Discovery of zeylenone from Uvaria grandiflora as a potential botanical fungicide.

ABSTRACT

BACKGROUND: Botanical pesticides play an important role in organic agricultural practices and are widely used in integrated pest management (IPM). Uvaria grandiflora was mainly reported as traditional medicines and possessed antibacterial, antioxidant, and antiprotozoal activities. Therefore, important biological activities of U. grandiflora may suggest that they have the potential to be used as botanical pesticides. RESULTS: The extract of U. grandiflora exhibited broad-spectrum inhibitory activity toward phytopathogenic fungi and oomycetes, particularly against Colletotrichum musae and Phytophthora capsici, and its secondary metabolite zeylenone also displayed strong antifungal and anti-oomycete activities against phytopathogens. Particularly, half maximal effective concentration (EC50 ) values of zeylenone against Phytophthora capsici and C. musae were 6.98 and 3.37 µg mL-1 , showing better inhibitory effects than those of commercial fungicides (azoxystrobin and osthole). Additionally, the pot experiments showed that the extract of U. grandiflora could effectively control Pseudoperonospora cubensis, Phytophthora infestans, Phytophthora capsici and Podosphaera xanthii. In the field experiment, 5% microemulsion of U. grandiflora extract exhibited 79.72% efficacy against cucumber powdery mildew at 87.5 g ha-1 on the 14th day after two sprayings, which was better than that of 21.5% trifloxystrobin and 21.5% fluopyram SC at 200.9 g ha-1 . Surprisingly, 5% microemulsion of U. grandiflora extract could promote cucumber growth significantly. Furthermore, the action mechanism analysis indicated that zeylenone may damage the cytoderm and affect energy metabolism of Phytophthora capsici. CONCLUSION: It is the first time that the extract of U. grandiflora and zeylenone have been discovered leading to broad application prospects in the development as botanical fungicides. © 2021 Society of Chemical Industry.