A novel galactose- and arabinose-specific lectin from the sponge Pellina semitubulosa: isolation, characterization and immunobiological properties

Marine Sponge is a Promising Natural Source of Anti-SARS-CoV-2 Scaffold

The current pandemic caused by SARS-CoV2 and named COVID-19 urgent the need for novel lead antiviral drugs. Recently, United States Food and Drug Administration (FDA) approved the use of remdesivir as anti-SARS-CoV-2. Remdesivir is a natural product-inspired nucleoside analogue with significant broad-spectrum antiviral activity. Nucleosides analogues from marine sponge including spongouridine and spongothymidine have been used as lead for the evolutionary synthesis of various antiviral drugs such as vidarabine and cytarabine. Furthermore, the marine sponge is a rich source of compounds with unique activities. Marine sponge produces classes of compounds that can inhibit the viral cysteine protease (Mpro) such as esculetin and ilimaquinone and human serine protease (TMPRSS2) such as pseudotheonamide C and D and aeruginosin 98B. Additionally, sponge-derived compounds such as dihydrogracilin A and avarol showed immunomodulatory activity that can target the cytokines storm. Here, we reviewed the potential use of sponge-derived compounds as promising therapeutics against SARS-CoV-2. Despite the reported antiviral activity of isolated marine metabolites, structural modifications showed the importance in targeting and efficacy. On that basis, we are proposing a novel structure with bifunctional scaffolds and dual pharmacophores that can be superiorly employed in SARS-CoV-2 infection.

Porifera Lectins: Diversity, Physiological Roles and Biotechnological Potential

An overview on the diversity of 39 lectins from the phylum Porifera is presented, including 38 lectins, which were identified from the class of demosponges, and one lectin from the class of hexactinellida. Their purification from crude extracts was mainly performed by using affinity chromatography and gel filtration techniques. Other protocols were also developed in order to collect and study sponge lectins, including screening of sponge genomes and expression in heterologous bacterial systems. The characterization of the lectins was performed by Edman degradation or mass spectrometry. Regarding their physiological roles, sponge lectins showed to be involved in morphogenesis and cell interaction, biomineralization and spiculogenesis, as well as host defense mechanisms and potentially in the association between the sponge and its microorganisms. In addition, these lectins exhibited a broad range of bioactivities, including modulation of inflammatory response, antimicrobial and cytotoxic activities, as well as anticancer and neuromodulatory activity. In view of their potential pharmacological applications, sponge lectins constitute promising molecules of biotechnological interest.

Marine sponge lectins: actual status on properties and biological activities

Marine sponges are primitive metazoans that produce a wide variety of molecules that protect them against predators. In studies that search for bioactive molecules, these marine invertebrates stand out as promising sources of new biologically-active molecules, many of which are still unknown or little studied; thus being an unexplored biotechnological resource of high added value. Among these molecules, lectins are proteins that reversibly bind to carbohydrates without modifying them. In this review, various structural features and biological activities of lectins derived from marine sponges so far described in the scientific literature are discussed. From the results found in the literature, it could be concluded that lectins derived from marine sponges are structurally diverse proteins with great potential for application in the production of biopharmaceuticals, especially as antibacterial and antitumor agents.

Halilectin 1 (H-1) and Halilectin 2 (H-2): two new lectins isolated from the marine sponge Haliclona caerulea

Two new lectins named Halilectin 1 (H-1) and Halilectin 2 (H-2) were isolated from the marine sponge Haliclona caerulea using a combination of affinity chromatography on stroma fixed onto Sephadex G-25 and cation and anion exchange chromatography. H-1 is a monomeric protein with a molecular mass of 40 kDa estimated using sodium dodecyl sulfate polyacrylamide gel electrophoresis and 15 kDa estimated using a TSK gel. Conversely, H-2 is a homodimeric protein with 15 kDa monomers linked via weak interactions. H-1 more effectively agglutinates trypsinized rabbit erythrocytes, whereas H-2 more effectively agglutinates native rabbit erythrocytes. The hemagglutinating activity of H-1 could be not inhibited by any tested sugars, but H-2 was inhibited by orosomucoid and porcine stomach mucin. Neither lectin was dependent on divalent ions. H-1 was stable at basic pH range and temperatures up to 50 °C, whereas H-2 was stable at acid pH range and temperatures up to 80 °C. The H. caerulea lectins exhibited dose-dependent toxicity against Artemia nauplii. Additionally, 76% of the primary structure of H-2 was determined using tandem mass spectrometry to contain a unique amino acid sequence with no similarity to any members of the animal lectin family.

Lectins of marine hydrobionts

Data from the literature and results of our research on lectins isolated from some kinds of marine hydrobionts such as clams, ascidians, sea worms, sponges, and algae are presented in this review. Results of comparative analysis of the basic physicochemical properties and biological activity of lectins isolated from various sources are discussed.

A lactose-binding lectin from the marine sponge Cinachyrella apion (Cal) induces cell death in human cervical adenocarcinoma cells

Cancer represents a set of more than 100 diseases, including malignant tumors from different locations. Strategies inducing differentiation have had limited success in the treatment of established cancers. Marine sponges are a biological reservoir of bioactive molecules, especially lectins. Several animal and plant lectins were purified with antitumor activity, mitogenic, anti-inflammatory and antiviral, but there are few reports in the literature describing the mechanism of action of lectins purified from marine sponges to induce apoptosis in human tumor cells. In this work, a lectin purified from the marine sponge Cinachyrella apion (CaL) was evaluated with respect to its hemolytic, cytotoxic and antiproliferative properties, besides the ability to induce cell death in tumor cells. The antiproliferative activity of CaL was tested against HeLa, PC3 and 3T3 cell lines, with highest growth inhibition for HeLa, reducing cell growth at a dose dependent manner (0.5–10 µg/mL). Hemolytic activity and toxicity against peripheral blood cells were tested using the concentration of IC₅₀ (10 µg/mL) for both trials and twice the IC₅₀ for analysis in flow cytometry, indicating that CaL is not toxic to these cells. To assess the mechanism of cell death caused by CaL in HeLa cells, we performed flow cytometry and western blotting. Results showed that lectin probably induces cell death by apoptosis activation by pro-apoptotic protein Bax, promoting mitochondrial membrane permeabilization, cell cycle arrest in S phase and acting as both dependent and/or independent of caspases pathway. These results indicate the potential of CaL in studies of medicine for treating cancer.

Biological activities of ACL-I and physicochemical properties of ACL-II, lectins isolated from the marine sponge Axinella corrugata

Lectin II from the marine sponge Axinella corrugata (ACL-II) was purified by affinity chromatography on rabbit erythrocytic stroma incorporated into a polyacrylamide gel, followed by gel filtration on Ultrogel AcA 44 column. Purified ACL-II is a lectin with an Mr of 80 kDa and 78 kDa, estimated by SDS-PAGE and by FPLC on Superose 12 HR column, respectively. ACL-II mainly agglutinates native rabbit erythrocytes and this hemagglutinating activity is independent of Ca(2+), Mg(2+) and Mn(2+), but is inhibited by d-galactose, chitin and N-acetyl derivatives, with the exception of GalNAc. ACL-II is stable for up to 65 °C for 30 min, with a better stability at a pH range of 2 to 6. In contrast, ACL-I displays a strong mitogenic and cytotoxic effect.

A lactose specific lectin from the sponge Cinachyrella apion: purification, characterization, N-terminal sequences alignment and agglutinating activity on Leishmania promastigotes

Crude extract from the sponge Cinachyrella apion showed cross-reactivity with the polyclonal antibody IgG anti-CvL (Cliona varians lectin) and also a strong haemagglutinating activity towards human erythrocytes of all ABO groups. Thus, it was submitted to acetone fractionation, IgG anti-deglycosylated CvL Sepharose affinity chromatography, and Fast Protein Liquid Chromatography (FPLC-AKTA Purifier) gel filtration on a Superose 6 10/300 column to purify a novel lectin. C. apion lectin (CaL) agglutinated all types of human erythrocytes with preference for papainized type A erythrocytes. The haemagglutinating activity is independent of Ca2+, Mg2+ and Mn2+ ions, and it was strongly inhibited by the disaccharide lactose, up to a minimum concentration of 6.25 mM. CaL molecular mass, determined by FPLC-gel filtration on a Superose 12 10/300 column and SDS gel electrophoresis, was approximately 124 kDa, consisting of eight subunits of 15.5 kDa, assembled by hydrophobic interactions. The lectin was heat-stable between 0 and 60 degrees C and pH-stable. The N-terminal amino acid sequence of CaL was also determined and a blast search on amino acid sequences revealed that the protein showed similarity only with a silicatein. Leishmania chagasi promastigotes were agglutinated by CaL and this activity was abolished by lactose, indicating that lactose receptors could be presented in this parasite stage. These findings are indicative of the potential biotechnological application of CaL as diagnostic of pathogenic protozoa.

Purification and characterization of a novel lectin from the toxic wild mushroom Inocybe umbrinella

From the dried fruiting bodies of the toxic mushroom Inocybe umbrinella, a novel lectin with a molecular mass of 17 kDa has been isolated with about 160-fold purification. The purification protocol comprised ion exchange chromatography on DEAE-cellulose, and CM-cellulose, and gel filtration on Superdex 75. Among the carbohydrates tested, raffinose, d-melibiose, alpha-lactose and d(+)-galactose could inhibit the hemagglutinating activity of the lectin. The hemagglutinating activity was stable between 10 and 60 degrees C, in 12.5-100mM HCl, and in 50mM NaOH. The hemagglutinating activity was inhibited by Ca(2+), Mn(2+)and Mg(2+) ions, but was unaffected by Fe(3+), Zn(2+) and Al(3+) ions. The lectin inhibited HIV-1 reverse transcriptase with an IC(50) of 4.7+/-0.2 microM. Proliferation of tumor cells including hepatoma HepG2 cells and breast cancer MCF7 cells was inhibited by the lectin with an IC(50) of 3.5+/-0.2 microM and 7.4+/-0.3 micoM, respectively. The lectin has a unique N-terminal amino acid sequence, DGVLATNAVA. It did not exhibit antifungal activity. The present report is the first on an Inocybe lectin and represents one of the very few reports on lectins from toxic mushrooms.

ACL-I, a lectin from the marine sponge Axinella corrugata: isolation, characterization and chemotactic activity

The lectin from the marine sponge Axinella corrugata (ACL-I) was purified by affinity chromatography on rabbit erythrocytic stroma incorporated into a polyacrylamide gel followed by gel filtration on Ultrogel AcA 44 column. Purified ACL-I is a hexameric glycoprotein with a Mr of 82.3 kDa estimated by SDS-PAGE and 78.5 kDa by FPLC on Superose 12 HR column. The pI of lectin is 6.3 and ACL-I is constituted of 13.9 kDa similar subunits some of them linked by disulphide bridges. This lectin agglutinates native rabbit, goat and dog erythrocytes and in less extent human erythrocytes. The hemagglutinating activity is independent of Ca(2+), Mg(2+) and Mn(2+), but it is strongly inhibited by carbohydrates containing N-acetyl groups. ACL-I is stable up to 70 degrees C for 30 min, with optimum pH between 7 and 8, and it is also resistant to enzymatic proteolysis in vitro. In the presence of reducing or denaturant agents, the lectin activity decreases. ACL-I displays chemotactic effect on rat neutrophil in vitro which is inhibited by N-acetyl-d-glucosamine.

Pro-inflammatory effect in mice of CvL, a lectin from the marine sponge Cliona varians

CvL, a lectin from the marine sponge Cliona varians agglutinated type A papainized erythrocytes and was strongly inhibited by d-galactose and sucrose. Models of leukocyte migration in vivo were used to study the inflammatory activity of CvL through of mouse paw oedema and peritonitis. Effect of CvL on peritoneal macrophage activation was analysed. Effects of corticoids and NSAIDS drugs were also evaluated on peritonitis stimulated by CvL. Results showed that mouse hind-paw oedema induced by subplantar injections of CvL was dose dependent until 50 microg/cavity. This CvL dose when administered into mouse peritoneal cavities induced maxima cell migration (9283 cells/microL) at 24 h after injection. This effect was preferentially inhibited by incubation of CvL with the carbohydrates d-galactose followed by sucrose. Pre-treatment of mice with 3% thioglycolate increases the peritoneal macrophage population 2.3 times, and enhanced the neutrophil migration after 24 h CvL injection (75.8%, p<0.001) and no significant effect was observed in the presence of fMLP. Finally, pre-treatment of mice with dexamethasone (cytokine antagonist) decreased (65.6%, p<0.001), diclofenac (non-selective NSAID) decreased (34.5%, p<0.001) and Celecoxib (selective NSAID) had no effect on leukocyte migration after submission at peritonitis stimulated by CvL, respectively. Summarizing, data suggest that CvL shows pro-inflammatory activity, inducing neutrophil migration probably by pathway on resident macrophage activation and on chemotaxis mediated by cytokines.

CvL, a lectin from the marine sponge Cliona varians: Isolation, characterization and its effects on pathogenic bacteria and Leishmania promastigotes

CvL, a lectin from the marine sponge Cliona varians was purified by acetone fractionation followed by Sepharose CL 4B affinity chromatography. CvL agglutinated papainized treated human erythrocytes with preference for type A erythrocytes. The lectin was strongly inhibited by monosaccharide d-galactose and disaccharide sucrose. CvL is a tetrameric glycoprotein of 28 kDa subunits linked by disulphide bridges with a molecular mass of 106 kDa by SDS-PAGE and 114 kDa by Sephacryl S300 gel filtration. The lectin was Ca2+ dependent, stable up to 60 degrees C for 60 min, with optimum pH of 7.5. CvL displays a cytotoxic effect on gram positive bacteria, such as Bacillus subtilis and Staphylococcus aureus. However, CvL did not affect gram negative bacteria, such as Escherichia coli and Pseudomonas aeruginosa. Leishmania chagasi promastigotes were agglutinated by CvL up to 2(8) titer. These findings are indicative of the physiological defense roles of CvL and its possible use in the antibiosis of bacteria and protozoa pathogenic.

Isolation and characterization of a novel lectin from the mushroom Armillaria luteo-virens

From the dried fruiting bodies of the mushroom Armillaria luteo-virens, a dimeric lectin with a molecular mass of 29.4 kDa has been isolated. The purification procedure involved (NH(4))(2)SO(4) precipitation, ion exchange chromatography on DEAE-cellulose, CM-cellulose, and Q-Sepharose, and gel filtration by fast protein liquid chromatography on Superdex 75. The hemagglutinating activity of the lectin could not be inhibited by simple sugars but was inhibited by the polysaccharide inulin. The activity was stable up to 70 degrees C but was acid- and alkali-labile. Salts including FeCl(3), AlCl(3), and ZnCl(2) inhibited the activity whereas MgCl(2), MnCl(2), and CaCl(2) did not. The lectin stimulated mitogenic response of mouse splenocytes with the maximal response achieved by 1microM lectin. Proliferation of tumor cells including MBL2 cells, HeLa cells, and L1210 cells was inhibited by the lectin with an IC(50) of 2.5, 5, and 10 microM, respectively. However, proliferation of HepG2 cells was not affected. The novel aspects of the isolated lectin include a novel N-terminal sequence, fair thermostability, acid stability, and alkali stability, together with potent mitogenic activity toward spleen cells and antiproliferative activity toward tumor cells.

A normal mucin-binding lectin from the sponge Craniella australiensis

A lectin, Craniella australiensis (CAL), was isolated from sponge C. australiensis by ion-exchange on DEAE-Sephacel and purified by gel filtration on Sephadex G-150 and HPLC on DEAE-5PW. The purified lectin was a trimeric protein as revealed by SDS-PAGE and MALDI-TOF analysis. SDS-PAGE showed that the CAL protein had a molecular mass of 54 kDa, and consisted of three 18 kDa subunits. Gel filtration of purified lectin on Sephadex G-200 indicates that it exists as a 54 kDa protein in its native state. The amino acid composition was rich in Thr and Glx. CAL was found to agglutinate native and trypsinized human A, B erythrocytes, and agglutinate native erythrocytes of mouse, sheep, rabbit and chicken, and trypsinized erythrocytes of sheep and rabbit. The hemagglutination activity was inhibited by glycoproteins such as PSM and asialo-PSM, but not by any of the monosaccharides tested. The activity was stable between 20 and 70 degrees C. Significant CAL activity was observed between pH 5 and 8. The lectin reaction is independent of the presence of divalent cations Ca2+ and Mg2+. The sequence of N-terminal residues of CAL was determined as TSSCQSIVVE. The lectin showed a potent mitogenic response towards BALB/c splenocytes.

First report of an arabinose-specific fungal lectin

To date, arabinose-binding lectins have been reported only from the human opportunistic pathogen Pseudomonas aeruginosa, the plant aggressive pathogen Ralstonia solanacearum, and the sponge Pellina semitubulosa. An arabinose-binding lectin with mitogenic activity toward splenocytes and a high specific hemagglutinating activity was isolated in the present study from a wild discomycete mushroom, Peziza sylvestris. The maximal mitogenic activity was induced by a lectin concentration of 8 microM. The lectin was a single-chained protein with a molecular mass of 20 kDa. Its N-terminal sequence showed only slight resemblance to other mushroom lectins. It was adsorbed on both diethylaminoethyl-cellulose and carboxymethyl-cellulose. Unlike previously reported mushroom lectins, the hemagglutinating activity of the lectin was inhibited by arabinose, but not by a large variety of other carbohydrates. The lectin activity was adversely affected in the presence of 0.05 M NaOH or 0.025 M HCl, and when the ambient temperature was elevated above 35 degrees C.

A novel lectin from the sponge Haliclona cratera: isolation, characterization and biological activity

A lectin from the Adriatic sponge Haliclona cratera was purified by ion-exchange and gel chromatography. The molecular mass of the lectin is approximately 29 kDa. Purified lectin is rich in hydrophobic and basic amino acids and has an isoelectric point at pH 8.6. H. cratera lectin is relatively heat- and pH-stable. It agglutinates native and trypsinized, papainized and neuraminidase-treated human A, B, O, AB and sheep erythrocytes, and the hemagglutinating activity is independent of Ca(2+), Mn(2+) and Mg(2+) ions; D-galactose and N-acetyl-D-galactosamine are found to be moderate inhibitors of the activity. H. cratera lectin displays cytotoxic effect on HeLa and FemX cells and weak mitogenic effect on human T-lymphocytes pretreated with phytohemagglutinin (PHA).

Lectins from tropical sponges. Purification and characterization of lectins from genus Aplysina

Only a few animal phyla have been screened for the presence and distribution of lectins. Probably the most intensively studied group is the mollusk. In this investigation, 22 species from 12 families of tropical sponges collected in Los Roques National Park (Venezuela) were screened for the presence of lectins. Nine saline extracts exhibited strong hemagglutinating activity against pronase-treated hamster red blood cells; five of these reacted against rabbit red blood cells, four with trypsin-treated bovine red blood cells, and five with human red blood cells regardless of the blood group type. Extracts from the three species studied from genus Aplysina (archeri, lawnosa, and cauliformis) were highly reactive and panagglutinating against the panel of red blood cells tested. The lectins from A. archeri and A. lawnosa were purified to homogeneity by ammonium sulfate fractionation, affinity chromatography on p-aminobenzyl-beta-1-thiogalactopyranoside-agarose, and gel filtration chromatography. Both lectins exhibited a native molecular mass of 63 kDa and by SDS-polyacrylamide gel electrophoresis under reducing conditions have an apparent molecular mass of 16 kDa, thus suggesting they occur as homotetramers. The purified lectins contain 3-4 mol of divalent cation per molecule, which are essential for their biological activity. Hapten inhibition of hemagglutination was carried out to define the sugar binding specificity of the purified A. archeri lectin. The results indicate a preference of the lectin for nonreducing beta-linked d-Gal residues being the best inhibitors of red blood cells binding methyl-beta-d-Gal and thiodigalactoside (Gal beta 1-4-thiogalactopyranoside). The behavior of several glycans on immobilized lectin affinity chromatography confirmed and extended the specificity data obtained by hapten inhibition.

Adhesive and growth properties of lectin from the ascidian Didemnum ternatanum on cultivated marine invertebrate cells

The effects of N-Acetyl-D-glucosamine-specific lectin (M(r) 27 kDa) isolated from the ascidian Didemnum ternatanum on cultivated cells of molluscs and echinoderms were studied. This lectin was found to stimulate the growth or the differentiation of cultivated marine invertebrate cells depending on the stage of embryonic development at which primary cell cultures were obtained. In addition, it has been shown to increase the attachment of cells in primary cultures of these animals. The degree of attachment is considerably increased when collagen or polylysine substrates are used. Using scanning electron microscopy we have demonstrated the stage-specific effect of this lectin on embryonic sea urchin and molluscan cells. Intensive cell spreading and an alteration of cell shape were observed only at the gastrula stage, when the switching from maternal information to embryonic genes occurred. The ascidian lectin seems to have some characteristics of both an adhesive factor and a growth factor.

Triangulynes A-H and trangulynic acid, new cytotxic polyacetylenes from the marine sponge Pellina triangulata

Nine new polyacetylenes, triangulynes A-H (1-8) and triangulynic acid (9), have been isolated from the marine sponge Pellina triangulata (Oceanapiidae) through cytotoxicity-guided fractionation. Structural elucidations and stereochemistry assignments were based on chemical and spectral studies.