Antitumor and HIV‐1 Reverse Transcriptase Inhibitory Activities of a Hemagglutinin and a Protease Inhibitor from Mini‐Black Soybean

Abstract

Protease inhibitors (PIs) and hemagglutinins are defense proteins produced by many organisms. From Chinese mini-black soybeans, a 17.5-kDa PI was isolated using chromatography on Q-Sepharose, SP-Sepharose, and DEAE-cellulose. A 25-kDa hemagglutinin was purified similarly, but using Superdex 75 instead of DEAE-cellulose in the final step. The PI inhibited trypsin and chymotrypsin (IC50 = 7.2 and 8.8 μM). Its trypsin inhibitory activity was stable from pH 2 to pH 13 and from 0°C to 70°C. The hemagglutinin activity of the hemagglutinin was stable from pH 2 to pH 13 and from 0°C to 75°C. The results indicated that both PI and hemagglutinin were relatively thermostable and pH-stable. The trypsin inhibitory activity was inhibited by dithiothreitol, signifying the importance of the disulfide bond to the activity. The hemagglutinating activity was inhibited most potently by D (+)-raffinose and N-acetyl-D-galactosamine, suggesting that the hemagglutinin was specific for these two sugars. Both PI and hemagglutinin inhibited HIV-1 reverse transcriptase (IC50 = 3.2 and 5.5 μM), proliferation of breast cancer cells (IC50 = 9.7 and 3.5 μM), and hepatoma cells (IC50 = 35 and 6.2 μM), with relatively high potencies.

A thermostable trypsin inhibitor with antiproliferative activity from small pinto beans

“…On the other hand, small pinto bean trypsin inhibitor only showed moderate pH stability. It remained stable in the pH range of 2-10, unlike mini-black soybean and small black glossy soybean trypsin inhibitors that were more resistant to changes in ambient pH (pH 3-13) 25,26 .…”

“…Its heat resistance was stronger than most of the trypsin inhibitors from other beans. For example, the trypsin inhibitors from small glossy black soybeans, Faba beans and mini-black soybean were only stable up to 60-70 C [25][26][27] . On the other hand, small pinto bean trypsin inhibitor only showed moderate pH stability.…”

“…Since small pinto bean trypsin inhibitor was easily affected by DTT, the disulfide bonds of the trypsin inhibitor were indispensable to its trypsin inhibitory activity. Similarly trypsin inhibitors from small glossy black soybeans, Faba beans and mini-black soybean were also inactivated by DTT [25][26][27] .…”

“…It is known that some trypsin inhibitors have antifungal activity 23,24 whereas others do not [25][26][27][28][29][30][31] .…”

Antiproliferative Activity of Lavatera cashmeriana- Protease Inhibitors towards Human Cancer Cells

“…IC 50 values suggest that NCIH322 lung cancer cells are strongly inhibited by both inhibitors at lower concentrations in comparison to other cell lines. Their pharmacological effects may be mediated through inhibition of the protease activity and the subsequent modulation of the protease pro-survival signaling as LC-pi I and II strongly inhibited the in vitro activity of trypsin, elastase and chymotrypsin (Clemente et al, 2010), also TI1B, a major Bowman-Birk isoinhibitor from pea (Pisum sativum L.) on HT29 colon cancer cells (Clemente et al, 2012) and antitumor Protease Inhibitor from Mini-Black Soybean (Ye and Ng, 2011). These evidences have made the plant protease inhibitors to be considered as neutraceutical proteins, owing to prevention and treatment of cancer (de Mejia and Dia, 2010).…”