Comparison of inhibitory effects of the drugs physostigmine and procaine on the acetycholinesterase activity

Background and Objective: The acetylcholinesterase (AChE) is an enzyme that takes responsibility for substrate hydrolysis of acetylcholine, and it is seen structurally, as monomer, dimer and tetramer units. The objective of this study was to examine and compare the inhibitory effect of the two drugs, physostigmine and p < /a> hydrochloride in vitro.



Materials and Methods: In this study, the inhibitory rate of this enzyme was examined and compared by the two drugs, physostigmine and procaine hydrochloride in vitro. The rate of enzyme activity in accordance to Ellman method was measured in the presence and absence of different concentrations of drugs, and the inhibitory percentage of the drugs was obtained.



Results: The enzyme values of Km and Vmax with substrate acetylthiocholine were obtained respectively equal to 52.63µM/ml/mg and 0.11 mM. The IC50 for the drugs, procaine and physostigmine was determined respectively equal to 0.175 and 0.00004 mM indicating the high inhibitory power of physostigmine as compared to procaine. In addition, kinetic parameters of the enzyme, including Km in the presence of procaine and physostigmine were obtained respectively equal to 0.62and 2.22 mM. The Vmax enzyme was also the same in the presence and absence of drugs.



Conclusion: The results indicate the high inhibitory power of physostigmine compared to procaine. These drugs are also introduced as competitive inhibitors of the acetylcholinesterase enzyme.