Shabina Ansari - Academia.edu (original) (raw)

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Papers by Shabina Ansari

Research paper thumbnail of CCDC 2178744: Experimental Crystal Structure Determination

The Cambridge Structural Database, 2023

Research paper thumbnail of Metal‐free sp2‐C7−H Borylation of Tryptophan Containing Peptides and Late‐stage Modification

Chemistry – An Asian Journal

The discovery of milder and robust strategies to enable the introduction of organoboronates in pe... more The discovery of milder and robust strategies to enable the introduction of organoboronates in peptides remains conspicuously underdeveloped. Herein, we demonstrate an efficient method for the site‐selective sp2‐C7−H borylation of tryptophan under metal‐free condition using BBr3 directed by pivaloyl group. The versatility of this approach is that gram scale synthesis and C7‐borylated N‐Phth‐Trp(N‐Piv)(C7‐BPin)‐OMe was modified into various C7‐substituted derivatives. Moreover, the strategy enables for the peptide elongation and late‐stage borylation of peptides, natural product Brevianamide F and drug Oglufanide.

Research paper thumbnail of Design and synthesis of N-acyl and dimeric N-Arylpiperazine derivatives as potential antileishmanial agents

Research paper thumbnail of Design and synthesis of novel halogen rich salicylanilides as potential antileishmanial agents

European Journal of Medicinal Chemistry

Research paper thumbnail of Bio-evaluation of fluoro and trifluoromethyl-substituted salicylanilides against multidrug-resistant S. aureus

Medicinal Chemistry Research

Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Staphylococcus aureus... more Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Staphylococcus aureus (VRSA) are primary causes of skin and soft tissue infections worldwide. To address the emergency caused due to increasing multidrug-resistant (MDR) bacterial infections, a series of novel fluoro and trifluoromethyl-substituted salicylanilide derivatives were synthesized and their antimicrobial activity was investigated. MIC data reveal that the compounds inhibited S. aureus specifically (MIC 0.25-64 µg/mL). The in vitro cytotoxicity of compounds with MIC < 1 µg/mL against Vero cells led to identification of four compounds (20, 22, 24 and 25) with selectivity index above 10. These four compounds were tested against MDR S. aureus panel. Remarkably, 5-chloro-N-(4'-bromo-3'-trifluoromethylphenyl)-2-hydroxybenzamide (22) demonstrated excellent activity against nine MRSA and three VRSA strains with MIC 0.031-0.062 µg/mL, which is significantly better than the control drugs methicillin and vancomycin. The comparative time-kill kinetic experiment revealed that the effect of bacterial killing of 22 is comparable with vancomycin. Compound 22 did not synergize with or antagonize any FDA-approved antibiotic and reduced pre-formed S. aureus biofilm better than vancomycin. Overall, study suggested that 22 could be further developed as a potent anti-staphylococcal therapeutic.

Research paper thumbnail of CCDC 2178744: Experimental Crystal Structure Determination

The Cambridge Structural Database, 2023

Research paper thumbnail of Metal‐free sp2‐C7−H Borylation of Tryptophan Containing Peptides and Late‐stage Modification

Chemistry – An Asian Journal

The discovery of milder and robust strategies to enable the introduction of organoboronates in pe... more The discovery of milder and robust strategies to enable the introduction of organoboronates in peptides remains conspicuously underdeveloped. Herein, we demonstrate an efficient method for the site‐selective sp2‐C7−H borylation of tryptophan under metal‐free condition using BBr3 directed by pivaloyl group. The versatility of this approach is that gram scale synthesis and C7‐borylated N‐Phth‐Trp(N‐Piv)(C7‐BPin)‐OMe was modified into various C7‐substituted derivatives. Moreover, the strategy enables for the peptide elongation and late‐stage borylation of peptides, natural product Brevianamide F and drug Oglufanide.

Research paper thumbnail of Design and synthesis of N-acyl and dimeric N-Arylpiperazine derivatives as potential antileishmanial agents

Research paper thumbnail of Design and synthesis of novel halogen rich salicylanilides as potential antileishmanial agents

European Journal of Medicinal Chemistry

Research paper thumbnail of Bio-evaluation of fluoro and trifluoromethyl-substituted salicylanilides against multidrug-resistant S. aureus

Medicinal Chemistry Research

Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Staphylococcus aureus... more Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Staphylococcus aureus (VRSA) are primary causes of skin and soft tissue infections worldwide. To address the emergency caused due to increasing multidrug-resistant (MDR) bacterial infections, a series of novel fluoro and trifluoromethyl-substituted salicylanilide derivatives were synthesized and their antimicrobial activity was investigated. MIC data reveal that the compounds inhibited S. aureus specifically (MIC 0.25-64 µg/mL). The in vitro cytotoxicity of compounds with MIC < 1 µg/mL against Vero cells led to identification of four compounds (20, 22, 24 and 25) with selectivity index above 10. These four compounds were tested against MDR S. aureus panel. Remarkably, 5-chloro-N-(4'-bromo-3'-trifluoromethylphenyl)-2-hydroxybenzamide (22) demonstrated excellent activity against nine MRSA and three VRSA strains with MIC 0.031-0.062 µg/mL, which is significantly better than the control drugs methicillin and vancomycin. The comparative time-kill kinetic experiment revealed that the effect of bacterial killing of 22 is comparable with vancomycin. Compound 22 did not synergize with or antagonize any FDA-approved antibiotic and reduced pre-formed S. aureus biofilm better than vancomycin. Overall, study suggested that 22 could be further developed as a potent anti-staphylococcal therapeutic.

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