Plant-derived molecules from Saussurea grandifolia as inhibitors of aldose reductase

Abstract

Saussurea grandifolia was tested for aldose reductase (AR) inhibition as part of a search for potentially therapeutic natural compounds. Stepwise polarity fractions were tested for in vitro inhibition of rat lens AR. Of these, the ethyl acetate (EtOAc) and n-butanol (n-BuOH) fractions exhibited AR inhibitory activities. A chromatographic separation of the active EtOAc and n-BuOH fractions led to the isolation of nine compounds, which were known and identified as vitexin (1), genkwanin-5-O-glucoside (2), vitexin 2 ''-p- hydroxybenzoate (3), kaempferol-3-O-rutinoside (4), isovitexin (5), quercitrin (6), isoquercitrin (7), 1,5-di-O-caffeoylquinic acid (8), and vicenin 1 (9). Among these compounds, compounds 6, 7, and 8 showed very strong inhibitory activities against AR (IC50 's = 0.34, 0.32, and 0.08 mu M, respectively). The results suggest that S. grandifolia is clearly a potential source for therapeutic agent that might be useful for the treatment of diabetic complications.