Preliminary Study On The Supercritical Extraction Process Of Bitter Melon Seed Oil And Its Effects And Mechanisms Of Anti-obesity

Bitter melon is a kind of medicinal and edible food, which is widely consumed in Asia. It is well known for its obvious anti-obesity effect. Bitter gourd seed was gradually got attention as people are interested in the content of unsaturated fatty acids in the diet. Although bitter melon seed oil has been reported to promote lipid metabolism, but the mechanism remains unclear, especially the central nervous regulating mechanism.The shelling bitter seeds were used in this study. We applied supercritical CO2 fluid extraction technology to extract oil and optimize the extraction conditions. UV spectrum scanning, thin layer chromatography and gas chromatography-mass spectrometry techniques were used to determine the composition of fatty acid. Furthermore, the obesity model was established in C57BL/6J mice feeding with high-fat diet (HFD). Then the mice were treated with BMSO at the dosages of 1 g/kg,5 g/kg,10 g/kg by intragastric administration. The effects of bitter melon seed oil on peripheral related indicators were studied by the measurement of body weight, lipid-related ingredients, fat and liver circumstances. In addition, Western Blot and Golgi-Cox assays were used to study the effect of bitter melon seed oil on mTOR-related signals and the structure and function of neurons in hypothalamus. In terms of preliminary elucidate the mechanism of bitter melon seed oil on energy metabolism. The results are as follows:1. The optimum extraction of bitter melon seed oil by supercritical CO2 fluid was 25MPa,50℃ with 100min under the same particle size of material and the flow of CO2, and the extraction rate was 36.1% under such condition. The results of UV spectrum scanning and TLC analysis revealed the presence of conjugate unit with less impurities. The composition of fatty acid in bitter melon seed oil, which was measured by GC-MS, was 61.65% of conjugated linolenic acid,19.59% of stearic acid,9.54% of oleic acid,6.67% of linoleic acid and others.2. High-fat diet could increase body weight, reflected as lee’s index increased significantly. What’s more, there showed significantly increase in food intake, serum total cholesterol, low-density lipoprotein and the size of fat cells, while the content of free fatty acid decreased. Increased body fat leaded to an increase in serum leptin. Bitter melon seed oil of high dose (lOg/kg) significantly improved the intake of the above changes caused by high-fat diet. The periphery index showed that bitter melon seed oil has the effect of anti-obesity.3. High-fat diet could increase the expression of NMDA-2B receptors in hypothalamus, indicating that high-fat diet could affect synaptic transmission from a certain extent. But bitter melon seed oil didn’t eliminate the impact of high-fat foods at this point. At the same time, high-fat diet could increase the phosphorylation of ribosomal protein S6 in hypothalamus, and bitter melon seed oil could change this influence. This indicated that the effect of bitter melon seed oil on the regulation of energy metabolism might be associated with mTOR signaling pathway. In addition, the results of Golgi-cox staining showed that high-calorie food could decrease spine density, while bitter melon seed oil could increase the density of dendritic spines. This phenomenon reveals the improvement of bitter melon seed oil on the structure of neurons. Structure determines function, it also potentially explains the beneficial effects of bitter melon seed oil on neurons’function.In summary, bitter melon seed oil extracted by supercritical CO2 fluid contains large amounts of unsaturated fatty acids, which has the physiological role of regulating energy metabolism without changing the diet. This process involves the changes of signals in periphery, and ultimately regulated by central nervous system, especially the mTOR signaling pathway. In addition, bitter melon seed oil can affect the structure and function of neurons.