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 tymphimurium strain TM677 when metabolically activated using a 9000 x 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 gas chromatography/mass spectrometry. The major pathways of such steviol mammalian metabolism proved to be allylic oxidation and epoxidation. 15-Oxosteviol, a product of oxidation of the major steviol metabolite, 15alpha-hydroxysteviol, was found to be a direct-acting mutagen [corrected].

High-Performance Liquid Chromatographic Separation and Quantitation of Stevioside and Its Metabolites

“…Compadre et al 13 reported that there are 22 possible derivatives of steviol and of these, only 15 have been studied by mass spectral analysis. We have developed a method to separate stevioside and its metabolites, namely, steviol-16,17α-epoxide, 15α-hydroxysteviol, steviolbioside, isosteviol, and steviol.…”

Steviol Glucuronide as Excretion Product of Stevioside in Human Volunteers: Lack of Carcinogenic Properties of Steviol Glycosides and Steviol

“…Mutagenic effects of steviol, the aglycone of stevioside, and/or its metabolites were reported in the forward mutation assay using Salmonella typhimurium TM677 (12; concentrations tested: 0,0.1,0.5, 1,2.5 and 10 mg/ml; [14][15][16][17]. After metabolic activation, it was shown that so far unknown steviol metabolites caused mutations in Salmonella typhimurium TM677, i.e.…”

Mutagenicity and Human Chromosomal Effect of Stevioside, a Sweetener from Stevia rebaudiana Bertoni

“…The mutagenicity of crude stevia extract, stevioside, and steviol have been reported (18)(19)(20)(21)(22)(23). Stevioside showed no mutagenicity in bacterial systems (18)(19)(20); however, its aglycone, steviol, was mutagenic after metabolic activation in the forward mutation assay using only Salmonella typhimurium TA677 (TM677) (21) but not mutagenic in the reverse mutation test using Salmmellka typhimurium TA100, TA98, TA102, or TA97.…”

“…Stevioside showed no mutagenicity in bacterial systems (18)(19)(20); however, its aglycone, steviol, was mutagenic after metabolic activation in the forward mutation assay using only Salmonella typhimurium TA677 (TM677) (21) but not mutagenic in the reverse mutation test using Salmmellka typhimurium TA100, TA98, TA102, or TA97. When steviol was metabolically activated with S-9 from Aroclor 1254-pretreated rats, 15-oxosteviol was found to be the mutagenic product in the forward mutation assay (22). It was suggested (23) that this major, oxidized steviol was responsible for the indirect mutagenicity of steviol in TM677, probably by selectively inducing a deletion or insertion of more than one base pair, which cannot be found in strains of TA98, TA100, and TA102, which are regularly used in the Ames test.…”