Mass spectral analysis of some derivatives andin vitro metabolites of steviol, the aglycone of the natural sweeteners, stevioside, rebaudioside a, and rubusoside

Abstract
Steviol (ent‐13‐hydroxykaur‐16‐en‐19‐oic acid), the aglycone of various plant‐derived glycoside sweeteners consumed by human populations, is known to be mutagenic toward Salmonella typhimurium strain TM677 when metabolically activated using a 9000 × g supernatant fraction derived from the liver of Aroclor 1254‐pretreated rats. Mass spectral analysis of this diterpenoid and some analogs revealed characteristic patterns reflecting differential stereochemistry at the C/D rings and variations in the nature of the substituents present. Such information has been used to help identify several in vitro metabolites of steviol in conditions known to produce a mutagenic response, when analyzed by human populations, is known to be mutagenic toward Salmonella typhimurium strain TM677 when metabolically be allylic oxidation and epoxidation. 15‐Oxosteviol, a product of oxidation of the major steviol metabolite, 15α‐hydroxysteviol, was found to be a direct‐acting mutagen.