Biol. Pharm. Bull. 30(4) 661—666 (2007)

portant role in the development of tissue damage and pathological events in living organisms. Oxidative stress is found to implicate in several cardiovascular diseases, including septic shock, ischemic reperfusion injury, hear failure, atherosclerosis, hypertension and diabetes. Epidemiological studies have shown that dietary intake of polyphenol-rich foods such as fruits and vegetables is inversely associated with the incidence of cardiovascular diseases. Supplementation of antioxidants has been shown to alleviate vascular dysfunction in hemolytic anemia, inflammatory response syndrome, coronary heart disease, hypertension and atherosclerosis. Several population-based studies have suggested that consumption of plants containing bioactive phytochemicals reduces the risk of developing cardiovascular diseases and cancer. The association between risk reduction and intake of dietary herbal plants may be partly explained by the antioxidant protection, however, the mechanisms underlying such protection are not fully understood. Diet rich in bioactive phytochemicals has long been recognized essential to maintaining healthy body systems. A large number of plant species which are important source of traditional medicine are widely cultivated throughout the kingdom of Thailand. Many of them are used as dietary plants in Southeast Asian countries and claimed for health promotion in traditional medicine. This work describes the ethnopharmacological activity of the three popular dietary and herbal plants, including Cratoxylum formosum (Guttiferae), Syzygium gratum (Myrtaceae), and Limnophila aromatica (Scrophulariaceae). The selected plants are mostly grown in the Northeast of Thailand and commonly consumed in daily diet. The plants are used in Thai traditional medicine as herbal remedies for the treatments of dyspepsia, indigestion, peptic ulcer, diarrhea, bacterial infection, inflammation, asthma, blood disorders, and cardiovascular disease. To date, there are very limited scientific evidences supporting these health benefits beyond their nutrient contributions. It is, therefore, still required to verify their biological effects. Previous studies of these plants demonstrated some active compounds. The main compound in C. formosum is identified as chlorogenic acid which comprises 60% of the alcoholic extracts and follows by dicaffeoylquinic acid and ferulic acid derivatives. L. aromatica contains several flavonoids, such as nevadensin, nevadensin-7-O-b glycopyranoside, gardenin B and other flavones, which are polyphenolic compounds with antioxidant activity. Although there is no report about active compounds in S. gratum, several plants from Syzygium species contain high total phenolic contents, such as gallic acid, proanthocyanidins, and conjugated flavonoids, which suggest they are rich sources of antioxidant compounds. Previous studies on biological activities of C. formosum, S. gratum and L. aromatica demonstrated that the crude extracts from these plants possess antimutagenic, antibacterial, and antioxidant properties. However, scientific data supporting the antioxidant activity relating with cardiovascular diseases of these plants are still lacking. The present study was designed to investigate the antioxidant and vascular protective properties of the three Thai herbal plant extracts in both in vitro and in vivo animal model of phenylhydrazine (PHZ)-induced oxidative stress and vascular dysAntioxidant and Vascular Protective Activities of Cratoxylum formosum, Syzygium gratum and Limnophila aromatica