Jin Qiu, Yu Huahua, Wang Xueqin, Li Kecheng, Li Pengcheng
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong, China.
University of Chinese Academy of Sciences, Beijing, China.
PeerJ. 2017 May 3;5:e3279. doi: 10.7717/peerj.3279. eCollection 2017.
Obesity has become a worldwide burden to public health in recent decades. Given that obesity is caused by an imbalance between caloric intake and expenditure, and that dietary fat is the most important energy source of all macronutrients (by providing the most calories), a valuable strategy for obesity treatment and prevention is to block fat absorption via the gastrointestinal pathway. In this study, the fat- and cholesterol-binding capacities and the inhibition of pancreatic lipase by water-soluble chitosan (WSC) with different weight-average molecular weight (Mw) were tested and compared , in order to determine the anti-obesity effects of WSC and the influence of its Mw.
In this study, WSC with different Mw (∼1,000, ∼3,000, ∼5,000, ∼7,000 and ∼9,000 Da) were prepared by oxidative degradation assisted with microwave irradiation. A biopharmaceutical model of the digestive tract was used to determine the fat- and cholesterol-binding capacity of WSC samples. The pancreatic lipase assays were based on p-nitrophenyl derivatives.
The results showed that all of the WSC samples exhibit great fat- and cholesterol-binding capacities. Within the testing range, 1 g of WSC sample could absorb 2-8 g of peanut oil or 50-65 mg of cholesterol, which are both significantly higher than the ability of cellulose to do the same. Meanwhile, all the WSC samples were proven to be able to inhibit pancreatic lipase activity to some extent.
Based on the results, we suggest that there is a significant correlation between the binding capacity of WSC and its Mw, as WSC2 (∼3,000 Da) shows the highest fat- and cholesterol-binding capacities (7.08 g g and 63.48 mg g, respectively), and the binding ability of WSC declines as its Mw increases or decreases from 3,000 Da. We also suggest WSC as an excellent resource in the development of functional foods against obesity for its adsorption, electrostatic binding and entrapment of cholesterol, fat, sterols and triglycerides in the diet.
近几十年来，肥胖已成为全球公共卫生的负担。鉴于肥胖是由热量摄入与消耗之间的不平衡所致，且膳食脂肪是所有宏量营养素中最重要的能量来源（提供的热量最多），通过胃肠道途径阻断脂肪吸收是肥胖治疗和预防的一项重要策略。在本研究中，测试并比较了不同重均分子量（Mw）的水溶性壳聚糖（WSC）的脂肪和胆固醇结合能力以及对胰脂肪酶的抑制作用，以确定WSC的抗肥胖效果及其Mw的影响。
本研究通过微波辐射辅助氧化降解制备了不同Mw（约1000、约3000、约5000、约7000和约9000 Da）的WSC。采用消化道生物制药模型测定WSC样品的脂肪和胆固醇结合能力。胰脂肪酶测定基于对硝基苯基衍生物。
结果表明，所有WSC样品均表现出很强的脂肪和胆固醇结合能力。在测试范围内，1 g WSC样品可吸收2 - 8 g花生油或50 - 65 mg胆固醇，均显著高于纤维素的吸收能力。同时，所有WSC样品均被证明能在一定程度上抑制胰脂肪酶活性。
基于这些结果，我们认为WSC的结合能力与其Mw之间存在显著相关性，因为WSC2（约3000 Da）表现出最高的脂肪和胆固醇结合能力（分别为7.08 g/g和63.48 mg/g），且当Mw从3000 Da增加或降低时，WSC的结合能力下降。我们还建议将WSC作为开发抗肥胖功能性食品的优质资源，因为它能吸附、静电结合并捕获饮食中的胆固醇、脂肪、固醇和甘油三酯。
