‘宁紫薯1号’花青素组分鉴定及其对大鼠高脂诱导肥胖的预防效果

【目的】紫甘薯是天然抗氧化物花青素的重要来源。鉴定‘宁紫薯1号’花青素(PSPC)组成成分,探索紫甘薯花青素对高脂诱导肥胖的预防效果并探讨其分子机制。【方法】通过液质联用技术分析紫甘薯新品种‘宁紫薯1号’的花青素组分;采用p H示差法测定制备的样品中总花青素含量。建立因高脂摄入过多导致机体产生营养性肥胖的动物模型,并灌胃不同剂量的紫甘薯花青素比较其预防肥胖效果。每周定时测量大鼠禁食6 h后的体重,通过试剂盒检测大鼠血清样品血糖(Glu)、甘油三酯(TG)、总胆固醇(TC)的含量,采用酶联免疫法检测瘦素(Leptin)含量。通过荧光定量PCR法(RT-PCR)检测下丘脑样品瘦素及其受体的m RNA表达,采用蛋白质免疫印迹法(Western blot)检测瘦素及其下游蛋白的信号表达。【结果】分离鉴定出11种PSPC组分,其中10种为已知的矢车菊素和芍药素酰基化衍生物,峰1为新发现的1种化合物。制备的花青素样品中矢车菊素-3-葡萄糖苷含量为17.4%。体重指标直接表明高剂量花青素组预防肥胖效果最好,为(358.2±20.1)g,中剂量组其次,为(371.6±16.3)g;效果最差的为低剂量组,体重为(384.0±7.2)g。紫甘薯花青素各剂量组大鼠血糖、甘油三酯和总胆固醇的3项血生化指标均趋于正常水平,有效预防肥胖的发生。血清瘦素检测结果显示,高脂组比对照组多释放65.50%;低剂量、中剂量和高剂量紫甘薯花青素组血清瘦素含量分别为(3.13±0.05)、(2.84±0.12)和(2.64±0.06)ng·m L~(-1),与高脂组相比均显著下降。同时不同剂量紫甘薯花青素组下丘脑中瘦素及瘦素受体的m RNA表达均显著高于高脂组。而高剂量紫甘薯花青素组可以调节下丘脑中瘦素信号,从而降低下游腺苷酸活化蛋白激酶α(AMPKα)的磷酸化。【结论】高剂量紫甘薯花青素可以通过调节下丘脑中leptin/AMPKα信号通路有效抑制高脂诱导肥胖的形成。

Identification of Purple Sweet Potato Color of Cultivar Ningzi No. 1 by HPLC-QTOF/MS and Its Effect on Preventing Obesity in High-Fat-Diet-Treated Rats

【Objective】Purple sweet potato are the main source for natural antioxidants. This study aims to identify the components of purple sweet potato color of cultivar Ningzi No. 1, and investigate the effectiveness of PSPC for the prevention of obesity and the regulatory mechanism of PSPC in obesity prevention.【Method】 Purple sweet potato color was analyzed using an Agilent 1290 series high-performance liquid chromatography connected to an Accurate-Mass Quadrupole Time-of-Flight/MS (HPLC-QTOF/MS). A pH-differential method was used to determine the total PSPC content. Eight-week-old male Sprague Dawley strain rats were fed on either a normal diet containing 11.4% fat, or a HFD containing 40% fat and intragastrically administered PSPC once a day. Body weights of the rats were measured every week after 6 h of fasting. Activities of serum glucose, triglyceride, and total cholesterol were determined using commercial kits. Serum leptin levels were measured using enzyme-linked immunosorbent assay kits. Expression of leptin and leptin receptor mRNAs in the hypothalamus were detected using Real-time Quantitative PCR. Expression of leptin and its downstream proteins in the hypothalamus were analyzed using Western blotting.【Result】Eleven constituents were separated. Based on previous reports, ten constituents were identified and Peak 1 was newly reported herein. The cyanidin 3-glucoside content of PSPC was 17.4%. After 6 weeks, we first examined the changes in body weight. Our data showed that the effect of middle-dose PSPC (371.6±16.3) g was better than low-dose PSPC (384.0±7.2) g, and the effect of high-dose PSPC (358.2±20.1) g was best. Obesity was prevented and glucose, triglyceride, and total cholesterol induced by the HFD were restored to near-normal levels. Compared with control group rats (2.29±0.28) ng·mL^-1, the levels of serum leptin in HFD group rats significantly increased by 65.50%. Compared with HFD group rats (3.79±0.24) ng·mL^-1, the levels of serum leptin in low (3.13±0.05) ng·mL^-1, middle (2.84±0.12) ng·mL^-1, and high-dose (2.64±0.06) ng·mL^-1 PSPC group rats were significantly decreased. Both of leptin and leptin receptor mRNAs expression in the hypothalamus was upregulated in the different-dose PSPC group compared with that in the HFD group. High-dose PSPC preserved the leptin signaling capability, leading to a decrease in hypothalamic AMPK α activity.【Conclusion】The anti-obesity effects of high-dose PSPC were mediated via a regulation of leptin/AMPKα signaling in the hypothalamus.