##STR1## Therapeutic or preventive agents for diseases requiring apoptosis induction, cancerous diseases, diseases requiring the inhibition of active oxygen production, those requiring the inhibition of nitrogen monoxide production, those requiring the inhibition of prostaglandin synthesis, those requiring the inhibition of synovial cell proliferation, those requiring the induction of heat shock protein production or those requiring the inhibition of .alpha.-glycosidase, which contain as the active ingredient compounds selected from among compounds represented by general formula (I), (wherein X and Y are each H or CH.sub.2 OH, provided that when X is CH.sub.2 OH, Y is H, while when X is H, Y is CH.sub.2 OH), those represented by general formula (II), (wherein R is a residue obtained by freeing a compound having an SH group from the SH group) and salts of both; and foods, drinks, cosmetics and so on, containing compounds selected from among compounds of general formula (I), those of general formula (II) and salts of both.