Analysis of Phenolic and Flavonoid and Evaluation of Antioxidant Activity of Ostericum koreanum Root Extract

In this study, the total polyphenol and flavonoid contents of hot water and 95% ethanol extracts of the roots of <i>Ostericum koreanum</i> were determined. The phenolic composition and contents of the extracts were further investigated by high-performance liquid chromatography(HPLC) based on 13 phenolic acid and flavonoid reference standards. In addition, the antioxidant activities of the extracts were evaluated <i>in vitro</i> by measuring DPPH and ABTS radical-scavenging activities, superoxide dismutase(SOD)-like activity, and ferric reducing antioxidant power (FRAP). The hot-water extract contained 5.75±0.05 mg GAE/g total polyphenols and 3.52±0.02 mg RE/g total flavonoids, whereas the 95% ethanol extract contained 4.63±0.08 mg GAE/g and 2.62±0.02 mg RE/g, respectively. In the composition and content profile of the HPLC analysis, five types of phenolic acids (gallic acid, chlorogenic acid, caffeic acid, ferulic acid, p-coumaric acid) and two types of flavonoids (rutin, quercetin) were detected in the hot water extract, and in the 95% ethanol extract, isovanillic acid was added to these, resulting in a total of eight types detected. However, since data regarding repeatability, LOD, and LOQ were not secured, this HPLC assay content was limited to a preliminary comparative value for the initial screening stage. At 1 mg/mL, the hot-water and 95% ethanol extracts showed DPPH activities of 77.45% and 78.47%, ABTS activities of 68.01% and 59.27%, SOD-like activities of 20.71% and 5.18%, and FRAP values of 2570.22 and 594.20 μM TE/mL, respectively. Therefore, the hot water and 95% ethanol extracts of <i>O. koreanum</i> roots may have potential as natural antioxidant materials. However, further studies are warranted to establish their potential as functional ingredients with antioxidant activity, including investigations at the cellular level using human fibroblast cell lines and comprehensive evaluations of their safety and biological effects.