A novel lectin with highly potent antiproliferative and HIV-1 reverse transcriptase inhibitory activities from the edible wild mushroom Russula delica

A dimeric lectin with a molecular weight of 60 kDa and high hemagglutinating activity was isolated from fresh fruiting bodies of the wild mushroom Russula delica. The lectin was composed of two identical subunits, each with a molecular weight of 30 kDa. It was adsorbed on both SP-Sepharose and Q-Sepharose and unadsorbed on DEAE-cellulose. Its hemagglutinating activity was stable up to 70A degrees C, and in HCl and NaOH solutions of concentrations up to 25 and 12.5 mM, respectively. The activity was inhibited by inulin and o-nitrophenyl-beta-D-galactopyranoside. Al3+, Fe3+ and Zn2+ ions, but not by Ca2+, Mg2+ and Mn2+ ions. Mg2+ ions at 10 mM concentration potentiated the hemagglutinating activity of the lectin. Russula delica lectin was devoid of mitogenic activity toward mouse splenocytes, but potently inhibited proliferation of HepG2 hepatoma and MCF 7 breast cancer cells, with an IC50 value of 0.88 A mu M and 0.52 A mu M, respectively. It potently inhibited HIV-1 reverse transcriptase activity with an IC50 of 0.26 mu M.