Polyphenolic extract of lotus root (edible rhizome of Nelumbo nucifera) alleviates hepatic steatosis in obese diabetic db/db mice

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is emerging as the most common liver disease of industrialized countries. Thus, discovering food components that can ameliorate NAFLD is of interest. Lotus root, the edible rhizome of Nelumbo nucifera, contains high levels of polyphenolic compounds, and several health-promoting properties of lotus root have been reported. In this study, we tested whether feeding a polyphenolic extract of lotus root to db/db mice protects them from hepatic steatosis. RESULTS: After 3 weeks of feeding, the hepatomegaly and hepatic triglyceride accumulation were markedly alleviated in the lotus polyphenol-diet-fed db/db mice relative to the control mice. Although the lipolytic enzyme activity was not changed, the activities of lipogenic enzymes, such as fatty acid synthase and malic enzyme, were significantly lower in the lotus polyphenol diet-fed db/db mice. Additionally, the ESI-IT/MS and MALDI-TOF MS spectra revealed the presence of B-type proanthocyanidin polymers with polymerization degree up to 9 in the polyphenolic lotus root extract. CONCLUSION: We speculate that the condensed tannins contained in lotus root can alleviate hepatic steatosis by suppressing the lipogenic enzyme activity in the livers of db/db mice.