Safety assessment of Zanthoxylum alatum Roxb. essential oil, its antifungal, antiaflatoxin, antioxidant activity and efficacy as antimicrobial in preservation of Piper nigrum L. fruits

The investigation deals with antifungal, antiaflatoxin and antioxidant efficacy of Zanthoxylum alatum Roxb. essential oil (EO), its two major constituents and their comparison with five commonly used organic acid preservatives. The chemical profile of EO, characterized through GC and GC–MS analysis, revealed linalool (56.10%) and methyl cinnamate (19.73%) as major components. The EO, linalool and methyl cinnamate completely inhibited the growth of a toxigenic strain of A. flavus (LHP-10) as well as aflatoxin B1 secretion at different concentrations. Methyl cinnamate was found to be more efficacious than EO, linalool and five organic acid preservatives, showing antifungal and antiaflatoxigenic efficacy at a low concentration (0.6 μl/ml) and the nature of its toxicity was fungicidal. However, EO showed strong antioxidant activity with an IC50 value at 5.6 μl/ml. Moreover, EO was found to have negligible mammalian toxicity as its LD50 value, determined through oral administration on mice, was calculated to be 6124 μl/kg body weight during safety profile assessment. During in vivo investigation on fruit systems, the Zanthoxylum EO, when tested as fumigant, provided 66.27% and 86.33% protection respectively at 1.25 μl/ml and 2.5 μl/ml against fungi infesting Piper nigrum L. fruits demonstrating its practical efficacy as a plant based antimicrobial for post harvest application.