Abstract
Three antifugal glycosides named holotoxin A (major), B, and C have been isolated from the Far Eastern sea cucumber Stichopus japonicus SELENKA. Aqueous acid hydrolysis of holotoxin A furnished genin-1 (a mixture of stichopogenin A2 (3b) and the isomer) and stichopogenin A4 (=genin-2) (3a) in addition to xylose, quinovose, 3-O-methyl-glucose, and glucose, while mild methanolic acid hydrolysis of holotoxin A gave 3a and another new aglycone named 25-O-methyl-stichopogenin A4 (=genin-3) (3c). On the basis of chemical and physicochemical evidence, the structure of stichopogenin A4, the genuine aglycone of holotoxin A, has been elucidated to be expressed as 3a rather than previously proposed 2, and the structure of 25-O-methyl-stichopogenin A4 as 3c.
