Brown seaweeds usually contain alginate as a major polymer. The second major sulfated polymer in brown seaweeds is fucoidan, which has huge potential in medicinal applications. In this study, the photosynthetic pigments from Turbinaria decurrens were first extracted using chloroform/methanol in the ratio of 1:1 (v/v), followed by fucoidan extraction with yields of 5.58% (crude) and 1.28% (purified fucoidan) from the dry weight of seaweed, whereas alginate was extracted with a yield of 14.7% DW of seaweed. The isolated fucoidan possessing anticoagulation property was identified and characterized as (1–3)-α-l-fucopyranosyl residues with sulfate groups primarily at the C4 position and to a lesser extent at the C2 position, whereas in the case of galactose, at the C3 and C6 positions. The AgNPs synthesized using isolated fucoidan exhibit strong anticoagulant activity and possess a good antibacterial property against Gram-negative clinical bacteria. Functional groups such as O–H, C–H, and SO associated with sugar residues in sulfated fucoidan are involved in the synthesis of the nanoparticles with a spherical shape, size ranging from 10 to 60 nm, and showing polydispersity. From this study, we conclude that fucoidan-coated anionic AgNPs synthesized from T. decurrens have tremendous potential in drug development.

Radish (Raphanus sativus L.) and carrot (Daucus carota L.), plants with underground storage organs grown in the field, were exposed to either ambient (UVA) or 20 % UV-B (UVE) enhanced solar radiation till their root yield stage. In radish, UVE produced a significant increase in shoot and root fresh mass (FM), increase in the contents of chlorophyll, carotenoids, flavonoids, and total proteins per unit FM, Hill reaction rate, and root yield. In contrast, carrot responded negatively to UVE showing a loss in the above parameters.

This study aimed for green synthesis of silver nanoparticles (Ag-NPs) from the antimicrobial crude extracted in chloroform: methanol(1:1 v/v) from the two brown seaweeds Spatoglossum asperum and Hedophyllum sessile active against two pathogenic bacteria (Xanthomonas axonopodis pv. citri and X. oryzae pv. oryzae) and a fungus Ustilaginoidea virens cause diseases in plants under in vitro assay. Crude extracts exhibit high antibacterial activity and low antifungal activity. Green synthesized Ag-NPs showed very high antimicrobial properties on comparing its crude extracts. Among the crudes, extract of Spatoglossum asperum exhibits higher bioactivity than the extract of Hedophyllum sessile but Ag-NPs prepared from the extract of H. sessile possess very strong bioactivity over Ag-NPs of Spatoglossum asperum. Reduction of Ag-NPs was confirmed by UV spectra. FTIR data indicate that active groups related to terpenoids and phenols found in the crude extracts were responsible for the reduction of Ag-NPs. The XRD data showed that the pure three types of crystal silver structure at 2θ values 32.51, 46.50 and 74.62 corresponding to 111, 200 and 220 planes for silver, respectively. This study concludes that chloroform: methanol (1:1 v/v) extracts of Hedophyllum sessile and Spatoglossum asperum containing active groups related to terpenoids and phenols and they are acting as reducing agents for green synthesis of silver nanoparticles which are potential source for controlling the plant pathogens studied.

Seaweeds are regarded to be a significant source of bioactive molecules. The macroalgae showed diverse amounts of biochemical constituents such as, total carbohydrate, total protein and total lipids. In the present study, biochemical composition of edible seaweeds was examined. The result was indicated that Champia purvula consists of an elevated amount of protein followed by carbohydrates and lower lipid molecule. The biochemical composition of alga indicates their suitability for use in food and pharmaceutical industry

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