Antimicrobial potential of Agave spp. extracts against fungi and phytopathogenic bacteria

Abstract

ABSTRACT The excessive use of synthetic fungicides has increased the search for sustainable alternatives to manage phytopathogens. In this study, we evaluated the antifungal and antibacterial potential of extracts of three species of Agave (A. americana, A. attenuata, and A. angustifolia) against fungi of agricultural importance (Fusarium oxysporum, Colletotrichum spp., and Trichoderma reesei) and the bacterium Xanthomonas campestris. Crude, aqueous, and butanolic leaf extracts had their minimum inhibitory concentration (MIC) determined using in vitro assays. A. americana had the highest antifungal activity, especially in the butanolic extract, with MIC values of 1.000 mg L-1 against F. oxysporum and 8.000 mg L-1 against Colletotrichum spp.. These values were significantly lower than those observed for the other species. The crude extract had much higher MIC values than the butanolic extract, showing that butanol efficiently fractioned the antifungal compounds in the extracts. For T. reesei, a microorganism beneficial to agriculture, MIC values were much higher (16,000-32,000 mg L-1), indicating partial selectivity of the extract. Antibacterial activity was limited, with inhibition of X. campestris occurring only at higher concentrations (≥4,000 mg.L-1). These results show that crude and butanolic extracts of Agave, especially A. americana, contain bioactive compounds with potential use as natural biocontrol agents. These extracts may contribute to more sustainable agricultural management strategies with lower environmental impact.