Rational Design of Small Peptides for Optimal Inhibition of Cyclooxygenase-2: Development of a Highly Effective Anti-Inflammatory Agent

Among the small peptides 2–31, (H)­Gly-Gly-Phe-Leu­(OMe) (30) reduced prostaglandin production of COX-2 with an IC50 of 60 nM relative to 6000 nM for COX-1. The 5 mg kg–1 dose of compound 30 rescued albino mice by 80% from capsaicin-induced paw licking and recovered it by 60% from carrageenan-induced inflammation. The mode of action of compound 30 for targeting COX-2, iNOS, and VGSC was investigated by using substance P, l-arginine, and veratrine, respectively, as biomarkers. The interactions of 30 with COX-2 were supported by isothermal calorimetry experiments showing a Ka of 6.10 ± 1.10 × 104 M–1 and ΔG of −100.3 kJ mol–1 in comparison to a Ka 0.41 × 103 ± 0.09 M–1 and ΔG of −19.2 ± 0.06 kJ mol–1 for COX-1. Moreover, compound 30 did not show toxicity up to a 2000 mg kg–1 dose. Hence, we suggest peptide 30 as a highly potent and promising candidate for further development into an anti-inflammatory drug.