Amberlyst-15 catalysed sonochemical synthesis of 2-amino-4,6-disubstituted nicotinonitrile derivatives and their biological evaluation

The 2-amino nicotinonitrile framework has been explored first time for the identification of potential inhibitors of SIRT1. Thus a series of targeted 2-amino-4,6-disubstituted nicotinonitrile derivatives were synthesized by employing an ultrasound assisted MCR of ketones, aldehydes, malononitrile and ammonium acetate. The MCR was carried out in the presence of Amberlyst-15 in MeCN under mild conditions to give the desired product in good yields. The reaction was less efficient in the absence of air whereas combination of Amberlyst-15, ultrasound, air and MeCN was essential for the success of this MCR. Several of the synthesized compounds showed good activities when tested for their SIRT1 inhibitory potential in vitro among which 5c, 5e and 5n were identified as the most potent (IC50 similar to 3 mu M) and were better than the known inhibitor nicotinamide (IC50 similar to 109 mu M). In the in silico docking studies these three compounds showed better binding energy (> 100 kcal/mol) and higher number of interactions than nicotinamide (binding energy -88.38 kcal/mol). While both amino (-NH2) and cyano (-CN) groups of nicotinonitrile derivatives formed H-bonds with the ASN346 and HIS363 residue respectively the nicotinamide showed similar interactions with ASP348 and ILE347 through its amide (-CONH2) moiety. Compound 5c, 5e and 5n has been identified as initial hits for further study. (C) 2021 Elsevier B.V. All rights reserved.