Objective: In the present study, fucoidan extracted from three brown algae, Sargassum wightii, Turbinaria ornata, and Padina tetrastromatica, was purified, characterized, and evaluated for antioxidant and cytotoxic properties. Methods: Algal powders were sequentially extracted with five solvents based on polarity and residue was subjected to acidic extraction. The filtrates were precipitated for alginates, and resultant supernatant was precipitated for fucoidan. The precipitate was centrifuged; pellet dialyzed and lyophilized to yield crude fucoidan, which was purified by diethylaminoethyl cellulose chromatography and characterized by biochemical tests and Fourier-transform infrared (FT-IR) spectrometry. Solvent extracts and fucoidans were subjected to 2,2-diphenyl-1-picrylhydrazyl assay. Fucoidans were subjected to trypan blue cytotoxicity assay. Results: Antioxidant activity was highest in methanol extracts and Padina crude fucoidan, while lowest in hexane extracts and purified Sargassum fucoidan. Sargassum yielded the highest amount of fucoidan (7.14%). Total carbohydrates increased as Sargassum> Padina > Turbinaria, sulfates as Padina > Turbinaria > Sargassum, and protein content was 0.16±0.001%. Cytotoxicity increased in a dose-dependent manner; the highest and lowest for Padina at 200 mg mL-1 (40%) and 10 mg mL-1 (4%), respectively. Antioxidant and cytotoxic properties exhibited a positive correlation with sulfate content. FT-IR spectral values were characteristic to fucoidan. Conclusion: Fucoidans from the three algae effectively scavenged free radicals and showed good cytotoxic activity. There was a positive correlation between sulfate content and bioactivity of fucoidans, supporting its structure-function relationship. Thus, extracts and fucoidans from these algae are found to be potential candidates for pharmacological applications.

In the present study, Haematococcus lacustris RRGK which is the former name of H. lacustris HPI-001 isolated from Himachal Pradesh, India, and another strain H. lacustris SAG-19a retrieved from Gottingen Culture Collection, Germany, were used. The H. lacustris SAG-19a served as a control. The both strains were grown in a Bold basal medium in which the components of NaNO 3 , K 2 HPO 4 •3H 2 O and KH 2 PO 4 were replaced with agriculture fertilizers such as NPK (17:17:17), urea (CH 4 N 2 O) and DAP (diammonium phosphate; (NH 4 ) 2 HPO 4 + potash (K 2 CO 3 ) in different concentrations. The isolate of H. lacustris HPI-001 showed maximum growth at 1.2 mM NPK, while the H. lacustris SAG-19a showed maximum growth at 1.5 mM. However, both the strains showed maximum astaxanthin content at 0.6 mM NPK. The H. lacustris HPI-001 showed a maximum growth and astaxanthin content with 3.3 mM and 4.9 mM of urea, respectively, while H. lacustris SAG-19a showed maximum growth and astaxanthin accumulation with 3.3 mM and 6.6 mM of urea, respectively. The H. lacustris HPI-001 showed maximum growth at 250 mg/L (NH 4 ) 2 HPO 4 + 200 mg/L K 2 CO 3 and maximum astaxanthin content at 150 mg/L (NH 4 ) 2 HPO 4 + 100 mg/L K 2 CO 3 , while the maximum growth in H. lacustris SAG-19a was observed at 200 mg/L (NH 4 ) 2 HPO 4 + 150 mg/L K 2 CO 3 , and the maximum astaxanthin content at 150 mg/L (NH 4 ) 2 HPO 4 + 100 mg/L K 2 CO 3 . The basal medium was also amended with the addition of commercial NaHCO 3 wherein the maximum growth and content of astaxanthin in H. lacustris HPI-001 was at 0.6 mM and 1.5 mM of NaHCO 3 , respectively. The H. lacustris SAG-19a showed maximum growth and astaxanthin content at 1.5 mM and 0.6 mM, respectively. Based on the investigation, a medium was formulated and named as modified HPI-001 medium. The results of the present study suggest that commercial agricultural fertilizers may be used as excellent substitutes to enhance cell growth and astaxanthin production in H. lacustris.

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The microbial flora present on vegetables and fruit is commercially significant as they cause spoilage and potential health risks in consumers. Synthetic chemicals used to combat food microbes posed serious health and environmental hazards leading to the search for natural alternatives. In this study, phlorotannins from three Indian brown seaweeds, Sargassum myriocystum, Turbinariaornata, and Padina tetrastromatica were evaluated for antimicrobial, antioxidant, and fruit spoilage prevention potentials. The crude phlorotannin of Padina with the highest content (0.114±0.0005g kg-1) and antioxidant activity (92.65±3.43%) was purified by column chromatography. The Padina water fraction I with the highest antioxidant potential was characterized by Fourier Transform Infra-Red spectroscopy and a 5 % solution was applied as a coating on tomatoes segregated into control chilled (CC), treated chilled (TC), control non-chilled (CNC) and treated non chilled (TNC). Spoilage parameters were studied over twenty days, using a swab and spread plate methods to assess the microbial load on tomatoes. Compared to the control sets, the treated sets exhibited a low number of microbial colonies and retained a fresh look and yellow color. The antibacterial and antioxidant properties of phlorotannin coating as a natural alternative for preservatives, effectively reduced bacterial load, inhibiting the early decay of tomatoes

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