Isolation and Structural Determination of Squalene Synthase Inhibitor from Prunus mume Fruit

Squalene synthase plays an important role in the cholesterol biosynthetic pathway. Inhibiting this enzyme in hypercholesterolemia can lower not only plasma cholesterol but also plasma triglyceride levels. A squalene synthase inhibitor was screened from Prunus mume fruit, and then purified via sequential processes of ethanol extraction, HP-20 column chromatography, ethyl acetate extraction, silica gel column chromatography, and crystallization. The squalene synthase inhibitor was identified as chlorogenic acid with a molecular mass of 354 Da and a molecular formula of $C_{16}H_{18}O_9$ based on UV spectrophotometry, $^1H$ and $^{13}C$ NMRs, and mass spectrometry. Chlorogenic acid inhibited the squalene synthase of pig liver with an $IC_{50}$ level of 100 nM. Since chlorogenic acid was an effective inhibitor against the squalene synthase of an animal source, it may be a potential therapeutic agent for hypercholesterolemia.