The effectiveness and specificity of a tannin inhibition on human salivary amylase (HSA) catalyzed hydrolysis was studied using 2-chloro-4-nitrophenyl 4-O-β-d-galactopyranosyl-α-maltoside (GalG2-CNP) and amylose substrates. Aleppo tannin was isolated from the gall nut of Aleppo oak. This tannin is a gallotannin, in which glucose is esterified with gallic acids. This is the first kinetic report, which details the inhibitory effects of this compound on HSA. A mixed non-competitive type inhibition has been observed on both substrates. The extent of inhibition is markedly dependent on the substrate-type. Kinetic constants were calculated from Lineweaver-Burk secondary plots for GalG2-CNP (KEI0.82 μg mL-1, KESI3.3 μg mL-1). This indicates a 1:1 binding ratio of inhibitor-enzyme and/or inhibitor-enzyme-substrate complex. When amylose was the substrate the binding ratio of inhibitor to enzyme-substrate complex was found to be 2:1, with the binding constants of KEI17.4 μg mL-1, KESI14.9 μg mL-1, KESI29.6 μg mL-1. Presumably, the tannin inhibitor can bind not only to HSA, but to the amylose substrate, as well. Kinetic data suggest that Aleppo tannin is a more efficient amylase inhibitor than the recently studied other tannin with quinic acid core (GalG2-CNP: KEI9.0 μg mL-1, KESI47.9 μg mL-1). © 2006 Elsevier Ltd. All rights reserved.
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