Adebajo A C, Olawode E O, Omobuwajo O R, Adesanya S A, Begrow F, Elkhawad A, Akanmu M A, Edrada R, Proksch P, Schmidt T J, Klaes M, Verspohl E J
Department of Pharmacognosy, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria.
Planta Med. 2007 Mar;73(3):241-50. doi: 10.1055/s-2007-967125. Epub 2007 Feb 22.
The aqueous infusion (tea) of Stachytarpheta cayennensis leaves is used ethnomedically in Peru, Nigeria and other tropical countries for the management of diabetes. Oral administration (p. o.) of aqueous (125 mg/kg) and methanolic (2000 mg/kg) extracts of the leaves to alloxan-diabetic rats showed significant blood glucose reductions by 43 and 53%, respectively, at the end of a 4 hour period similar to the strong effect of glibenclamide (5 mg/kg, P. O.). The methanolic extract was successively partitioned into ethyl acetate, butanol and water fractions, and the same test showed that the butanol fraction (2000 mg/kg) had the highest (50%) hypoglycaemic activity at 4 hours after oral administration. It was also the most active fraction when tested in vitro [insulin release from an insulin secreting cell line (INS-1)] and was also active in normal rats and rats made hyperglycaemic by a glucose load. Its activity was comparable to that of glibenclamide (positive control) in these models. This active butanol fraction was subjected to chromatographic subfractionation; some subfractions reduced hyperglycaemia in alloxan-diabetic rats to 60 and 78% and induced insulin release from the INS-1 cells; other subfractions, however, gave hyperglycaemic activities IN VIVO and inhibition of insulin release from the INS-1 cells. Three major compounds of the butanol fraction were isolated and characterised as 6beta-hydroxyipolamide, ipolamide and isoverbascoside; they increased insulin secretion from INS-1 cells to 125, 128 and 127%, respectively, whereas glibenclamide increased insulin secretion to 157%. The results justify the ethnomedical use of the plant in the management of diabetes and suggest that the butanol fraction and some of its isolated constituents mediate their actions primarily by stimulating insulin release directly.
在秘鲁、尼日利亚和其他热带国家，人们在民族医学中使用假马鞭草叶的水浸剂（茶）来治疗糖尿病。给四氧嘧啶诱导的糖尿病大鼠口服叶的水提取物（125毫克/千克）和甲醇提取物（2000毫克/千克），在4小时结束时，血糖分别显著降低了43%和53%，这与格列本脲（5毫克/千克，口服）的强效作用相似。甲醇提取物依次被分离成乙酸乙酯、丁醇和水部分，同样的试验表明，丁醇部分（2000毫克/千克）在口服给药4小时后具有最高的（50%）降血糖活性。在体外试验[从胰岛素分泌细胞系（INS-1）释放胰岛素]中，它也是最具活性的部分，并且在正常大鼠和葡萄糖负荷诱导的高血糖大鼠中也有活性。在这些模型中，其活性与格列本脲（阳性对照）相当。对这个活性丁醇部分进行色谱亚分馏；一些亚分馏物使四氧嘧啶诱导的糖尿病大鼠的高血糖降低到60%和78%，并诱导INS-1细胞释放胰岛素；然而，其他亚分馏物在体内具有高血糖活性，并抑制INS-1细胞释放胰岛素。从丁醇部分分离并鉴定出三种主要化合物，分别为6β-羟基异波拉酰胺、异波拉酰胺和异毛蕊花糖苷；它们分别使INS-1细胞的胰岛素分泌增加到125%、128%和127%，而格列本脲使胰岛素分泌增加到157%。这些结果证明了该植物在糖尿病治疗中的民族医学用途，并表明丁醇部分及其一些分离成分主要通过直接刺激胰岛素释放来发挥作用。
