RIBOSOME INACTIVATING PROTEIN-LIKE ACTIVITY IN SEEDS OF DIVERSE CUCURBITACEAE PLANTS

1. Seed extracts of 20 plants species belonging to the family Cucurbitaceae were examined for their ability to inhibit protein synthesis in rabbit reticulocyte lysate and induce mid-term abortion in mice. 2. Eleven extracts were found to inhibit protein synthesis by about or over 90%, seven extracts produced about 80% inhibition, one caused about 70% inhibition and one brought about approx. 40% inhibition, when the extracts were tested at a final concentration of 10 mu g per ml. 3. All of the seed extracts possessed potent mid-term abortifacient activity. 4. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the seed extracts disclosed the existence of a Coomassie Blue-stainable band with a mol. wt of ca 30,000 Da. This band probably accounts for the protein synthesis inhibiting and mid-term abortifacient activities. 5. There was a similarity in the electrophoretograms of seed extracts of plants belonging to the same genus.