Bioactivity‑Guided Isolation of Antioxidant Compounds from Pouzolzia zeylanica (L.) Benn

Background: Pouzolzia zeylanica (L.) Benn. (Family: Urticaceae), which is widely distributed in China, is consumed as food and as a traditional herbal medicine for the treatment of numerous diseases. Objective: The aim of the present study was to explore the antioxidant compounds of P. zeylanica. Materials and Methods: A petroleum ether extract, an ethyl acetate extract (EAE), an n‑butanol extract, and the remaining part were separated by liquid–liquid extraction from a 90% aqueous ethanol extract and a water extract of P. zeylanica and were evaluated using two complementary antioxidant assays, namely 2,2‑diphenyl‑1‑picrylhydrazyl‑free radical scavenging and ferric‑reducing antioxidant power assays. Results: The EAE, which possessed the highest antioxidant activity, contained the highest total phenolic content (263.5 ± 4.8 mg/g) and total flavonoid content (388.3 ± 5.6 mg/g). In addition, three compounds with antioxidant activity, quercetin, kaempferol, and N‑[2‑(3‑hydroxy‑4‑methoxyphenyl)‑2‑hydroxyethyl]‑3‑(4‑methoxyphenyl) prop‑2‑enamide, were isolated from the EAE. Conclusions: These results demonstrate that the flavonoids and phenolic compounds from P. zeylanica could be used as natural antioxidants.