Antinociceptive activity of sulfated carbohydrates from the red algae Bryothamnion seaforthii (Turner) Kütz. and B. triquetrum (S.G. Gmel.) M. Howe

Sulfated Polysaccharides Derived from Hypnea valentiae and Their Potential of Antioxidant, Antimicrobial, and Anticoagulant Activities with In Silico Docking

Carrageenan, a sulfated polysaccharide, was produced by certain species of marine red seaweeds, which have been used as a significant source of food, feed, and antibiotic agent throughout history due to their alleged human health benefits. The present study aimed to derive the polysaccharides from Hypnea valentiae and describe the biological applications. Carrageenan was characterized by FT-IR, C-NMR, AFM, and their antimicrobial, antioxidant, and anticoagulant capabilities; furthermore, the larvicidal effect of methanol extract was generated from the seaweed against Aedes aegypti larvae at various concentrations. The molecular docking experiments were carried out computationally for finding the molecular insight of the macromolecules and small molecules' interaction using GLIDE docking by using Schrodinger software. Antibacterial zones of inhibition in different concentrations are compared with the 40 mg/mL higher activity against bacterial pathogens. Carrageenan is strong in all antioxidant activities, with the overall antioxidant (70.1 ± 0.61%) of radical at 250 μg/mL concentration being exhibited. The DPPH scavenging is effective in the inhibition of (65.74 ± 0.58%) radical at a concentration of 160 μg/mL and the hydroxyl scavenging (65.72 ± 0.60%) of activity at a concentration of 125 μg/mL being exhibited. Anticoagulant activities (APPT and PT) of carrageenan fraction were tested. H. valentiae and heparin sulphate shows higher activity of APTT (106.50 IU at 25 μg/mL) in comparison with the PT test (57.86 IU at 25 μg/mL) and the methanol extraction of higher larvicidal activity on A. aegypti (LC₅₀ = 99.675 μg/mL). In this study, the carrageenan was exploited through in vitro and in silico molecular docking studies against antimicrobial, antioxidant, and anticoagulant properties. The results were establishing the potentiality of the carrageenan which is an alternative source to control the mosquitocidal property in the future. Moreover, molecular docking of carrageenan against multiple targets results in −7 to −6 Kcal/mol binding score. Findings of carrageen from in vitro to in silico studies are needed for further validation of clinical pieces of evidence.

Marine lectins and their medicinal applications

Marine organisms have been extensively explored for the last several decades as potential sources of novel biologically active compounds, and extensive research has been conducted on lectins. Lectins derived from marine organisms are structurally diverse and also differ from those identified from terrestrial organisms. Marine lectins appear to be particularly useful in some biological applications. They seem to induce negligible immunogenicity because they have a relatively small size, are more stable due to extensive disulfide bridge formation, and have high specificity for complex glyco-conjugates and carbohydrates instead of simple sugars. It is clear that many of them have not yet been extensively studied when compared with their terrestrial counterparts. Marine lectins can be used to design and develop new potentially useful therapeutic agents. This review encompasses recent research on the isolation and identification of marine lectins with potential value in medicinal applications.

Algal lectins as promising biomolecules for biomedical research

Lectins are natural bioactive ubiquitous proteins or glycoproteins of non-immune response that bind reversibly to glycans of glycoproteins, glycolipids and polysaccharides possessing at least one non-catalytic domain causing agglutination. Some of them consist of several carbohydrate-binding domains which endow them with the properties of cell agglutination or precipitation of glycoconjugates. Lectins are rampant in nature from plants, animals and microorganisms. Among microorganisms, algae are the potent source of lectins with unique properties specifically from red algae. The demand of peculiar and neoteric biologically active substances has intensified the developments on isolation and biomedical applications of new algal lectins. Comprehensively, algal lectins are used in biomedical research for antiviral, antinociceptive, anti-inflammatory, anti-tumor activities, etc. and in pharmaceutics for the fabrication of cost-effective protein expression systems and nutraceutics. In this review, an attempt has been made to collate the information on various biomedical applications of algal lectins.

Anti-inflammatory and antinociceptive activities of methanolic extract from red seaweed Dichotomaria obtusata

The aim of the present work was to investigate the anti-inflammatory and antinociceptive effects of methanolic extract from D. obtusata using classic models in mice (croton oil-induced ear edema and acetic acid-induced writhing) and a phospholipase A2 activity test. Qualitative analysis of the chemical composition of seaweed was also determined by extraction with solvents of increasing polarity and precipitation and color tests. Results of qualitative chemical study showed the presence of lactonic and phenolic compounds, reduced carbohydrates, other sugars, flavonoids, fatty compounds, triterpenes and steroids. The extract inhibited mouse ear edema in a dose-dependent manner with an efficacy higher than 90% and a mean effective dose of 4.87µg/ear, while intraperitoneal administration presented a moderate activity. The extract did not inhibit phospholipase A2 activity. In the writhing test, the intraperitoneal administration of the extract showed a strong antinociceptive activity (80.2%), while the oral route showed a lower efficacy. In conclusion, this study demonstrated the anti-inflammatory and antinociceptive effects of methanol extract of D. obtusata in experimental models, suggesting its therapeutic potential in the treatment of peripheral painful and/or inflammatory pathologies.

Antinociceptive and anti-inflammatory activities of crude methanolic extract of red alga Bryothamnion triquetrum

The marine environment is an extraordinary reservoir of bioactive natural products, many of which exhibit chemical and structural features not found in terrestrial natural products. In this regard, the aim of this study was to investigate the possible antinociceptive and anti-inflammatory activities of a crude methanolic extract of the red alga Bryothamnion triquetrum (BT-MeOH) in murine models. Groups of Swiss mice of both sexes (25-30 g) were used throughout the experiments. The potential antinociceptive of BT-MeOH was evaluated by means of the following tests: acetic acid-induced writhing, hot-plate test and glutamate- and formalin-induced nociception. The anti-inflammatory activity of BT-MeOH was investigated using the zymosan A-induced peritonitis test. The tests were conducted using 100 mg/kg (p.o.) BT-MeOH, 33.3 mg/kg (p.o.) dipyrone, 35.7 mg/kg (p.o.) indomethacin and 5.7 mg/kg (s.c.) morphine. The extract and all standard drugs were administered 40 min before the nociceptive/inflammatory stimulus. In the acetic acid-induced writhing test, BT-MeOH and dipyrone inhibited the nociceptive response by 55.9% (22.2 ± 2.0 writhings; p < 0.01) and 80.9% (9.6 ± 2.1 writhings; p < 0.01). In the hot-plate test, BT-MeOH did not increase the latency time of the animals in the time evaluated. In addition, BT-MeOH inhibited glutamate-induced nociception by 50.1%. While BT-MeOH did not inhibit the neurogenic phase in formalin-induced nociception, the inflammatory phase was inhibited by 53.1% (66.8 ± 14.2 s; p < 0.01). Indomethacin inhibited the inflammatory phase by 60.2% (56.8 ± 8.7 s; p < 0.01). In the zymosan-induced peritonitis test, BT-MeOH inhibited 55.6% (6.6 ± 0.2 × 10(6) leukocytes/mL; p < 0.01) of leukocyte migration, while indomethacin inhibited 78.1% (3.2 ± 0.1 × 10(6) leukocytes/mL; p < 0.01). Based on the results obtained in this study, we conclude that BT-MeOH has peripheral antinociceptive and anti-inflammatory activities. However, more studies need to be conducted to confirm these properties.

A report of a galactan from marine alga Gelidium crinale with in vivo anti-inflammatory and antinociceptive effects

The sulfated galactan of the red marine alga Gelidium crinale (SG-Gc) was purified by ion exchange chromatography and tested by intravenous (i.v.) route in rodent experimental models of inflammation and nociception. The anti-inflammatory activity of SG-Gc (0.01, 0.1 and 1 mg/kg) was evaluated in the model of rat paw edema induced by different inflammatory stimuli, while SG-Gc (0.1, 1 and 10 mg/kg) antinociceptive effect was assessed in models of nociception/hyperalgesia elicited by chemical (formalin test), thermal (hot plate), and mechanical (von Frey) stimuli in mice. In addition, the toxicity was evaluated after rat treatment with SG-Gc (1 mg/kg; i.v.) during 10 days, followed by analysis of the wet weight of animal's body/organs and hematological/biochemical parameters. Sulfated galactan of G. crinale inhibited the time course of dextran-induced paw edema, at all doses, showing maximal effect at 1 mg/kg (42%) and that induced by carrageenan at 0.01 (18%) and 1 mg/kg (20%), but was ineffective on the edema elicited by zymosan. At the highest dose, SG-Gc also inhibited the paw edema induced by histamine (49%), compound 48/80 (32%), and phospholipase A(2) (44%). Sulfated galactan of G. crinale inhibited both neurogenic and inflammatory phases of the formalin test, at all doses, and at 10 mg/kg, the animals flinch reaction in the von Frey test in the 1st and 3rd h by 19 and 26%, respectively. Additionally, SG-Gc treatment was well tolerated by animals. In conclusion, SG-Gc presents anti-inflammatory effect involving the inhibition of histamine and arachidonic acid metabolites and also antinociceptive activity, especially the inflammatory pain with participation of the opioid system.

Opioid-like antinociceptive effects of oral administration of a lectin purified from the seeds of Canavalia brasiliensis

The objective of this study was to evaluate the antinociceptive effects of a lectin from Canavalia brasiliensis (ConBr) when administered orally to murine models of chemical and thermal nociception. ConBr up to 100 mg/kg produced significant and dose-dependent antinociceptive effects: 81% reduction in abdominal writhing induced by 0.6% acetic acid; 26 and 52% reduction in early- and late-stage paw licking, respectively, induced by 2.5% formalin; and 155% increase in reaction latency (heightened thermal pain threshold). In all models, the antinociceptive effect was reversed by the lectin-binding carbohydrate α-d-methyl-mannoside and by the nonselective opioid antagonist naloxone. The antinociceptive effect observed in the formalin test was inhibited by the δ-selective antagonist naltrindole and the κ-selective antagonist nor-binaltorphimine but not by the μ-selective antagonist cyprodime. In conclusion, when administered orally to Swiss mice, the ConBr lectin displayed antinociceptive activity, both peripheral and central, mediated by the opioid system and involving δ-and κ-receptors and the lectin domain.

BIOACTIVE PROTEINS, PEPTIDES, AND AMINO ACIDS FROM MACROALGAE(1)

Macroalgae are a diverse group of marine organisms that have developed complex and unique metabolic pathways to ensure survival in highly competitive marine environments. As a result, these organisms have been targeted for mining of natural biologically active components. The exploration of marine organisms has revealed numerous bioactive compounds that are proteinaceous in nature. These include proteins, linear peptides, cyclic peptides and depsipeptides, peptide derivatives, amino acids, and amino acid-like components. Furthermore, some species of macroalgae have been shown to contain significant levels of protein. While some protein-derived bioactive peptides have been characterized from macroalgae, macroalgal proteins currently still represent good candidate raw materials for biofunctional peptide mining. This review will provide an overview of the important bioactive amino-acid-containing compounds that have been identified in macroalgae. Moreover, the potential of macroalgal proteins as substrates for the generation of biofunctional peptides for utilization as functional foods to provide specific health benefits will be discussed.

Vascular Effects of a Sulfated Polysaccharide from the Red Marine Alga Solieria Filiformis

Anticoagulant and antithrombotic properties of sulfated-polysaccharides (SP) from marine algae are extensively exploited. However, reports on the vascular effects of SP from red algae are rare in the literature. The polysaccharide from Solieria filiformis (Sf-SP) was isolated by ion exchange chromatography, analyzed by agarose gel electrophoresis and tested in male Wistar rats. The inflammation studies were performed using the paw-edema model and the relaxant activity in isolated aorta precontracted with phenylephrine. The anticoagulant effect was evaluated by the test of partial thromboplastin activation time. The SP (1 mg/kg) was not antiinflammatory, but induced acute edema with maximal activity at 30 min (0.35 ± 0.04 mL) compared to controls (0.05 ± 0.03 mL). Cumulative addition of Sf-SP in phenylephrine-contracted tissues produced relaxation with maximal inhibition of 69% (IC50 29.3 ± 9.0 μg/mL) at 300 μg/mL in comparison to controls (0.51 ± 0.09 g). Sf-SP also extended human plasma coagulation time by 2.1 times. These substances could be used as important tools for the study of vascular alterations.

Antinociceptive properties in mice of a lectin isolated from the marine alga Amansia multifida Lamouroux

The antinociceptive effects of a lectin (LEC) isolated from the marine alga Amansia multifida were determined in Swiss mice. The LEC (1, 5, and 10 mg/kg) inhibited acetic acid-induced abdominal writhings in a dose-dependent manner after intraperitoneal or oral administration. A partial but significant inhibition of writhings was observed after the combination of LEC (10 mg/kg) with avidin (1 mg/kg), a potent inhibitor of the hemmaglutinant activity of the lectin. However, total writhing inhibition was demonstrable in the group of mice treated with LEC plus mannose (1 mg/kg), as compared to LEC alone or to control groups. Furthermore, avidin and mainly mannose also play a role in antinociception, somehow facilitating the interaction of LEC with its active cell sites. In the formalin test, although both phases of the response were significantly inhibited, the effect of LEC was predominant during phase 2, causing inhibition of licking time that ranged from 48 to 88% after oral (5 and 10 mg/kg) and intraperitoneal (1 to 5 mg/kg) administration. As is the case with morphine, the effect of LEC (2 mg/kg) was reversed by naloxone (2 mg/kg), indicating the involvement of the opioid system. LEC was also effective in the hot-plate test, producing inhibitory responses to the thermal stimulus, and its effects were blocked by naloxone. In the pentobarbital-induced sleeping time, although LEC did not alter the onset of sleep significantly, it increased the time of sleep within the same dose range compared to control. These results show that LEC presents antinociceptive effects of both central and peripheral origin, possibly involving the participation of the opioid system.