Unveiling the Dual Anti-Inflammatory–Antioxidant Effect of Scopoletin and Myricetin: An In Vitro Evaluation

Abstract

AIM- The aim of the present investigation is to study the in-vitro effect of two bioactive flavonoids. MATERIAL & METHODS- Both flavonoids were analysed at concentrations of 100 to 500 μg/mL. Indomethacin and NS-398 were used as standards in COXs inhibition tests, whereas zileuton was used in 5-LOX assay. Cyclooxygenase inhibitory activity was assessed using a modified version of the method described by Jäger et al. (1996), based on measuring PGE₂ formation from arachidonic acid (AA) by COX-1 (from ram seminal vesicles) and human recombinant COX-2. COX-1 (1 unit/reaction) or COX-2 (0.5 unit/reaction) was added to 180 μL of an incubation mixture containing 100 mM Tris buffer (pH 8.0), 5 μM porcine hematin, 18 mM (−)-epinephrine, and 50 μM Na₂EDTA. The assay was carried out following the method described by Adams et al. (2004). Venous blood (45 mL) from healthy donors was allowed to sediment in 20 mL of a dextran solution (6% dextran T-500, 1% NaCl) at 4 °C. After 1 hour, the supernatant was collected, centrifuged at 1600 rpm for 10 minutes at 4 °C, and discarded. The resulting pellet was washed with a buffer solution (7.4% CaCl₂·2H₂O, 0.1% D-glucose, 0.2% MgCl₂·6H₂O, 0.04% KCl, and 1.75% Tris, pH 7.6) and centrifuged again. The DPPH assay was conducted following the in vitro procedure described by Sharma and Bhat (2009). Oxygen radical absorbance capacity (ORAC) assay was carried out following a slightly modified procedure of Ou et al. (2001). RESULTS- Among the both flavonoids Scopoletein was found to be the most active flavonoid towards COX-1 with an IC50 value of 6.65 μg/mL. Moderate efficacy was found for Myricetin with IC50 values ranging from 9.85 μg/mL. Indomethacin and NS-398 inhibited COX-1 with the IC50 values at 0.40 and 28.22 μg/mL, respectively. Likewise as in COXs assays, the Scopoletein and Myricetin were determined as the most effective inhibitor of 5-LOX enzyme and Scopoletein was found to be potent against LOX with IC50 value 4.80 μg/mL. CONCLUSION- These findings suggest that scopoletin and myricetin may serve as promising candidates for the development of new, safer plant-derived agents with anti-inflammatory and/or antioxidant activity. However, further investigations, including detailed chemical characterization and in vivo evaluations, are necessary to confirm their potential practical applications.