Phenolic Compounds from the Leaves of Homonoia riparia and their Inhibitory Effects on Advanced Glycation End Product Formation

ABSTRACT

In a search for novel treatments for diabetic complications from natural resources, we found that the ethyl acetate-soluble fraction from the 80% ethanol extract of the leaves of Homonoia riparia has a considerable inhibitory effect on advanced glycation end product (AGE) formation. Bioassay-guided isolation of this fraction resulted in identification of 15 phenolic compounds (1 – 15). These compounds were evaluated in vitro for inhibitory activity against the formation of AGE. The majority of tested compounds, excluding ethyl gallate (15), markedly inhibited AGE formation, with IC₅₀ values of 2.2 – 89.9 µM, compared with that of the positive control, aminoguanidine (IC₅₀ = 962.3 µM). In addition, the effects of active isolates on the dilation of hyaloid-retinal vessels induced by high glucose (HG) in larval zebrafish was investigated; (–)-epigallocatechin-3-O-gallate (6), corilagin (7), and desmanthine-2 (11) significantly decreased HG-induced dilation of hyaloid–retinal vessels compared with the HG-treated control group.