Modifications of flexible nonyl chain and nucleobase head group of (+)-erythro-9-(2′s-hydroxy-3′s-nonyl)adenine [(+)-EHNA] as adenosine deaminase inhibitors

A series of terminal nonyl chain and nucleobase modified analogues of (+)-EHNA (III) were synthesized and evaluated for their ability to inhibit adenosine deaminase (ADA). The constrained carbon analogues of (+)-EHNA, 7a-7h, 10a-c, 12, 13, 14 and 17a-c appeared very potent with Ki values in the low nanomolar range. Thio-analogues of (+)-EHNA 24a-e wherein 5 ' C of nonyl chain replaced by sulfur atom found to be less potent compared to (+)-EHNA. Docking of the representative compounds into the active site of ADA was performed to understand structure-activity relationships. Compounds 7a (Ki: 1.1 nM) 7b (Ki: 5.2 nM) and 26a (Ki: 5.9 nM) showed suitable balance of potency, microsomal stability and demonstrated better pharmacokinetic properties as compared to (+)-EHNA and therefore may have therapeutic potential for various inflammatory diseases, hypertension and cancer. (C) 2017 Elsevier Ltd. All rights reserved.