Soybeans soaked in warm water naturally release key cancer-fighting substance

Hari B. Krishnan and colleagues explain that the substance, Bowman-Birk Protease Inhibitor (BBI), has shown promise for preventing certain forms of cancer in clinical trials. Those human tests resulted from evidence of BBI's beneficial effects, including indications that BBI derived from the large amounts of soybeans in traditional Japanese diets might underpin low cancer mortality rates in Japan. However, the current method of extracting BBI from soybeans is time-consuming and involves harsh chemicals. The scientists set out to see if there might be a greener and more environmentally friendly way of obtaining BBI.

They found that soybean seeds incubated in water at 122 degrees Fahrenheit naturally release large amounts of BBI that can easily be harvested from the water. The protein appeared to be active, with tests showing that it stopped breast cancer cells from dividing in a laboratory dish. "The abundance of BBI in soybean seed exudates by incubating the seeds in warm water provides a simple and alternative method to isolate this low molecular weight protein," the researchers said.

The scientists acknowledge funding from the Agricultural Research Service of the U.S. Department of Agriculture.