Pancreatic lipase activity in vitro

Fig. (6) Effects of the aqueous extract of Platycodi radix and inulin isolated from the aqueous extract of Platycodi radix on pancreatic lipase activity in vitro. Results are expressed as mean + s.e.m. of four experiments.

FIGURE 15.1 Effect of non-shaved kombu (NSK) and tororokombu (TK) on pancreatic lipase activity in vitro. Pancreatic lipase (from porcine) activity was measured using a Lipase Kit S according to the manufacturer s protocoL Data are presented as the mean SE (n = 5). p < 0.05, p < 0.005 versus control p < 0.05 NSK versus TK. 

Pancreatic lipase is a key enzyme for TAG absorption and many studies have associated polyphenols with lipase inhibition. Sugiyama et al. (2007) showed that oligomeric apple procyanidins had an inhibitory effect on pancreatic lipase activity in vitro which was higher than other polyphenolic compounds of an apple extract. These results were also confirmed in both an animal and a human study where oligomeric apple procyanidins inhibited postprandial TAG absorption. ... 

Within the small intestine, bile-acid binding interferes with micelle formation. Nauss et al. [268] reported that, in vitro, chitosan binds bile acid micelles in toto, with consequent reduced assimilation of all micelle components, i.e., bile acids, cholesterol, monoglycerides and fatty acids. Moreover, in vitro, chitosan inhibits pancreatic lipase activity [269]. Dissolved chitosan may further depress the activity of lipases by acting as an alternative substrate [270]. 

Pancreatic preparations have been widely used as digestive aids, because they contain proteases, amylase and lipase. They have been prescribed for patients who have pancreatic disorders or after removal of the pancreas. The various activities present in the pancreatic preparations can be duplicated by in vitro methods from blends of microbial enzymes derived from Bacillus subtilis, Aspergillus flavus-oryzae and Aspergillus niger. Cellulase derived from Aspergillus niger is often added to the microbial preparation. The pancreatic preparations still hold the major share of the market, but this could be a useful application for the right combination of microbial enzymes. 

Much of our information about lipases comes from studies on the enzyme isolated from pancreatic juice this is the enzyme primarily responsible for the digestion of dietary lipids in the animal digestive tract, a process that is described in detail in section 5.3.1. Pancreatic lipase is a glycoprotein of molecular mass 50kDa. The first step in the catalytic process is the adsorption of the enzyme on to the hydrophobic interface of the substrate micelles. Detergent molecules, like bile salts, tend to compete with the lipase for binding sites and the adsorption of the enzyme is assisted by a helper molecule called co-lipase, which is a small protein. In vitro, it can be shown that the activity of lipase is inhibited by high concentrations of bile salts and that this inhibition can be overcome by the addition of co-lipase. 

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