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In recent years, the emergence of drug resistance and sensitivity in leading diseases has heightened global interest in natural nutraceuticals as primary health supplements. However, comprehensive scientific scrutiny is essential before marketing these as supplements. In this study, we assessed the nutritional composition, antioxidant activities, and trace metal accumulation in eleven selected Sri Lankan coastal seaweed species. Gracilaria corticata had the highest (p < 0.05) ash and crude fiber content among the species. Protein content ranged from 4.87% to 23.67% (DW), with Ulva rigida displaying the highest (p < 0.05). Crude fat content ranged from 0.09% to 4.13% (DW), with Cladophora herpestica having the highest (p < 0.05) crude fat content. Sargassam cinereum, Turbinaria ornata and Sargassum crassifolium had the highest (p < 0.05) TPC content (51.32 ± 0.61–28.90 ± 2.68 mg/GAE g) and the highest (p < 0.05) radical scavenging antioxidant activity compared to other seaweeds. The study findings indicate that most of the studied metals in seaweeds exceeded the WHO-recommended levels. Aluminum was the highest (p < 0.05) accumulated metal in seaweeds compared to other metals. Toxic heavy metals, such as arsenic, cadmium and chromium, levels in all of the studied seaweeds surpassed the WHO limits. While seaweeds displayed acceptable nutritional and antioxidant properties, heavy metal presence poses a potential health risk to consumers. Products using seaweeds with accumulated heavy metals may have lower nutritional quality. Thus, this study underscores the need for comprehensive scientific investigation before developing high-quality natural food products or supplements from seaweeds. [ABSTRACT FROM AUTHOR]

Background: Carbohydrate is the primary source of energy in the human diet and plays an important role in a healthy diet. In this study, 15 different carbohydrate sources (white raw rice, red raw rice, white basmati rice, red basmati rice, wheat, atta flour, soy, black gram, corn, finger millet, water lily seeds, kithul, chickpea, oats, and palmyra sprouts) in Sri Lanka were investigated for their physicochemical and functional properties. Results: The shape of the extracted starch granules varied according to the source, and the amylose content ranged from 17.22% to 36.12%. Kithul and black gram showed the highest water swelling capacity and water absorption index, respectively. Flour of white raw rice and finger millet showed significantly higher (p < 0.05) freeze–thaw stability than other sources. Flour of Soy, black gram, and chickpea showed significantly higher (p < 0.05) dietary fiber content and potassium content than other samples. Water lily seeds showed remarkable in vitro prebiotic activity from the studied carbohydrate sources. Conclusion: The study indicates the potential utilization of raw white rice, palmyra, and finger millet starch in the food processing industry as alternatives to conventional starch sources. Furthermore, the flour from water lily seeds, white basmati rice, soy, and black gram has the potential for use in functional food preparation, offering a wide range of health benefits. [ABSTRACT FROM AUTHOR]

Cyanobacteria have gained increasing attention in the food and pharmaceutical industries as a natural source of antioxidants. However, more knowledge is needed regarding the antioxidant and nutritional properties of cyanobacteria found in water bodies worldwide, including those in Sri Lanka. This study investigated the antioxidant activities and microstructural properties using FTIR-ATR (Fourier Transform Infrared Spectroscopy-Attenuated total reflectance) analysis and the fatty acid composition of three cyanobacterial species: Chroococcidiopsis sp., Gleocapsa sp., and Merismopedia sp., which were isolated from water bodies in Sri Lanka. The water extract of Chroococcidiopsis sp. Exhibited the highest (p ≤ 0.05) phenolic content (2.26 ± 0.09 mg GAE/g DW) and ABTS activity (13.28 ± 0.36 mmol TE/g DW) among the tested species. The methanol extract of Merismopedia sp. Displayed the highest (p ≤ 0.05) DPPH activity (IC 50 -15.21 mg/mL) and notable (p ≤ 0.05) ORAC values (112.50 ± 5.79 mmol TE/g DW). Analysis by FTIR-ATR revealed the presence of nutritional components, including proteins, lipids, and polysaccharides, as well as functional compounds such as phenolics and amides in the studied cyanobacterial species. The fatty acid composition indicated that the studied cyanobacteria contain twenty different saturated and unsaturated fatty acids, with compositions ranging from 60 to 70% and 29–39%, respectively. Saturated fatty acids, caprylic, capric, pentadecanoic, heptadecanoic, palmitic, and lignoceric acids, were detected in all species, while elaidic, palmitoleic, and Cis -10- heptadecanoic acids were identified as prominent monounsaturated fatty acids among them. Gleocapsa sp. Had the highest (p ≤ 0.05) saturated fatty acid content, while Merismopedia sp. Showed the highest (p ≤ 0.05) unsaturated fatty acid content. Based on the results, Merismopedia sp. Has demonstrated promising potential as a rich source of antioxidants and unsaturated fatty acids. [Display omitted] • The growth and survival abilities are high in Chrooccocidiopsis sp. • Methanolic extracts of Merismopedia sp. Are rich in antioxidants activities. • Gleocapsa sp. Showed the highest unsaturated fatty acid content. • Polysaccharides, lipids, and proteins are available in all three species. [ABSTRACT FROM AUTHOR]