Abstract: Dalbergieae tribe lectins, possessing binding affinity for galactose and mannose, present inflammatory and nociceptive effects, while those for N-acetylglucosamine are anti-inflammatory. Since the anti-inflammatory effect of the seed lectin of L. araripensis (LAL) had been already demonstrated in mice, this effect was presently evaluated in rat models of acute inflammation. LAL (0.01-1 mg/kg) was administered by intravenous (i.v.) route in male Wistar rats 30 min before paw edema induction by dextran or carrageenan, and peritonitis by carrageenan. LAL (1 mg/kg) was incubated with N-acetylglucosamine for allowing lectin-sugar interactions before injection into animals. LAL toxicity was evaluated by the parameters: body mass, organs weight, stomach macroscopy, hematological and biochemical dosage. Statistical analysis was performed by ANOVA and Bonferroni’s test (p<0.05). The paw edema induced by carrageenan (AUC: 0.96 ± 0.09) was inhibited by LAL about 39% (0-2 h) at all doses, and about 72% (3-5 h) at 0.1 and 1 mg/kg. The increase in the neutrophil migration stimulated by carrageenan was also inhibited by LAL (83%). In both models, LAL inhibitory effect was prevented by GlcNAc. The sub-chronic treatment with LAL was well tolerated by animals. LAL possesses anti-inflammatory effect via lectin domain, indicating potential modulator role in cellular inflammatory events.

ABSTRACT Freshwater algae are rich sources of structurally biologically active metabolites, such as fatty acids, steroids, carotenoids and polysaccharides. Among these metabolites, lectins stand out. Lectins are proteins or glycoproteins of non-immune origin which bind to carbohydrates or glycoconjugates, without changing ligand structure. Many studies have reported on the use of Spirogyra spp. as effective bioindicators of heavy metals; however, reports on Spirogyra molecular bioprospecting are quite limited. Therefore, this study aimed to detect, isolate, purify and characterize a lectin present in the freshwater green algae Spirogyra. Presence of the lectin protein in the extract was detected by hemagglutination assays. Subsequently, the protein extract was subjected to a sugar inhibition assay to identify the lectin-specific carbohydrate. Following this, the extract was applied to a guar gum column to afford the pure lectin. The lectin was inhibited by N-acetyl-glucosamine and N-acetyl-beta-D-mannose, but more strongly by D-galactose. The apparent molecular mass of the purified lectin was evaluated by Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE). Electrophoretic analysis revealed a single protein band with an apparent molecular mass of 56 kDa. Thus, it could be concluded that a lectin was purified from Spirogyra spp.

Vinte espécies de invertebrados marinhos, coletados na costa brasileira, foram avaliados quanto à presença de atividade hemaglutinante/hemolítica. Em pelo menos doze espécies testadas, a atividade hemaglutinante foi diferencial para diferentes grupos sanguíneos, sugerindo a presença de lectinas. Extratos de quatro espécies apresentaram atividade hemolítica. Duas novas lectinas foram purificadas da esponja marinha Cliona varians (CvL-2) e do pepino-domar Holothuria grisea (HGL). CvL-2 foi capaz de aglutinar eritrócitos de coelho e foi inibida por galactosídeos. A atividade hemaglutinante foi estável em pH neutro e temperaturas abaixo de 70 °C. CvL-2 é uma proteína trímero com subunidades de 175 kDa. Por outro lado, HGL apresentou atividade hemaglutinante e hemolítica em eritrócitos humanos e de coelho, mas a hemólise pôde ser inibida por proteção osmótica, enquanto que a aglutinação foi inibida por mucina. HGL mostrou-se estável em valores de pH de 4-10 e temperaturas até 90 °C. Em eletroforeses e gel filtração, HGL foi uma proteína monômero de 15 kDa. CvL-2 e HGL mostraram diferentes níveis de toxicidade contra náuplios de Artemia. CvL-2 apresentou LC50 de 850,1 μg/mL, enquanto que HGL apresentou LC50 de 9,5 μg/mL.

Twenty species of marine invertebrates from the Brazilian coast were screened for hemagglutinating/hemolytic activity. In at least twelve tested species, hemagglutinating activity was different for different blood types, suggesting the presence of lectins. Extracts from four species showed hemolytic activity. Two new lectins were purified from the marine sponge Cliona varians (CvL-2) and sea cucumber Holothuria grisea (HGL). CvL-2 was able to agglutinate rabbit erythrocytes and was inhibited by galactosides. The hemagglutinating activity was optimal in pH neutral and temperatures below 70 °C. CvL-2 is a trimeric protein with subunits of 175 kDa. On the other hand, HGL showed both hemagglutinating and hemolytic activity in human and rabbit erythrocytes, but hemolysis could be inhibited by osmotic protection, and agglutination was inhibited by mucin. HGL was stable in pH values ranging from 4 to 10 and temperatures up to 90 °C. In electrophoresis and gel filtration, HGL was a monomeric protein with 15 kDa. CvL-2 and HGL showed different levels of toxicity to Artemia naplii. CvL-2 showed LC50 of 850.1 μg/mL, whereas HGL showed LC50 of 9.5 µg/mL.

Antioxidantes naturais encontrados em macroalgas marinhas são substâncias bioativas conhecidas por desempenhar um papel importante na prevenção de doenças associadas com o envelhecimento, protegendo as células de danos oxidativos. O objetivo deste estudo foi avaliar as atividades antioxidante e citotóxica de extratos etanólicos de duas espécies de algas vermelhas, Amansia multifida eMeristiella echinocarpa. A atividade antioxidantein vitro foi determinada pela capacidade de sequestro do radical DPPH, o poder de redução do ferro (FRAP), o poder de quelação do íon ferroso (FIC), o teste de oxidação acoplada β-caroteno/ácido linoleico (BCB), bem como a quantificação do conteúdo fenólico total. A citotoxicidade foi avaliada pelo teste de letalidade contra Artemia sp. Os valores das substâncias fenólicas observados no presente estudo indicaram que as espéciesA. multifida e M. echinocarpa são ricas em substâncias fenólicas, atingindo valores de 45,40 e de 28,86 mg de ácido gálico equivalente (AGE) g−1de extrato etanólico, respectivamente. A capacidade de seqüestro do radical DPPH e o poder de quelação do íon ferroso foram 60% e 17%, respectivamente. Ambos os extratos algáceos inibiram a oxidação do β-caroteno em torno de 40%. Nenhum dos extratos algáceos foi potencialmente citotóxico. Os resultados mostraram que os extratos destas espécies de rodófitas apresentam potencial antioxidante e baixa toxicidade. Elas são fontes de compostos antioxidantes naturais.

Natural antioxidants found in marine macroalgae are bioactive compounds known to play an important role in the prevention of diseases associated with aging cells protecting them against the oxidative damage. The purpose of this study was to evaluate the antioxidant and cytotoxic activity of ethanolic extracts of two species of red seaweeds, Amansia multifida and Meristiella echinocarpa. In vitro antioxidant activity was determined by DPPH radical scavenging assay, ferric-reducing antioxidant power (FRAP) assay, ferrous ion chelating (FIC) assay, β-carotene bleaching (BCB) assay and total phenolic content (TPC) quantification. Cytotoxicity was evaluated with the brine shrimp Artemia sp. lethality test. The TPC values observed in the present study indicated that both species A. multifida and M. echinocarpa are rich in phenolic compounds, reaching values of 45.40 and 28.46 mg gallic acid equivalent (GAE) g−1 of ethanolic extract, respectively. DPPH radical scavenging and ferrous ion chelating showed values of 60% and 17%, respectively. Both seaweed extracts inhibited β-carotene oxidation by approximately 40%. None of the algal extracts were potentially cytotoxic. The results have showed that extracts of both species of marine red algae exhibit antioxidant potential and low toxicity. They are sources of natural antioxidant compounds.