Antioxidants, cancer-fighting compounds from beans, tomatoes.

USDA/ARS researchers have found dry beans to be a highly concentrated source of healthful antioxidants, comparable if not superior to tomatoes and other fruits and vegetables. They also have learned more about the formation of lycopene in tomatoes. Tomatoes with much more lycopene than those now found in stores may be on the horizon. Lycopene may help reduce the risk of cancer.

In a series of beans with different seed coat colors, scientists have discovered eight flavonoids. They also have developed an assay that shows that six of the eight compounds have strong antioxidant activity. Flavonoids appear to be responsible for much of the protective power of fruits and vegetables, including their antiaging and anticancer properties.

The flavonoids with strong antioxidant activity were found in the seed coating that makes up about 10% of the bean. The flavonoids are linked to genes responsible for seed coat color-a useful cue for breeders seeking to improve color as well as antioxidant content. Scientists are examining flavonoids from the seed coats of light red kidney beans and red Mexican beans. They also plan to test major market classes, such as dark red kidney, navy, black turtle and cranberry beans.

Meanwhile, while working with tomato tissues cultures, an ARS researcher uncovered clues about ripening and lycopene formation. As expected, the culture developed into a tomato fruit. Surprisingly, the fruit's green outer leaves, known as the calyx, also ripened into fruitlike tissue.

In a particular tomato, scientists found that low growing temperatures triggered ripening in nonfruit tissue. Because the fruit was very dark red, they tested the lycopene content and found it to be 10 times the amount in most commercial tomatoes.

The scientists are looking for the genes that are activated to increase lycopene production. When they identify the genes, they hope to activate them in commercial varieties.

Further information. On the beans: Clifford Beninger, USDA/ARS Sugarbeet and Bean Research Unit, Michigan State University, Crop and Soil Science, Room 494, Plant and Soil Science Building, East Lansing, MI 48824; phone: [phone]; fax: [phone]; email: [e-mail]. On the tomatoes: Betty Ishida, USDA/ARS Western Regional Research Center, Process Chemistry and Engineering Unit, Room 0123, 800 Buchanan St., Albany, CA 94710; phone: [phone]; fax: [phone]; email: [e-mail].