Proximate, physicochemical, bioactive and antiproliferative characteristics of Gracilaria debilis extract reveal its nutraceutical potential

Seaweeds are nutritionally rich and contained antioxidants, phenolics, flavonoids, and key metabolites of medicinal benefits. Water and 60% methanol (MeOH) extract of Gracilaria debilis were evaluated for their physiobiochemical characteristics, antioxidant, antinutritional and antiproliferative activities. Metabolite profiling revealed that the water extract is enriched with organic acids and carbohydrates, whereas the MeOH extracts contained relatively high level of fatty acids and amino acids. The MTT assay revealed that the MeOH extract was effective against the Huh- 7, CHO and HeLa cell lines, with EC₅₀ values of 167.73, 223.26, and 145.08 μg, respectively. Similarly, MeOH extract efficiently inhibited the cell migration, suggesting its potential antimetastatic activity. Compared with the water extract, the MeOH extract had higher yield of proteins (0.827 ± 0.050%), lipids (6.50 ± 0.74%), phenolics (27.80 ± 1.21 mg GAE/g), and flavonoids (104.1 ± 5.8 mg QUE/g). Antioxidant assays revealed that the water extract exhibited high ABTS radical scavenging (EC₅₀: 76.41 ± 3.95 μg/ml) and total antioxidant capacity, whereas the MeOH extract showed high DPPH radical scavenging (EC₅₀: 435.9 ± 32.51 μg/ml) and FRAP reducing activities (EC₅₀: 16.35 ± 2.82 μg/ml). Acceptable level of antinutritional factors such as phytic acid, saponins and terpenoids were detected in the G. debilis. Mineral analysis indicated that the water extract was contained high Na, Mg and K, whereas the MeOH extract had higher Ca and Fe contents. These findings showed that G. debilis, particularly MeOH extract, is a rich source of bioactive compounds with high antioxidant activities, supporting its nutraceutical potential and to be supplemented used as functional food.