A MUSHROOM FRUITING BODY-INDUCING SUBSTANCE INHIBITS ACTIVITIES OF REPLICATIVE DNA-POLYMERASES

We found and isolated two natural products in the extract from a basid iomycete, Ganoderma lucidum, as eukaryotic DNA polymerase inhibitors. The compounds were identified as cerebrosides, (4E,8E)-N-D-2'-hydroxyp almitoyl-1 -beta-D-glucopyranosyl-9-methyl-4,8-sphingadienine and beta -D-glucopyranosyl-9-methyl-4,8-sphingadienine, and were found to be id entical to the mushroom fruiting body-inducing substances (FIS) report ed. These cerebrosides selectively inhibited the activities of replica tive DNA polymerases, especially the alpha-type, from phylogenetically broad eukaryotic species, whereas they hardly influenced the activiti es of DNA polymerase beta, prokaryotic DNA polymerases, terminal deoxy nucleotidyl transferase, HIV reverse transcriptase, RNA polymerase, de oxyribonuclease I, and ATPase. The inhibition of another replicative p olymerase, the delta-type, was moderate. The inhibitions of the replic ative polymerases were dose-dependent, and the IC50 for animal or mush room DNA polymerase alpha was achieved at approximately 12 mu g/ml (16 .2 mu M) and for animal DNA polymerase delta at 57 mu g/ml (77.2 mu M) . FIS is possibly a DNA polymerase inhibitor specific to the replicati ve enzyme group, and the fruiting body formation may be required for t he suppression of the DNA replication or the vegetative growth of the mycelium. (C) 1998 Academic Press.