Inhibition of aldehyde reductase I by some isoquinoline alkaloids

Abstract

Aldehyde reductase I has been found to be inhibited by certain isoquinoline alkaloids (protoberberines, protopines, benzylisoquinolines, benzyltetrahydroisoquinolines, phthalideisoquinolines, pavinanes) and narceine imide. The sensitivity of this enzyme to the compounds tested was compared with that of alcohol dehydrogenase and/or aldehyde reductase II to them; alcohol dehydrogenase proved more selective in binding the alkaloids. The kinetics of the inhibitory action of berberine and other results suggest that the binding site of aldehyde reductase I for alkaloids is relatively large, has a hydrophobic nature, and probably contains a group with a positive charge. This binding site is probably not identical with the active centre of the nezyme.