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The trypanocidal activity of naturally occurring 6-(3,4-dihydroxystyryl)-4-hydroxy-2-pyrone (hispidin) prompted us to examine its cytotoxic activity toward normal and cancerous cells in culture. Hispidin synthesized in our laboratory to a high degree of purity (checked by 1H and 13C NMR spectroscopy) was shown to be cytotoxic (between 10(-3) mol/L and 10(-7) mol/L) toward normal human MRC-5 fibroblasts, human cancerous keratinocytes (SCL-1 cell line), and human cancerous pancreatic duct cells (Capan-1 cell line). Interestingly, addition of hispidin in three successive doses (between 10(-5) mol/L and 10(-7) mol/L) led to a 100-fold increase in activity with an enhanced activity on cancer cells compared to normal cells (50%). Synthetic hispidin was found to inhibit isoform beta of protein kinase C (IC50 of 2 x 10(-6) mol/L), but not E. coli and placental type XV alkaline phosphatases. The enhanced activity of hispidin toward the cancerous cell lines is discussed.

Many mushrooms are toxic to insects. To identify the chemicals involved in insecticidal activity, the toxicity of 14 species has been studied for water solubility, thermolability, and dialysis. The data strongly suggest that proteins are responsible for most of the insecticidal activity of mushroom fruitbodies and may be a source of genes available for plant protection against insects. Among proteins, lectins and hemolysins were good insecticide candidates because the toxicities were not affected by protease.

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