Characterization and Biological Activities of the Ulvan Polysaccharide-Rich Fraction Obtained from Ulva rigida and Ulva pseudorotundata and Their Potential for Pharmaceutical Application.

Seaweed from the genus Ulva (Ulvales, Chlorophyta) has a worldwide distribution and represents a potential biomass source for biotechnological applications. In the present study, we investigated the ulvan polysaccharide-rich fraction (UPRF) isolated from two Ulva species (U. rigida and U. pseudorotundata), naturally occurring on the Spanish Mediterranean coast. Chemical characterization of UPRFs was performed in order to explore the polysaccharides' composition. Biological assessments of UPRFs were compared by antioxidant activity and in vitro toxicity tests in the human cell lines: HCT-116 (colon cancer), G-361 (malignant melanoma), U-937 (leukemia), and HaCaT cells (immortalized keratinocytes). Chemical analysis revealed that both UPRFs presented rhamnose as the major relative sugar constituent, followed by glucose in U. rigida and xylose in U. pseudorotundata. Both also presented glucuronic acid, galactose, ribose, and mannose as the remaining monosaccharides. Similar antioxidant activity was obtained, where we observed increased activity in response to increased polysaccharide concentrations. Both UPRFs presented moderate toxicity against HCT-116 cell lines and a selectivity index ≥ 3, suggesting a good potential for use in pharmaceutical products.

Photobiological Effects on Biochemical Composition in Porphyridium cruentum (Rhodophyta) with a Biotechnological Application.

This study describes the relation of photosynthetic capacity, growth and biochemical compounds in the microalgae Porphyridium cruentum under saturated irradiance (200 µmol m-2  s-1 ) by white light (WL) and low-pressure sodium vapor lamps (SOX lamps-control) and supplemented by fluorescent lamps (FLs) with different light qualities (blue: λmax = 440 nm; green: λmax = 560 nm; and red: λmax = 660 nm). The maximum photosynthetic efficiency (Fv / Fm ) showed a positive correlation with the light quality by saturating light SOX in mixture with stimulating blue light than the white light (WL) at the harvest day (10 days). The production, that is maximal electron transport rate (ETRmax ), and energy dissipation, that is maximal nonphotochemical quenching (NPQmax ), had the same pattern throughout the time (3-6 days) being the values higher under white light (WL) compared with SOX and SOX plus supplemented different light qualities. Total protein levels increased significantly in the presence of SOX light, while phycoerythrin (B-PE) showed significant differences under SOX+ blue light. Arachidonic acid (ARA) was higher under SOX and SOX plus supplemented different light qualities than that under WL, whereas eicosapentaenoic acid (EPA) was the reverse. The high photomorphogenic potential by SOX light shows promising application for microalgal biotechnology.