Nalamolu Koteswara Rao, Nammi Srinivas
Pharmacology Division, GITAM Dental College, Visakhapatnam 530045, Andhra Pradesh, India.
BMC Complement Altern Med. 2006 May 7;6:17. doi: 10.1186/1472-6882-6-17.
Terminalia chebula (Combretaceae) has been widely used in Ayurveda for the treatment of diabetes. In the present investigation, the chloroform extract of T. chebula seed powder was investigated for its antidiabetic activity in streptozotocin-induced diabetic rats using short term and long term study protocols. The efficacy of the extract was also evaluated for protection of renal functions in diabetic rats.
The blood glucose lowering activity of the chloroform extract was determined in streptozotocin-induced (75 mg/kg, i.p.; dissolved in 0.1 M acetate buffer; pH 4.5) diabetic rats, after oral administration at the doses of 100, 200 and 300 mg/kg in short term study. Blood samples were collected from the eye retro-orbital plexus of rats before and also at 0.5, 1, 2, 4, 6, 8 and 12 h after drug administration and the samples were analyzed for blood glucose by using glucose-oxidase/peroxidase method using a visible spectrophotometer. In long term study, the extract (300 mg/kg) was administered to streptozotocin-induced diabetic rats, daily for 8 weeks. Blood glucose was measured at weekly intervals for 4 weeks. Urine samples were collected before the induction of diabetes and at the end of 8 weeks of treatments and analyzed for urinary protein, albumin and creatinine levels. The data was compared statistically using one-way ANOVA with post-hoc Dunnet's t-test.
The chloroform extract of T. chebula seeds produced dose-dependent reduction in blood glucose of diabetic rats and comparable with that of standard drug, glibenclamide in short term study. It also produced significant reduction in blood glucose in long term study. Significant renoprotective activity is observed in T. chebula treated rats. The results indicate a prolonged action in reduction of blood glucose by T. chebula and is probably mediated through enhanced secretion of insulin from the beta-cells of Langerhans or through extra pancreatic mechanism. The probable mechanism of potent renoprotective actions of T. chebula has to be evaluated.
The present studies clearly indicated a significant antidiabetic and renoprotective effects with the chloroform extract of T. chebula and lend support for its traditional usage. Further investigations on identification of the active principles and their mode of action are needed to unravel the molecular mechanisms involved in the observed effects.
诃子（使君子科）在阿育吠陀医学中已被广泛用于治疗糖尿病。在本研究中，采用短期和长期研究方案，对诃子种子粉末的氯仿提取物在链脲佐菌素诱导的糖尿病大鼠中的抗糖尿病活性进行了研究。还评估了该提取物对糖尿病大鼠肾功能的保护作用。
在短期研究中，以100、200和300mg/kg的剂量口服给药后，测定链脲佐菌素诱导（75mg/kg，腹腔注射；溶解于0.1M醋酸盐缓冲液；pH4.5）的糖尿病大鼠中氯仿提取物的降血糖活性。在给药前以及给药后0.5、1、2、4、6、8和12小时，从大鼠眼眶后静脉丛采集血样，并使用可见分光光度计通过葡萄糖氧化酶/过氧化物酶法分析血样中的血糖。在长期研究中，将提取物（300mg/kg）给予链脲佐菌素诱导的糖尿病大鼠，每日给药，持续8周。在4周内每周测量一次血糖。在糖尿病诱导前以及治疗8周结束时收集尿样，并分析尿蛋白、白蛋白和肌酐水平。使用单因素方差分析和事后Dunnet t检验对数据进行统计学比较。
诃子种子的氯仿提取物使糖尿病大鼠的血糖呈剂量依赖性降低，在短期研究中与标准药物格列本脲相当。在长期研究中，它也使血糖显著降低。在诃子治疗的大鼠中观察到显著的肾脏保护活性。结果表明诃子降低血糖的作用具有持久性，可能是通过增强胰岛β细胞分泌胰岛素或通过胰腺外机制介导的。诃子强大的肾脏保护作用的可能机制有待评估。
本研究清楚地表明诃子氯仿提取物具有显著的抗糖尿病和肾脏保护作用，支持了其传统用途。需要进一步研究确定其活性成分及其作用方式，以阐明所观察到的效应背后的分子机制。
