Sulfated polysaccharides from red seaweed Gracilaria cornea induce macrophages polarization to an antitumor M1 phenotype

Marine seaweeds are a rich source of sulfated polysaccharides (SPs) with several biological activities, including antitumor effect. Some polysaccharides are also described to activate macrophages (MΦs) to an antitumor M1-like phenotype. Here, we evaluated the capacity of SPs extracts obtained from three seaweed species, Gracilaria cornea (Gc-E), Gracilaria birdiae (Gb-E), and Solieria filiformis (Sf-E), to activate the MΦs antitumor M1 phenotype. The nitric oxide production, MHCII, and CD86 M1 markers were evaluated to screening the bioactive SPs profile on murine MΦs (RAW 264.7 cells). The direct SPs antiproliferative effect was tested on melanoma B16-F10 cells. In another experimental setting, B16-F10 cells were incubated with a conditioned medium obtained from MΦs exposed to SPs. The three SPs tested induced NO release. Sf-E directly inhibited B16-F10 cells proliferation compared with the saline group, but Gc-E and Gb-E failed to inhibit cell proliferation. Notably, a conditioned medium (CM) of MΦs incubated with Gc-E and Sf-E, but not of Gb-E, inhibited the proliferation of B16-F10 cells. Gc-E also induced TNF-α release and increase of M1 markers such as iNOS, MHCII, and CD86. Therefore, Gc-E activates a macrophage M1 phenotype, which in turn releases a factor that inhibits B16-F10 proliferation.

Salinity tolerance of macroalgae Gracilaria birdiae

ABSTRACT: This study aimed to determining the manner in which salinity influenced the growth of the macroalgae Gracilaria birdiae, with the objective of identifying its tolerance limits to this abiotic variable. The specimens were submitted to nutrient-enriched water of varying salinities (0, 10, 20, 30, 40, 50, and 60 ppt) for a 30-day period. Initially, under extreme salinity conditions (0 and 60 ppt) the growth of the G. birdiae suffered a negative impact. The macroalgae biomass exposed to 0 and 10 ppt salinities showed a reduction from day six until the experiment was completed. The macroalgae biomass exposed to salinities 20, 30, 40, and 50 ppt showed an increase, with no significant differences between the four treatments. This suggested that this salinity range was comfortable for this species to develop. We concluded that salinity is a crucial parameter which controls the growth of the G. birdiae. This seaweed was negatively influenced when exposed to values equal to or below 10 ppt and equal to 60 ppt, demonstrating good tolerance to salinities of 20, 30, 40 and 50 ppt.

Antioxidant Sulfated Polysaccharide from Edible Red Seaweed Gracilaria birdiae is an Inhibitor of Calcium Oxalate Crystal Formation

The genus Gracilaria synthesizes sulfated polysaccharides (SPs). Many of these SPs, including those synthesized by the edible seaweed Gracilaria birdiae, have not yet been adequately investigated for their use as potential pharmaceutical compounds. Previous studies have demonstrated the immunomodulatory effects of sulfated galactans from G. birdiae. In this study, a galactan (GB) was extracted from G. birdiae and evaluated by cell proliferation and antioxidant tests. GB showed no radical hydroxyl (OH) and superoxide (O2−) scavenging ability. However, GB was able to donate electrons in two further different assays and presented iron- and copper-chelating activity. Urolithiasis affects approximately 10% of the world’s population and is strongly associated with calcium oxalate (CaOx) crystals. No efficient compound is currently available for the treatment of this disease. GB appeared to interact with and stabilize calcium oxalate dihydrate crystals, leading to the modification of their morphology, size, and surface charge. These crystals then acquired the same characteristics as those found in healthy individuals. In addition, GB showed no cytotoxic effect against human kidney cells (HEK-293). Taken together, our current findings highlight the potential application of GB as an antiurolithic agent.