The aglycone forms of three steroidal glycoalkaloids-
solanidine (derived by hydrolytic removal of the
carbohydrate side chain from the potato glycoalkaloids
alpha-chaconine and
alpha-solanine),
solasodine (derived from
solasonine in eggplants) and
tomatidine (derived from
alpha-tomatine in tomatoes)-were evaluated for their effects on liver weight increase (
hepatomegaly) in non-pregnant and pregnant mice and on fecundity in pregnant mice fed for 14 days on a diet containing 2.4 mmol/kg of aglycone. In non-pregnant mice, observed ratios of % liver weights to
body weights (%LW/BWs) were significantly greater than those of the control values as follows (all values in % vs matched controls+/-S.D.):
solanidine, 25.5+/-13.2;
solasodine 16.8+/-12.0; and
tomatidine, 6.0+/-7.1. The corresponding increases in pregnant mice were:
solanidine, 5.3+/-10.7;
solasodine, 33.1+/-15.1;
tomatidine, 8.4+/-9.1. For pregnant mice (a)
body weight gains were less with the algycones than with controls:
solanidine, -36.1+/-14.5;
solasodine, -17.9+/-14.3;
tomatidine, -11.9+/-18.1; (b) litter weights were less than controls:
solanidine, -27.0+/-17.1;
solasodine, -15.5+/-16.8;
tomatidine, no difference; (c) the %LTW/BW ratio was less than that of the controls and was significant only for
solasodine, -8.7+/-13.7; and (d) the average weight of the fetuses was less than the controls:
solanidine, -11.2+/-15.2;
solasodine, -11.4+/-9.4;
tomatidine, no difference. Abortion of fetuses occurred in five of 24 pregnant mice on the
solanidine and none on the other diets. To obtain evidence for possible mechanisms of the observed in vivo effects, the four glycoalkaloids (
alpha-chaconine,
alpha-solanine,
solasonine and
alpha-tomatine) mentioned above and the aglycones
solanidine and
tomatidine were also evaluated in in vitro assays for estrogenic activity. Only
solanidine at 10 microM concentration exhibited an increase in the MCF-7 human
breast cancer cell proliferation assay. Generally, the
biological effects of
solanidine differ from those of the parent potato glycoalkaloids. Possible mechanisms of these effects and the implication of the results for food safety and plant physiology are discussed.