Kinetic modeling is an indispensible part of in vitro drug metabolism and/or inhibition studies. Psidiumguajava Linn leaf is used traditionally in Indian medicine to control hypertension in human. The aim of this work was to study the hypotensive effect of Psidiumguajava Linn. leaf extract in human. Hypertension is due to the activity of the Angiotensin-Converting Enzyme that catalyzes the conversion of the inactive Angiotensin I to the active Angiotensin II.
Angiotensin II functions as a potent vasoconstrictor causing hypertension. Hence, ACE inhibitors are considered to be the first choice treatment of hypertension. The ACE inhibitory activity of Psidiumguajava Linn.leaf extract in human was studied by its in vitro inhibitory effect on human serum-ACE using the substrate FA-PGG (N-(3-(2-Furyl) acryloyl)-L-phenylalanyl-glycyl-glycine). The enzyme kinetics of ACE inhibition was investigated by Michaelis-Menten kinetics and Lineweaver-Burk graph and Vmax and Km values were calculated.The results show that there is a decrease in both Vmax and Km values in the presence of Psidumguajava leaf extract. The decreased Vmax and Km seen with Psidiumguajava indicates that Psidiumguajava binds to
other alternative sites rather than the active site of the ACE and hence the inhibition is uncompetitive. The decreased Vmax/Km value indicates decreased catalytic ability/affinity of enzyme-substrate due to the presence of the inhibitor Psidiumguajava leaf extract. From these we could conclude that P. guajava Linn leaf extract inhibit human serum-ACE uncompetitively and it has hypotensive effects in human. (Jomon Sebastian, Evaluation of in vitro angiotensin-converting enzyme inhibitory activity of Psidiumguajava Linn. leaf extract and a study on enzyme kinetics)
Last date updated on July, 2014