Synthesis and Biological Evaluation of Nitrogen and Sulphur Containing Heterocyclic Compounds

Abstract

The thesis is aimed at the design of novel nitrogen and sulphur-containing heterocyclic compounds by various principles of synthetic organic chemistry. The thesis comprises of the sections like introduction, review of literature, description of the materials used, and experimental methods employed, results and discussion and finally summary, conclusions and future prospects of the research work. As a part of our research efforts in developing new heterocycles containing both nitrogen and sulfur moieties, and after screening their microbial studies. In the present investigation, a first novel series of compounds 4-oxo-thiazolidine containing pyridine derivatives (6a-j) were synthesized by Multi‐component reactions (MCRs). An efficient multi‐component reaction approach is used for the synthesis of series of N-methyl-4-[4-(4-oxo-2-aryl-1,3-thiazolidin-3-yl)phenoxy]- pyridine-2-carboxamide derivatives. The newly synthesized molecules are characterized by elemental analysis, FT-IR, 1H-NMR, 13C-NMR, Mass spectroscopy etc. and studied for their antimicrobial and antioxidant activities. In addition, docking studies were also performed to get greater insight into the shown activity of these molecules. The present chapter deals with newly synthesized thiazolidine compounds (6a-j) were screened for their antimicrobial activity against different strains of bacteria and fungi using pour plate method. An antioxidant activity of compounds (6a-j) was carried out by DPPH and NO scavenging method. Few compounds have shown a significant microbial and antioxidant activity against selected bacterial strains (IC50). Molecular modeling studies of N-methyl-4-[4-(4-oxo-1,3-thiazolidin-3-yl)phenoxy]pyridine-2- carboxamide series derivatives 6a, 6f and 6g are the most active among all synthesized analogs. Another novel series of fluorine containing quinolone amide derivatives (4a–j) were synthesized. The structures of synthesized compounds were characterized by IR, 1HNMR, 13CNMR and mass spectroscopy. The present paper deals with newly synthesized quinoline compounds (4a–j) were screened for their antimicrobial activity against different strains of bacteria and fungi using pour plate method. Antioxidant activities of compounds (4a–j) were carried out by DPPH and NO scavenging method. We synthesized novel series of 2,4,6- trimethoxy chalcone with moderate antimicrobial and antifungal activity. These chalcone are further treated with hydrazine hydrate to get novel 2,4,6-trimethoxy pyrazoline derivatives. These derivatives screed for antibacterial activity and antioxidant activities, out of the synthesized compounds, compounds 3a, 3b, 3c and compound 5a, 5b, 5c. Also Compound 3e, 3h and 5f showed the excellent antioxidant activity. It is concluded that, synthesized derivatives shows moderate to excellent activities. The molecules under study have exhibited moderate to excellent antimicrobial and antifungal and antioxidant activity. Further structural modifications may be required to improve the biological activity of the synthesized five and six membered heterocyclic derivatives.