Background: Herbal Essential Oils (EOs) are natural, volatile, and complex compounds that are defined by a strong odor. This study was conducted to investigate and compare antioxidant and antifungal properties of EO extracted from flowers and leaves of Origanum vulgare ssp. gracile from Iran.

Methods: EOs of leaves and flowers of O. vulgare ssp. gracile were extracted using a modified Clevenger apparatus and hydro-distillation method. In vitro antioxidant properties of the EOs were evaluated by 2,2- diphenyl-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethyl benzo thiazoline-6-sulphonic acid, ABTS⁺) assays and their antifungal properties were assessed against Aspergillus flavus and A. niger by agar disk diffusion and micro well dilution methods. The EOs exhibited both fungistatic and fungicidal activity against tested fungal species. Statistical analysis of data was performed using SPSS, Inc, Chicago, IL software (v.16.0).

Results: Minimum Fungicidal Concentration (MFC) values for A. niger and A. flavus were 200 and 100 µg/ml, respectively; however, the MFC values for the mentioned fungi were 400 and 200, respectively. The flower EOs had significantly (p<0.05) higher inhibitory activities against both fungal species comparing to leave EOs. Also, it was found that A. flavus was significantly (p<0.05) more susceptible to EOs than A. niger. Remarkable antioxidant capacity was observed in both EOs, but it was significantly (p<0.05) lower than Butylated Hydroxy Toluene (BHT) as a synthetic antioxidant.

Conclusion: Although, antioxidant as well as antifungal efficacy of flowers EO was significantly higher than the leaves EO, both leaves and flowers EOs could be recommended as an antifungal preservative in food industries for their application in hurdle systems.