Antioxidant, Biological Activity and Chromatographic Characterization of Polygonum cuspidatum Sieb. et Zucc Natural Products by Solvent Fractionation

This study investigated the natural bioactive compounds in Polygonum cuspidatum Sieb. et Zucc（P. cuspidatum）by fractionating a 70% ethanol extract using n-hexane, chloroform, ethyl acetate, n-butanol, and water. The total phenolic content and total flavonoid contents of each fraction were determined, and their antioxidant activities were evaluated using DPPH, ABTS, and FRAP assays. Additionally, anti-diabetic potential was assessed via α-glucosidase inhibition, while anti-obesity activity was evaluated using lipase inhibition. The fractions were also tested for tyrosinase inhibition and elastase inhibition to assess skin-whitening and anti-wrinkle potential, and their antibacterial activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa was determined using the agar diffusion method. Finally, bioactive compounds were identified and quantified using HPLC and GC-MSD. The ethyl acetate fraction exhibited the highest total phenolic content and total flavonoid content, along with strong antioxidant, anti-diabetic, anti-obesity, skin-whitening, anti-wrinkle, and antibacterial activities. HPLC-PDA and GC-MSD analysis identified tannic acid and emodin as key bioactive compounds. These findings suggest that the ethyl acetate fraction of P. cuspidatum extract, rich in phenolic and flavonoid compounds, is a promising natural source of bioactive ingredients for applications in the food, pharmaceutical, and cosmetic industries. Further research is needed to explore its mechanisms and therapeutic applications.