Inhibitory Activity of Caffeoylquinic Acids from the Aerial Parts of Artemisia princeps on Rat Lens Aldose Reductase and on the Formation of Advanced Glycation End Products

Caffeoylquinic acids -3,4-di-O-caffeoylquinic acid (1); 1,3,5-tri-O-caffeoylquinic acid (2); and 3,4,5-tri-O-caffeoylqunic acid (3)- were isolated from an acetone-soluble fraction of the aerial parts of Artemisia princeps. Their structures were determined spectroscopically using 1D- and 2D-nuclear magnetic resonance (NMR) studies, as well as by comparing the NMR results with previously published structures. All the isolates were subjected to in vitro bioassays to evaluate their efficacy in inhibiting rat lens aldose reductase (RLAR) activity and the formation of advanced glycation end products (AGEs). We found 1,3,5-tri-O-caffeoylquinic acid (2) to be the most potent AGE inhibitor, and the concentration that resulted in 50% inhibition (IC50) was 22.18 +/- 1.46 mM, as compared to the aminoguanidine and chlorogenic acid controls, which had IC50 values of 1,093.11 +/- 10.95 and 117.63 +/- 0.20 mM, respectively. In the RLAR assay, the three caffeoylquinic acids were found to have IC50 values in the range of 1.78-2.40 mu M, demonstrating a 5- to 10-fold greater efficacy in RLAR inhibition as compared to the quercetin control, which had an IC50 value of 17.91 mu M.