For initial characterisation of the assay systems (DGGR and olive oil) three replicates were used. The analysis between the level of inhibition by alginates from two seaweed sources was tested with a one way ANOVA with Tukey post test. All subsequent measurements used six replicates. The number of replicates is shown in each figure legend. Using DGGR as a substrate, the activity of lipase could be measured by the increase in absorbance
(Panteghini et al., 2001). As expected, there was a marked change in the absorbance over time for the negative control (lipase http://www.selleckchem.com/products/ABT-263.html plus substrate) illustrating the maximum rate of reaction (Fig. 1), whereas, for the inhibition control (Orlistat (0.025 mg/ml)) there was minimal change in absorbance over time. Fig. 1 also shows that alginate could inhibit the activity of lipase. To compare the inhibition of a range of alginates, the absorbance at 12 min reaction time was chosen. This time point was used because the reaction was still close to the linear phase. Fig. 2A shows that there was a significant difference in the level of inhibition depending
selleck chemicals on the seaweed source of the alginate. The alginates extracted from Laminaria hyperborea seaweed inhibited pancreatic lipase to a significantly higher degree (two way ANOVA, p = 0.0015) than the alginates extracted from Lessonia nigrescens. A dose dependent inhibition was seen for both sets of seaweed alginates. Fig. 2B shows that
for Laminaria hyperborea alginate the percentage of lipase inhibition increased with increasing concentration. For LFR5/60, there was a 75% relative increase in inhibition when the alginate concentration was increased fourfold from 0.21 mg/ml to 0.86 mg/ml, and a 56% increase from 0.86 mg/ml to 3.43 mg/ml. Similarly, the increases for alginates SF120 and SF/LF were 90% and 122%, respectively when the alginate concentration was increased from 0.21 to 0.86 mg/ml, and again 64% and 47%, respectively increased to 3.43 mg/ml. The alginate SF200 level of inhibition increased 44% and 46% when the alginate concentration increased from 0.21 to 0.86 and then 3.43 mg/ml. Phenylethanolamine N-methyltransferase As seen in Fig. 2, not all alginates inhibited lipase to the same extent, even those from the same genus of seaweed. To understand why the levels differed, the compositional characteristics of the various alginates were correlated with the level of lipase inhibition (Table 2). Statistical significant positive correlations were found between levels of inhibition and increasing guluronate content (F(G)), the fraction of guluronate dimers (F(GG)), the fraction of guluronate trimers (F(GGG)) and the number of guluronate blocks greater than one in the alginate polymer (N(G > 1)). Surprisingly, the reciprocal correlations with mannuronate levels were not always significant. Only F(M) and F(MG) were statistically significant negative correlations.