Adenosine deaminase activity modulation by some street drug: molecular docking simulation and experimental investigation

Background: Adenosine deaminase (ADA) is an enzyme that plays important roles in proliferation, maturation, function and development of the immune system. ADA activity may be altered by variety of substances including synthetic or natural products. Morphine, cocaine and their analogs exert immune suppressive activities by decreasing immune system function. The purpose of this study is to confirm that this possible effect may be modulated by interaction of these substances with ADA activity by experimental and computational method. Methods: The structural changes in ADA have been studied in presence of cocaine, ethylmorphine, homatropine, morphine and thebaine by determination of ADA hydrolytic activity, circular dichroism and fluorescence spectroscopy in different concentrations. Docking study was performed to evaluate interaction method of test compound with ADA active site using AutoDock4 software. Results: According to in-vitro studies all compounds inhibited ADA with different potencies, however thebaine activated it at concentration below 50 μM, ethylmorphine inhibited ADA at 35 μM. Moreover, fluorescence spectra patterns were differed from compounds based on structural resemblance which were very considerable for cocaine and homatropine. Conclusion: The results of this study confirms that opioids and some other stimulant drugs such as cocaine can alter immune function in illegal drug abusers. These findings may lead other investigators to develop a new class of ADA activators or inhibitors in the near future.