Antioxidant activity, delayed aging, and reduced amyloid-β toxicity of methanol extracts of tea seed pomace from camellia tenuifolia

Abstract

There is a growing interest in the exploitation of the residues generated by plants. This study explored the potential beneficial health effects from the main biowaste, tea seed pomace, produced when tea seed is processed. DPPH radical scavenging and total phenolic content assays were performed to evaluate the in vitro activities of the extracts. Caenorhabditis elegans was used as in vivo model to evaluate the beneficial health effects, including antioxidant activity, delayed aging, and reduced amyloid-β toxicity. Among all soluble fractions obtained from the extracts of tea seed pomace from Camellia tenuifolia, the methanol (MeOH)-soluble fraction has the best in vivo antioxidant activities. The MeOH-soluble extraction was further divided into six fractions by chromatography with a Diaion HP-20 column eluted with water/MeOH, and fraction 3 showed the best in vitro and in vivo antioxidant activities. Further analysis in C. elegans showed that the MeOH extract (fraction 3) of tea seed pomace significantly decreased intracellular reactive oxygen species, prolonged C. elegans lifespan, and reduced amyloid-β (Aβ) toxicity in transgenic C. elegans expressing human Aβ. Moreover, bioactivity-guided fractionation yielded two potent constituents from fraction 3 of the MeOH extract, namely, kaempferol 3-O-(2-glucopyranosyl)-rutinoside and kaempferol 3-O-(2-xylopyranosyl)-rutinoside, and both compounds exhibited excellent in vivo antioxidant activity. Taken together, MeOH extracts of tea seed pomace from C. tenuifolia have multiple beneficial health effects, suggesting that biowaste might be valuable to be explored for further development as nutraceutical products. Furthermore, the reuse of agricultural byproduct tea seed pomace also fulfills the environmental perspective. ? 2014 American Chemical Society.