Purification and characterization of a lectin with antiproliferative activity toward cancer cells from the dried fruit bodies of Lactarius flavidulus

The isolation of a dimeric 29.8-kDa lectin (LFL) from dried Lactarius flavidulus fruit bodies is reported herein. The chromatographic procedure utilized comprised anion-exchange chromatography on DEAE-cellulose, cation-exchange chromatography on CM-cellulose, anion-exchange chromatography on SP-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. The hemagglutinating activity of LFL was inhibited by a variety of simple sugars, such as lactose, p-nitrophenyl α-d-glucopyranoside, p-nitrophenyl β-d-glucopyranoside and inositol, and by the polysaccharide inulin. The activity of LFL was stable up to 40 °C. There was a precipitous drop in activity when the temperature was elevated to 50 °C. Hemagglutinating activity was retained when LFL was exposed to 6.25–12.5 mM HCl and NaOH. The activity was potently inhibited by Fe2+ and Fe3+ ions, and slightly inhibited by Al3+ and Mn2+ ions. LFL suppressed the proliferation of hepatoma (HepG2) and leukemic (L1210) cells with an IC50 of 8.90 and 6.81 μM, respectively. It inhibited the activity of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) with an IC50 of 5.68 μM. However, LFL did not exhibit antifungal activity.

N-terminal sequence of the dimeric 29.8-kDa Lactarius flavidulus lectin is SGTYTIFNSAFDNSVID.Figure optionsDownload as PowerPoint slide