Title: Alternative Sweeteners

Stevioside 179
side given as an infusion up to 16 mg/kg body weight/hr was found to be secreted
by way of the renal tubular epithelium to induce a fall in the renal tubular reabsorption
of glucose (39). The effect of stevioside (90% purity; 16 mg/kg body
weight/hr infusion) on renal function in both normal and hypertensive rats was
investigated using clearance techniques, and, in an analogous fashion to S. rebaudiana
extracts, this compound was found to induce hypotension, diuresis, and
natiuresis (40). On the basis of the results obtained, stevioside has actually been
suggested for the clinical treatment of hypertension in humans (40).
Urinary enzyme levels, changes in blood urea nitrogen (BUN) and plasma
creatinine levels, and ultrastructural changes in the kidney have been examined
after a single high dose of 1.5 g/kg body weight of stevioside in rats administered
by subcutaneous injection. The levels of BUN and plasma creatinine both increased,
as did urinary glucose. Histopathological examination showed nephrotoxicity
in the proximal convoluted tubules of the kidney rather than the glomeruli
or other tubules, and it was concluded that the mechanism of toxicity did not
involve lipid peroxidation (41).
A series of studies on the effects of stevioside and several of its glycosidic
and nonglycosidic derivatives on cellular and subcellular metabolism have been
performed and reviewed by Brazilian investigators. The activities of these compounds
have been probed in systems such as rat liver mitochondria, rat renal
cortical tubules, human and rabbit erythrocytes, and rabbit reticulocytes. In general,
S. rebaudiana glycosidic constituents such as stevoside and steviolbioside
are either inactive in these systems or else found to be less active than their
hydrolytic products steviol and isosteviol (2).
VIII. CARIOGENICITY POTENTIAL
Pure stevioside and rebaudioside A were tested for cariogenicity in an albino rat
model. Sixty Sprague-Dawley rats were colonized with Streptococcus sobrinus
and were divided into groups fed basal diet 2000 supplemented with either 0.5%
stevioside, 0.5% rebaudioside A, 30% sucrose, or no compound addition. All
four groups were killed after 5 weeks of feeding, and viable S. sobrinus counts
were enumerated, and caries was evaluated according to Keyes’ technique. It
was concluded that stevioside and rebaudioside were not cariogenic under the
conditions of the study (42). In a recent in vitro study, the eight sweet constituents
of S. rebaudiana (stevioside, rebaudiosides A-E, dulcoside A, steviolbioside) and
two hydrolytic products of stevioside (steviol and isosteviol) were tested against
a panel of cariogenic and periodontopathic oral bacteria. Their antibacterial activity
and their ability to inhibit sucrose-induced adherence, glucan binding, and
glucosyltransferase (GTF) activity were evaluated. None of these compounds
suppressed the growth or acid production of the cariogenic organism, Streptococ-