Mellein, a dihydroisocoumarin with bioherbicidal activity from a new strain of Lasiodiplodia pseudotheobromae C1136

Abstract

The use of synthetic herbicides poses a serious threat to environment, health and food safety. The developmentof safe and effective bioherbicides for selective control of weeds is thus the primary concern in crop productionaround the world. Efforts are being made to investigate the use of a safe, ecofriendly and highly selectiveherbicides from biological origin. Coumarin and its derivatives are natural compounds renowned for theirphytotoxic potential.Mellein, a dihydroisocoumarin designated as (R)-8-hydroxy-3-methylisochroman-1-one was isolated as anactive metabolite from the broth of a new strain (this strain is one of the best among phytopathogenic strainscollected) ofLasiodiplodia pseudotheobromae. The structural characterization of the compound was achieved byusing combined spectroscopic analysis i.e. 1D and 2D NMR and LC–MS. The host range study was carried-outagainst plants fromCucurbitaceae,SolanaceaeandLeguminosae,Poaceae and Valerianaceaefamilies, the isolatedphytotoxic metabolite fromLasiodiplodia pseudotheobromaeat a concentration 10 μg/μl showed selective in-hibition at 56%–66% against the latter two families only when inoculated.Hence, purified compound fromLasiodiplodia pseudotheobromaeis recommended for large scale production ofbioherbicides for the management of weeds in conventional farming to improve yield and enhance food security.