Abstract

Aqueous and organic basidiocarp extracts of the edible mushroom Lactarius indigo were evaluated for their antibacterial and cytotoxic effects. 10, 20 and 30 mg of organic extracts were tested against diarrheagenic Escherichia coli strains (EIEC, EPEC, ETEC-LT and ETEC-ST), Pseudomonas aeruginosa, Enterobacter cloacae,Staphylococcus aureus and Salmonella enterica. 10 mg of hexane extract showed activity against ETEC-LT (18.8 mm zone of inhibition) and P. aeruginosa (10.5 mm). All levels of the ethyl acetate extract inhibited all the strains, with stronger activity against EIEC (19.0 mm) and P. aeruginosa (21.0 mm) at 30 mg. Methanol extract inhibited all bacterial growth, but E. cloacae. 100 μg/ml of aqueous extract showed antiproliferative activity against MCF7 cells, but not on HeLa, A549 and normal bovine mammary epithelium cells. Methanol and ethyl acetate extracts inhibited proliferation of HeLa cells (50 to 1000 ng/ml) but increased proliferation of A549 (100 ng/ml), as did methanol extract (500 ng/ml). Methanol extract did not inhibit normal rabbit serum fibroblast cells, while hexane and ethyl acetate extracts showed an inhibitory effect with 50 and 100 ng/ml, respectively, less than in proliferation of HeLa cells. These results show that L. indigo basidiocarps contain substances with antibacterial and cytotoxic activities.

Key words: Lactarius indigo extracts, antibacterial activity, cytotoxic activity.