Chemical Constituent and Biological Activities of Spatoglossum asperum J. Agardh from Oman Sea

Extension of shelf life of Nile tilapia (Oreochromis niloticus) fillets using seaweed extracts during refrigerated storage

The effects of seaweed (Padina tetrastromatica, Sargassum natans, and Sargassum fluitans) ethanolic extracts on the quality and shelf life extension of Nile tilapia (Oreochromis niloticus) fillets were investigated during refrigerated storage for 20 days. Each of the seaweed ethanolic extracts solution (2%, w/v) was used for dipping the fish fillets for 10 min at 4°C. The control and seaweed extract-treated fillets were stored at 4 ± 1°C in air-tight polyethylene bags, and chemical, bacteriological, and sensory evaluation were performed at every 4 days' intervals. During the storage period, P. tetrastromatica extract significantly (p < .05) reduced the increment of pH, peroxide value, thiobarbituric acid reactive substances, and total volatile basic nitrogen values in Nile tilapia fillets compared to other seaweed extracts-treated and untreated fillets. The maximal total viable count of control, P. tetrastromatica, S. natans, and S. fluitans extracts-treated fillets was 6.53, 7.11, 6.75, and 7.10 log CFU/g at the 8th, 20th, 12th, and 16th days of storage, respectively. The total psychrotrophic count of control and seaweed extracts-treated fillets was also significantly increased (p < .05) throughout the storage period. The P. tetrastromatica extracts-treated fillets showed better sensory characteristics than other seaweed extracts-treated and control fillets. Results of this study suggest that ethanolic extracts (2%, w/v) of P. tetrastromatica extend the shelf life for 12 days longer than the control fillets in refrigerated conditions.

Antioxidant, Scavenging, Reducing, and Anti-Proliferative Activities of Selected Tropical Brown Seaweeds Confirm the Nutraceutical Potential of Spatoglossum asperum

Brown seaweeds have shown high potential of bioactivity and provide health benefits as an important functional food ingredient. Therefore, four abundantly growing tropical brown seaweeds—Iyengaria stellata, Spatoglossum asperum, Sargassum linearifolium, and Stoechospermum polypodioides—were collected from the Saurashtra Coast of the Arabian Sea. They were analyzed for metabolite profiling, biochemical activities (including total antioxidant, reducing, scavenging, and anti-proliferative characteristics), and total phenolic and flavonoid contents. A concentration-dependent antioxidant, reducing, and scavenging activities were observed for all four brown seaweeds. The S. asperum and I. stellata extracts showed maximum total antioxidant activity. S. asperum also showed high scavenging and reducing activities compared to other studied brown seaweeds. Further, S. asperum contained high total phenolic and flavonoid content compared to other brown seaweeds collected from the same coast. A multivariate correlation study confirmed a positive correlation between total phenolic and flavonoid contents, and biochemical activities (total antioxidant, scavenging and reducing) for all brown seaweeds. About 35% anti-proliferative activity was observed with S. asperum extract on Huh7 cells; in contrast S. polypodioide showed about 44% proliferation inhibition of Huh7 cells. Similarly, 26% proliferation inhibition of HeLa cells was observed with S. asperum extract. Overall, S. asperum possesses high total flavonoid and phenolic amounts, and showed potential antioxidant, scavenging and reducing characteristics. The study confirmed the nutraceutical potential of S. asperum and that it could be a promising functional food ingredient.

Anti-proliferative and ROS-inhibitory activities reveal the anticancer potential of Caulerpa species

Seaweeds are considered a promising functional food and safe for human consumption as they have significant health benefits. Five abundant tropical seaweeds, Caulerpa racemosa var. macrophysa, Caulerpa scalpelliformis, Grateloupia indica, Sargassum linearifolium, and Spatoglossum asperum rich in metabolites, phenolic, and flavonoid compounds, were analyzed for the anti-proliferative and ROS inhibitory activities including transcript expression of cancer-linked key genes and apoptosis. C. racemosa var. macrophysa showed the maximum effective activities with a lower dose of extract, about 130 ± 30 and 23 ± 1 μg ml^-1 EC₅₀ dose for HeLa and Huh-7, respectively, followed by C. scalpelliformis, showing EC₅₀ dose about 200 ± 10 and 140 ± 30 μg ml^-1, respectively. Similarly, about 56% and 54% ROS inhibition were determined with Caulerpa spp. for HeLa and Huh-7 cells, respectively. Results indicated that tropical green seaweed Caulerpa spp. (C. racemosa var. macrophysa and C. scalpelliformis) have substantial potential of ROS inhibition. Further, it was observed that different cancer-linked marker proteins encoding genes were deferentially expressed with seaweed extracts in different cell lines. Overall, it is concluded that Caulerpa spp. are rich in antioxidant and anti-proliferative activities. Caulerpa spp. have potential to be explored further for cancer preventive properties or functional food or nutraceuticals applications.