Legumes: Nature’s Medicine Chest

Winged bean, jack bean, velvet bean, snout bean, ringworm bush, and fish poison bean: These aren’t exactly household names even among farmers, but they’re all sources of agricultural products that could lead to future drugs.

These plants also are part of a special legume collection maintained by the Agricultural Research Service. The collection contains more than 4,000 accessions that scientists describe as an “unopened medicine chest.” These legumes are a central source of experimental plant material for public and private researchers worldwide.

Winged bean, for example, has high levels of proteins called lectins, which are used as diagnostic tools in medical research because they bind to certain blood cells. Winged beans also contain erucic acid (an antitumor medication) and polyunsaturated fatty acids that can be used to treat acne and eczema.

Another legume in the collection, kudzu, is best known as a prolific but unwanted roadside weed. But it’s also a source of a number of chemicals including daidzein (an anti-inflammatory and antimicrobial), daidzin (a cancer preventive) and genistein (an antileukemic).

Velvet bean is a source of dopa, which the brain converts into the neurotransmitter dopamine. Reductions in dopamine have been associated with Parkinson’s disease, which occurs when dopamine-producing brain cells are destroyed. Velvet bean also contains serotonin, another brain neurotransmitter that may be involved in learning, sleep, and control of moods.

Along with their pharmaceutical potential, these legumes also “fix” nitrogen--transforming atmospheric nitrogen into a form plants can use for growth--enriching the soil and making them ideal candidate crops for sustainable agriculture. Some legumes can add up to 500 kilograms of nitrogen per hectare to the soil, alleviating the need for fertilizer and lessening the chance of water pollution.

A feature article about this research appears in the November 1996 issue of ARS’ Agricultural Research magazine. The article is on the World Wide Web.

Scientific contact: Brad Morris, USDA-ARS Plant Genetic Conservation Resources Unit, Griffin, Ga., phone (770) 229-3253, bmorris@ars-grin.gov.