To understand the effects of alginates on lipase activity further we decided to investigate the relationships using a different assay system that used a natural substrate, olive oil. Lipase activity was measured by changes in turbidity of an olive oil solution due to the breakdown of triacylglycerol to free fatty acids and monoacylglycerol. As seen with the previous assay system, alginate again inhibited lipase activity (Fig. 3) and the levels of inhibition varied depending on the alginate source (Fig. 4A). Although the levels of inhibition with an olive oil substrate were lower than that shown with the synthetic substrate, they were not significantly different. However,
the difference between the two species of alginates was statistically NVP-BGJ398 molecular weight significantly different (Fig. 4A) using olive oil as the substrate. Alginates extracted from the seaweed species Laminaria hyperborea
inhibited pancreatic lipase to a significantly higher degree than alginates extracted from Lessonia nigrescens ( Fig. 4A). The difference between the two alginate sources was apparent at all concentration of alginate tested; at 3.43, 0.86 and 0.21 mg/ml with a p value of less than 0.001 for 3.43 and 0.86 mg/ml, and a p value of 0.012 for the 0.21 mg/ml. There was less variation between the level of inhibition by the Lessonia nigrescens alginates when comparing the two substrates; 10.4% (±8.1) learn more – 35.6% (±22.4) for DGGR ( Fig. 2A) compared to 21.0% (±4.1) – 29.8% (±2.3) for olive oil ( Fig. 4A). The same statistical difference was observed with the Laminaria hyperborea alginates showing an overall
higher level of inhibition compared to the Lessonia nigrescens alginates, whichever substrate was Protein kinase N1 used. A dose dependent relationship for the Laminaria hyperborea alginate was again demonstrated with olive oil as the substrate. Fig. 4B shows that decreasing the concentration from 3.43 to 0.86 and then to 0.21 mg/ml of alginate in the reaction mixture decreases the level of lipase inhibition. The same is also true for alginates extracted from Lessonia nigrescens species seaweed (data not shown). There was an increase of 1.7-fold and 2.3-fold in the level of inhibition when the concentration of LFR5/60 alginate was increased from 0.21 mg/ml to 0.86 mg/ml and from 0.86 mg/ml to 3.43 mg/ml. This was also similar for the other three Laminaria hyperborea alginates. When there was a fourfold increase in the alginate concentration from 0.21 mg/ml to 0.86 mg/ml, there was an increase in the level of inhibition observed, 100.0%, 76.4%, and 85.0% increase for SF120, SF/LF, and SF200, respectively. When the concentrations of the same alginates were increased fourfold (3.43 mg/ml), again the level of inhibition increased 83.2%, 117.2%, and 77.4%, respectively for alginates SF120, SF/LF, and SF200.