Enrichment optimisation and identification of total iridoid glycosides from <i>Lonicera japonica</i> Thunb. and its anti-inflammatory activity

The total iridoid glycosides (TIG) from <i>Lonicera japonica</i> Thunb. were firstly enriched by D316 anion exchange resin, using the response surface method (RSM) model to optimise the enrichment parameters, leading to the optimised RSM parameters of 1.25 g sample weight, 8.83 h adsorption time, 3.65 BV elution volume. Quantitative analysis of TIG showed the content increased from 12.71 mg/g to 74.62 mg/g after enrichment. The TIG obtained was analysed by UPLC-Q-TOF-MS/MS, identifying 34 iridoid glycosides. The anti-inflammatory activity of TIG was evaluated by LPS-induced RAW264.7 cells <i>in vitro</i>, effectively inhibiting the production of NO at the concentrations of 0.8,1.6, 3.2 mg/mL. TIG from <i>L. japonica</i> were successfully enriched by D316 resin to remove the abundant phenolic acids through acid-base reaction, which provided material basis for the further efficacious constituents revelation for <i>L. japonica</i>, as well as the further exploitation of TIG as anti-inflammatory drug.