Inhibitory Action of Nephroma Water Extracts on the Metabolism of Physarum polycephalum

Abstract

Hot water extracts of Nephroma arctkum (lichenized Ascomycete) show a fungistatic effect. They possess an inhibitory action on the growth of the lower eucaryote Physarum polycephalum (Myxomycetae), which was used as a model system. The biological action of Nephroma extracts can be accounted for in microplasmodia by an initial inhibition of respiration leading to a secondary inhibition of DNA, RNA and protein synthesis. Although microplasmodia can be readily killed by Nephroma extracts, reversibility of their action can be observed. Reversibility depends upon the relative amount of Nephroma extract and of microplasmodia. These observations can account for the described action of Nephroma extracts on fungi, plant and animal cells. In spite of the observed respiratory inhibition after addition of Nephroma extract, no effect was detected in vitro on the oxygen consumption of rat mitochondria suggesting that the active substance could be a metabolite.