Soil bacterial hydrolysis leading to genuine aglycone—IX : A steroidal prosapogenol of new type from epigeous part of Metanarthecium luteo-viride maxim. and characterization of 3-epi-metagenin

By virtue of the soil bacterial hydrolysis method, a mixture (ca 12:1) of prosapogenols has been isolated, and on the basis of chemical and physicochemical evidence, the structure of major component (designated as NE-1A) has been established as 2β - acetoxy - 3α - hydroxy - 11α- (tri -O- acetyl - α - L - arabinopyranosyl)oxy - 5β, 25R - spirostane (10), and the minor presumed as its 3-epimer (11). NE-1A (10) is characteristic of possessing a fully acetylated arabinoside linkage at C-11 of a new steroidal aglycone 3-epi-metagenin (9), which is a ninth spirostanol isolated from the titled plant.Finally, NE-1A (10) has been subjected to detailed PMR examinations including homonuclear INDOR, double and triple resonance experiments, and the prominent signals have been assigned.