Inhibitory effect of a marine-sponge toxin, okadaic acid, on protein phosphatases. Specificity and kinetics

The inhibitory effect of a marine-sponge toxin, okadaic acid, was examined on type 1, type 2A, type 2B and type 2C protein phosphatases as well as on a polycation-modulated (PCM) phosphatase. Of the protein phosphatases examined, the catalytic subunit of type 2A phosphatase from rabbit skeletal muscle was most potently inhibited. For the phosphorylated myosin light-chain (PMLC) phosphatase activity of the enzyme, the concentration of okadaic acid required to obtain 50% inhibition (ID50) was about 1 nM. The PMLC phosphatase activities of type 1 and PCM phosphatase were also strongly inhibited (ID50 0.1-0.5 microM). The PMCL phosphatase activity of type 2B phosphatase (calcineurin) was inhibited to a lesser extent (ID50 4-5 microM). Similar results were obtained for the phosphorylase a phosphatase activity of type 1 and PCM phosphatases and for the p-nitrophenyl phosphate phosphatase activity of calcineurin. The following phosphatases were not affected by up to 10 microM-okadaic acid: type 2C phosphatase, phosphotyrosyl phosphatase, inositol 1,4,5-trisphosphate phosphatase, acid phosphatases and alkaline phosphatases. Thus okadaic acid had a relatively high specificity for type 2A, type 1 and PCM phosphatases. Kinetic studies showed that okadaic acid acts as a non-competitive or mixed inhibitor on the okadaic acid-sensitive enzymes.

Purification and characterization of the agglutinins from the sponge Aaptos papillata and a study of their combining sites

The lectins from the sponge Aaptos papillata were isolated by affinity chromatography using polyleucyl blood group A + H substances from hog stomach linings as an absorbent and eluting with 3 M MgCl2. Further separation on diethylaminoethylcellulose and preparative disc electrophoresis on polyacrylamide gave the three fractions, Aaptos lectins I, II, and III. They were essentially homogenous in polyacrylamide electrophoresis and sedimentation analysis: a small second component was seen in lectins I and II in immunoelectrophoresis at high concentration. The S20,W0 values for Aaptos lectins I, II, and III were 3.5, 6.0, and 5.5. By electrophoresis in sodium dodecyl sulfate with an without beta-mercaptoethanol Aaptos lectin I showed two bands corresponding to molecular weights of 12 000 and 21 000; Aaptos lectins II and III gave only one band of molecular weight of 16 000. In isoelectric focusing, Aaptos lectin I showed bands at pH 4.7 and 5.4 and in the range between 6.8 and 7.6, while Aaptos lectins II and III were almost identical with bands at pH 3.8, 4.7 to 4.9, and 5.3. Aaptos lectin I differed from II and III in amino acid composition but the latter two were very similar. They contained no significant carbohydrate. Aaptos lectin I reacted best with blood group substances with terminal nonreducing N-acetyl-D-glucosamine residues precipitating about two-thirds of the lectin N added while blood group substances with terminal nonreducing DGalNAc were almost inactive. However, Aaptos lectin II was completely precipitated by blood group substances and glycoproteins containing terminal DGalNAc, DGlcNAc, or sialic acid residues. Aaptos lectin III had a precipitation pattern similar to Aaptos lectin II. DGlcNAc but not DGalNAc inhibited precipitation of Aaptos lectin I by blood group substances and N, N', N'', N'''-tetraacetylchitotetraose was the best inhibitor and was 2000 times more active than DGlcNAc. Precipitin reactions with Aaptos lectin II were inhibited by equal amounts of DGlcNAc and by sialic acid which were four times more potent than DGalNAc. N,N',N''-triacetylchiotriose was the best inhibitor and was 13 times better than DGlcNAc. At 37 degrees C three to four times higher amounts of inhibitor were necessary to inhibit precipitation of Aaptos lectin II than were needed at 4 degrees C, indicating higher affinity of blood group substances for Aaptos lectin II with increasing temperature. Aaptos lectin I was precipitated by the monofunctional hapten p-nitrophenyl-alphaDGalNAc, while p-nitrophenyl-betaDGalNAc did not precipitate and was a good inhibitor. Both phenomena indicate involvement of hydrophobic bonds.

A novel antagonist of serotonergic receptors, hymenidin, isolated from the Okinawan marine sponge Hymeniacidon sp

A novel bromine-containing pyrrole compound, hymenidin, has been isolated from the Okinawan marine sponge Hymeniacidon sp. as a potent antagonist of serotonergic receptors and its structure elucidated using spectral data.

(+)-Curcuphenol and dehydrocurcuphenol, novel sesquiterpenes which inhibit H,K-ATPase, from a marine sponge Epipolasis sp

Two H,K-ATPase inhibitors and an inactive related compound have been isolated from a marine sponge Epipolasis sp. They are aromatic sesquiterpene alpha-curcumenes.

Unusual C24, C25, C26 and C27 polyunsaturated fatty acids of the marine sponge Microciona prolifera

(1) Complete characterization of the fatty acids of the marine sponge Microciona prolifera, including double bond positional isomers, has identified 95 different acids in amounts of 0.1% or more. Trace amounts of 23 other acids were found. (2) 48% of the fatty acids present have C24--C28 chain lengths. These are all saturates, monoenes, dienes and trienes; the tetraene, pentaene and hexaene acids possess the usual C18--C22 carbon chains. The numerous C24--C28 acids present apparently originate within the sponge itself, indicating a highly active chain elongation system. (3) A new family of C24, C25, C26 and C27 polyunsaturated acids with isolated double bonds has been discovered. All contain delta 5,9 unsaturation. Specific acids identified were 5,9-24:2; 5,9-25:2; 5,9-26:2; 5,9,17-26:3; 5,9,19-26:3; 5,9,19-27:3 and 5,9,20-27:3. Biosynthetic pathways for such acids are proposed, based on intermediates found in our fatty acid analyses.

Marine natural products. XXIII. Three new cytotoxic dimeric macrolides, swinholides B and C and isoswinholide A, congeners of swinholide A, from the Okinawan marine sponge Theonella swinhoei

Following the characterization of swinholide A (1), the major cytotoxic dimeric macrolide, three new congeneric dimeric macrolides, named swinholide B (2), swinholide C (3) and isoswinholide A (10), have been isolated from the Okinawan marine sponge Theonella swinhoei. The structures of these dimeric macrolides have been elucidated on the basis of chemical and physicochemical evidence. These dimeric macrolides were shown to exhibit potent cytotoxicities toward KB cell lines.

In vitro inactivation of the neurotoxic action of beta-bungarotoxin by the marine natural product, manoalide

The irreversible neurotoxic action of beta-bungarotoxin (beta-BuTx) can be prevented by preincubation of the toxin with manoalide, a non-steroidal anti-inflammatory agent. Manoalide was also found to inactivate purified phospholipase A2 and thus prevent hydrolysis of phosphatidylcholine. PLA2 is a component found in several neurotoxic venoms and is also a rate limiting enzyme important in phospholipid metabolism and prostaglandin synthesis in man.

The inhibition of human immunodeficiency virus type 1 reverse transcriptase by avarol and avarone derivatives

We have analyzed the effects of several natural compounds related to avarols and avarones on the catalytic functions of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT). The most potent substances, designated as avarone A,B and E and avarol F, inhibited indiscriminately the enzymatic activities of HIV-1 RT, namely the RNA-dependent and DNA-dependent DNA polymerase as well as the ribonuclease H. The inhibition of the DNA polymerase activity was found to be non-competitive with respect to either the template-primer or the deoxynucleotidetriphosphate. These studies suggest that the hydroxyl group at the ortho position to the carbonyl group at the quinone ring is involved in blocking the RT activity. The identification of the active site of the inhibitors will hopefully lead to the rational design of new potent anti-HIV drugs.

Lectin, a possible basis for symbiosis between bacteria and sponges

From the marine sponge Halichondria panicea a lectin was isolated and characterized. The homogeneous lectin (composed of protein to 80.7% and of neutral carbohydrates to 14.1%) had a molecular weight of 78,000 (determined by gel filtration) and consisted of four subunits with a molecular weight of 21,000 each (determined by gel electrophoresis in the presence of sodium dodecyl sulfate). The hemagglutinating activity was only slightly dependent upon ionic strength and incubation temperature and did not require divalent cations, but it was inhibited by reagents for thiol groups. The Halichondria lectin was completely inhibited in hemagglutination competition experiments in the presence of fetuin, D-galacturonic acid, D-glucuronic acid, polygalacturonic acid, or L-fucose. The purified Halichondria lectin did not cause reaggregation of dissociated H. panicea cells. From the same sponge species bacteria were isolated and identified as Pseudomonas insolita. These bacteria were cultivated in marine broth 2216. Under these culture conditions the bacteria grew only in the presence of the homologous lectin; the lectin-caused effect was not abolished by D-glucuronic acid or D-galacturonic acid. However, after addition of a polysaccharide-containing fraction isolated from P. insolita, the lectin-caused, growth-promoting effect was abolished. Other lectins were found to exhibit no growth-promoting effect. On the basis of colony counts, P. insolita was the predominant bacterial species in the sponge extract; 1.9 X 10(6) Pseudomonas colonies were measured in extracts isolated from 1 g of sponge. The assumption of an interrelationship between the sponge and the bacterium is supported by the results indicating that the Halichondria lectin has no effect on the growth of such bacteria isolated from six other marine sponge species. Evidence is presented which indicates that the Halichondria lectin is not utilized during growth of the Pseudomonas species. Lectin activity was detected on the surface of mucoid cells from H. panicea. From the data obtained the possibility is discussed that the Halichondria lectin is a basis for a symbiotic relationship between the sponge and the bacterium.

Preparation of monoclonal antibodies against okadaic acid prepared from the sponge Halichondria okadai

Three murine monoclonal antibodies, OA-1, OA-2 and OA-3, against okadaic acid were prepared from hybridoma clones obtained by fusion of mouse 653 myeloma cells with mouse immune spleen cells sensitized to okadaic acid-ovalbumin conjugate. Each antibody reacted with dinophysistoxin-1 ( = 35-methylokadaic acid) as well as okadaic acid, but did not react with the other diarrhetic shellfish poisons or related compounds, such as 7-O-palmitoyl-okadaic acid (analogue of dinophysistoxin-3), pectenotoxin-1 and yessotoxin. A competitive inhibition enzymelinked immunosorbent assay which employed OA-3 antibody was performed and showed a sensitivity of about 10 ppb (10 ng/ml) for okadaic acid. This simple and time-saving ELISA assay system may be useful for the specific detection of diarrhetic shellfish poisons.

Steroids in Porifera. II. Steroid derivatives from two sponges of the family Halichondriidae. Sokotrasterol sulfate, a marine steroid with a new pattern of side chain alkylation

A trisulfated derivative of 24,25,26,26-tetramethyl-5 alpha-cholest-23E-ene-2 alpha, 3 beta, 6 alpha-triol (sokotrasterol sulfate) has been isolated from the sponge Halichondriidae gen. sp., collected near Sokotra Island (Arabian Sea), and its structure has been elucidated. The side chain of the new steroid involves a "normal" alkylation at C-24 and the unprecedented addition of two extra methyl groups at C-26 and one extra methyl group at C-25. A free sterol fraction contained only 24-isopropyl-5-cholesten-3 beta-ol and 24-isopropyl-5, 22E-cholestadien-3 beta-ol. 24-Isopropyl-5, 22E-cholestadien-3 beta-ol as sole monohydroxy sterol and halistanol sulfate as major polyhydroxylated steroid derivative have been detected in Halichondria sp., a Madagascar sponge.

Characterization of the trimeric, self-recognizing Geodia cydonium lectin I

A D-galactose-specific lectin I was extracted from the sponge Geodia cydonium and purified by affinity chromatography. The molecular weight of lectin I as determined by high-pressure liquid gel chromatography, was found to be 36500 +/- 1300. Disc gel electrophoresis in the presence and in the absence of sodium dodecyl sulfate showed that lectin I is a trimer composed of three different subunits (Mr: 13800, 13000 and 12200); two of the three subunits are linked by one disulfide bond. Isoelectric focusing gave a pI of 5.6 for the native molecule and a pI of 4.4 and of 7.4 for the subunits. The three subunits carry carbohydrate side chains, composed of D-galactose (94%) and of arabinose (5%). Based on experiments with lectins, the terminal D-galactose residues are bound by beta 1 leads to 6 and/or beta 1 leads to 4 glycosidic linkages. The Geodia lectin I contains, besides two carbohydrate recognition sites, at least one receptor site for a second lectin I molecule.

Hymenin, a novel alpha-adrenoreceptor blocking agent from the Okinawan marine sponge Hymeniacidon sp

A novel bromine-containing alkaloid, hymenin, has been isolated from the Okinawan marine sponge Hymeniacidon sp. as a potent alpha-adrenoceptor blocking agent and its structure determined to be 1 on the basis of the spectral data.

Isoprenoid fatty acids from marine sponges. Are sponges selective?

The burrowing sponges Anthosigmella varians and Spheciospongia vesparium were found to be rich in the isoprenoid phospholipid fatty acid 4,8,12-trimethyltridecanoic (5.2% and 23%, respectively, of the total fatty acid composition), while the burrowing sponge Chondrilla nucula and the demosponge Agelas dispar contained the acid 3,7,11,15-tetramethylhexadecanoic (13.8% and 8.6%, respectively, of the total phospholipid fatty acid composition). No other isoprenoid fatty acid was found, and the two acids described in this work did not occur concomitantly in the same sponge.

Cell membrane localization of long chain C24-C30 fatty acids in two marine demosponges

Subcellular fractionation by differential centrifugation was performed on two previously unstudied marine sponges (Reniera sp. and Pseudaxinyssa sp.) that represent both major subclasses of the Demospongiae. Long chain fatty acids (LCFA) with 24-30 carbon units were found as major constituents of cell membrane isolates of both sponges. Most LCFA were polyunsaturated and were constituents of the phospholipids, which are typical membrane lipids, and in particular the amino-phospholipids. The LCFA composition of phospholipids from whole sponge tissue was shown to provide a reliable indication of the LCFA composition of cell membrane phospholipids in the sponges studied. An unusual triply branched C16 isoprenoid fatty acid, 4,8,12-trimethyltridecanoic acid, also was identified as a cell membrane acid in the sponge Pseudaxinyssa sp.