Synthesis, Structural Characterization, And Biological Evaluation Of Cyclic Tripeptides: Investigating Their Antimicrobial, Anti-Inflammatory, And Antioxidant Potential Through Spectroscopic And Bioactivity Assays

The goal of this study was to create new cyclic tripeptides (CTRIP-1 and CTRIP-2) and assess their pharmacological potential for antibacterial, anti-inflammatory, and antioxidant properties. TLC, mass spectrometry, FTIR, melting point measurement, and NMR spectroscopy were used to synthesise and characterise both peptides. The agar well diffusion method was used to measure antibacterial activity against Staphylococcus aureus and Escherichia coli. Zones of inhibition for CTRIP-2 increased dose-dependently and approached those of norfloxacin at higher doses, demonstrating its better antibacterial activity over CTRIP-1. COX-1 and COX-2 inhibition assays revealed significant anti-inflammatory activity for both peptides, with CTRIP-2 showing stronger inhibition (COX-1: 82.85%; COX-2: 85.76%) relative to CTRIP-1. Antioxidant potential was evaluated using the ABTS radical decolorization assay, where CTRIP-2 (IC₅₀: 118.92 µg/mL) showed better radical scavenging ability than CTRIP-1 and was comparable to Vitamin C. The results collectively highlight CTRIP-2 as a promising candidate for further development due to its potent and broad-spectrum bioactivity.