T. cruzi, Leishmania donovani, and Plasmodium falciparum. The main component of the oil was identified as carvacrol (70.6%), followed by linalool (9.7%), p-cymene (7%), γ-terpinene (2.1%), and thymol (1.8%). The oil showed significant in vitro activity against T. b. rhodesiense (IC50 180 ng/mL), and moderate antileishmanial and antiplasmodial effects, without toxicity to mammalian cells. Carvacrol, thymol, and 10 additional abundant oil constituents were tested against the same panel; carvacrol and thymol retained the oil's in vitro antiparasitic potency. In the T. b. brucei mouse model, thymol, but not carvacrol, extended the mean survival of animals. This study indicates the potential of the essential oil of O. onites and its constituents in the treatment of protozoal infections.

Keywords: Lamiaceae; Origanum onites; Trypanosoma; Turkish oregano; antiprotozoal; carvacrol; essential oil; thymol.

MeSH terms

  • Animals
  • Antiprotozoal Agents / administration & dosage*
  • Antiprotozoal Agents / chemistry*
  • Antiprotozoal Agents / pharmacology
  • Cymenes / administration & dosage
  • Cymenes / pharmacology
  • Disease Models, Animal
  • Gas Chromatography-Mass Spectrometry
  • Inhibitory Concentration 50
  • Mice
  • Molecular Structure
  • Oils, Volatile / administration & dosage*
  • Oils, Volatile / chemistry*
  • Oils, Volatile / pharmacology
  • Origanum / chemistry*
  • Plant Oils / chemistry
  • Plant Oils / pharmacology
  • Thymol / administration & dosage
  • Thymol / pharmacology
  • Trypanosoma brucei rhodesiense / drug effects
  • Trypanosomiasis, African / drug therapy*


  • Antiprotozoal Agents
  • Cymenes
  • Oils, Volatile
  • Plant Oils
  • Thymol
  • carvacrol