Discovery of Novel Antioomycete Metabolites from the Marine-Derived Fungus Paraconiothyrium sporulosum.

ABSTRACT

In our screening program for natural products that are effective in controlling plant diseases, we found that the culture filtrate of Paraconiothyrium sporulosum SFC20160907-M11 effectively suppressed the development of tomato late blight disease caused by Phytophthora infestans. Using a bioassay-guided fractionation of antioomycete activity, 12 active compounds (1-12) were obtained from an ethyl acetate extract of the culture filtrate. Chemical structures of five new compounds 1-5 were determined by the extensive analyses of nuclear magnetic resonance (NMR), high resolution mass spectrometry (HRMS), and circular dichroism (CD) data. Interestingly, mycosporulonol (1) and botrallin (8) completely inhibited the growth of P. infestans at concentrations of 8 and 16 µg/mL, respectively. Furthermore, the spray treatment of 1 and 8 (500 µg/mL) successfully protected tomato seedlings against P. infestans with disease control values of 92%. Taken together, these results suggest that the culture filtrates of P. sporulosum SFC20160907-M11 and their bioactive metabolites can be used as new antioomycete agents for Phytophthora late blight control.