Free radical scavenging activities of pigment extract from <i>Hibiscus syriacus</i> L. petals <i>in vitro</i>

Abstract

The macroporous resin adsorption method was used to purify the pigment from Hibiscus syriacus L. petals. Through the comparison of the adsorption and desorption rates of six types of macroporous resins including AB-8, S-8, NKA-9, DM-130, D101 and 860021 to the pigment, 860021 resin was selected as the most appropriate resin to purify the pigment. The antioxidant capacities of the pigment extract (PE) were evaluated through in vitro experiments using hydroxyl radical scavenging assay, 1,1- diphenyl-2-picrylhydrazyl (DPPH) scavenging assay and lipid peroxidantion (LPO) inhibition capacity assay induced by Fe²⁺-H₂O₂. Total flavonoid content (TFC) of PE was determined using the colorimetric methodology and total phenolic content (TPC) using Folin–Ciocalteu reagent. PE produced significant antioxidant activity. In addition, PE demonstrated higher TFC and TPC of 63.4±1.8 mg rutin equivalents/g and 172.6±2.4 mg gallic acid equivalents/g, respectively. This study suggests that H. syriacus L. petal can be used potentially as a source of natural antioxidants.

Key words: Macroporous resin, Hibiscus syriacus L., pigment, free radical.