Synthesis, Characterization and Biological Evaluation of N-Mannich Bases of Heterocyclic Pharmacophores

Abstract

Mankind has always suffered from multiple diseases. Therefore, there has been a rigorous need in the field of medicinal chemistry for the design and discovery of new and potent molecular entities. A total of 52 new compounds (N-Mannich bases) were synthesized after optimizing the reaction conditions. The obtained aminomethylated compounds were divided into 4 libraries, based on the nature of the heterocyclic pharmacophore; each library comprises 13 Mannich bases. All the newly synthesized compounds were isolated and obtained in good yield after purifying them by flash column chromatography (FCC) and recrystallization techniques. All compounds were evaluated computationally to determine theirs in silico and pharmacokinetic profile. All the newly synthesized compounds exhibited a good pharmacokinetic profile and all complied with Lipinski’s rule of five (RO5) except SP7. All the compounds exhibited good absorption and permeability profile, only 4 (SF5, SF6, SP5, and SP6) showed poor absorption and permeability profile determined by BOILED-Egg method. Compounds were evaluated to determine their antioxidant potential by using three in vitro antioxidant assays i.e. DPPH assay, TAC and TRP estimation. SH1 showed the most potent activity against DPPH free radical at 9.94 µg/mL, followed by SH13, SF8, SF1 and SF6. SF5 showed significant activity in TAC and TRP assays. Compounds were screened against alpha-amylase enzyme. Among the 52 compounds, SP2, SH3, SF5, SF9, SH2 and SP8 exhibited a more potent effect than the standard (acarbose). Compounds were assessed to determine their antimicrobial potential. Compounds exhibited moderate antibacterial and antifungal activity against these strains. Compounds were prescreened against HepG2 cells based on the results of preliminary cytotoxic assays i.e. brine shrimp lethality (LD50) and cell viability assay (IC50). Only 14 compounds were selected from each library for further analysis against hepatocellular carcinoma cells. Compounds were tested at 24, 48 and 72 h. Compounds exhibited potent cytotoxic behavior at 72 h as compared to that of 48 and 24 h. An in vitro LPS-induced NO assay was performed using the Griess reagent method. A total of 13 compounds were selected from and their anti-inflammatory potential was evaluated using the carrageenan-induced acute paw edema inflammation model. A dose-optimization study was conducted at first to optimize the dose. 10 mg/kg dose of the compound was selected. All the compounds exhibited good anti-inflammatory potential compared with acetylsalicylic acid (ASA).