Drug effects on retinol oxidation: retinal alcohol:NAD+ oxidoreductase.

A spectrophotometric method was used to follow the oxidation of retinol by preparations of cattle retinas. Two-tenths millimole chlorpromazine (CPZ) and thioridazine (TRDZ) activated the initial rate. This was followed by inhibition. These effects are reversible. The ring sulfoxide of chlorpromazine and thioridazine thiomethyl sulfoxide (TPS-23) had no apparent effect. Lower concentrations (0.01 and 0.1 mM.) of CPZ and TRDZ have no demonstrable effect on the standard reaction, and no differences between CPZ and TRDZ could be shown. Chloroquine (0.2 mM.) and sodium lauryl sidfate (1.0 mM.) were shown to activate the reaction without changing the pseudomonomolecular characteristic of the standard reactions. These data were discussed with regard to the known surface activities and previously demonstrated enzyme inhibitory effects of the drugs.