Assessing essential oil components as plant-based preservatives against fungi that deteriorate herbal raw materials

This study assesses the antifungal efficacy of 14 essential oil (EO) components and some of their combinations as inhibitory to the growth of the aflatoxigenic fungus Aspergillus flavus LHPA9 isolated from biodeteriorating Asparagus racemosus herbal raw materials. The aim was to determine whether they could be recommended as plant-based preservatives for enhancement of the shelf life of herbal raw materials. Thymol, eugenol, menthol, and their combinations were highly efficacious as their minimum inhibitory concentration (MIC) for inhibition of fungal growth as well as aflatoxin B1 secretion was less than 1.0 μl ml−1. Geranyl acetate, linalool, β-asarone, 1, 8-cineol, and E-citral were moderately antifungal as their MIC ranged between 1.0 and 5.0 μl ml−1. During antioxidant activity 2, 2-diphenyl-1-picrylhydrazyl assay, thymol, eugenol, and β-caryophyllene showed strong radical scavenging activity, whereas β-asarone and p-cymene showed moderate activity. Some combinations of EO components showed synergism while others exhibited an additive or antagonism effect in their activity. The findings point to a recommendation that EO components are good alternatives to synthetic preservatives to prevent deterioration of stored herbal raw materials by fungal and aflatoxin contamination and free-radical oxidation.

► Antifungal antiaflatoxigenic and radical scavenging activity efficacy of fourteen essential oil components.
► Thymol, eugenol and Menthol are showing strong fungitoxicity.
► Essential oils components are recommended as plant based safe prservatives.