Enrichment and separation of quercetin-3-O-β-d-glucuronide from lotus leaves (nelumbo nucifera gaertn.) and evaluation of its anti-inflammatory effect

This work aimed to establish a systematic strategy to enrich and separate quercetin-3-O-β-d-glucuronide (Q3GA) from lotus leaves with macroporous resin and semi-preparative HPLC. Six resins were tested, and LX-5 was chosen as the appropriate resin for Q3GA based on the adsorption and desorption performances. After one-step enrichment, the content of Q3GA increased from 2.15% in crude extract to 52.25% in 30% ethanol fraction with yield of 11.97%. The Q3GA was then isolated from the 30% ethanol fraction by semi-preparative HPLC, and the purity of Q3GA was above 98.00% with yield of 19.76%. These results suggested that the aforementioned strategy was a useful and economic method to enrich and separate Q3GA from lotus leaves. Additionally, the anti-inflammatory effect of Q3GA was evaluated in lipopolysaccharide-treated RAW264.7 macrophages, and the result demonstrated that Q3GA could significantly inhibit LPS-induced NO release in vitro in a dose-dependent manner compared with control group.