Effect of Phytate and Other Myo-Inositol Phosphate Esters on Lipase Activity

The effects of phytate and other myoinositol phosphate esters (containing one or more phosphate groups) on lipase activity were evaluated by an in vitro procedure. Porcine pancreatic lipase was treated with four concentrations of phytate (0–4 mM) and myo-inositol-2-monophosphate (0–12 mM). The lipase was also treated with six myoinositol phosphate ester fractions (4 mM) isolated from hydrolyzed phytate. The enzyme was incubated (0.5 hr) with the esters prior to addition of substrate and measurement of fatty acid production. Phytate at 4 mM and 1-2-MP at 12 mM caused significant inhibition of lipase, 14.5% and 8.2%, respectively. The isolated inositol phosphate ester fractions caused significant decreases in lipase activity. The decrease in enzymatic activity was highly correlated (r = 0.980) with degree of inositol phosphorylation.