Chemical profile and antifungal activity of plant extracts on Colletotrichum spp. isolated from fruits of Pimenta dioica (L.) Merr.

Pimenta dioica (L.) Merr. is a popular seasoning species. During its production, there are losses of up to 50% due to anthracnose caused by fungi of the genus Colletotrichum. In this study, we evaluated the effect of ethanolic extracts on the in vitro and in vivo control of isolated Colletotrichum spp. Allspice. Extracts of leaves of P. dioica, Piper auritum, Plectranthus amboinicus and Psidium guajava were chemically characterized by gas chromatography and high performance liquid chromatography. Several monoterpenes, sesquiterpenes, flavonoids, organic acids, alkaloids and monoterpenoid phenols were identified among other organic compounds. Alpha-ocimene in P. dioica; alpha-thujene and isosafrole in P. auritum; kumatakenin, cirsilineol, taxifolin and retusin in P. amboinicus are reported for the first time. The extracts of P. amboinicus and P. dioica inhibited mycelial growth, spore germination in Colletotrichum spp. at concentrations of 5, 10 and 20 mg/mL, while the extracts of P. guajava and P. auritum did so at concentrations of 30 and 40 mg/mL. The extracts of P. amboinicus, P. dioica and P. auritum modified the size of the spores, caused degradation and formation of vacuoles in the spores of C. acutatum and C. gloeosporioides. The incidences in fruit inoculated with C. boninense and treated with the extracts of P. amboinicus and P. dioica were of 12% and 4% respectively. The severity was 1.5% with the extract of P. amboinicus and 0% with P. dioica. The results show the richness of bioactive compounds present in the extracts and their possible application to develop biotechnological products against phytopathogenic fungi.