Intraduodenal infusion of cyanidin-3-glucoside transiently promotes triglyceride excretion into bile in rats

Flavonoids purportedly have a role in improving lipid metabolism. In our preliminary study, highly concentrated flavonoid metabolites appeared in bile juice in rats, which also contains various lipids. Biliary flavonoid metabolites generally have amphiphilic properties, may influence lipid solubility, and possibly contribute to the improvement of dyslipidemia. However, the influence of biliary flavonoid metabolites on the biliary lipid profile is not well known. Therefore, we hypothesized that the amphiphilic property of biliary flavonoid metabolites alters biliary lipid profiles. To estimate the influence of flavonoids on the biliary lipid profile, we laparotomized rats under anesthesia, intraduodenally injected them with cyanidin-3-glucoside chloride (C3G) or quercetin, and analyzed their biliary metabolite concentrations for 2 hours. Concentrations of C3G and quercetin metabolites peaked at 30 minutes after the injection; those of quercetin were 6 to 10 times higher than those of C3G throughout the sampling period up to 2 hours. Biliary triglyceride (TG) concentrations were higher in the C3G group at 30 and 45 minutes; biliary cholesterol and phospholipid concentrations were lower in the quercetin group at 30 minutes than those in the control group. Hepatic TG content after the 2-hour sampling was lower in the C3G group than in the control group. These results suggest that C3G, but not quercetin, may transiently promote TG excretion into bile, with a reduction in hepatic TG content. This C3G effect may be involved in improvement of TG metabolism.