Methods: Water-soluble vegetable extracts were screened for various types of functionality such as antioxidant action, the inhibition of platelet aggregation, blood coagulation, and the enzymatic actions of α-glucosidase and pancreatic lipase. Antioxidant activity was measured as the ability to scavenge 1,1-diphenyl-2-picrylhydrazine (DPPH) radicals and the inhibitory activity of rat intestinal α-glucosidase was evaluated by measuring amounts of glucose produced from maltose. Lipase activities were measured using porcine pancreatic lipase and synthetic substrate. Platelet aggregation was measured using bovine whole blood stimulated with collagen. Plasma coagulation activities were measured using human plasma. Coagulation was initiated using intrinsic and extrinsic coagulation initiators and coagulation times were measured using a coagulometer. 

Results: All extracts from cabbage, onion, eggplant, tomato, green pepper, Japanese radish, and Chinese cabbage and their cultivars exerted antioxidant activities. All vegetable extracts had weak α-glucosidase inhibitory activity, but one Chinese cabbage cultivar had significantly more of such activity. All vegetable extracts had very weak ability to inhibit pancreatic lipase and did not inhibit platelet aggregation or affect intrinsic and extrinsic blood coagulation activity. 

Conclusion: Although further investigations are needed, the present findings provide fundamental information about the functionality of some vegetables consumed in Japan.