Bisthiourea Derivatives of Dipeptide Conjugated Benzo[d]isoxazole as a New Class of Therapeutics: Synthesis and Molecular Docking Studies.

BACKGROUND: Studies on anti-inflammatory and antimicrobial agents remains a challenging and important area in medicinal chemistry research due to more toxic and rapid development of resistance against first effective drugs. In search of novel anti-inflammatory and antimicrobials agents, bisthiourea derivatives of dipeptide conjugated to 6-fluoro-3- (piperidin-4-yl)benzo[d]isoxazole were synthesized. METHODS: The peptides were synthesized by solution phase method and conjugated to 6- fluoro-3-(piperidin-4-yl)benzo[d]isoxazole using 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide (EDCI)/hydroxybenzotriazole (HOBt) as a coupling agent and N-methylmorpholine (NMM) as a base. The protecting group, 2-chlorobenzyloxycarbonyl (2-ClZ) and tertbutyloxycarbonyl (Boc) were deblocked and further reacted with substituted phenyl isothiocyanates to obtain bisthiourea derivatives. RESULTS: The molecules 1-24 were examined for their in vitro anti-inflammatory activity by employing human erythrocyte suspension test and it was found that the IC50 values of 9, 12, 21 and 24 were lower than the IC50 of standard references indomethacin and ibuprofen. Further, all the molecules were also evaluated for their in vitro antibacterial and antifungal activities against various pathogens of human origin by agar well diffusion method. In addition, binding interaction of active molecules (7-12 and 19-24) was performed on active site of cyclooxygenase-2 (COX-2) and Staphylococcus aureus (SA) TyrRS showing good binding profile. CONCLUSION: Molecular docking result, along with the biological assay data, revealed that the compounds containing electron withdrawing group (F) on phenyl ring of thiourea moiety were potential anti-inflammatory and antimicrobial agents.

Detection of Quorum Sensing Molecules and Biofilm Formation in Ralstonia solanacearum.

Many bacteria use small diffusible signaling molecules to communicate each other termed as quorum sensing (QS). Most Gram-negative bacteria use acyl homoserine lactone (AHL) as QS signal molecules. Using these signaling molecules, bacteria are able to express specific genes in response to population density. This work aimed to detect the production of QS signal molecules and biofilm formation in Ralstonia solanacearum isolated from various diseased tomato plants with symptoms of bacterial wilt. A total of 30 R. solanacearum strains were investigated for the production of QS signal molecules using Chromobacterium violaceum CV026 and Agrobacterium tumefaciens NT1 (pZLR4) biosensor systems. All 30 bacterial isolates from various bacterial wilt-affected tomato plants produced AHL molecules that induced the biosensor. The microtiter plate assay demonstrated that of the 30 bacterial isolates, 60 % formed biofilm, among which four isolates exhibited a higher degree of biofilm formation. The biofilm-inducing factor was purified from these four culture supernatants. The structure of the responsible molecule was solved using nuclear magnetic resonance and mass spectroscopy and was determined to be 2-hydroxy-4-((methylamino)(phenyl)methyl) cyclopentanone (HMCP), which was confirmed by chemical synthesis and NMR. The Confocal laser scanning microscopic analysis showed well-developed biofilm architecture of bacteria when treated with HMCP. The knowledge we obtained from this study will be useful for further researcher on the role of HMCP molecule in biofilm formation.