Controlling anthracnose by means of extracts, and their major constituents, from Brosimum rubescens Taub

Highlights • Extracts of less polarity from B. rubescens displayed significant antifungal activity. • Two coumarins (xanthyletin and 7-demethylsuberosin) were isolated from antifungal extracts of B. rubescens. • A chromatographic method to detect and quantify both coumarins is described. • Xanthyletin and 7-demethylsuberosin exhibited in vivo and in vitro strong antifungal activity. • 7-Demethylsuberosin was metabolized slowly by C. gloeosporioides to marmesin and decursinol.
Anthracnose, caused by the fungus Colletotrichum gloeosporioides (Penz.) Penz. & Sacc., is the most limiting fungal disease of mango and papaya crops in Colombia. The in vivo and in vitro activity against C. gloeosporioides of the extracts from sawdust of Brosimum rubescens Taub. (Moraceae) was evaluated. The extracts of less polarity (n-hexane and dichloromethane) displayed the greatest inhibitory effects. Then, the coumarins xanthyletin (2.74 % d.w.) and 7-demethylsuberosin (2.19 % d.w.) were isolated from these extracts. The compound 7-demethylsuberosin displayed a strong in vivo and in vitro antifungal activity. Furthermore, the metabolism of 7-demethylsuberosin by the fungus C. gloeosporioides was analyzed. The fungus slowly detoxified 7-demethylsuberosin to marmesin and decursinol. Therefore, the high antifungal activity and low level of detoxification make 7-demethylsuberosin, and the extracts that contain it, promising candidates for controlling C. gloeosporioides. Sawdust of B. rubescens may be considered a valuable source of extracts and coumarins with antifungal activity.