Aldose reductase inhibitory activity of compounds from Zea mays L

Abstract

Aldose reductase (AR) inhibitors have a considerable therapeutic potential against diabetes complications and do not increase the risk of hypoglycemia. Through bioassay-guided fractionation of an EtOH extract of the kernel from purple corn (Zea mays L.), 7 nonanthocyanin phenolic compounds (compound 1-7) and 5 anthocyanins (compound 8-12) were isolated. These compounds were investigated by rat lens aldose reductase (RLAR) inhibitory assays. Kinetic analyses of recombinant human aldose reductase (rhAR) were performed, and intracellular galactitol levels were measured. Hirsutrin, one of 12 isolated compounds, showed the most potent RLAR inhibitory activity (IC(50), 4.78 μ M). In the kinetic analyses using Lineweaver-Burk plots of 1/velocity and 1/substrate concentration, hirsutrin showed competitive inhibition against rhAR. Furthermore, hirsutrin inhibited galactitol formation in rat lens and erythrocytes sample incubated with a high concentration of galactose; this finding indicates that hirsutrin may effectively prevent osmotic stress in hyperglycemia. Therefore, hirsutrin derived from Zea mays L. may be a potential therapeutic agent against diabetes complications.

Figure 1

Isolation scheme for the compounds from purple corn (Zea mays L).

Figure 2

Chemical structures of phenolic compounds isolated from Zea mays L.

Figure 3

Lineweaver-Burk plots showing the reciprocal of the velocity (1/V) of recombinant human aldose reductase versus the reciprocal of substrate concentration (1/S) with dL-glyceraldehyde as the substrate concentration from 0.1 to 1 mM hirsutrin (a), 3′-methoxyhirsutrin (b).