Inhibition of aldose reductase by dihydroflavonols inEngelhardtia chrysolepis and effects on other enzymes

Astilbin and neoastilbin, dihydroflavonol rhamnosides fromEngelhardtia chrysolepis, showed potent inhibition of lens aldose reductase. Kinetic analysis showed astilbin exhibited uncompetitive inhibition against bothdl-glyceraldehyde and NADPH. These taxifolin glycosides were selective inhibitors of aldose reductase with no inhibition of NADH oxidase.     

Biliverdin as an electron transfer catalyst for superoxide ion in aqueous medium

Summary Stopped flow experiments gave evidence of the formation of a biliverdin-superoxide complex and/or a biliverdin radical anion by reaction of aqueous O₂ ^– with biliverdin. Such transient species are likely intermediates both in the bleaching of biliverdin, during exposure to the aerobic xanthine oxidase reaction, and in the reduction of ferricytochromec under the same conditions.