Synthesis and Pharmacological Evaluation of Azetidin-2-ones and Thiazolidin-4-ones Encompassing Benzothiazole

The Microwave Rotational Electric Resonance (RER) Spectrum of Benzothiazole

The microwave spectra of benzothiazole were measured in the frequency range 2-26.5 GHz using a pulsed molecular jet Fourier transform microwave spectrometer. Hyperfine splittings arising from the quadrupole coupling of the ¹⁴N nucleus were fully resolved and analyzed simultaneously with the rotational frequencies. In total, 194 and 92 hyperfine components of the main species and the ³⁴S isotopologue, respectively, were measured and fitted to measurement accuracy using a semi-rigid rotor model supplemented by a Hamiltonian accounting for the ¹⁴N nuclear quadrupole coupling effect. Highly accurate rotational constants, centrifugal distortion constants, and ¹⁴N nuclear quadrupole coupling constants were deduced. A large number of method and basis set combinations were used to optimize the molecular geometry of benzothiazole, and the calculated rotational constants were compared with the experimentally determined constants in the course of a benchmarking effort. The similar value of the χ_cc quadrupole coupling constant when compared to other thiazole derivatives indicates only very small changes of the electronic environment at the nitrogen nucleus in these compounds. The small negative inertial defect of -0.056 uŲ hints that low-frequency out-of-plane vibrations are present in benzothiazole, similar to the observation for some other planar aromatic molecules.

Application and synthesis of thiazole ring in clinically approved drugs

The development of heterocyclic derivatives has progressed considerably over the past few decades, and many new agents of synthetic and natural origin have been produced. Among heterocyclic compounds, thiazole is a unique five-membered heterocyclic motif characterized by nitrogen and sulfur atoms, which is widely used as an important core skeleton in a variety of pharmaceutically important compounds due to their diverse biological activities, such as antibacterial, antivirus, and antifungal. To the best of our knowledge, more than 90 thiazole-containing derivatives have been currently under clinical investigation, and some thiazole analogs have been approved to treat various diseases. As the potentially privileged scaffolds, thiazole derivatives can be further extensively explored to search for new drugs characterized by improved therapeutic efficacy and similar biological targets. This review aims to outline the applications and synthetic routes of some representative thiazole-containing drugs approved in the clinic, which may guide medicinal researchers to rationally design more effective thiazole-containing drug candidates.

Dry Grinding Synthesis and Docking Study of Cyclopentanone-Sulfur Containing Compounds with Anti-Proliferative Activity for HepG-2 and A-549 Cancer Cell Lines

BACKGROUND

The dry grinding method is a green technique for efficient organic synthesis with numerous advantages, such as: mild reaction conditions, environmental acceptability, simple segregation and refinement as well as the elevated selectivity and efficiency.

OBJECTIVE

The aim of the present work is to design and synthesize of cyclopentylidene-hydrazino)-thiazole derivatives using dry grinding condition to investigate their antitumor activity aganist two cell lines namely, HepG-2 and A-549.

METHODS

In this context, we synthesized series of thiazole incorporated cyclopentane through hydrazone-group and 2-cyclopentylidenehydrazine-1-carbimidic-2-ethoxy-N-aryl-2-oxoacetohydrazonic thioanhydride under dry grinding within minutes and excellent to good yield.

RESULTS

All spectral data confirmed the proposed structures. The molecular docking studies have been performed using Macrophage Migration Inhibitory Factor (Pdb: 4k9g) and Lysozyme C (Pdb: 2f4a), the overexpressed proteins in human liver cancer cell (HepG-2) and lung cancer cell lines (A-549), respectively, in addition to the antitumor activity investigations contra the two types of tumor cells.

CONCLUSION

Two derivatives 9b and 9d showed the highest antitumor activity against the two cell lines HepG-2 and A-549. Also, docking results revealed high energy score ranging from -7.1590 to -5.9364 Kcal/mol with Macrophage Migration Inhibitory Factor (Pdb: 4k9g) which is more than the energy score = -4.118 Kcal/mol of co-crystallized ligand. Moreover, the tested derivatives showed energy score varies from -6.0802 to -4.5503 Kcal/mol against Lysozyme C (Pdb: 2f4a).

Facile synthesis, antimicrobial and antiviral evaluation of novel substituted phenyl 1,3-thiazolidin-4-one sulfonyl derivatives

A series of novel substituted phenyl 1, 3-thiazolidin-4-one sulfonyl derivatives 5 (a-t) were synthesized and screened for their in-vitro anti-microbial and anti-viral activity. The result of the anti-microbial assay demonstrated compounds 5d, 5f, 5g, 5h, 5i, 5j showed prominent inhibitory activity against all the tested Gram-positive and Gram-negative bacterial strains, while compounds 5g, 5j, 5o, 5p, 5q showed significant activity against the entire set of fungal strains as compared to standard drug Ampicillin and Clotrimazole, respectively. The antimicrobial study revealed that compounds having electron-withdrawing groups showed significant antimicrobial potency. The most active antibacterial compound 5j showed potent inhibition of S. aureus DNA Gyrase enzyme as a possible mechanism of action for antimicrobial activity. Moreover, the antiviral testing of selected compounds showed considerable activity against Herpes simplex virus-1(KOS), Herpes simplex virus-2 (G), Herpes simplex virus-1(TK^- KOS ACV^r), Vaccinia virus, Human Coronavirus (229E), Reovirus-1, Sindbis virus, Coxsackie virus B4, Yellow Fever virus and Influenza A, B virus. Compounds 5h exhibited low anti-viral activity against HIV-1(strain IIIB) and HIV-2 (strain ROD). The study clearly outlined that synthesized compounds endowed with good antimicrobial property together with considerable antiviral activity.

Novel anti-inflammatory and analgesic agents: synthesis, molecular docking and in vivo studies

Twelve new derivatives of benzothiazole bearing benzenesulphonamide and carboxamide were synthesised and investigated for their in vivo anti-inflammatory, analgesic and ulcerogenic activities. Molecular docking showed an excellent binding interaction of the synthesised compounds with the receptors, with 17c showing the highest binding energy (–12.50 kcal/mol). Compounds 17c and 17i inhibited carrageenan-induced rat paw oedema at 72, 76, and 80% and 64, 73, and 78% at 1 h, 2 h, and 3 h, respectively. In the analgesic activity experiment, compounds 17c, 17 g, and 17i had ED₅₀ (µM/kg) of 96, 127, and 84 after 0.5 h; 102, 134, and 72 after 1 h and 89, 156, and 69 µM/kg after 2 h, respectively, which were comparable with 156, 72, and 70 µM/kg for celecoxib. The ulcerogenic index of the most active derivatives 17c and 17i were 0.82 and 0.89, respectively, comparable to 0.92 for celecoxib. The physicochemical studies of the new derivatives showed that they will not have oral bioavailability problems.

Synthesis of novel inhibitors of β-glucuronidase based on the benzothiazole skeleton and their molecular docking studies

Benzothiazole derivatives (1–20) were evaluated for β-glucuronidase inhibitory activity.

1-(5-Chloro-6-fluoro-1,3-benzothiazol-2-yl)hydrazine

In the title compound, C₇H₅ClFN₃S, the 1,3-benzothia­zole ring system is nearly planar (r.m.s. deviation = 0.023 Å). In the crystal, mol­ecules are linked via inter­molecular N—H⋯N hydrogen bonds into a two-dimensional network parallel to (100).

1-(6-Fluoro-1,3-benzothia-zol-2-yl)-2-(1-phenyl-ethyl-idene)hydrazine

The asymmetric unit of the title compound, C₁₅H₁₂FN₃S, consists of two independent mol­ecules with comparable geometries. In one mol­ecule, the 1,3-benzothia­zole ring system (r.m.s. deviation = 0.011 Å) forms a dihedral angle of 19.86 (6)° with the phenyl ring. The corresponding r.m.s. deviation and dihedral angle for the other mol­ecule are 0.014 Å and 22.32 (6)°, respectively. In the crystal, mol­ecules are linked via N—H⋯N, C—H⋯F and C—H⋯N hydrogen bonds into a three-dimensional network. The crystal studied was a non-merohedral twin with a refined BASF value of 0.301 (2).

Synthesis and Antimicrobial Activities of Some New Azetidin-2-ones and Thiazolidin-4-ones

Various (4-substituted) phenyl-3-β-[(N-benzenesulphonyl/tosyl)-4-(un)substituted anilino]propionylamido-1,3-thiazolidine-4-ones (3a–x) and 1-β-[(N-benzenesulphonyl/tosyl)-4-(un)substituted anilino]-propionylamido-3-chloro-4-(4-substituted)phenyl-azetidin-2-ones (4a–x) have been synthesised by the cyclocondensation of Schiff bases (2a-x) with thioglycolic acid and chloroacetyl chloride, respectively. The structures of the newly synthesised compounds have been established on the basis of their spectral data and elemental analysis. All compounds were evaluated for antimicrobial activities against Escherichia coli, Bacillus cirroflagellosus, Aspergillus niger and Colletotrichum capsici. Most compounds investigated exhibited significant antifungal activity against Colletotrichum capsici, comparable to that of fluconazole, the standard used.

6-Fluoro-2-(4-methoxyphenyl)imidazo[2,1-b][1,3]benzothiazole

The asymmetric unit of the title compound, C₁₆H₁₁FN₂OS, comprises two independent mol­ecules in which the benzothia­zole rings are essentially planar, with maximum deviations of 0.038 (2) and 0.045 (3) Å. The central benzothia­zole ring makes dihedral angles of 4.87 (13) and 0.64 (12)° and 4.04 (12) and 3.67 (12)° with the two terminal phenyl rings in the two independent mol­ecules. In the crystal, mol­ecules are connected via weak inter­molecular C—H⋯O hydrogen bonds forming supra­molecular chains along the c axis.

1-(6-Fluoro-1,3-benzothia-zol-2-yl)-3-phenyl-1H-pyrazole-4-carbaldehyde

The asymmetric unit of the title compound, C(17)H(10)FN(3)OS, consists of two crystallographically independent mol-ecules. In one mol-ecule, the pyrazole ring makes dihedral angles of 6.51 (7) and 34.02 (9)°, respectively, with the terminal 1,3-benzothia-zole ring system and the phenyl ring, while in the other mol-ecule these values are 6.41 (8) and 23.06 (9)°. In the crystal, the molecules are linked by weak π-π [centroid-centroid distance = 3.7069 (10) Å] and C-H⋯π inter-actions.

7-Chloro-3-phenylbenzo[4,5]thiazolo[2,3-c][1,2,4]triazole

In the title compound, C₁₄H₈ClN₃S, the dihedral angle between the approximately planar triple-fused ring system (r.m.s. deviation = 0.065 Å) and the pendant phenyl ring is 62.25 (5)°. In the crystal, mol­ecules are linked into infinite chains along the c-axis direction by C—H⋯N hydrogen bonds. Aromatic π–π stacking inter­actions [centroid–centroid distances = 3.7499 (8) and 3.5644 (8) Å] and weak C—H⋯π inter­actions are also observed.