Evaluation of Antifungal Potential of Indigenous Plant Extracts against Grey Mould and HPLC And LC-MS Based Identification of Phytochemical Compounds in Polygonum amplexicaule D. Don Extracts

Abstract

Grey mould disease is one of the highly destructive post-harvest strawberry disease caused by the fungus Botrytis cinerea. Several synthetic compounds are being used against B. cinerea but due to resistance development by synthetic fungicide many alternative management strategies have explored nowadays.  In this study, antifungal potential of indigenous plant extracts against grey mould was evaluated and amongst these plant extracts HPLC and LC-MS based identification of phytochemical compounds in Polygonum amplexicaule was also done. In this regards, firstly in vitro evaluation of the antifungal properties of twelve plant extracts was undertaken against B. cinerea using fungal growth medium, of which five plants extracts (P. amplexicaule, T. vulgaris, D. viscosa S. nigrum and E. globules) indicated the percent mycelia inhibition in fungal growth is greater than 75% which were then used for in vivo experiment. P. amplexicaule showed (81%) the highest growth inhibition in vitro as well as in in vivo (80%) activity during storage conditions (on strawberry fruits) against the fungus. HPLC analysis of methanolic extracts of P. amplexicaule showed, the total phenolics 6.176 (µg GAE/mg SW)   including 0.157 (µg GAE/mg SW) gallic acid and protocatechic acid. While total fluorescence were 1.85 (µg cate/mg SW) including catechin, procyanidin and epicatechin. Total hyrdoxycinnamates were found to be 7.696 (µg CAE/mg SW) comprising on chlorogenic acids, neochlorogenic acids and 4-caffeoylquinic acids. LC-MS based identification also showed the presence of acids like caffeic, and gallic acid. Other showed the presence of rutin, quercetin, catechin, kaemferol and myricetin. It was concluded that Polygonum amplexicaule extract has effective against grey mould amongst all indigenous plant extracts and detected known and unknown compounds from the plant are well known for antimicrobial activity. Therefore in future further investigation can carried out for synthesis of bio based fungicide from these compounds of Polygonum plant extract on commercial scale against post-harvest pathogens of strawberry.