Antifungal evaluation of Ocimum sanctum essential oil against fungal deterioration of raw materials of Rauvolfia serpentina during storage
Abstract Raw materials (roots) of Rauvolfia serpentina were found associated with various storage moulds. During mycological screening, total 887 fungal isolates were recovered and among them Aspergillus flavus exhibited the highest relative density (35.74%). The essential oil (EO) of Ocimum sanctum was isolated through Clevenger's hydro-distillation apparatus and investigated against A. flavus LHPRS7, isolated from raw materials. The GC–MS analysis of EO showed 41 considerable peaks. Eugenol (61.30%) was found as major component followed by β-Caryophyllene (11.89%) and Germacrene D (9.14%). The minimum inhibitory concentration (MIC) of O. Sanctum against A. flavus was found at 0.3 μl ml−1 while aflatoxin B1 production was completely checked at 0.2 μl ml−1. The O. sanctum EO exhibited broad fungitoxic spectrum and also found efficacious in reducing fungal incidence during in vivo study. The EO reduces the number of A. flavus isolates up to 62.94, 67.87 and 74.01% fumigated at concentration 0.3, 0.5 and 1.0 μl ml−1 respectively. The HPTLC (high performance thin layer chromatography) analysis of raw materials in in vivo study reveals that alkaloid ajmaline was firmly degraded by fungal contamination while in the samples fumigated with O. sanctum EO, ajmaline was protected from fungal degradation due to antifungal efficacy of EO. The prospects of exploitation of O. sanctum EO as acceptable plant based additive in qualitative as well as quantitative control of biodeterioration of herbal raw materials have been discussed.