Evaluation of antioxidant potential of marine red alga Gracilaria edulis from the Coast of Mannar—Possible targets in oral health

Introduction: Reactive oxygen species (ROS) play a crucial role in the pathogenesis of periodontal disease, oral mucosal disorders, dental caries, and potentially malignant oral disorders by inducing oxidative stress, tissue damage, and delayed healing. Natural antioxidants help neutralize ROS and maintain oral tissue homeostasis. Marine algae are rich sources of bioactive compounds with potent antioxidant properties. This study aimed to evaluate the antioxidant potential of the red alga Gracilaria edulis collected from the Gulf of Mannar for possible applications in oral healthcare. Materials and Methods: Dried algal samples (25 g) were subjected to Soxhlet extraction using ethanol. The crude extract was evaluated for phytochemical constituents, total phenolic content (TPC) using the Folin–Ciocalteu method, and antioxidant activity using the DPPH radical scavenging assay. All experiments were performed in triplicate, and statistical analysis was carried out by one-way ANOVA, with P < 0.05 considered significant. Results: Phytochemical screening revealed the presence of alkaloids, flavonoids, phenolics, terpenoids, and glycosides. The total phenolic content was 65.57 mg PGA g ⁻¹ DW dry weight. The extract exhibited significant dose-dependent DPPH radical scavenging activity ( P < 0.05). The inhibitory concentration (IC ₅₀ ) value was 69 μg/mL for the ascorbic acid (standard), and for the ethanolic extract of Gracilaria edulis, the value was 144 μg/mL, indicating considerable antioxidant potential compared with standard ascorbic acid. Conclusion: The ethanolic extract of Gracilaria edulis demonstrated significant antioxidant activity, likely attributed to its high phenolic content. These findings suggest its potential as a natural antioxidant source for oral healthcare applications. Further studies involving bioactive compound isolation and in vivo validation are recommended.