Blending chitosan with polycaprolactone: porous scaffolds and toxicity

The preparation and characterization of porous scaffolds from chitosan-PCL blends by freeze extraction, freeze gelation and freeze drying is reported. Using freeze extraction, stable structures were obtained only from PCL, but these were not porous. No stable scaffolds were obtained using the freeze gelation process. Stable scaffolds of chitosan/PCL mixtures could not be obtained using 77% acetic acid by any of these techniques. With 25% aqueous acetic acid, stable scaffolds of chitosan/PCL mixtures were obtained by the freeze drying technique. The stability and pore morphology of freeze dried scaffolds were dependent on the relative mass ratio of chitosan and PCL. A chorioallantoic membrane assay showed that formed 3D chitosan/PCL mixtures were not toxic to vasculature.     

Base dependent purported synthesis of congested 2-aminobenzylamines and tetrahydro-2-oxoquinazolines from 2-pyranones

An expeditious and concise synthesis of highly congested 2-amino-3-aminomethyl-5-methylsulfanyl/-sec-aminobiphenyl-4-carbonitrile 4 and 1-tert-butoxycarbonyl-6-sec-amino-8-aryl-5-cyano-2-oxo-1,2,3,4-tetrahydroquinazoline 5 has been delineated through base catalyzed ring transformation of 6-aryl-4-methylsulfanyl/-sec-amino-2H-pyran-2-one-3-carbonitrile 1 with 1,3-bis(tert-butoxycarbonylamino)-2-propanone 2, followed by TFA catalyzed hydrolysis of the intermediate [3-tert-butoxycarbonylaminomethyl-4-cyano-5-methylsulfanyl/-sec-aminobiphenyl-2-yl]carbamic acid tert-butyl ester 3 in moderate yield. The mechanism of formation of 5 has been established through isolation and transformation of the intermediate 3 to the 1-tert-butoxycarbonyl-6-sec-amino-8-aryl-5-cyano-2-oxo-1,2,3,4-tetrahydroquinazoline.     

Three novel tetracyclic triterpenoids of biogenetic interest from the leaves of Azadirachta indica

From the methanolic extract of Azadirachta indica leaves, we have isolated three new tetracyclic triterpenoids of biogenetic interest, namely, melianol 1, desfurano-desacetylnimbin-17-one 2 and meliatetraone 3. The structure elucidation is based on extensive spectral studies including ¹H–¹H-COSY, NOESY, HMQC, and HMBC experiments.     

Synthesis and Antibacterial Activity of New Diaryldiamines

Several new quinolines and quinazolines ( 4, 10, 13 ) have been synthesized from cheap and readily available chemicals through a series of simple chemical transformations. Most of the synthesized compounds have been evaluated for antibacterial activity against Gram positive and Gram negative strains. Some of the synthesized compounds displayed interesting activity but not very promising for further development.     

Electron delocalization and aromaticity variations in the stacked nucleic acid base pairs

A newly developed exchange-correlation functional (MPWB1K) in density functional theory has been applied to evaluate the electron delocalization of individual fragments in the stacking interaction between nucleic acid bases (NABs). Electronically and structural-based indices have been employed to investigate the aromaticity variation during stacking interaction. A quantitative study of NABs in their isolated and stacked forms reveals that stacking interaction causes a decrease in bond delocalization. It is shown that the decrease in the aromaticity is accompanied by local decrease in two-center delocalization indices within the pyrimidine rings. We found that the aromaticity exhibits a similar trend for NABs in both their isolated and stacked forms. Moreover, it is indicated that aromatic fluctuation index is more sensible index to delineate the aromaticity variation during stacking interaction.

     

Preparation, structure and spasmolytic activities of some derivatives of harmine series of alkaloids

Keeping in view the interesting chemistry and pharmacological importance of harmine series of bases -- the beta-carboline alkaloids, a number of new derivatives of tetrahydroharmine and harmalol have been prepared and characterized through spectral studies. Some of these derivatives showed spasmolytic activity. It was observed that all the N-acyl tetrahydroharmine derivatives are stable, not labile and no ring opening occurs in these compounds, as reported recently.     

Synthesis,Antimicrobial, Anticancer,PASS, Molecular Docking,Molecular Dynamic Simulations & Pharmacokinetic Predictions of Some Methyl β-D-Galactopyranoside Analogs

A series of methyl β-D-galactopyranoside (MGP, 1) analogs were selectively acylated with cinnamoyl chloride in anhydrous N,N-dimethylformamide/triethylamine to yield 6-O-substitution products, which was subsequently converted into 2,3,4-tri-O-acyl analogs with different acyl halides. Analysis of the physicochemical, elemental, and spectroscopic data of these analogs revealed their chemical structures. In vitro antimicrobial testing against five bacteria and two fungi and the prediction of activity spectra for substances (PASS) showed promising antifungal functionality comparing to their antibacterial activities. Minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) tests were conducted for four compounds (4, 5, 6, and 9) based on their activity. MTT assay showed low antiproliferative activity of compound 9 against Ehrlich’s ascites carcinoma (EAC) cells with an IC₅₀ value of 2961.06 µg/mL. Density functional theory (DFT) was used to calculate the thermodynamic and physicochemical properties whereas molecular docking identified potential inhibitors of the SARS-CoV-2 main protease (6Y84). A 150-ns molecular dynamics simulation study revealed the stable conformation and binding patterns in a stimulating environment. In-silico ADMET study suggested all the designed molecules to be non-carcinogenic, with low aquatic and non-aquatic toxicity. In summary, all these antimicrobial, anticancer and in silico studies revealed that newly synthesized MGP analogs possess promising antiviral activity, to serve as a therapeutic target for COVID-19.     

Synthesis of Supramolecular Organogels Derived from Urea and Bisurea Derivatives of Dehydroabietylamine

The gelation ability of diterpenes was investigated by applying aromatic linker steroid strategy. Four new mono (1) and bis-urea (2–4) derivatives of dehydroabietylamine (DAA) (a tricyclic diterpene amine) were synthesized on reaction of respective isocyanates with DAA and characterized through spectroscopic data. Three of these (1, 2, and 4) were obtained as low-molecular-weight organogelators that can form thermally reversible organogels.

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