Mechanism of antioxidant and antifungal properties of Pimenta dioica(L.) leaf essential oil on Aspergillus flavus.

The study explores the antioxidant activity, volatile chemical profile and antifungal potential of Pimenta dioica leaf essential oil (EO) against toxin producing Aspergillus flavus. GC-MS analysis of EO revealed the presence of 41 compounds with eugenol (54%), as the major compound followed by myrcene (16.0%) and chavicol (12.5%). It exhibited the strong antioxidant activity with IC50 value of 19.40 µg/ml and polyphenolic content of 526.9 mg g-1 gallic acid equivalent. The aflatoxin producing IISRaf1strain from nutmeg (Myristica fragrans) was identified by 18S rRNA sequencing as Aspergillus flavus (MH345939). MIC of P. dioica leaf EO against A. flavus was found to be at 0.04%. The changes in hyphae growth and architecture after treatment with EO were observed under light microscopy. Antifungal compounds eugenol which got separated at the particular spot caused the clear zone at the TLC plate by agar overlay bioassay. The mode of action of antifungal activity of EO was recorded in terms of its effect on ergosterol content of plasma membrane and malate dehydrogenases activity (MDH) of A. flavus. Thus P. dioica leaf EO might be viable alternative as plant based preservative in perspective on its antioxidant, antifungal activity and efficacy in food system. © Association of Food Scientists & Technologists (India) 2020.