| Berberine (BBR) is an isoquinoline alkaloid. It was mainly used for the treatment of gastroenteritis and bacillary dysentery. BBR has been widely used in clinical practice for the last few years. Highly antihyperglycemic activity of BBR on Type 2 Diabetes Mellitus patients was revealed by massive experiments and clinical investigations. Reported in the investigations:In additional to its effects of blood glucose and lipids regulating, insulin secretion promoting and insulin resistance improving,BBR can also block the intestinal absorption of sugar. But BBR showed very low absorption in intestine and high dose (up to 3g/d) on clinical practice as an oral antihyperglycemic drug. It was discovered that 8- hydroxyl substituted compound (BBRH) which was modified by BBR was significantly superior to BBR (p <0.05) on treating diabetic rat models. And the dose of BBRH group was lower than BBR group an order of magnitude (respectively,16.32,187mg·kg-1·d-1). By comparing the intestinal absorption of BBRH and BBR as well as their influences on the intestinal absorption of sugar, the mechanism of BBRH's low-dose and high activity would be revealed in this experiment. The acute toxicity of BBRH was also carried out, and the LD50 of BBRH was determinated to investigate the perspective for the R&D of BBRH. The main research was summarized as follows:1. Study on the intestinal absorption of BBRH and BBR in ratsThe absorption of BBRH and BBR in intestine was investigated by in situ perfusion model, HPLC as an analysis method was used to determine the concentrations of BBRH and BBR. The results showed that the absorptivity of BBR in small intestine was below 10% ,the rate of absorption constants of BBR at concentration of 5,10 and 20μg?mL-1 were (0.0306±0.0016) h-1,(0.0317±0.0081) h-1,(0.0314±0.0013) h-1 respectively. The absorptivity of BBR increased with increasing concentration, and the absorptivity of the BBRH at concentration of 5,10μg?mL-1 group were nearly 20 times higher than BBR group. The rate of absorption constants of BBRH at concentration of 5,10,20ug·ml-1 were (0.8803±0.10030) h-1,(0.3998±0.3601) h-1,(0.3957±0.3868) h-1 respectively, which were bigger than each group of BBR an order of magnitude possibly lead to the mechanism of highly antihyperglycemic activity of BBRH. Except that, it was indicated that the absorption of BBRH in intestine has saturation, besides, the passive diffusion mechanism,facilitated diffusion or active transport may also make a role of the transport process.2.The study on the influences to intestinal absorption of sugar of BBRH and BBRIn situ perfusion model was used to study the influences on intestinal absorption of sugar of BBRH and BBR. Glucose oxidase method and UV spectrophotometry were used to determine the concentrations of glucose and sucrose in perfusion fluid. The result showed that BBRH inhibit absorption of glucose in dose-dependent, the area under the curve of control group and each dose group of BBRH were( 368.80±8.37) mM×min,( 349.74±5.38) mM×min,( 379.20±5.87)mM×min,( 388.17±6.56) mM×min, respectively. BBR also inhibit glucose absorption but not in dose-dependent,the area under the curve of control group and each dose group of BBR were(368.80±8.37) mM×min,( 349.74±5.38) mM×min,( 379.20±5.87) mM×min,( 388.17±6.56) mM×min,respectively. Inhibition of sucrose absorption by BBRH was also dose-dependent,the area under the curve of control group and each dose group of BBRH were:(343.11±8.14)mM×min,(349.50±2.21)mM×min,(393.27±3.24)mM×min,(409.3±2.81)mM×min,respecively. BBR inhibit sucrose absorption in dose-dependent. the area under the curve of control group and each dose group of BBR were(320.70±7.933)mM×min,(359.80±10.27)mM×min,( 362.00±5.32)mM×min,( 369.3±6.49)mM×min,respectively.3 .The acute toxicity of BBRHWhile BBRH with a high rate of absorption and its inhibition of sugar in intestine was clarified, acute toxicity of BBRH was carried out and its LD50 was determinated. The LD50 of BBR was 741.31mg˙kg-1, its 95℅confidence interval was 300.61 mg˙kg-1 to 1819.7 mg˙kg-1. The LD50 of BBR was 392 mg˙kg-1. So the toxicity of BBRH was significantly less than that of BBR.Generally speaking,the absorptivity of BBRH was more than 70%, which was higher than that of BBR. Besides, the absorptivity of the BBRH at concentration of 5,10μg·mL-1 were nearly 20 times higher than that of BBR. It would be revealed that the mechanism of BBRH had a chracteristic of low-dose and high activity. On one hand,BBRH absorbed more easily in the body to show a highly antihypoglycemic effect; on the other hand,they both had a certain degree of inhibition of intestinal absorption of sugar.The mechanism of high antihypoglycemic activity in vivo remained a further study. By combining the results of acute toxicity test,it was preliminary indicated that BBRH had a broad development prospective because of its advantages of low dose,high efficacy and low toxicity.
|
PDF Full Text Request