Synthesis and anti-bacterial activity of a library of 1,2-benzisothiazol-3(2H)-one (BIT) derivatives amenable of crosslinking to polysaccharides

Synthesis, chemical characterization, and biological evaluation of a novel auranofin derivative as an anticancer agent

A novel gold(I) complex inspired by the known medicinal inorganic compounds auranofin and thimerosal, namely ethylthiosalicylate(triethylphosphine)gold(I) (AFETT hereafter), was synthesized and characterised and its structure was resolved through X-ray diffraction. The solution behavior of AFETT and its interactions with two biologically relevant proteins (i.e. human serum albumin and haemoglobin) and with a synthetic dodecapeptide reproducing the C-terminal portion of thioredoxin reductase were comparatively analyzed through ³¹P NMR and ESI-MS. Remarkable binding properties toward these biomolecules were disclosed. Moreover, the cytotoxic effects produced by AFETT on two ovarian cancer cell lines (A2780 and A2780 R) and one colorectal cancer cell line (HCT116) were analyzed and found to be strong and nearly superimposable to those of auranofin. Interestingly, for both compounds, the ability to induce downregulation of vimentin expression in A2780 R cells was evidenced. Despite its close similarity to auranofin, AFETT is reported to exhibit some peculiar and distinctive features such as a lower lipophilicity, an increased water solubility and a faster reactivity towards the selected target biomolecules. These differences might confer to AFETT significant pharmaceutical and therapeutic advantages over auranofin itself.

Synthesis of novel series of 3,5-disubstituted imidazo[1,2-d] [1,2,4]thiadiazoles involving SNAr and Suzuki–Miyaura cross-coupling reactions

The first access to 3,5-disubstituted imidazo[1,2-d][1,2,4]thiadiazole derivatives is reported. The series were generated from 2-mercaptoimidazole, which afforded the key intermediate bearing two functional positions. The S_NAr reactivity toward tosyl release at the C-3 position was investigated and a regioselective electrophilic iodination in C-5 position was performed to allow a novel C–C bond using Suzuki–Miyaura reaction. Palladium-catalyzed cross-coupling conditions were optimized. A representative library of various boronic acids was employed to establish the scope and limitations of the method. To complete this methodological study, the influence of the nature of the C-3 imidazo[1,2-d][1,2,4]thiadiazole substitutions on the arylation in C-5 was investigated.

A convenient design of 3,5-disubstituted imidazo[1,2-d][1,2,4]thiadiazoles is reported from 2-mercaptoimidazole, which afforded a versatile platform that was then used to access a variety of original heterocycles.

Antimicrobial efficacy of Egyptian Eremina desertorum and Helix aspersa snail mucus with a novel approach to their anti-inflammatory and wound healing potencies

Snail mucus is composed of bioactive compounds thought to have different biological properties for the treatment of some skin problems. Although Helix aspersa mucus is used in several cosmetic products, a detailed characterization of Eremina desertorum mucus composition and its biological activities is still missing. Mucus extracts (MEs) from H. aspersa and E. desertorum were prepared and tested for their antimicrobial and anti-inflammatory activities with their potencies in wound healing. Also, chemical characterization was performed by GC-MS analysis. Results showed that ME of E. desertorum gave higher inhibitory activity against resistant strains related to burn wound infections compared to ME of H. aspersa. Additionally, it revealed a significant anti-inflammatory activity. Moreover, we found that ME of E. desertorum lacked cytotoxicity and was able to significantly induce cell proliferation and migration through up-regulation of TGF-β1 and VEGF gene expression. Our results suggested that MEs of E. desertorum have higher biological effects than H. aspersa, which are attributable to antimicrobial, anti-inflammatory activities, cell proliferation and pave the way for further investigating its potential effect as a human therapeutic agent.

Construction, petro-collecting/dispersing capacities, antimicrobial activity, and molecular docking study of new cationic surfactant-sulfonamide conjugates

Surfactants with their diverse activities have been recently involved in controlling the spread of new coronavirus (COVID-19) pandemic as they are capable of disrupting the membrane surrounding the virus. Using hybrids approach, we constructed a novel series of cationic surfactant-sulfonamide conjugates (3a-g) through quaternization of the as-prepared sulfonamide derivatives (2a-g) with n-hexadecyl iodide followed by structural characterization by spectroscopy (IR and NMR). Being collective properties required in petroleum-processing environment, the petro-collecting/dispersing capacities on the surface of waters with different degrees of mineralization, and the antimicrobial performance against microbes and sulfate-reducing bacteria (SRB) that mitigate microbiological corrosion were investigated for the synthesized conjugates. Among these conjugates, 3g (2.5% aq. solution) exhibited the strongest ability to disperse the thin petroleum film on the seawater surface, whereas K_D is 95.33% after 96 h. In diluted form, 3f collected the petroleum layer on distilled water surface (K_max = 32.01) for duration exceeds 4 days. Additionally, almost all compounds revealed high potency and comparable action with standard antimicrobials, especially 3b and 3f, which emphasize their role as potential biocides. Regarding biocidal activity against SRB, 3g causes a significant reduction in the bacterial count from 2.8 × 10⁶ cells/mL to Nil. Moreover, the conducted molecular docking study confirms the strong correlation between RNA polymerase binding with bioactivity against microbes over other studied proteins (threonine synthase and cyclooxygenase-2).

Synthetic flavonoids as potential antiviral agents against SARS-CoV-2 main protease

The COVID-19 pandemic has claimed more than a million lives worldwide within a short time span. Due to the unavailability of specific antiviral drugs or vaccine, the infections are causing panic both in general public and among healthcare providers. Therefore, an urgent discovery and development of effective antiviral drug for the treatment of COVID-19 is highly desired. Targeting the main protease (M^pro) of the causative agent, SARS-CoV-2 has great potential for drug discovery and drug repurposing efforts. Published crystal structures of SARS-CoV-2 M^pro further facilitated in silico investigations for discovering new inhibitors against M^pro. The present study aimed to screen several libraries of synthetic flavonoids and benzisothiazolinones as potential SARS-CoV-2 M^pro inhibitors using in silico methods. The short-listed compounds after virtual screening were filtered through SwissADME modeling tool to remove molecules with unfavorable pharmacokinetics and medicinal properties. The drug-like molecules were further subjected to iterative docking for the identification of top binders of SARS-CoV-2 M^pro. Finally, molecular dynamic (MD) simulations and binding free energy calculations were performed for the evaluation of the dynamic behavior, stability of protein–ligand complex, and binding affinity, resulting in the identification of thioflavonol, TF-9 as a potential inhibitor of M^pro. The computational studies further revealed the binding of TF-9 close to catalytic dyad and interactions with conserved residues in the S1 subsite of the substrate binding site. Our in-silico study demonstrated that synthetic analogs of flavonoids, particularly thioflavonols, have a strong tendency to inhibit the main protease M^pro, and thereby inhibit the reproduction of SARS-CoV-2.

Communicated by Ramaswamy H. Sarma

Transition-metal-free S–N bond formation: synthesis of 5-amino-1,2,4-thiadiazoles from isothiocyanates and amidines

A novel and green method for the synthesis of 5-amino-1,2,4-thiadiazoles has been developed by the reaction of isothiocyanates with amidines.