Lipid composition and metabolism of Hep G2 cells treated with geraniol, a natural monoterpene.

POLO, MP; BELLINI, MJ; BRAVO, MG DE

Villa Carlos Paz, Argentina

Congreso; XXXVII Anual Meeting of SAIB; 2001

SAIB

Monoterpenes are nonnutritive dietary components found in the essential oils of citrus and other plants. They have multiple pharmacologic effects on mevalonate metabolism; some of them may account for their effects on some tumor cells. We have previously reported that geraniol, a natural monoterpene, inhibits growth and HMG-CoA reductase activity in Hep G2 cells. The aim of this work was to study the effect of geraniol on lipid composition, mevalonate pathway and fatty acid metabolism. Cells were treated with geraniol (0-400 mM) and the composition of fatty acids, cholesterol and phosphorus content and exogenous cholesterol incorporation, were determined. Incorporation and metabolism of  14C-acetate, 3H-mevalonate and  14C-fatty acid were determined using geraniol 400 mM. Results show no differences in fatty acids composition and an incremented exogenous cholesterol uptake at doses of geraniol that inhibit HMG-CoA reductase activity. Geraniol 400mM causes a diminished acetate and mevalonate incorporation into cholesterol and an incremented mevalonate incorporation into lanosterol  and esqualene. It also diminishes D5 desaturase activity but has no effects on D6 or D9 desaturases. Our results demonstrate that in Hep G2 geraniol inhibits D5 desaturase as well as, at least, one enzyme involved in the conversion of lanosterol into cholesterol. Cholesterogenesis inhibition seems to be compensated by an increment of exogenous cholesterol uptake, giving rise to an unaltered cellular cholesterol content.