The inhibitory effect of anthocyanins-rich Thai berries extracts on lipid digestion and absorption

Dyslipidemia is one of the major risk factor that contributes to chronic diseases such as cardiovascular disease and diabetic mellitus. Anthocyanin-rich Thai berries have been documented to have hypolipidemic activity. However, no scientific data is available regarding the mechanism of lipid lowering property. Thus, the objective of this study was to elucidate the mechanism of action of Thai berries including Prunus domestica L., Antidesma bunius (L.) Spreng, Syzygium cumini (L.) Skeels, Syzygium nervosum A. Cunn. Ex DC, and Muntingia calabura L. on a reduction of lipid digestion and absorption in vitro. Phytochemical compounds of Thai berries, including total phenolic (TP), total flavonoids (TF) and total anthocyanins (TA) were determined. The lipid lowering activities were evaluated via bile acid binding, pancreatic lipase and cholesterol esterase activities and cholesterol micellization. Furthermore, cholesterol uptake into intestinal Caco-2 cells was also observed. Total phenolic, total flavonoids and total anthocyanins contents of five Thai berries were range form 222.7-579.5 mg gallic acid equivalents/g extract, 91.2-184.3 mg catechin equivalents/g extract and 37.9-49.5 mg cyanindin-3-glucoside equivalent/g extract, respectively. All five Thai-berries extracts (1 mg/mL) bound to taurocholic acid (primary bile acid), taurodeoxycholic acid and glycodeoxycholic acid (secondary bile acids) ranged from 20.1-42.3%, 16.4-36.2%, and 27.9-39.3%, respectively. In addition, Thai berries extracts showed inhibitory activities against pancreatic lipase and cholesterol esterase with IC50 values ranged from 90.6-336.9 µg/mL and 288.7-469.1 µg/mL, respectively. The extracts (0.25 mg/mL) also reduced the solubility of cholesterol in mixed micelles with inhibitory value of 53.0-67.3%. Our finding indicated that Prunus domestica L. had the highest TF, TA and also demonstrated the strongest potent to bind to bile acid, inhibit pancreatic lipase, and reduce cholesterol micellization. Therefore, Prunus domestica L. was then further subjected to investigate cholesterol absorption in Caco-2 cells. It was found that the extract reduced cholesterol absorption in Caco-2 cells in a concentration-dependent manner. Moreover, the combination of Prunus domestica L. (0.1 mg/mL) with ezetimibe (0.05 mg/mL) exhibited additive effect on the reduction of cholesterol uptake into the cells which had more ability than Prunus domestica L. and ezetimibe alone (p< 0.05). These results illustrate that anthocyanins-rich Thai berries are able to contribute lipid lowering effects via binding to bile acids, decreasing pancreatic lipase and cholesterol esterase activities and also reducing cholesterol incorporation into mix micelle. Moreover, Prunus domestica L. decreases cholesterol absorption into the intestinal cells. Taken together, our finding provides scientific evidence supporting the potential of anthocyanins-rich Thai berries extracts can be used as a new and efficient lipid lowering agents.