Exploration of novel TOSMIC tethered imidazo[1,2-a]pyridine compounds for the development of potential antifungal drug candidate.

New candidates of imidazo[1,2-a]pyridine were designed by combining 2-amino pyridine, TOSMIC and various assorted aldehydes to explore their antioxidant and antifungal potential. The design of these derivatives was based on utilizing the antifungal potential of azoles and TOSMIC moiety. These derivatives were synthesized by adopting multi-component reaction methodology, as it serves as a rapid and efficient tool to target structurally diverse heterocyclic compounds in quantitative yield. The resulting imidazo[1,2-a]pyridine derivatives were structurally verified by 1 HNMR, 13 CNMR, HRMS, and HPLC. The compounds were analyzed for their antioxidant and fluorescent properties and it was observed that compound 15 depicted highest potential. The compounds were evaluated for their antifungal potential to highlight their medical application in the area of Invasive Fungal Infections (IFI). Compound 12 gave the highest antifungal inhibition against Aspergillus fumigatus 3007 and Candida albicans 3018. To elucidate the antifungal mechanism, confocal images of treated fungi were analyzed, which depicted porous nature of fungal membrane. Estimation of fungal membrane sterols by UPLC indicated decrease in ergosterol component of fungal membrane. In silico studies further corroborated with the in vitro results as docking studies depicted interaction of synthesized heterocyclic compounds with amino acids present in the active site of target enzyme (lanosterol 14 alpha demethylase). Absorption, distribution, metabolism, and excretion (ADME) analysis was indicative of drug-likeliness of the synthesized compounds.

Luminescence Sensitization of Eu(III) Complexes with Aromatic Schiff Base and N,N'-Donor Heterocyclic Ligands: Synthesis, Luminescent Properties and Energy Transfer.

Five luminescent Eu(III)-4-fluoro-N-salicylideneaniline (Fsa) complexes with different N,N'- donor heterocyclic ligands (L) were synthesized (where L = 2,2'-bipyridine (bipy), 4,4'-dimethoxy-2,2'-bipyridine (dmbp), 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (neo) and 2,2'-biquinoline (biq)) and characterized by structural, thermal and spectroscopic analyses. The photophysical studies of the complexes viz. UV-Vis absorption spectra, emission spectra, lifetime decay curve, radiative, non-radiative transition rates and quantum yields were investigated. The photophysical properties indicated that fluorine substituted salicylideneaniline acts as a better sensitizer for Eu3+ ion after involvement of ancillary ligands which leads to efficient energy transfer resulted in bright red emission due to 5D0 → 7F2 transition. The highest overall quantum yield (32.78%) and sensitization efficiency (75.30%) of [Eu(Fsa)3neo] showed that it is a potential candidate in optical field. Graphical Abstract Sensitization of europium(III)-Schiff base complexes by antenna effect.

Novel Imbricatolic acid derivatives as protein tyrosine phosphatase-1B inhibitors: Design, synthesis, biological evaluation and molecular docking.

Protein tyrosine phosphatase (PTP-1B) antagonizes insulin signaling and is a potential therapeutic target for insulin resistance associated with obesity and type 2 diabetes. To find potential PTP-1B inhibitors, derivatives of Imbricatolic acid (1) have been synthesized by introducing various nitrogenous functionalities at C-15 and C-19 positions. They were evaluated for PTP-1B enzyme inhibition activity. Compounds 3, 6, 14, and 15 exhibited promising PTP-1B inhibitory activity at 10 µM concentrations with IC50 6.3, 6.8, 7.0 and 7.8 values, respectively. Structure activity relationship and molecular docking studies of these derivatives demonstrated that the integrity of the polar substituents were important for significant PTP-1B inhibitory activity. The Imbricatolic acid and active derivatives in this study might represent a starting point for development of new potential PTP-1B inhibitors.

Eu3+, Yb3+ and Eu3+-Yb3+ complexes with salicylic acid and 1,10-phenanthroline: synthesis, photoluminescent properties and energy transfer.

This paper reports the synthesis of mononuclear Eu(3+), Yb(3+) and binuclear Eu(3+)-Yb(3+) complexes by solution technique, maintaining the stoichiometric ratios of salicylic acid (sal) and 1,10-phenanthroline (phen) as ligands and their structural, optical and morphological properties were demonstrated. The FTIR absorption spectra indicates that sal and phen are coordinated to the rare earth ion through the chemical bonds formed between oxygen and nitrogen atoms of the ligands and rare earth ion. The UV-vis absorption spectra of the complexes reflect the absorption spectra of the ligands and there is no significant change in the wavelength and band profiles between the spectra of the ligands and that of complexes except a slight red shift. The photoluminescent emission spectra of the complexes in visible and near-infrared (NIR) region was recorded and indicated the emission quenching in complex (2) due to the energy transfer from Eu(3+) ion to Yb(3+) ion. The morphological properties of the complexes as characterized by SEM revealed different morphologies of mononuclear and binuclear complexes.