Bioactive polyphenols in kinkéliba tea (Combretum micranthum) and their glucose-lowering activities.

Herbal tea kinkéliba prepared from the leaves of Combretum micranthum has been widely consumed in West African countries for its flavor, nutritional and medicinal properties. Under bio-guided screening, the kinkéliba leaves were chemically investigated using various chromatographic and spectrometric methods that led to the identification of thirteen different flavonoid compounds. Further biological tests illustrated that the identified compounds may have synergistic effects to decrease the expression of phosphoenolpyruvate carboxykinase (PEPCK) mRNA and glucose production in an H4IIE hepatoma cell line, indicating its potential use for insulin-resistant diabetes treatment. Further in vivo study on C57BL/6J mice indicates that kinkéliba can lower plasma glucose levels in a dose-dependent manner without significant weight loss and toxicity. The ethyl acetate extract in rich of flavonoids could also increase the glucose tolerance (GT) after seven weeks' administrations. Both in vitro and in vivo experiments support a potential new application of kinkéliba leaves as an anti-diabetes agent.