Fruit extracts from 17 to 18 representatives of three strawberry species [Fragaria virginiana Mill., F. chiloensis (L.) Mill., and F. xananassa Duchesne ex Rozier] were tested for the ability to inhibit proliferation of A549 human lung epithelial cancer cells. The fruit extracts also were tested for activities against free radicals, (peroxyl radicals, hydroxyl radicals, singlet oxygen, and superoxide radicals), the activities of antioxidant enzymes [glutathione peroxidase (EC 126.96.36.199), superoxide dismutase (EC 188.8.131.52), guaiacol peroxidase (EC 184.108.40.206), ascorbate peroxidase (EC 220.127.116.11), monodehydroascorbate reductase (EC 18.104.22.168), dehydroascorbate reductase (EC 22.214.171.124), and glutathione reductase (EC 126.96.36.199)], and the activities of nonenzyme antioxidant components, ascorbic acid and glutathione. Correlations between the proliferation of cancer cells and these antioxidant activities were calculated. At the species level, F. virginiana fruit extract inhibited the proliferation of A549 human lung epithelial cancer cells to a significantly greater extent (34% inhibition) than the extracts from fruit of either F. chiloensis (26%) or F. xananassa (25%) (P < 0.0001). Extracts from fruit of F. virginiana also had significantly greater antioxidant activities and higher activities of antioxidant enzymes and nonenzyme components than did extracts from the other two species. Among individual genotypes, there was a high positive correlation between antiproliferation of A549 cancer cells, antioxidant activities against free radicals, activities of antioxidant enzymes, and activities of nonenzyme components. Although all fruit extracts from all the strawberry genotypes inhibited proliferation of A594 cancer cells, fruit extracts from seven F. virginiana genotypes showed significantly greater antiproliferative effects than any of the F. xananassa or F. chiloensis genotypes. These genotypes, CFRA 0982, JP 95-1-1, NC 95-19-1, RH 30, NC 96-48-1, JP 95-9-6, and LH 50-4, may be especially useful in developing cultivars with greater anticancer potential.
Shiow Y. Wang, U.S. Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Fruit Laboratory, Bldg. 010A, BARC-West, 10300 Baltimore Avenue, Beltsville, MD 20705-2350