In vitro antifungal activity of saponins-rich fractions from Enterolobium cyclocarpum and Amphipterygium adstringens against Colletotrichum gloeosporioides

Avocado (Persea americana) crop suffers important economic losses due to fungal diseases. Enterolobium cyclocarpum and Amphipterygium adstringens are saponins-producing species and their crude extracts have shown antimicrobial activity. The aim of this work was to evaluate in vitro antifungal activity of aqueous extracts from E. cyclocarpum (leaves and bark), A. adstringens (branches), and their saponins-rich fractions against Colletotrichum gloeosporioides, an avocado pathogen. The fungus was isolated from avocado fruits from Uruapan Michoacan (Mexico) and its molecular identification was performed by sequencing. Saponins-rich fractions (SRF) were obtained by partitioning infusions with n-butanol followed by precipitation with acetone. Antifungal activity of infusions and SRF was evaluated by the agar diffusion method and the strongest growth inhibition of C. gloeosporioides (33%) was achieved with the SRF of E. cyclocarpum bark. Erythrocyte hemolysis was observed with the three infusions and the sarsasapogenin was putatively identified in the product of Amphipterygium branch aqueous extract (ARA) acid hydrolysis by gas chromatography-flame ionization detector (GC-FID). These results highlight the antifungal potential of saponins from this medicinal plant against avocado pathogenic fungi.