Inhibition of Diacylglycerol Acyltransferase by Betulinic Acid fromAlnus hirsuta

During the screening for diacylglycerol acyltransferase (DGAT) inhibitors from natural products, the lupane-type triterpenoid betulinic acid was isolated from the methanol extract of Alnus hirsuta. It potently inhibited DGAT in the rat liver microsomes with an IC50 value of 9.6 μM. Enzyme kinetic studies showed apparent Km and Ki values of 13.3 μM and 8.1 μM using [14 C]oleoyl-CoA as a substrate. A decrease in the apparent Vmax was observed with...