荷叶总生物碱降脂减肥作用的体内外试验

Effect of total alkaloids from lotus leaves on body mass and lipid regulation in vivo and in vitro

通过体内、体外试验探究荷叶总生物碱的降脂减肥作用.给予高脂血症大鼠模型组不同剂量荷叶总生物碱和降脂药物辛伐他汀(阳性药物对照组),观察荷叶总生物碱对高脂血症大鼠体质量、体脂以及血清脂质相关指标的影响;用对硝基苯酚法检测不同质量浓度荷叶总生物碱处理对大鼠胰脂肪酶活性的影响.结果显示:荷叶总生物碱能显著降低高脂血症大鼠的体质量,显著降低血清总胆固醇、血清甘油三酯、低密度脂蛋白胆固醇含量,显著降低谷草转氨酶、谷丙转氨酶活性以及动脉粥样系数,升高高密度脂蛋白胆固醇/血清总胆固醇比值;荷叶总生物碱能抑制脂肪酶活性,抑制类型为非竞争性抑制;在荷叶总生物碱质量浓度为12.5～600μg/mL范围内,对脂肪酶的抑制效果随其质量浓度的增加而增强,在600μg/mL时达到最大抑制率,为25.6%,当荷叶总生物碱质量浓度继续增加时,抑制率趋于平缓,保持在最大值附近.体内、体外试验结果均表明,荷叶总生物碱类物质具有降脂减肥作用,提示其可能具有预防肥胖、调节脂代谢紊乱的功效.

Obesity and disorder of lipid metabolism, also called dyslipidemia, have been one of the most important diseases threating people health worldwide, and is closely connected with hypertension, high serum glucose and other cardiac-cerebral vascular diseases. The high fat diet is the main pathogenic cause of obesity and dyslipidemia, how to regulate blood lipid and control body mass effectively has been hotspots on nutriology research nowadays. Agents from natural products that inhibit fat digestion and absorption are of theoretical benefit in the treatment of obesity and dyslipidemia. Among them, lotus （Nelurnbo nucifera） leaf is a kind of natural plant material used both in food and medicine, which contains multiple useful components. In modern research, scientists found that alkaloids were one of the main bioactive ingredients in them, helping lowing the serum lipid level and controlling body mass. Thus, this study aims to investigate the effect of lotus leaf total alkaloids on the body mass and lipid regulation in in vivo and in vitro experiments, and to find a new potential food additive to prevent effectively obesity from abnormal fat accumulation. Lipid-lowering efficacy in vivo of lotus leaf total alkaloids was determined by animal experiment. After adapting to the feeding environment for 10 days, 30 experimental rats were randomly divided into six experimental groups according to their serum-lipid level and body mass, including general diet group （blank group）, high fat diet with lotus leaf total alkaloid （high, moderate, low doses） groups, positive drug control group and high fat diet group （model group）. Except for the general diet group feeding normal diet, the other five groups were fed high fat diet for 40 d to set up the model of hyperlipidemia rats. Then, the contents of TC （total cholesterol）, TG （triglyceride）, LDL-C （low density lipoprotein-cholesterol）, HDL-C （high density lipoprotein-cholesterol）, the levels of AST （aspartate aminotransferase） and ALT （alanine aminotransferase） in serum were assayed in hyperlipidemia rats which had been fed lotus leaf total alkaloids of 20, 40, 80 mg/（kg, d） and positive drug of 10 mg/（kg, d） simvastatin for another 40 days, respectively. In addition, the body mass and liver mass, body length, tail length were measured. Lipid-lowering efficacy in vitro of lotus leaf total alkaloids was determined by measuring the inhibitory activity against pancrelipase by monitoring the hydrolysis of pNP-b, which released the yellow chromogen p-nitrophenol, and the buffer solution was adjusted to the condition of 37 ℃, pH=7.4. The results showed that, compared with high fat diet group （model group）, the body mass decreased significantly in the high fat diet with lotus leaf total alkaloid （high, moderate, low doses） groups, as well as the Lee＇s index, liver and spleen mass of rats; moreover, the contents of TC, TG, LDL-C, the levels of AST and ALT in serum and atherosclerosis index （AI） were significantly decreased and the ratios of HDL-C/TC and apoAI/apoB increased in the hyperlipidemia rat fed with lotus leaf total alkaloids. The maximum inhibitory rate of lotus leaf total alkaloids of 600 μg/mL against pancrelipase activity was 25.6%. Based on the Linweaver-Burk plots, the lipase inhibitor demonstrated non-competitive inhibition for pancrelipase. It is concluded that the lotus leaf total alkaloids are effective in significant reduction of body mass, body fat and obesity-related body indicators, and can inhibit lipase activity. Also, it is sure that the alkaloids from lotus leaves have potential to prevent effectively obesity from abnormal fat accumulation.