摘要：

A bioassay guided approach was followed to isolate, major chemical constituents from the Himalayan lichen Ramalina roesleri Nyl. These constituents were characterized using 1H NMR, 13C NMR, 2D NMR spectroscopy and mass spectrometry and were identified as usnic acid, homosekikaic acid and sekikaic acid. The constituents were evaluated against highly devastating soil borne plant pathogenic fungi, Sclerotium rolfsii, Rhizoctonia solani, Fusarium udum and Pythium aphanidermatum following Poisoned Food technique at different concentrations (250, 125 and 62.5 μg ml-1). Effective dose for 50% inhibition (ED50) value was also calculated using probit analysis (Basic LD50 program version 1.1). Antifungal activity of usnic acid against R. solani (with ED50 value 15.99) and sekikaic acid against S. rolfsii (with ED50 value 13.00μg ml-1) was found to be comparable to the activity of commercial fungicide hexaconazole.

展开