The aging of populations worldwide is driving greater demands for dietary polyphenols which have been recognized as promising prophylactic and/or therapeutic agents in the context of neurodegeneration, and are ubiquitously present in plant-based diets. In particular, grape-derived products encompass a wide array of phenolic compounds purported with multiple health benefits including neuroprotective efficacy. Despite the increasing preclinical and clinical evidence demonstrating high potential of grape polyphenol (GPP)-rich botanicals in preventing and attenuating diverse neurodegenerative disorders, the limited bioavailability of GPPs, especially in the brain, generates questions as to their applications and effectiveness in neuroprotection. To address this issue, significant research efforts have been made to enhance oral bioavailability of GPPs via application of novel strategies. This review highlights some critical issues related to the bioavailability and neuroprotective efficacy of GPPs and GPP-rich botanicals. The representative bioavailability-enhancing strategies are critically reviewed to provide practical solutions for augmenting the bioefficacy of GPP-rich botanicals. Synergistic applications of encapsulation techniques (for physiochemical protection and bypassing xenobiotic metabolism) and dietary intervention strategies involving modulation of gut microbiota (for generating more bioavailable phenolic metabolites) appear promising, and may substantially enhance the bioefficacy, especially the neuroprotective efficacy, of orally consumed GPPs.

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.