Porphyridium cruentum is a unicellular microalga that can synthesize and secrete to the culture medium-high amounts of polysaccharides. In this study, the immunomodulatory, cytotoxic effect and antioxidant activity of the sulfated polysaccharides (PcSPs) were determinate. The PcSPs were precipitated with 2% Cetylpyridinium bromide hydrate and ethanol and purified by dialysis. The extract was lyophilized for its characterization by Fourier transform-Infrared (FT-IR) spectroscopy and gas chromatography–mass spectrometry (GC-MS). The antioxidant activity of PcSPs were examined with assay 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and compared with that of the biomass, observing significant differences between the results obtained from the PcSPs and biomass. To determine their ability to induce cytokine production Tumor Necrosis Factor alpha (TNF-α) and interleukina-6 (IL-6), the immunomodulatory activity of the PcSPs has been evaluated. In the mouse macrophage cell line (RAW 264.7), PcSPs are potent inducers of IL-6 cytokines but mainly of TNF-α. The cytotoxic capacity of PcSPs was measured by the MTT colorimetric assay in colorectal carcinoma (HTC-116), human leukemia (U-937 and HL-60), breast cancer (MCF-7), lung cancer (NCI-H460) and human gingival fibroblasts (HGF-1) cell lines. The IC₅₀ value of 2311.20 µg mL⁻¹, 1676.74 µg mL⁻¹, 1089.63 µg mL⁻¹, 5498.14 µg mL⁻¹ and 2861.49 µg mL⁻¹ respectively in the tumor lines and 5022.55 µg mL⁻¹ in gingival fibroblasts were obtained. Our study suggested that PcSPs from P. cruentum have a moderate immunomodulatory and cytotoxic effect. The results obtained indicate that the polysaccharides from P. cruentum are potent inducers of IL-6 cytokines and, most importantly, of TNF-α. PcSPs showed no evidence of antigenic activity or hypersensitivity when administered intraperitoneally in mice. Furthermore, the in vivo study revealed an improvement of local inflammatory response against stress in the peritoneum. These findings suggest that the PcSPs from P. cruentum might have potential as a valuable ingredient in nutraceutical products.

The present work focuses on: (1) the evaluation of the potential of Chlorella fusca to grow and synthesize metabolites of biotechnological interest, after being exposed for fourteen days to urban wastewater (UW) from Malaga city (UW concentrations: 25%, 50%, 75%, and 100%); (2) the study of the capacity of C. fusca to bioremediate UW in photobioreactors at laboratory scale; and (3) the evaluation of the effect of UW on the physiological status of C. fusca, as photosynthetic capacity by using in vivo Chl a fluorescence related to photosystem II and the production of photosynthetic pigments. C. fusca cell density increased in treatments with 50% UW concentration, followed by the treatment with 100% UW, 75% UW, the control, and finally 25% UW. Protein content increased to 50.5% in 75% UW concentration. Stress induced to microalgal cultures favored the increase of lipid production, reaching a maximum of 16.7% in 100% UW concentration. The biological oxygen demand (BOD₅) analysis indicated a 75% decrease in 100% UW concentration. Dissolved organic carbon (DOC) levels decreased by 41% and 40% in 50% UW and 100% UW concentration, and total nitrogen (TN) decreased by 55% in 50% UW concentration. The physiological status showed the stressful effect caused by the presence of UW on photosynthetic activity, with increasing impact as UW concentration grew. In the framework of circular economy, we seek to deepen this study to use the biomass of C. fusca to obtain metabolites of interest for biofuel production and other biotechnological areas. Graphical

The present study was carried out to determine the bioactivity of polysaccharides extracted from Euglena gracilis (EgPs). These were characterized by FT-IR and GC-MS. Cytotoxicity analyses (MTT) were performed on healthy human gingival fibroblast cell lines (HGF-1), obtaining an IC₅₀ of 228.66 µg mL⁻¹, and cell lines with anticancer activity for colon cancer (HCT-116), breast cancer (MCF-7), human leukemia (U-937, HL-60) and lung cancer (NCl-H460), showing that EgPs have anticancer activity, mainly in HTC-116 cells (IC₅₀ = 26.1 µg mL⁻¹). The immunological assay determined the immunomodulatory capacity of polysaccharides for the production of proinflammatory cytokines IL-6 and TNF-α in murine macrophages (RAW 264.7) and TNF-α in human monocytes (THP-1). It was observed that the EgPs had a stimulating capacity in the synthesis of these interleukins. The antioxidant capacity of polysaccharides and their biomass were analyzed using the ABTS method (18.30 ± 0.14% and (5.40 ± 0.56%, respectively, and the DPPH method for biomass (17.79 ± 0.57%). We quantitatively profiled HGF-1 proteins by liquid chromatography–tandem mass spectrometry analysis, coupled with 2-plex tandem mass tag labelling, in normal cells. In total, 1346 proteins were identified and quantified with high confidence, of which five were considered to be overexpressed. The data is available through ProteomeXchange, under identifier PXD029076.