Synthesis, characterization, and evaluation of novel diphenylpyrazole-based hydrazine-1-carboximidamides as broad-spectrum antibacterial leads with antibiofilm and virulence-modulating activities
10 affiliations
- 1Department of Pharmacology and Toxicology, College of Pharmacy, Taibah University Madinah Saudi Arabia
- 2Department of Pharmacognosy and Pharmaceutical Chemistry, College of Pharmacy, Taibah University Madinah Saudi Arabia
- 3Medical Laboratory Sciences, Fakeeh College for Medical Sciences, Fakeeh Care Group Jeddah 21461 Saudi Arabia
- 4Pharmacy Student, College of Pharmacy, Taibah University Madinah 41477 Saudi Arabia
- 5Pharmaceutical Science Department, College of Pharmacy, King Saud bin Abdulaziz University for Health Science Riyadh Saudi Arabia
- 6Department of Chemistry, Faculty of Science, Islamic University of Madinah Madinah 42351 Saudi Arabia
- 7Department of Pharmaceutical Chemistry, College of Pharmacy, Jouf University Sakaka 72388 Saudi Arabia
- 8Department of Pharmacognosy, College of Pharmacy, Jouf University Sakaka Aljouf 72388 Saudi Arabia
- 9Microbiology and Immunology Department, Faculty of Pharmacy, Al-Azhar University Nasr City 11884 Cairo Egypt
- 10Pharmaceutical Organic Chemistry Department, Faculty of Pharmacy, Al-Azhar University Cairo 11884 Egypt
Abstract
The emergence of multidrug-resistant bacterial pathogens and biofilm-associated infections highlights the urgent need for antibacterial agents with novel chemical architectures and complementary modes of action. In the present study, a new series of diphenylpyrazole-based hydrazine-1-carboximidamide derivatives (5a–i) was designed, synthesized, and evaluated as potential antibacterial and antibiofilm agents. The target compounds were obtained through a three-step synthetic sequence involving phenylhydrazone formation, Vilsmeier–Haack cyclization/formylation, and subsequent condensation with aminoguanidine bicarbonate. Structural characterization was established using spectroscopic and mass spectrometric techniques. The synthesized derivatives exhibited variable antibacterial activity against representative Gram-positive and Gram-negative bacteria, demonstrating a pronounced structure-dependent response. Among the series, compound 5g bearing a nitrophenyl substituent emerged as the most promising derivative, displaying MIC values of 8, 4, 4, and 16 µg mL−1 against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa, respectively. Compound 5g also showed substantial antibiofilm activity at 0.5 × MIC, with inhibition values of 75.95%, 53.33%, 77.57%, and 63.73% against the corresponding bacterial strains. Time-kill studies demonstrated a concentration- and time-dependent bactericidal effect against E. coli ATCC 25922, while potassium leakage and scanning electron microscopy provided complementary evidence of bacterial membrane perturbation and cellular-envelope damage. Furthermore, compound 5g exhibited promising anti-quorum-sensing activity against P. aeruginosa, significantly reducing pyocyanin production by 26.80% and 54.33% at ¼ and ½ MICs, respectively. Importantly, 5g exhibited low cytotoxicity toward WI-38 normal human cells (IC50 = 255 ± 22.1 µg mL−1) and a favorable selectivity index of 32. Collectively, these findings identify diphenylpyrazole carboximidamide 5g as a promising multifunctional antibacterial lead with direct antibacterial, antibiofilm, membrane-perturbing, and anti-quorum-sensing activities, warranting further optimization and mechanistic investigation.
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BibTeX
@article{almadani2026synthesis,
title = {{Synthesis, characterization, and evaluation of novel diphenylpyrazole-based hydrazine-1-carboximidamides as broad-spectrum antibacterial leads with antibiofilm and virulence-modulating activities}},
author = {Sara A. Almadani and Ahmed K. B. Aljohani and Bandar D. Alrehaili and Safaa A. Turkistani and Shahad N. Almuzani and Maysa M. Aljuhani and Ghada Y. Alsayed and Ruba A. Alharbi and Hadeel Z. Alraddadi and Sobhi M. Gomha and Mohamed A. Abdelgawad and Arafa Musa and Raed Alghamdi and Mohammed S. Abdulrahman and Hany E. A. Ahmed},
journal = {RSC advances},
year = {2026},
month = oct,
doi = {10.1039/d6ra08952f},
url = {https://europepmc.org/article/PMC/PMC13720906},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Synthesis, characterization, and evaluation of novel diphenylpyrazole-based hydrazine-1-carboximidamides as broad-spectrum antibacterial leads with antibiofilm and virulence-modulating activities
AU - Sara A. Almadani
AU - Ahmed K. B. Aljohani
AU - Bandar D. Alrehaili
AU - Safaa A. Turkistani
AU - Shahad N. Almuzani
AU - Maysa M. Aljuhani
AU - Ghada Y. Alsayed
AU - Ruba A. Alharbi
AU - Hadeel Z. Alraddadi
AU - Sobhi M. Gomha
AU - Mohamed A. Abdelgawad
AU - Arafa Musa
AU - Raed Alghamdi
AU - Mohammed S. Abdulrahman
AU - Hany E. A. Ahmed
PY - 2026
DA - 2026/10/30
JO - RSC advances
DO - 10.1039/d6ra08952f
UR - https://europepmc.org/article/PMC/PMC13720906
AB - The emergence of multidrug-resistant bacterial pathogens and biofilm-associated infections highlights the urgent need for antibacterial agents with novel chemical architectures and complementary modes of action. In the present study, a new series of diphenylpyrazole-based hydrazine-1-carboximidamide derivatives (5a–i) was designed, synthesized, and evaluated as potential antibacterial and antibiofilm agents. The target compounds were obtained through a three-step synthetic sequence involving phenylhydrazone formation, Vilsmeier–Haack cyclization/formylation, and subsequent condensation with aminoguanidine bicarbonate. Structural characterization was established using spectroscopic and mass spectrometric techniques. The synthesized derivatives exhibited variable antibacterial activity against representative Gram-positive and Gram-negative bacteria, demonstrating a pronounced structure-dependent response. Among the series, compound 5g bearing a nitrophenyl substituent emerged as the most promising derivative, displaying MIC values of 8, 4, 4, and 16 µg mL−1 against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa, respectively. Compound 5g also showed substantial antibiofilm activity at 0.5 × MIC, with inhibition values of 75.95%, 53.33%, 77.57%, and 63.73% against the corresponding bacterial strains. Time-kill studies demonstrated a concentration- and time-dependent bactericidal effect against E. coli ATCC 25922, while potassium leakage and scanning electron microscopy provided complementary evidence of bacterial membrane perturbation and cellular-envelope damage. Furthermore, compound 5g exhibited promising anti-quorum-sensing activity against P. aeruginosa, significantly reducing pyocyanin production by 26.80% and 54.33% at ¼ and ½ MICs, respectively. Importantly, 5g exhibited low cytotoxicity toward WI-38 normal human cells (IC50 = 255 ± 22.1 µg mL−1) and a favorable selectivity index of 32. Collectively, these findings identify diphenylpyrazole carboximidamide 5g as a promising multifunctional antibacterial lead with direct antibacterial, antibiofilm, membrane-perturbing, and anti-quorum-sensing activities, warranting further optimization and mechanistic investigation.
SN - 2046-2069
ER -