Synthesis andin vitro-Anticancer and Antimicrobial Evaluation of Some Novel Quinoxalines Derived from 3-Phenylquinoxaline-2(1H)-thione

Recent advances in the synthesis and utility of thiazoline and its derivatives

Thiazolines and their derivatives hold significant importance in the field of medicinal chemistry due to their promising potential as pharmaceutical agents. These molecular entities serve as critical scaffolds within numerous natural products, including curacin A, thiangazole, and mirabazole, and play a vital role in a wide array of physiological reactions. Their pharmacological versatility encompasses anti-HIV, neurological, anti-cancer, and antibiotic activities. Over the course of recent decades, researchers have extensively explored and developed analogs of these compounds, uncovering compelling therapeutic properties such as antioxidant, anti-tumor, anti-microbial, and anti-inflammatory effects. Consequently, thiazoline-based compounds have emerged as noteworthy targets for synthetic endeavors. In this review, we provide a comprehensive summary of recent advancements in the synthesis of thiazolines and thiazoline-based derivatives, along with an exploration of their diverse potential applications across various scientific domains.

Facile Synthesis of Quinoxaline-2-thiol and Quinoxaline from α-Oxosulfines and o-Arylenediamines

A series of quinoxaline-2-thiols and quinoxalines were prepared in moderate to good yields from various phenacyl sulfoxides bearing 1-methyl-1H-tetrazole and o-arylenediamines. The proposed reaction mechanism involves generation of sulfines from the phenacyl sulfoxides bearing 1-methyl-1H-tetrazole through thermolysis elimination. Then, site-selective carbophilic addition of sulfines by o-arylenediamines, followed by elimination, intramolecular nucleophilic addition, and dehydration condensation. The current method provides a direct and simple strategy for the preparation of quinoxaline-2-thiols and quinoxalines.

Synthesis, Molecular Docking, and Biological Evaluation of 2,3-Diphenylquinoxaline Derivatives as a Tubulin's Colchicine Binding Site Inhibitor Based on Primary Virtual Screening

BACKGROUND AND OBJECTIVE

Tubulin inhibitors have proved to be a promising treatment against cancer. Tubulin inhibitors target different areas in microtubule structure to exert their effects. The colchicine binding site (CBS) is one of them for which there is no FDA-approved drug yet. This makes CBS a desirable target for drug design.

MATERIALS AND METHODS

Primary virtual screening is done by developing a possible pharmacophore model of colchicine binding site inhibitors of tubulins, and 2,3-diphenylquinoxaline is chosen as a lead compound to synthesis. In this study, 28 derivatives of 2,3-diphenylquinoxalines are synthesized, and their cytotoxicity is evaluated by the MTT assay in different human cancer cell lines, including AGS (Adenocarcinoma gastric cell line), HT-29 (Human colorectal adenocarcinoma cell line), NIH3T3 (Fibroblast cell line), and MCF-7 (Human breast cancer cell).

RESULTS

Furthermore, the activity of the studied compounds was investigated using computational methods involving molecular docking of the 2,3-diphenylquinoxaline derivatives to β-tubulin. The results showed that the compounds with electron donor functionalities in positions 2 and 3 and electron-withdrawing groups in position 6 are the most active tubulin inhibitors.

CONCLUSION

Apart from the high activity of the synthesized compounds, the advantage of this report is the ease of the synthesis, work-up, and isolation of the products in safe, effective, and high-quality isolated yields.

New strategy for identifying potential natural HIV-1 non-nucleoside reverse transcriptase inhibitors against drug-resistance: an in silico study

Non-nucleosides reverse transcriptase inhibitors (NNRTIs), specifically targeting the HIV-1 reverse transcriptase (RT), play a unique role in anti-AIDS agents due to their high antiviral potency, structural diversity, and low toxicity in antiretroviral combination therapies used to treat HIV. However, due to the emergence of new drug-resistant strains, the development of novel NNRTIs with adequate potency, improved resistance profiles and less toxicity is highly required. In this work, a novel virtual screening strategy combined with structure-based drug design was proposed to discover the potential inhibitors against drug-resistant HIV strains. Seven structure-variant RTs, ranging from the wild type to a hypothetical multi-mutant were regarded as target proteins to perform structure-based virtual screening. Totally 23 small molecules with good binding affinity were identified from the Traditional Chinese Medicine database (TCM) as potential NNRTIs candidates. Among these hits, (+)-Hinokinin has confirmed anti-HIV activity, and some hits are structurally identical with anti-HIV compounds. Almost all these hits are consistent with external experimental results. Molecular simulations analysis revealed that top 2 hits (Pallidisetin A and Pallidisetin B) bind stably and in high affinity to HIV-RT, which are ready to be experimental confirmed. These results suggested that the strategy we proposed is feasible, trustworthy and effective. Our finding might be helpful in the identification of novel NNRTIs against drug-resistant, and also provide a new clue for the discovery of HIV drugs in natural products.Communicated by Ramaswamy H. Sarma.

Design and synthesis of some new 2,3′-bipyridine-5-carbonitriles as potential anti-inflammatory/antimicrobial agents

Aim: Inflammation may cause accumulation of fluid in the injured area, which may promote bacterial growth. Other reports disclosed that non-steroidal anti-inflammatory drugs may enhance progression of bacterial infection. Results: This work describes synthesis of new series of 2,3′-bipyridine-5-carbonitriles as structural analogs of etoricoxib, linked at position-6 to variously substituted thio or oxo moieties. Biological screening results revealed that compounds 2b, 4b, 7e and 8 showed significant acute and chronic AI activities and broad spectrum of antimicrobial activity. In addition, similarity ensemble approach was applied to predict potential biological targets of the tested compounds. Then, pharmacophore modeling study was employed to determine the most important structural parameters controlling bioactivity. Moreover, title compounds showed physicochemical properties within those considered adequate for drug candidates. Conclusion: This study explored the potential of such series of compounds as structural leads for further modification to develop a new class of dual AI-antimicrobial agents.

A novel method for heterocyclic amide-thioamide transformations

In this paper, we introduce a novel and convenient method for the transformation of heterocyclic amides into heteocyclic thioamides. A two-step approach was applied for this transformation: Firstly, we applied a chlorination of the heterocyclic amides to afford the corresponding chloroheterocycles. Secondly, the chloroherocycles and N-cyclohexyl dithiocarbamate cyclohexylammonium salt were heated in chloroform for 12 h at 61 °C to afford heteocyclic thioamides in excellent yields.

Crystal structure of 2-benzyl-amino-4-(4-bromo-phen-yl)-6,7-di-hydro-5H-cyclo-penta-[b]pyridine-3-carbo-nitrile

In the title compound C22H18BrN3, the cyclo-pentane ring adopts an envelope conformation with the central methyl-ene C atom as the flap. The dihedral angles between the central pyridine ring and the pendant benzyl and and bromo-benzene rings are 82.65 (1) and 47.23 (1)°, respectively. In the crystal, inversion dimers linked by pairs of N-H⋯Nn (n = nitrile) hydrogen bonds generate R 2 (2)(12) loops. These dimers are linked by weak π-π inter-actions [centroid-centroid distance = 3.7713 (14) Å] into a layered structure.

Design, synthesis and biological evaluation of novel 1,2,4-triazolo and 1,2,4-triazino[4,3-a]quinoxalines as potential anticancer and antimicrobial agents

Compound 9a showed dual anticancer and antimicrobial activity and compound 16 showed a broad spectrum antimicrobial activity.

Synthesis and antiproliferative activity of some steroidal thiosemicarbazones, semicarbazones and hydrozones

Steroidal thiosemicarbazones, semicarbazones and hydrazones have received extensive attention of scientists recently because they exhibit some biological activities such as antibacterial, antiviral and anticancer. Using different steroids as starting materials, through different chemical methods, 24 steroidal compounds with thiosemicarbazone, semicarbazone or hydrazone groups in their structures, were synthesized, characterized by IR, NMR and MS. The antiproliferative activity of the compounds was evaluated against human gastric cancer (SGC-7901) and human liver cancer (Bel-7404) cells. The structure-activity relationship of these compounds was discussed. The results showed that compound 3 and 12a-12c exhibited significant inhibitory activity to Bel-7404 cells, and IC50 values of them were 4.2, 11.0, 7.4 and 15.0μM respectively (Cisplatin, IC50: 11.6μM).

Synthesis and biological evaluation of thiazoline derivatives as new antimicrobial and anticancer agents

N'-(3,4-Diarylthiazol-2(3H)-ylidene)-2-(arylthio)acetohydrazides were synthesized and evaluated for their antimicrobial activity and cytotoxicity against NIH/3T3 cells. Compound 22 bearing 1-phenyl-1H-tetrazole and p-chlorophenyl moieties was found to be the most promising antibacterial agent against Pseudomonas aeruginosa, whereas compound 23 bearing 1-phenyl-1H-tetrazole and p-bromophenyl moieties was the most promising antifungal agent against Candida albicans. The most effective derivatives were also evaluated for their cytotoxicity against C6 glioma cells. The results indicated that compound 17 bearing 1-phenyl-1H-tetrazole and nonsubstituted phenyl moieties (IC₅₀ = 8.3 ± 2.6 μg/mL) was more effective than cisplatin (IC₅₀ = 13.7 ± 1.2 μg/mL) against C6 glioma cells. Compound 17 also exhibited DNA synthesis inhibitory activity on C6 cells. Furthermore, compound 17 showed low toxicity to NIH/3T3 cells (IC₅₀ = 416.7 ± 28.9 μg/mL).

1-Benzoyl-3-[3-cyano-8-methyl-4-(1-methyl-1H-pyrrol-2-yl)-5,6,7,8-tetra-hydro-quinolin-2-yl]thio-urea

In the N-substituted benzoyl-thio-urea, C(24)H(23)N(5)OS, the benzoyl-thio-urea unit is non-planar (r.m.s. deviation = 0.126 Å). The aliphatic part of the tetra-hydro-quinoline fused-ring system is disordered over two positions in a 0.592 (5):0.408 (5) ratio. The pyridine and pyrrole rings are twisted by 55.2 (1)° in order to avoid crowding of their respective substituents. Pairs of mol-ecules are linked by N-H⋯N hydrogen bonds, forming centrosymmetric dimers. Furthermore, an intra-molecular N-H⋯O hydrogen bond stabilizes the mol-ecular conformation.

3-[2-(3-Methyl-quinoxalin-2-yl-oxy)eth-yl]-1,3-oxazolidin-2-one

Two isomers were isolated during the reaction between 3-methyl-quinoxalin-2-one and bis-(2-chloro-ethyl)amine hydro-chloride. The crystal structure of one isomer has already been reported [Caleb, Bouhfid, Essassi & El Ammari (2009). Acta Cryst. E65, o2024-o2025], while that of the second isomer is the subject of this work. The title compound, C(14)H(15)N(3)O(3), has a new structure containing oxazolidine and quinoxaline rings linked by an eth-oxy group. The main difference between the two isomers is the position of the oxazolidine group with respect to the quinoxaline system. The dihedral angle between the fused planar rings and the oxazolidin-2-one ring is 41.63 (8)° in the title mol-ecule.

3-[2-(3-Methyl-2-oxo-1,2-dihydro-quinoxalin-1-yl)eth-yl]oxazolidin-2-one

The title heterocyclic compound, C(14)H(15)N(3)O(3), is a new synthetic mol-ecule containing oxazolidine and quinoxaline rings. It is built up from two fused six-membered rings linked to a five-membered oxazolidin-2-one ring by a C(2) chain. Both ring systems are essentially planar [maximum deviation = 0.894 (3) Å, r.m.s. deviation = 0.0043 Å]. The structure is held together by van der Waals forces [electrostatic interactions between dipoles, O⋯C = 3.002 (2) Å] between mol-ecules and by weak π-π stacking between symmetry-related mol-ecules, with an inter-planar distance of 3.579 Å and a centroid-centroid distance of 3.800 (1) Å. Inter-molecular C-H⋯O hydrogen bonds are also observed in the crystal structure.

Synthesis of Some New Quinoxalines and 1,2,4-Triazolo[4,3-a]-quinoxalines for Evaluation ofin vitro Antitumor and Antimicrobial Activities

Two novel series of quinoxalines derived from 3-phenylquinoxalin-2(1H)-one and 2-hydrazino-3-phenylquinoxaline, namely 1-substituted-3-phenylquinoxaline-2(1H)-ones, 2a-c, 3a-d, and 4; 2-(3-oxo-3,3a,4,5,6,7-hexahydroindazol-2-yl)-3-phenylquinoxaline 6; N- cyclopentylidene or benzylidene-N'-(3-phenylquinoxaline-2-yl)hydrazines, 7 and 18; 1-substituted-4-phenyl-1,2,4-triazolo[4,3-a]quinoxalines, 9, 10, 12, 13, 14, and 16 have been synthesized in order to evaluate their antitumor and antimicrobial activities. Preliminary screening at NCI showed that compounds 2b, 2c, 3b, 3c, and 9 exhibited a moderate to strong growth inhibition activity on various tumor panel cell lines between 10(-6) to 10(-5) molar concentrations. Compound 3b was the most active with a broad spectrum of activity. Compound 3c showed selectivity towards CNS-cancer SF-639, leukemia CCRF-CEM, and melanoma SK-MEL-5 (GI(50) = 4.03, 6.46, and 4.17 microM, respectively). On the other hand, the in vitro microbiological data revealed that the prepared compounds showed mild antimicrobial activity.