IN VITRO EVALUATION OF THE NITRIC OXIDE RADICAL SCAVENGING ACTIVITY OF THIPPILI RASAYANAM: SCIENTIFIC EVIDENCE FOR ITS ANTIOXIDANT POTENTIAL IN CHILDHOOD ASTHMA.

Abstract

Childhood asthma is a chronic inflammatory airway disease in which oxidative stress contributes significantly to airway inflammation, bronchial hyperresponsiveness, and disease progression through the excessive production of nitric oxide (NO) and other reactive oxygen species. Thippili Rasayanam, a classical Siddha polyherbal formulation traditionally used for the management of respiratory disorders, contains medicinal plants with documented antioxidant and anti-inflammatory properties; however, its nitric oxide radical scavenging activity has not been scientifically validated. The present in vitro experimental study evaluated the antioxidant potential of Thippili Rasayanam using the sodium nitroprusside–Griess assay. The formulation was tested at concentrations of 10–100 μg/mL, with gallic acid serving as the reference standard. Nitric oxide radical scavenging activity was determined by measuring the percentage inhibition of nitrite formation, and antioxidant potency was expressed as the half-maximal inhibitory concentration (IC₅₀). All experiments were performed in triplicate, and the results were analyzed using one-way analysis of variance (ANOVA) followed by Dunnett's multiple comparison test, with p < 0.05 considered statistically significant. Thippili Rasayanam exhibited concentration-dependent nitric oxide radical scavenging activity, with percentage inhibition increasing from 9.66 ± 2.59% at 10 μg/mL to 37.68 ± 1.49% at 100 μg/mL, whereas gallic acid showed significantly higher inhibition ranging from 25.57 ± 2.25% to 93.81 ± 2.13%. The IC₅₀ values of Thippili Rasayanam and gallic acid were 145.6 ± 4.74 μg/mL and 39.82 ± 3.53 μg/mL, respectively. These findings demonstrate that Thippili Rasayanam possesses significant in vitro nitric oxide radical scavenging activity in a concentration-dependent manner, providing scientific evidence for its traditional use in respiratory disorders. Although its antioxidant potency was lower than that of gallic acid, the formulation exhibited appreciable free radical scavenging activity, supporting its potential as a complementary therapeutic candidate for childhood asthma. Further phytochemical, mechanistic, in vivo, and clinical studies are warranted to validate its therapeutic efficacy.