Porcine Pancreatic Lipase Activity Research Articles

ε-Polylysine Inhibits Pancreatic Lipase Activity and Suppresses Postprandial Hypertriacylglyceridemia in Rats

Epsilon-polylysine (epsilon-PL) has been used as a food additive in Japan for many years. In this study, it inhibited human and porcine pancreatic lipase activity in substrate emulsions containing bile salts and phosphatidylcholine, in the concentration range of 10-1000 mg/L. At the same concentrations, it also destroyed the emulsifying activity, suggesting that lipase inhibitory activity and emulsion breakdown activity were associated. Epsilon-PL inhibited porcine pancreatic lipase activity and destroyed emulsion breakdown activity at 1000 mg/L in the substrate containing bile salts and phosphatidylcholine alone. Epsilon-PL did not inhibit lipase activity or affect emulsifying activity at 1000 mg/L in the substrates containing arabic gum and polyvinyl alcohol. A comparison of lipase inhibitory activity between epsilon-PL and three types of alpha-PL with differing polymerization rates was performed. The lipase inhibitory activity of epsilon-PL was not different from that of alpha-PL (44 lysine residues). Epsilon-PL maintained its inhibitory activity after incubation with trypsin, alpha-chymotrypsin and pepsin, whereas alpha-PL did not. The effect of epsilon-PL on postprandial hypertriacylglyceridemia was investigated in rats. The plasma triacylglycerol concentration in rats intragastrically administered > or =15 mg/kg of both fat emulsion and epsilon-PL was significantly lower at 2 and 3 h after administration than that in rats administered fat emulsion alone (P < 0.05). These results strongly suggest that epsilon-PL is able to suppress dietary fat absorption from the small intestine by inhibiting pancreatic lipase activity.

Salacia reticulata and Its Polyphenolic Constituents with Lipase Inhibitory and Lipolytic Activities Have Mild Antiobesity Effects in Rats

Salacia (S.) reticulata, a Hippocrateaceae plant distributed in Sri Lankan and Indian forests, has been used as a supplementary food in Japan to prevent obesity and diabetes. We examined the antiobesity effects of the hot water-soluble extract (SRHW) from the roots of S. reticulata using obese rat models and an in vitro study. Body weight (P = 0.07) and periuterine fat storage (P = 0.10) in female Zucker fatty rats (8-9 wk old) tended to be suppressed by oral administration of SRHW (125 mg/kg) for 27 d. Male rats fed a high fat diet were not affected by SRHW. Furthermore, SRHW inhibited porcine pancreatic lipase (PL), rat adipose tissue-derived lipoprotein lipase (LPL) and glycerophosphate dehydrogenase (GPDH) activities with 50% inhibitory concentrations (IC(50)) of 264 (95% confidence limits: 203-393) mg/L, 15 (12-18) mg/L and 54 (35-85) mg/L, respectively, but did not inhibit hormone-sensitive lipase activity in rat adipose tissue. Next, we examined the effects of polyphenols, di- and triterpenes and salacinol isolated from the roots of S. reticulata on lipid metabolizing enzymes and lipolysis. (-)-Epigallocatechin and (-)-epicatechin-(4beta-->8)-(-)-4'-O-methylepigallocatechin inhibited PL activity with IC(50) of 88 (not calculated) and 68 (26-122) mg/L, respectively. (-)-Epicatechin, 3beta, 22beta-dihydroxyolean-12-en-29-oic acid and the tannin fraction inhibited LPL activity with IC(50) of 81 (54-214), 89 (62-214) and 35 (24-62) mg/L. Only the tannin fraction inhibited GPDH activity with an IC(50) of 6.8 (3.4-10.9) mg/L. These constituents may be involved in the lipase and GPDH inhibitory activities of SRHW. On the other hand, SRHW at 100 mg/L tended to enhance lipolysis in rat adipocytes (P = 0.06). Significant lipolytic effects were exerted by mangiferin, (-)-4'-O-methylepigallocatechin and maytenfolic acid at 100 mg/L (P < 0.01). In conclusion, polyphenolic compounds may be involved in the antiobesity effects of SRHW in rats through inhibition of fat metabolizing enzymes (PL, LPL and GPDH) and enhanced lipolysis.

Effect of dietary copper and fat on nutrient utilization, digestive enzyme activities, and tissue mineral levels in weanling pigs.

Two 15-d nutrient balance trials were conducted using a total of 32 weanling barrows (averaging 6.8 kg, 26 d). The effect of the addition of 15 or 250 ppm Cu (as CuSO4.5H2O) to diets containing 0 or 5% added animal fat on nutrient utilization, digestive enzyme activities, and tissue mineral levels in weanling pigs was investigated. In each trial, four groups of four littermate barrows were randomly assigned to one of four treatments in a 2 x 2 factorial arrangement. The addition of 250 ppm Cu improved apparent fat digestibility and apparent nitrogen retention (P < .02). The addition of 5% fat increased apparent fat digestibility (P < .01). There were no Cu x fat interactions (P > .10) for any of the digestibility indices measured. The addition of 250 ppm of Cu stimulated small intestinal lipase (P < .01) and phospholipase A (P < .05) activities but had no effect (P > .10) on pancreatic lipase or phospholipase activities and no effect on trypsin, chymotrypsin, or amylase activities in the small intestine or the pancreas. The addition of 250 ppm Cu to the diet increased Cu (P < .001) in plasma, liver, and kidney and decreased Fe in plasma (P < .05) and liver (P < .02). The addition of 5% fat increased Fe in kidney (P < .05) and heart (P < .08). Copper x fat interactions were observed for spleen Ca (P < .01), Mg (P < .08), Na (P < .05), and K (P < .08) and spleen weight (P < .05). In additional in vitro assays, increased Cu concentrations tended to consistently stimulate purified porcine pancreatic lipase activity (linear, P < .01) but not purified porcine pancreatic phospholipase A activity (P > .10). The results from this study indicate that 250 ppm Cu stimulated intestinal lipase and phospholipase A activities, leading to an improvement of dietary fat digestibility in weanling pigs.

The activation of porcine pancreatic lipase by cis-unsaturated fatty acids

In the presence of taurodeoxycholate, cis-unsaturated fatty acids increase porcine pancreatic lipase activity 15-fold at pH 7.5. This effect is saturable with a low proportion of fatty acid to substrate. The overall angle of the fatty acid, the position of its double bond and the presence of a carboxyl group were critical factors in whether the fatty acid effectively increased lipase activity. When the substrate is emulsified by taurodeoxycholate, the pH optimum for lipase ranges from 6.2 to 7.0. In the presence of cis-unsaturated fatty acids, the overall activity of lipase increases, the pH optimum shifts, and the pH-activity curve becomes biphasic, with one optimum around pH 7.7, and the other around pH 8.8. Fluorescence studies indicate that fatty acids bind near aromatic residues in lipase, particularly tryptophan. Using the fluorescent fatty acid cis-parinaric acid, it was determined that multiple binding sites are present with K d values of approx. 10 −6 M. Far-UV circular dichroism (CD) studies indicate that in addition to a high affinity fatty acid binding site with a K d of approx. 10 −6 M, there is also a low affinity binding site with a K d of approx. 10 − 4 M. The far-UV CD data also show that cis-unsaturated fatty acids change the conformation of lipase. It is calculated that the percentage of α helix decreases, and the amount of β sheet and β turn structure increases. Because the three-dimensional crystal structure of lipase is known, a model is proposed to describe how cis-unsaturatcd fatty acids increase lipase activity.