|QI, JING - Jiangnan University|
|LI, YUE - Jiangnan University|
|MASAMBA, KINGSLEY - Jiangnan University|
|Yokoyama, Wallace - Wally|
|ZHONG, FANG - Jiangnan University|
|MA, JIANGUO - Jiangnan University|
Submitted to: Journal of Functional Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2015
Publication Date: 9/4/2015
Citation: Qi, J., Li, Y., Masamba, K.G., Yokoyama, W.H., Zhong, F., Ma, J. 2015. Cellulosic fraction of rice bran fibre alters the conformation and inhibits the activity of porcine pancreatic lipase. Journal of Functional Foods. doi: 10.1016/j.jff.2015.09.012.
Interpretive Summary: Population studies indicate that cereal fiber intake reduces risk of diabetes and cardiovascular disease. Cereal fibers are mainly insoluble fiber and are generally considered more biologically inert than soluble fibers. In this study we show that rice bran fiber prepared by acid treatment inhibits pancreatic lipase, the enzyme responsible for fat digestion. Pancreatic lipase binds to the fiber and its conformation is changed by binding.
Technical Abstract: The anti-lipase properties of insoluble dietary fiber obtained from rice bran treated with H2SO4 followed by 1.25% KOH were investigated and compared. Porcine pancreatic lipase (PL) adsorbed with higher velocity and saturated at a higher level on the rice bran fibers prepared with higher concentrations of acid, at the same lipase concentration, which was explained by the increased porosity and hydrophobicity of RBIDF-2.0 surface. The variation in decreased specific activity of adsorbed and unabsorbed PL was found independent of the PL amount but mainly dependent on the major conformational deformations of PL which was confirmed by circular dichroism (CD). The highest PL activity inhibitory efficiency of rice bran fiber decreased linearly with the increment of PL concentration to fiber amount ratio, which indicated that the anti-lipase effect of RBIDF was inverse with the PL concentration. Fluorescence spectroscopy revealed that the binding of PL to fiber mainly depends on hydrophobic and electrostatic interactions and the binding process is spontaneous and exothermic.