Potential mechanisms of hypocholesterolaemic effect of Thai spices/dietary extracts.

Several Thai spices/dietary ingredients were previously shown to have hypocholesterolaemic effects. These studies were mostly conducted in animal models in which the mechanisms of action were not yet well-established. Therefore, this study aimed to investigate the potential mechanism of hypocholesterolaemic action of 12 selected plants, namely Hibiscus sabdariffa L., Moringa oleifera Lam., Cucurbita moschata Duchesne, Ananas comosus (L.) Merr., Zingiber officinale, Morus alba L., Camellia sinensis (L.) Kuntze, Piper nigrum L., Alpinia galanga (L.) Willd., Curcuma zedoaria Rose, Bacopa monnieri (L.) Wettst. and Piper retrofractum Vahl., widely used as spices and ingredients in various types of Thai food. The extract of P. nigrum at 100 µg mL(-1) was found to be the most effective cholesterol uptake inhibitor whereas those of A. galanga and C. sinensis effectively inhibited pancreatic lipase activity with IC50 values of 8.99±3.41 and 12.36±1.23 µg mL(-1), respectively. The potency of extracts from H. sabdariffa, M. oleifera and C. moschata at 100 µg mL(-1) were found to be similar to 0.4 µg mL(-1) pravastatin in inhibiting HMG-CoA reductase and possibly reduced cholesterol biosynthesis. This study also demonstrated that several of the tested plants possessed multiple sites of action that were possibly responsible for their cholesterol-lowering effect in the in vivo model.