Antidiabetic effect of Nitobegiku, the herb Tithonia diversifolia, in KK-Ay diabetic mice.

Nitobegiku (the herb of Tithonia diversifolia (HEMSL) A. GRAY) has been used as a medicinal plant for diabetes. The antidiabetic effect of an 80% ethanol extract of Nitobegiku (Td) was investigated in KK-Ay-mice, an animal model of type 2 diabetes. Td (500 mg/kg body weight) reduced the blood glucose of KK-Ay mice 7 h after a single oral dose. No change in blood glucose in Td-treated normal mice (ddY) was seen. Td (500 mg/kg) reduced blood glucose in KK-Ay mice 3 weeks after a single oral dose and also significantly lowered plasma insulin in KK-Ay mice under similar conditions. Td-treated KK-Ay mouse blood glucose was significantly decreased in an insulin tolerance test. These results support the hypothesis that Td improves glucose metabolism by reducing insulin resistance. Therefore, Nitobegiku may be useful for the treatment of type 2 diabetes.