Antiproliferative and anti-inflammatory effects of fractionated crude lectins from boiled kidney beans (Phaseolus vulgaris).

In this study, we investigated the biological profile of lectins isolated from raw and boiled Japanese red Kintoki beans (red kidney beans [RKB]; Phaseolus vulgaris). Lectins in beans showing agglutination activity were retained after heating. Raw and boiled RKB lectins were fractionated using carboxymethyl- and diethylaminoethyl-Sepharose, respectively. Boiled RKB lectins were evaluated for carbohydrate specificity as well as cytokine-inducing and antiproliferative activities against cancer cells and compared with raw RKB lectins. Raw RKB lectins showed specificity for thyroglobulin and fetuin, whereas boiled lectins showed specificity for N-acetylneuraminic acid. Raw RKB lectins showed low resistance to proteases and tolerated temperatures greater than 80°C for 5 min. Notably, lectins from raw and boiled beans showed antiproliferative activity against five types of cancer cells B16, LM8, HeLa, HepG2, and Colo 679. In particular, lectins from raw beans exhibited a significantly stronger activity than those from boiled beans. Anti-inflammatory effects were notably observed in crude extracts from raw and boiled beans. Specifically, lectins fractionated from boiled beans markedly inhibited the expression of tumor necrosis factor-α and interleukin-6. Overall, our results showed that RKB lectins from boiled beans exert anti-inflammatory and anticancer effects and could be developed as potential chemopreventive agents. PRACTICAL APPLICATION: Japanese red kidney beans (RKB) are cultivated in numerous parts of the temperate zone and consumed in many countries. Lectins from boiled beans exhibited anticancer activity, similar to lectins from raw beans. Additionally, crude and fractionated lectins from boiled beans showed anti-inflammatory activity. Thus, boiled RKB lectins have the potential to be used as a bioactive protein for medical research and could be developed as anticancer agents.

Lectin Isolated from Japanese Red Sword Beans (Canavalia gladiata) as a Potential Cancer Chemopreventive Agent.

In this study, we investigated the chemical and biological profile of lectin isolated from Japanese red sword beans (Canavalia gladiata; RSBs). RSB lectin was purified using maltamyl-Sepharose 4B and subjected to amino acid composition and partial amino acid sequencing analyses, and evaluated for blood and carbohydrate specificity, mitogenic activity, splenic natural killer (NK) cell activity, and its effect on B16 melanoma cell proliferation, compared with Concanavalin A (Con A). The amino acid composition and sequences of RSB lectin were similar to those of Con A. RSB lectin showed specificity to mannose, glucose, maltose, methyl-D-mannoside, and thyroglobulin, but not rhamnose, using mouse, sheep, and rabbit erythrocytes. Compared with Con A, RSB lectin showed low resistance to proteases and to temperatures greater than 70 °C, but high mitogenic activity for mouse splenic cells. Notably, while treatment with RSB lectin and Con A (0.01 and 0.1 µg/mL) promoted similar levels of splenic NK cell activity, which were higher than that observed in the control (0 µg/mL) and interleukin 2 (IL-2) (25 U)-treated populations, RBS lectin exerted a significantly stronger anti-proliferative effect than Con A at a concentration of 125.0 µg per well. Overall, our results show that RSB lectin might exert immunological effects on mouse splenic cells and could thus be used as a potential cancer chemopreventive agent. PRACTICAL APPLICATION: Japanese red sword bean (RSB) is a tropical perennial legume consumed in many Asian countries. RSB lectin shows specificity to mannose, glucose, maltose, methyl-d-mannoside, and thyroglobulin, but not to rhamnose, using mouse, sheep, and rabbit erythrocytes. RSB lectin exhibits similarities to Concanavalin A in amino acid composition and sequence, shows mitogenic activity for mouse splenic cells and strong anti-proliferative activity for B16 melanoma cells, and also enhances the activity of splenic natural killer (NK) cells against YAC-1 cells. Thus, RSB lectin has the potential to be used as a bioactive protein in medical research.

Effects of Hull Scratching, Soaking, and Boiling on Antinutrients in Japanese Red Sword Bean (Canavalia gladiata).

The effects of hull processing, soaking, and boiling on the content or activity of antinutrients in the red sword bean (RSB; Canavalia gladiata) were investigated. RSB seeds were compared with kidney bean (KB; Phaseolus vulgaris) seeds that are starch based and often used as processed products in Japan. RSB seeds had higher weight, thicker hull, and higher protein content, but lower moisture content compared with KB seeds. Because of the strong and thick hull, the relative water absorption of untreated RSB seeds was very low after soaking. Seeds were soaked after dehulling, scratching, and roasting. The results showed that hull scratching was the optimal method for increasing water absorption during soaking compared with dehulling and roasting. After soaking, the water used for soaking was discarded, since it had a high content of polyphenols and bitter taste, and RSB seeds were boiled in fresh water for 20, 40, and 60 min. The results showed that polyphenol and tannin contents, antioxidant activity, and hemagglutinating activity, as well as maltase, sucrase, and trypsin inhibitor activities in scratched RSB seeds decreased significantly after boiling compared with those in raw seeds, whereas amylase inhibitor activity showed no significant change. Overall, it was concluded that the combination of hull scratching, soaking, and boiling in fresh water can reduce thermal-stable or sensitive antinutrients in RSB and thus, significantly improve its nutritional value.