Enrichment and purification of flavonoids from Euphorbia hirta L. and antioxidant activity evaluation.

This study aimed to enrich flavonoids from Euphorbia hirta L. (E. hirta) extracts, and the enrichment parameters were optimized by adsorption and desorption tests. The HPD-300 resin was chosen after a comparison of the flavonoids from E. hir15ta's adsorption and desorption capabilities on nine different types of macro porous resin. The optimal enrichment for purification of E. hirta extracts were determined as sample concentration of 3.0mg/mL, pH of 2.0 and a desorption solvent of 50% ethanol. The optimal dynamic parameters were loading 2.5 BV of sample at a feeding flow rate of 2 BV/h, cleaning the column with 5 BV of water and then eluting 50.0% ethanol at a 2 BV/h elution flow rate using 5 BV of eluent. Following a single treatment cycle with HPD-300 resin, the product's total flavonoid content rose from 6.32% to 28.8%, with an 80.01% recovery yield. Then, 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) and hydroxyl radical scavenging ability were used to evaluate the antioxidant properties of the purified flavonoids. The main chemical components of purified flavonoids from E. hirta are astragalin, quercetin-3β-D-glucoside, 9,16-dioxo-10,12,14-octadeca-trienoic acid and gallic acid. The results showed that purified flavonoids from E. hirta had a strong antioxidant effect, which indicated that it represented a valuable natural antioxidant source.