Effect of variation in medium on chloroquine inhibition of pigment production by serratia marcescens

ABSTRACT

Chloroquine Diphosphate (ARALEN) was found to inhibit the biosynthesis of a red pigment, Prodigiosin, by Serratia marcescens, Strain NIMA. Pigment production in two other strains, a PTR-treated orange variant (PTR-O) and a streptomycin-resistant mutant (Sm-Pow), were also inhibited without inhibiting growth. A similar effect has been observed with phosphate alone. In order to separate the drug effect from that of the phosphate alone, inhibition studies were tried on non-growing cultures. Phosphate alone did not affect pigment production by the Strain NIMA in a non-proliferating system using 2 DL-alanine medium. The diphosphate salt produced inhibition in both growing cultures and the non-proliferating system. Inhibition by the base and a hydroxy-derivative of the drug in nutrient agar medium further supports the above hypothesis. The precise mechanism of inhibition by either, however, remains unknown. Possibilities for the finer mechanism/s involved in these inhibitions are discussedThe reciprocal effects in nutrient agar and peptone-glycerol agar medium in the case of the base and the hydroxy-derivative as compared with the phosphate alone, however, was not observed in the case of the diphosphate salt. The role of metal chelation and pH variation is mentioned as possible explanation for variation in results obtained in solid media. Extrapolation of these effects to the efficacy of the drug in some collagen diseases is also discussed. (Summary)