A Green one-pot three component synthesis of thiazolidine-2,4-dione based bisspirooxindolo-pyrrolidines with [Bmim]BF4: their in vitro and in silico anti-TB studies.

A simple and effective three-component one-pot green methodology was employed for the synthesis of a new thiazolidine-2,4-dione based bisspirooxindolo-pyrrolidine derivatives using [Bmim]BF4 ionic liquid via [3 + 2] cycloaddition reaction. It is an environmentally benign, column chromatography-free, shorter reaction time, good yield and easy product isolation method. The synthesized compounds 10a-x, were thoroughly characterized by using various spectroscopic methods like FT-IR, 1H NMR, 13C NMR, Mass spectrometry and finally by single crystal X-ray diffraction method. In vitro anti-tubercular (anti-TB) activity studies were carried out on these synthesized compounds, and they showed good to moderate anti-TB activity against Mycobacterium tuberculosis H37Rv strain. The compound 10a exhibited good anti-TB activity, with an MIC (Minimum Inhibitory Concentration) value of 12.5 µg/mL, and the compounds 10m, 10o and 10r showed moderate activity with an MIC value of 25.0 µg/mL. Remaining compounds exhibited poor activity against Mycobacterium tuberculosis. Ethambutol, rifampicin and isoniazid were used as standard drugs. Furthermore, in silico molecular docking experiments on the TB protein (PDB ID: 1DF7) were carried out to understand the binding interactions, and they showed least binding energy values ranging from -8.9 to -7.2 kcal/mol.

Design, synthesis, anti-mycobacterial activity, molecular docking and ADME analysis of spiroquinoxaline-1,2,4-oxadiazoles via [3 + 2] cycloaddition reaction under ultrasound irradiation.

The development of anti-tuberculosis (anti-TB) drugs has become a challenging task in medicinal chemistry. This is because Mycobacterium tuberculosis (TB), the pathogen that causes tuberculosis, has an increasing number of drug-resistant strains, and existing medication therapies are not very effective. This resistance significantly demands new anti-TB drug profiles. Here, we present the design and synthesis of a number of hybrid compounds with previously known anti-mycobacterial moieties attached to quinoxaline, quinoline, tetrazole, and 1,2,4-oxadiazole scaffolds. A convenient ultrasound methodology was employed to attain spiroquinoxaline-1,2,4-oxadiazoles via [3 + 2] cycloaddition of quinoxaline Schiff bases and aryl nitrile oxides at room temperature. This approach avoids standard heating and column chromatography while producing high yields and shorter reaction times. The target compounds 3a-p were well-characterized, and their in vitro anti-mycobacterial activity (anti-TB) was evaluated. Among the screened compounds, 3i displayed promising activity against the Mycobacterium tuberculosis cell line H37Rv, with an MIC99 value of 0.78 µg/mL. However, three compounds (3f, 3h, and 3o) exhibited potent activity with MIC99 values of 6.25 µg/mL. To further understand the binding interactions, the synthesized compounds were docked against the tuberculosis protein 5OEQ using in silico molecular docking. Moreover, the most active compounds were additionally tested for their cytotoxicity against the RAW 264.7 cell line, and the cytotoxicity of compounds 3f, 3h, 3i, and 3o was 27.3, 28.9, 26.4, and 30.2 µg/mL, respectively. These results revealed that the compounds 3f, 3h, 3i, and 3o were less harmful to humans. Furthermore, the synthesized compounds were tested for ADME qualities, and the results suggest that this series is useful for producing innovative and potent anti-tubercular medicines in the future.

Design and synthesis of novel quinazolinyl-bisspirooxindoles as potent anti-tubercular agents: an ultrasound-promoted methodology.

The essential need for the potent anti-tubercular (anti-TB) agents with high selectivity and safety profile prompted us to synthesize a new series of quinazolinyl-bisspirooxindoles. The title compounds were synthesized by one-pot multicomponent [3 + 2] cycloaddition reaction under ultrasonication. Further, in vitro anti-TB activity was evaluated against Mycobacterium tuberculosis H37Rv. Among the screened compounds, two compounds (4q and 4x) showed potent activity with MIC value 1.56 µg/mL and four compounds exhibited significant activity (MIC = 3.125 µg/mL), and also cytotoxicity studies against RAW 264.7 cell lines reveal that most active compounds were less toxic to humans. In addition, in order to demonstrate the inhibitory properties, molecular docking studies were carried out and the results showed that the target compounds have good binding energy and better binding affinity within the active pocket, thus these compounds may consider to be as potent inhibitors toward selective targets.

Synthesis of spirooxindolocarbamates based on Betti reaction: antibacterial, antifungal and antioxidant activities.

A series of new spirooxindolocarbamates 4a-l and 6a-d were synthesized by using the Betti reaction. All the target compounds were well characterized by IR, NMR and mass spectrometry. The structures of the compounds 4a and 4e were confirmed by the single crystal X-ray diffraction. The in vitro antibacterial activity results revealed that the compounds 4f exhibited excellent antibacterial activity against E. coli with MIC value 7.5 µg/mL when compared with the standard drug ciprofloxacin with MIC value 9.25 µg/mL. The compounds 4l and 6c exhibit significant inhibiting activity against E. Coli with MIC values 10.5 µg/mL and 9.5 µg/mL, respectively. The compounds 4c and 4e showed significant activity against S. aureus with MIC value 10.5 µg/mL. The compounds 4a and 4f were exhibited moderate antifungal activity against A. niger with MIC values 17.5 µg/mL and 18.0 µg/mL, respectively. The compounds 4f and 4l exhibited the potent antioxidant activity with IC50 values 9.12 ± 0.01 µM and 7.06 ± 0.78 µM, respectively.

Ultrasonication-ionic liquid synergy for the synthesis of new potent anti-tuberculosis 1,2,4-triazol-1-yl-pyrazole based spirooxindolopyrrolizidines.

The aim of the study is to design and synthesis of a new series of potent anti-TB 1,2,4-triazol-1-yl-pyrazole based spirooxindolopyrrolizidines with their safety profile. A synergetic effect of ultrasonication and ionic liquid was shown successfully as a green methodology for the synthesis of title compounds 6a-t. These derivatives were obtained in shorter reaction time with good yields and well characterized by various spectroscopic methods, single-crystal X-ray diffraction (6f). The in vitro anti-tuberculosis activity for newly-synthesized derivatives has been screened against Mycobacterium tuberculosis. Among all, six compounds 6e, 6k, 6l, 6n, 6q and 6r exhibited equal potent activity compared to standard drug ethambutol (MIC: 1.56 µg/mL) and another compound 6h exhibited outstanding activity (MIC: 0.78 µg/mL) than the standard drug ethambutol. Cytotoxic nature of the anti-TB active compounds was evaluated against RAW 264.7 cells. The 6h, 6e, 6k, 6l, 6n, 6q and 6r exhibited lower toxicity which could be promising hits for anti-tuberculosis.

Design, synthesis, molecular modelling, ADME prediction and anti-hyperglycemic evaluation of new pyrazole-triazolopyrimidine hybrids as potent α-glucosidase inhibitors.

The aim of the present study is to design and synthesis of new pyrazole-triazolopyrimidine hybrids as potent α-glucosidase inhibitors. The target compounds 4a-n were synthesized by one-pot multicomponent approach with good yields and were characterized by various spectroscopic techniques and finally by single crystal X-ray diffraction method (4j). All the newly-synthesized derivatives have been screened for their α-glucosidase enzyme inhibition activity and acarbose taken as a standard drug. Among all the tested compounds, 4h has displayed excellent α-glucosidase enzyme inhibition activity with IC50 value 12.45 µM to the standard drug acarbose (IC50: 12.68 µM). Similarly, the compounds 4f and 4l have exhibited potent activity with IC50 values 14.47 µM and 17.27 µM respectively. Structure-activity relationship (SAR) studies of all the title compounds were established. The mode of binding interactions between the α-glucosidase enzyme and the compounds were studied. The drug-likeness properties (Lipinski parameters and in silico ADME properties) have predicted for the target compounds. The α-glucosidase inhibition, molecular docking and drug-likeness properties of the compounds 4h, 4f and 4l were suggested that these are promising hits for anti-diabetic activity.

Sorting of polymorphs based on mechanical properties. Trimorphs of 6-chloro-2,4-dinitroaniline.

Mechanical shearing of crystals of a polymorph with a layered structure may be used to separate them from harder crystals of a visually indistinguishable polymorph that resist such shearing.

Structural basis for bending of organic crystals.

Bending is observed in organic crystals when the packing is anisotropic in such a way that strong and weak interaction patterns occur in nearly perpendicular directions.

Polymorphism in acesulfame sweetener: structure-property and stability relationships of bending and brittle crystals.

Acesulfame is found to exist in two crystalline forms of which Form I (needles) shows bending upon mechanical stress. Crystal structures explain their mechanical response. This is the first case of aliphatic organic compounds featuring a bending phenomenon. Form I is physically more stable than Form II in ambient conditions.

Indomethacin-saccharin cocrystal: design, synthesis and preliminary pharmaceutical characterization.

PURPOSE: To design and prepare cocrystals of indomethacin using crystal engineering approaches, with the ultimate objective of improving the physical properties of indomethacin, especially solubility and dissolution rate. MATERIALS AND METHODS: Various cocrystal formers, including saccharin, were used in endeavours to obtain indomethacin cocrystals by slow evaporation from a series of solvents. The melting point of crystalline phases was determined. The potential cocrystalline phase was characterized by DSC, IR, Raman and PXRD techniques. The indomethacin-saccharin cocrystal (hereafter IND-SAC cocrystal) structure was determined from single crystal X-ray diffraction data. Pharmaceutically relevant properties such as the dissolution rate and dynamic vapour sorption (DVS) of the IND-SAC cocrystal were evaluated. Solid state and liquid-assisted (solvent-drop) cogrinding methods were also applied to indomethacin and saccharin. RESULTS: The IND-SAC cocrystals were obtained from ethyl acetate. Physical characterization showed that the IND-SAC cocrystal is unique vis-à-vis thermal, spectroscopic and X-ray diffraction properties. The cocrystals were obtained in a 1:1 ratio with a carboxylic acid and imide dimer synthons. The dissolution rate of IND-SAC cocrystal system was considerably faster than that of the stable indomethacin gamma-form. DVS studies indicated that the cocrystals gained less than 0.05% in weight at 98%RH. IND-SAC cocrystal was also obtained by solid state and liquid-assisted cogrinding methods. CONCLUSIONS: The IND-SAC cocrystal was formed with a unique and interesting carboxylic acid and imide dimer synthons interconnected by weak N-Hcdots, three dots, centeredO hydrogen bonds. The cocrystals were non-hygroscopic and were associated with a significantly faster dissolution rate than indomethacin (gamma-form).