Identification and Extraction Optimization of Active Constituents in Seib ex TANAKA Peel and Its Biological Evaluation.

Seib ex TANAKA possesses various biological effects. It has been used in oriental remedies for blood circulation and the common cold. Recently, biological effects of peel have been reported. However, optimization of the biological properties of peel preparations has yet to be reported on. We developed a high-performance liquid chromatography (HPLC) method for quantification of the active constituents in peel. Hot water and ethanolic extracts of peel were prepared and their chemical profiles and biological activities were evaluated. The 80% ethanolic extract demonstrated the greatest antioxidant activity and phenolic content, while the 100% ethanolic extract had the greatest xanthine oxidase inhibitory activity. Elastase inhibition activity was superior in aqueous and 20% ethanolic extracts. The contents of two flavonoids were highest in the 100% ethanolic extract. We postulated that the antioxidant and anti-aging effects of peel extract could be attributed to phenolics such as flavonoids. Our results suggest that the flavonoid-rich extract of may be utilized for the treatment and prevention of metabolic disease and hyperuricemia while the water-soluble extract of could be used as a source for its anti-aging properties.