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

The total iridoid glycosides (TIG) from Lonicera japonica 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 in vitro, effectively inhibiting the production of NO at the concentrations of 0.8,1.6, 3.2 mg/mL. TIG from L. japonica 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 L. japonica, as well as the further exploitation of TIG as anti-inflammatory drug.