Václav Kordač

The influence of chloroquine on the formation of porphyrins by yeasts

A single two-compartment model suitable for studying the production and elimination of porphyrins from cells was prepared. Chloroquine with increasing concentrations:-- Inhibits the total production of porphyrins. Reduces intracellular concentration of porphyrins. Increases transversal permeation of porphyrins through the cellular membrane.

Effect of chloroquine on membrane permeability in yeast—release of cellular coproporphyrin

1. The influx and efflux of labelled substances with and without chloroquine was studied in yeast cells. 2. The uptake of delta-aminolevulinic acid by Saccharomyces cerevisiae is characterized by a KT of 3-4 mM and Jmax of 1.0-1.2 mumol min-1 g dry weight-1. 3. A method for loading yeast with labelled coproporphyrin is suggested. 4. The uptake of sorbitol and coproporphyrin was slightly stimulated, while the uptake of 6-deoxyglucose was slightly, that of 2-aminoisobutyric acid and leucine strongly inhibited by chloroquine. 5. The efflux of coproporphyrin, 2-aminoisobutyric acid and sorbitol was stimulated while that of leucine was not influenced by chloroquine. 6. The result showed that chloroquine influenced directly but nonspecifically the membrane permeability, apparently mainly that of the vacuolar membrane.

A model for testing compounds influencing porphyrin synthesis

The yeast Saccharomyces cerevisiae cultivated semi-anaerobically in a synthetic medium was used as a model to establish (a) total porphyrin synthesis, (b) ratio of intracellular to extracellular porphyrin concentrations. The antimalarials used for the therapy of porphyria cutanea tarda, chloroquine and pyrimethamine, reduced the total synthesis of porphyrins, pyrimethamine being more effective than chloroquine, like in porphyric patients. Both drugs exerted an antagonistic influence on the release of porphyrins from cells. Chloroquine reduced the concentration ratio of porphyrins while pyrimethamine increased it, apparently through inhibition of permeation of porphyrins. Combined treatment with the two compounds may hold promise for the therapy of porphyria cutanea tarda.

The process of continuous production and isolation of coproporphyrin

SummaryThe production of coproporphyrin from glucose and urea has been achieved by semi-aerobic culture ofSaccharomyces cerevisiae. The cells were entrapped in alginate gel and packed into a column reactor for continuous long-term process. The porphyrins were isolated and simultaneously concentrated from the effluent by liquid-solid phase extraction, purified by liquid chromatography and finally crystallized. Using the process described the final product of high purity was obtained.