| Saponins from Tribulus terrestris L.(STT) at the dose of 100 mg/kg showed a significantly hypoglycemic effect on postprandial glucose levels in both normal and type 2 diabetic rats co-administered orally with 2 g/kg of sucrose, but had no such effect when glucose was administered. This was in quite consistence with that of acarbose, a potent and widely used a-glucosidase inhibitor, which delays the hydrolysis and subsequently retards the absorption of carbohydrate in guts. In vitro, STT dose-dependently inhibited the activity of a-glucosidase extracted from the small intestines of rats. Thus, we come to the putative conclusion that STT has the glycemia-lowing effect on postprandial glucose levels.The medicinal serum of STT, obtained from normal rats orally administered with 100 mg/kg of STT, markedly inhibited the activity of glucose-6-phosphatase extracted from liver of rats. In accordance with this inhibitory effect, in normal and type 2 diabetic rats administered orally with STT for continuous 14 d, the hepatic glycogen content was significantly increased and the fasting glucose levels markedly reduced, and in normal rats, the serum free fatty acid and lactate were markedly elevated. All of this was due to the inhibition of glucose-6- phosphatase actibvity, which reduced the glucose production from liver in both normal and diabetic rats and augmented the lipolysis in normal rats, and led to the accumulation of lactate in normal rats.STT noticeably influenced the lipid metabolism. When administered orally with STT for 14 days, both normal and type 2 diabetic rats showed a significantly lowered serum triglyceride and cholesterol, and the diabetic rats also had a markedly decreased levels of free fatty acid. The reasons for this may be complex, but the underlying contributor may be the improved insulin resistance. It is well known that insulin resistance and hyperglycemia are quite interwoven together, and although insulin resistance governs the hyperglycemia, chronic hyperglycemic state can also further worsen the former and the reduced glycemia can lead to the improved insulin resistance. Therefore, in the STT-administered diabetic rats improved glycemia gave rise to the improved insulin resistance, which then further improved glucose and lipid metabolism.we summarize our understandings about the mechanism by which STT modulate the metabolism of carbohydrate and lipid in diabetic rats as follows: (1)Inhibitingα-glucosidase and reducing postprandial glucose; (2) Inhibiting hepatic glucose-6-phosphatase and reducing glucose production from liver; (3)Augmenting anti-oxidation and protecting islet cells; (4) Improving insulin resistance resulting from the interactions of the effects mentioned above and further improving carbohydrate and lipid metabolism through the improved insulin resistance.Then, the resourses of Ying-Ji-Li (Tribulus terrestris L.) and Ruan-Ji-Li(Atriplex centralasiatica Iljin) were investigated both on their species and chemicals.Ying-Ji-Li, the dried ripe fruits of Tribulus terrestris L. has long been used in traditional Chinese medicine with no avowed genuineness among different sources. Based on the profile of chemical constituents obtained with high performance liquid chromatography and multi-wave length scanning, the chemical constituents of fruit of Tribulus terrestris collected from Xinjiang, Hebei, Shandong, Heilongjiang, Fujian and Yunnan provinces were fuzzily clustered using three different methods, and the fuzzy-setting results indicated that the chemical constituents of fruit of Tribulus terrestris in six provinces belong to the same class with a confidence level of above 0.95, which strongly suggests that there are very small differences between the chemical constituents of the fruits of Tribulus terrestris from six provinces. At the same time, the sequences of rDNA-ITS of Tribulus terrestris from six provinces were obtained using PCR and showed no differences. Taken into account the large distances of the six regions, Tribulus terrestris distributed in China may have no difference both in chemicals and in species. The different parts of Tribulus terrestris were also fuzzily clustered based on the chemical constituents profile obtained with high performance liquid chromatography and multi-wave length scanning, and the results showed that the fruit, stem, leaf and root were set into the same class with a confidence level of about 0.80, while fruit and shoot were put into one class with a confidence level of about 0.98. The results suggest that the fruit and shoot may have the same chemical constituents and they may be used alternatively in clinical use.The fruits of Atriplex centralasiatica Iljin, known as Ruan-Ji-Li, are often used in place of or mistaken for the fruits of Tribulus terrestris in clinics in some regions such as Shandong and Hebei probvinces. When fuzzily clusterde based on the chemical constituents profile obtained with high performance liquid chromatography and multi-wave length scanning, they belonged to the same class with a confidence level of about 0.80, which indicated that the fruits of Atriplex centralasiatica Iljin and Tribulus terrestris may have most common chemicals and thereby can be used alternatively in clinics. Furthermore, the sequences of rDNA-ITS of Tribulus terrestris and Atriplex centralasiatica Iljin were obtained and they showed much large diversities which, as well as the ITS sequence itself, guarantee a DNA fingerprint for identification of Atriplex centralasiatica Iljin and Tribulus terrestris.The primary results about the resources of Ying-Ji-Li and Ruan-Ji-Li were summarized as follows: (1) The fruits of Ying-Ji-Li from different regions in China belong to the same species; (2) The chemicals in the fruits and the airal part of Ying-Ji-Li have few differences; (3) The chemicals in the fruits of Ying-Ji-Li and Ruan-Ji-Li have few differences; (4) All of the diversities of ITS sequences, as well as the ITS sequences per se, guarantee a DNA fingerprint for distinguishing Ying-Ji-Li from Ruan-Ji-Li.
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