Cistus ladanifer L. essential oil as a plant based preservative against molds infesting oil seeds, aflatoxin B1 secretion, oxidative deterioration and methylglyoxal biosynthesis

The study explores the potential of Cistus ladanifer essential oil (CLEO) as plant based preservative against fungal and afiatoxin B-1 contamination of stored oil seeds. Aspergillus flavus AF-M-K5 was identified as the most afiatoxigenic isolate during mycofiora analysis of selected oil seeds. Chemical characterization of CLEO through GC MS revealed alpha-asarone (78.841%) as the major component. The minimum inhibitory concentration and minimum aflatoxin inhibitory concentration of CLEO against A. flatus AF-M-K5 were recorded to be 0.6, and 0.5 mu L/mL, respectively. Significant reduction in ergosterol content and enhancement of leakage of Ca2+, K+ and Mg2+ ions from treated fungal cells emphasized fungal plasma membrane as the site for antifungal action of CLEO. The CLEO caused reduction of methylglyoxal, the aflatoxin inducing substrate. This is the first report on an essential oil as methylglyoxal inhibitor suggesting a novel mode of action in reduction of AFB(1) biosynthesis. The IC50 values for CLEO as determined by DPPH' and ABTS'(+) assay were 7.3 mu L/mL and 1.13 mu L/mL respectively, depicting remarkable antioxidant activity. CLEO caused considerable protection of stored oil seeds from contamination of A. flavus (90.6%) and from storage molds (78.03%) without affecting seed germination.