The development of thymol-isatin hybrids as broad-spectrum antibacterial agents with potent anti-MRSA activity

• Published in: MedChemComm 2024-01, Vol.15 (1), p.234-253
• Main Authors: Singh, Atamjit, Kaur, Kirandeep, Mohana, Pallvi, Singh, Karanvir, Sharma, Aman, Prajapati, Jignesh, Goswami, Dweipayan, Khosla, Neha, Kaur, Uttam, Kaur, Rajanbir, Kaur, Rajinder, Rana, Abhineet, Kour, Sandeep, Ohri, Puja, Arora, Saroj, Chadha, Renu, Singh Bedi, Preet Mohinder
• Format: Article
• Language: English
• Subjects: Antibacterial activity; Antibacterial agents; Antimicrobial agents; Biocompatibility; Biofilms; Chemistry; Drug development; Drug resistance; Effectiveness; Hybridization; Hybrids; Immune response; Infectious diseases; Methicillin; Molecular docking; Multidrug resistance; Pharmacology; Public health; Staphylococcus infections; Thymol; Triazoles; Virulence factors
• ISSN: 2632-8682; 2040-2503; 2632-8682; 2040-2511
• DOI: 10.1039/d3md00580a

Bacterial resistance toward available therapeutic agents has become a nightmare for the healthcare system, causing significant mortality as well as prolonged hospitalization, thereby needing the urgent attention of research groups working on antimicrobial drug development worldwide. Molecular hybridization is a well-established tool for developing multifunctional compounds to tackle drug resistance. Inspired by the antibacterial profiles of isatin and thymol, along with the efficiency of a triazole linker in molecular hybridization, herein, we report the design, synthesis and antibacterial activity of a novel series of triazole tethered thymol-isatin hybrids. Most of the hybrids exhibited a broad-spectrum antibacterial efficacy against standard human pathogenic as well as clinically isolated multidrug-resistant bacterial strains listed in the WHO's 'priority pathogen' list and also in the ESKAPE group. Among them, hybrid compound AS8 was the most effective against methicillin-resistant Staphylococcus aureus (MIC = 1.9 μM and MBC = 3.9 μM), exhibiting biofilm inhibitory potential. AS8 exhibited dehydrosqualene synthase (CrtM) inhibitory potential in MRSA and decreased the production of virulence factor staphyloxanthin, which is one of the key mechanisms of its anti-MRSA efficacy, which was further supported by molecular docking and simulation studies. Moreover, AS8 was found to be non-toxic and showed a potent in vivo antibacterial efficacy (90% survival at 10 mg kg −1 ) as well as a modulated immune response in the larva-based ( Galleria mellonella ) model of systemic infections. Overall findings confirmed that AS8 can be a promising candidate or take the lead in the treatment and further drug development against drug-resistant infectious diseases, especially against MRSA infections. Triazole-tethered isatin-thymol hybrids are developed for targeting multidrug-resistant bacterial strains with efficacy against MRSA acting via CrtM inhibition. The most active hybrid showed bactericidal and antibiofilm efficacy against MRSA and was capable of rescuing larvae from in vivo infection.