Manmohan Chhibber

Acid-modified Zeolite A from industrial waste: a reusable catalyst for pharmaceutically important heterocyclic synthesis.

Worldwide, the ever-rising demand for coal in power plants has increased coal fly ash (CFA) production. Its disposal is a major environmental problem. CFA zeolitization offers a possible alternative for converting this hazardous solid waste into high-value products. This work uses the fusion-assisted ultrasonication method to synthesize zeolite. The material was characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) techniques. The synthesized zeolite, sodalite was mesoporous with a surface area of 22.13 m² g⁻¹ and an average pore size of 7 nm. This was used and optimized as a solid-state base for synthesizing diphenyl ethers (DPEs). The yields of twelve diphenyl ethers with aldehyde, chloro, methoxy, methyl and nitro groups ranged from 35 to 91%. The methodology offers an advantage over conventional processes in providing single-step synthesis of DPEs with electron-withdrawing groups on both rings.

The discharge of toxic cyanide ions in the environment and their uptake by life is inevitable due to industrialization. Therefore, its detection below the permissible limit is significant. Diphenyl ether‐based chromophores have been synthesized and optimized to highlight the proton abstraction mechanism for detecting anions. Absorption studies in the presence of different solvents (H ₂ O, MeOH, ACN, DMSO, CHCl ₃ and semi‐aqueous ACN) and pH (10 to 4) confirmed the proton abstraction mechanism validated using ¹ H NMR titration, IR studies and DFT calculations. The effect of substituents on the diphenyl ether motifs highlighted the selectivity of anions under different solvent conditions. Finally, compound‐2 [2‐(2‐methoxyphenoxy)‐5‐nitrobenzoic acid] and compound‐2 c [3‐methoxy‐4‐(2‐nitrophenoxy) benzoic acid] in ACN medium detected F ⁻ (280 nM, 17 μM) AcO ⁻ (41 nM, 40 μM) and CN ⁻ (50 nM. 1.5 μM) ions in nM and μM range respectively. However, the semi‐aqueous medium (5 % water in ACN) gave selective detection of the CN ⁻ ion up to 100 nM for the compound‐2 in a 1 : 1 stoichiometry. The use of an aqueous medium in the case of c ompound‐2 c did not show detection for any of the ions.

The past two decades have seen considerable attention given to chemical sensing due to its quick, reproducible, and accurate results. These are extensively used for the detection of cations and anions in different environmental matrices. Organic-molecule-based sensors have proved to be a great promising tool in determining target species. This communication demonstrates the use of triphenylether derivatives (L1–L4) as receptors for the sensing of cations and anions, using voltammetry as a sensing tool. The effect of the oxidative/reductive nature of the ionophores and, hence, their selectivity behavior was studied in MeCN and MeOH solvents. Three receptors (L2–L4) responded selectively towards cyanide ions following the intramolecular charge-transfer mechanism, while sensing in the case of L1 was not studied because it lacked a proper cavity size.

The identification and quantification of toxic Hg ²⁺ ions in biological fluids is significant due to its harmful effects. The ion is an exceptional contaminant due to its manifestation in the environment through anthropogenic emissions besides other industrial processes. The bioaccumulation of Hg ²⁺ ions through water bodies, soil and food causes damage to the central nervous system and endocrine glands. This work describes the synthesis of Compd‐ 2 (Compound 2), a thiocarbohydrazide‐based UV‐active sensor, that can detect Hg ²⁺ and Cu ²⁺ ions in the aqueous medium (HEPES buffer (3 mM) /acetonitrile = 99 : 1, v/v ). Compd‐ 2 responds linearly to the varying concentrations of Hg ²⁺ with a minimum detection limit of 27 nM and a 1 : 1 stoichiometry. ¹ H NMR titration with increasing Hg ²⁺ ion concentrations confirmed its interaction by shifting of the peak. In‐silico modelling using Gaussian 16.0 and IR spectroscopy verified a single binding site for the Hg ²⁺ ions. Aqueous solubility of Compd‐ 2 was used as an advantage to develop a methodology for the detection and quantification of Hg ²⁺ ions in the human urine sample. The work also demonstrates the nM quantification of Hg ²⁺ ions in the urine sample by the standard addition method.

A series of new fluoroquinolone analogs (3–18) were prepared, in three steps, by substituting chloro esters and esters with cyclic amines on the C‐7 endo‐nortropine derivatives of difluoroquinolone acid. All the synthesized compounds displayed good MIC against the Staphylococcus aureus when initially screened for Escherichia coli, S. aureus, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa. The molecules were further evaluated for their antibacterial activity against fluoroquinolone‐resistant strains of S. aureus and for cytotoxic assay. Based on the results, five of the sixteen compounds displayed the potential to be developed further for treatment against fluoroquinolone‐resistant strains of S. aureus.

Background: Exploration of antibiotics from microorganisms became widespread in the academia and the industry with the serendipitous discovery of Penicillin from Penicillium notatum by Sir Alexander Fleming. This embarked the golden era of antibiotics which lasted for over 60 years. However, the traditional phenotypic screening was replaced with more rational and smarter methods of exploration of bioactive compounds from fungi and microorganisms. Fungi have been responsible for providing a variety of bioactive compounds with diverse activities which have been developed into blockbuster drugs such as Cyclosporine, Caspofungin, Lovastatin and Fingolimod etc. It has been reported that ca. 40% of the 1453 New Chemical Entities (NCE’s) approved by USFDA are natural products, natural product inspired or mimics many of which have their origins from fungi. Hence fungal compounds are playing a very important role in drug discovery and development in the pharmaceutical industry.Methods: We undertook structured searches of bibliographic databases of peer-reviewed research literature which pertained to natural products, medicinal chemistry of natural products and drug discovery from fungi. With the strategic improvement in screening and identification methods, fungi are still a potential resource for novel chemistries. Thus the searches also comprised of bioactive agents from fungi isolated or derived from special ecological groups and lineages. To find different molecules derived or isolated from fungi under clinical studies, clinical trial data from the NIH as well as from pharmaceutical companies were also explored. This comprised of data wherein the pharmaceutical industries have acquired or licensed a fungal bioactive compound for clinical study or a trial.Results: Natural product chemistry and medicinal chemistry continue to play an important role in converting a bioactive compound into therapeutic moieties or pharmacophores for new drug development.Conclusion: Thus one can say fungal bioactive compounds are alive and well for development into new drugs as novel ecological groups of fungi as well as novel chemistries are being uncovered. This review further emphasizes the collaboration of fungal biologists with chemists, pharmacologists and biochemists towards the development of newer drugs for taking them into the drug development pipeline.

Here in we report a convenient synthesis of new fluoroquinolones substituted with endo- nortropine and its derivatives. All the synthesized molecules, when screened for their antibacterial activity by agar diffusion method against Vibrio cholerae, Bacillus subtilis, Staphylococcus aureus and Escherichia coli, were found to be active against first three strains. Two compounds in the series, RG and RO, were shortlisted for the quantitative determination of MIC values by micro-dilution broth assay. Compound RG was ten times more effective in case of S. aureus (15.0 nM), two times in case of V. cholerae (3.7 nM) and same as that of standard drug Levofloxacin in case of Bacillus subtilis (7.8 nM). Compound RO also displayed an impressive MIC value (62.5 nM) in case of S. aureus as compared to control (125 nM). The results have been supported by in-silico docking studies, where increased hydrogen bonding interactions in case of RG as compared to standard levofloxacin with DNA gyrase (2XCT) of S. aureus result in decreased energy of the former.