Pyrido-pyrimido-thiadiazinones: green synthesis, molecular docking studies and biological investigation as obesity inhibitors

Obesity is a global public health concern brought on by a combination of excessive dietary intake, inactivity and genetic predisposition. Pyridopyrimidines have received considerable interest in the development of obesity and diabetes. Mannich reaction was applied on 2-thioxo-pyridopyrimidinone derivative with a variety of aromatic and heterocyclic aromatic amines and formaldehyde by grinding at 25°C in the presence of HCl to obtain 18 fused thiadiazinones and two bis-fused thiadiazinone derivatives. Additionally, in silico docking was performed to investigate the mode of actions of the 20 synthesized compounds against fat mass and obesity-associated (FTO) protein. The ligand molecules are nicely docked to the target FTO with binding energies (ΔG_bind) ranging from −11.6 to −8.0 kcal/mol. Electrostatic potential map of semiempirical optimized compound 16 was performed using Gaussian 03. Interestingly, two bis-fused thiadiazinone derivatives showed marked amelioration of adiposity in the high-fat diet model especially in hepatic and adipose tissues.