A protein with antiproliferative, antifungal and HIV-1 reverse transcriptase inhibitory activities from caper (Capparis spinosa) seeds

A protein exhibiting an N-terminal amino acid sequence with some similarity to imidazoleglycerol phosphate synthase was purified from fresh Capparis spinosa melon seeds. The purification protocol entailed anion exchange chromatography on DEAE-cellulose, cation exchange chromatography on SP-Sepharose, and finally gel filtration by fast protein liquid chromatography on Superdex 75. The protein was adsorbed using 20 mM Tris–HCl buffer (pH 7.4) and desorbed using 1 M NaCl in the starting buffer from the DEAE-cellulose column and SP-Sepharose column. The protein demonstrated a molecular mass of 38 kDa in gel filtration and sodium dodecyl sulfate–polyacrylamide gel electrophoresis, indicating that it was monomeric. The protein inhibited proliferation of hepatoma HepG2 cells, colon cancer HT29 cells and breast cancer MCF-7 cells with an IC50 of about 1, 40 and 60 μM, respectively. It inhibited HIV-1 reverse transcriptase with IC50 of 0.23 μM. It inhibited mycelial growth in the fungus, Valsa mali. It did not exhibit hemagglutinating, ribonuclease, mitogenic or protease inhibitory activities.