Synthesis And Anti-obesity Effect Of 8-Alkyl-Berberine

Obesity is a chronic metabolic disease characterized by high body mass index and fat deposition, which is induced by increasing volume and number of body fat cells. Due to modern life style and eating habits, obesity is becoming a global disaster associated with various metabolic disorders such as type II diabetes, cardiovascular disease, and non-alcoholic fatty liver disease. Numerous studies have shown that obesity is the result of complex interactions between genetic and environmental factors which are only partially understood. Many factors could lead to obesity, such as:diet, genetics, lack of exercise, and other neurological factors. A series of studies in mice fed with high-fat diet found that there was a mutual influence between intestinal microflora and status of obesity with low inflammatory. However, the endotoxin produced by gut microbial metabolism is a key factor for causing inflammation in the body. In clinical, there are two ways to lose weight those are appetite and fat sbsorption suppression. Appetite suppressed by neural is inhibited due to its serious side effects. So it is urgent to develop a new drug with smaller toxicity and anti-obesity activity. Berberine is a major active ingredient in Rhizoma Coptidis (Huang Lian), which is widely used as a traditional Chinese medicine to treat diseases induced by inflammation or bacterial. Recently, berberine has gained great attention because of its variety of bioactivities, and demonstrated as a potential treatment for obesity, cancer, diabetes, hyperlipaemia, bacterial, inflammation. Studies on anti-obesity effect of berberine have reported several potential mechanisms, including inhibition the adipogenic enzyme expression and adipogenesis during the differentiation of 3T3-L1 pre-adipocytes, targeting of IkB kinase beta (IKKβ), decreasing peroxisome proliferator-activated receptor-y (PPAR-y) expression, inducing glycolysis, activating AMP activated protein kinase (AMPK), promoteing the expression of adiponectin, and reducing the level of leptin. Researches have revealed that Berberine blocked the transcription factor NF-κB signaling pathway whose activity is triggered in response to infectious agents and pro-inflammatory cytokines via the IKKβ. The activation of NF-κB triggers an outbreak of inflammatory cytokines which in turn have synergistic interaction with LPS to upregulate the expression of TLR4. However, berberine is greatly restricted by its poor intestinal absorption and high toxicity. Integrating long carbon-chain alkyl groups to berberine at the C-8 position may help to improve the bioavailability of berberine. Our previous studies have found that 8-alkyl-berberine derivatives could increase the activity of anti-microbial, and the activity rose with carbon chain elongation. Therefore, in the current study, the main purpose is to explore whether there is a potential anti-obesity activity and mechanism in golden hamster treated with 8-alkyl-berberine derivatives.The following is the main contents and results of this project:(1) Preliminary evaluation of anti-obesity activities of 8-alkyl-berberine derivatives was explored on hamsters fed with high-fat diet. The results show that high-fat or high-calorie diet promotes an excessive accumulation of fat in hamsters, and increases triglyceride levels. Besides, high-fat or high-calorie diet promotes an excessive accumulation of serum LPS in hamsters. Berberine derivatives reduced triglycerides and body weight, and 8-hexadecyl-berberine has the most obvious effect of this reduction on hamsters.(2) In experiments for exploring the anti-obesity activity of 8-hexadecyl-berberine on hamster fed with high-fat diet, it found that 8-hexadecyl-berberine reduced the body weight gain in a dose-dependent relationship after 12 weeks. Compared to 40 times dose of berberine,8-hexadecyl-berberine reduced more weight in hamsters. In addition, 8-hexadecyl-berberine has a significant effect in control liver weight and epididymal fat.(3) In experiments for exploring the anti-obesity activity of 8-hexadecyl-berberine on hamster fed with high-fat diet, it found that 8-hexadecyl-berberine had no effect on food intake compared to high-fat diet group. It means that 8-hexadecyl-berberine has no significant neural inhibition on hamsters.(4) In experiment for assessing intestinal permeability in hamsters by indicating the value of lactulose/mannitol in urine. We found that the value of lactulose/mannitol in high-fat diet group was higher compared to normal control group. It meant that high-fat diet significantly increased the permeability of intestinal mucosa in hamsters. Under the treatment with 8-hexadecyl-berberine, the value of lactulose/mannitol in hamsters was decreased in dose-dependently way compared to high-fat diet group. It demonstrated that 8-hexadecyl-berberine had a positive activity to reduce the permeability of intestinal mucosa induced by high fat diet.(5) Real-time quantitative PCR and ELISA were used to detect mRNA expression and protein expression of the endotoxin and lipid metabolism-related enzyme genes. Compared to normal control group, the levels of serum LPS, LBP, TNF-α, IL-6, leptin were higher in high-fat diet group. In addition, high-fat diet increased the levels of CD 14, TLR4 in liver, which is required for the signal recognition and transmembrane of LPS. This data showed that high-fat diet could promote the body’s inflammatory response. Compared to high-fat diet group, the results showed that,8-hexadecyl-berberine reduced the levels of serum LPS, LBP, TNF-a, IL-6, leptin, CD14 and TLR4 in liver. Besides, it showed a strong lowering effect on mRNA expression of CD 14, TLR4 in liver in a dose-dependent manner. However, the level of adiponectin in serum increased when treated with 8-hexadecyl-berberine, but there was no significantly effect on expression of intestinal lipase.In conclusion,8-hexadecyl-berberine owned an anti-obesity activity was confirmed in Syrian golden hamsters. Its mechanism may be improving the state of inflammation in hamsters. However,8-hexadecyl-berberine inhibited inflammation mainly by inhibiting transportation, signal recognition and transmembrane of LPS, reducing the secretion of inflammatory cytokines such as TNF-α、IL-6、leptin, increasing the expression of anti-inflammatory adipokine such as adiponectin. Taken all data together, these results suggest that 8-hexadecyl-berberine may be good candidate for development as promising agent for obesity.