Two new secondary metabolites,saccharochlorines A and B,from a marine bacterium Saccharomonospora sp. KCTC-19160

Two new chlorinated secondary metabolites, saccharochlorines A and B (1 and 2), were isolated from the saline cultivation of a marine-derived bacterium Saccharomonospora sp. (KCTC-19160). The chemical structures of the saccharochlorines were elucidated by 2D NMR and MS spectroscopic data. Saccharochlorines A and B (1 and 2) exhibit weak inhibition of β-secretase (BACE1) in biochemical inhibitory assay, but they induced the release of Aβ (1–40) and Aβ (1–42) in H4-APP neuroglial cells. This discrepancy might be derived from the differences between the cellular and sub-cellular environments or the epigenetic stimulation of BACE1 expression.     

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.     

Cross-species induction of antibacterial activity produced by epibiotic bacteria isolated from Indian marine sponge Pseudoceratina purpurea

Four antibiotic producing bacteria were isolated from the surface of the marine sponge Pseudoceratina purpurea and exposed to living cells of two human pathogenic bacteria as well as some marine fouling bacteria to induce the production of antimicrobial activity. Experimental results showed that these four marine epibiotic bacteria enhanced their antibacterial production, when exposed to these test strains. The highest induction was exhibited by the sponge isolate PS79 against fouling bacterium FB-9 (from 3 mm to 7 mm inhibition zone). All the four strains were induced and showed increased activity specifically against the challenged pathogenic or fouling bacteria tested. Specific induction by these species suggests that the induction might be attributed to the response to the chemical signals received from potential challenger strains.     

Cytotoxic and antimicrobial metabolites from marine lignicolous fungi, Diaporthe sp

A new compound (1), named diaporthelactone, together with two known compounds (2 and 3) were isolated from the culture of Diaporthe sp., a marine fungus growing in the submerged rotten leaves of Kandelia candel in the mangrove nature conservation areas of Fugong, Fujian Province of China. The new compound was elucidated to be 1,3-dihydro-4-methoxy-7-methyl-3-oxo-5-isobenzofuran-carboxyaldehyde (1), which showed cytotoxic activity against KB and Raji cell lines (IC50 6.25 and 5.51 microg mL(-1), respectively). Two known compounds, 7-methoxy-4,6-dimethyl-3H-isobenzofuran-1-one (2) and mycoepoxydiene (3), were also demonstrated to exhibit cytotoxic activities for the first time. All three compounds were assessed for antimicrobial activity.     

海洋细菌抗菌和细胞毒活性的初步研究

从不同海域的生物、海水和海泥中分离海洋细菌,利用琼脂扩散法和MTT法对细菌培养液的乙酸乙酯提取物进行了抗菌和细胞毒活性筛选。比较了活性菌株与来源的相关性．结果表明,在分离的341株海洋细菌中。42株细菌的代谢产物具有抗菌活性,7株具有细胞毒活性,其中来源于海洋无脊椎动物和海藻的活性菌株比例(22％和11％)大于来源于海水和海泥的细菌(7％和5％)．细菌分类鉴定结果显示,具有活性的细菌大部分属于假单胞菌属、发光杆菌属、梭状芽孢杆菌属、交替单胞菌属和黄杆菌属．     

Kakeromamide A,a new cyclic pentapeptide inducing astrocyte differentiation isolated from the marine cyanobacterium Moorea bouillonii

Kakeromamide A (1), a new cyclic pentapeptide encompassing a thiazole ring moiety and a β-amino acid, was isolated from the marine cyanobacterium Moorea bouillonii. Its structure was elucidated by the spectral analysis and the modified Marfey’s method. Compound 1 induced differentiation of neural stem cells into astrocytes at the concentration of 10?µM.     

The current status of natural products from marine fungi and their potential as anti-infective agents

A growing number of marine fungi are the sources of novel and potentially life-saving bioactive secondary metabolites. Here, we have discussed some of these novel antibacterial, antiviral, antiprotozoal compounds isolated from marine-derived fungi and their possible roles in disease eradication. We have also discussed the future commercial exploitation of these compounds for possible drug development using metabolic engineering and post-genomics approaches.     

Almiramide D,cytotoxic peptide from the marine cyanobacterium Oscillatoria nigroviridis

Marine benthic cyanobacteria are widely known as a source of toxic and potentially useful compounds. These microorganisms have been studied from many Caribbean locations, which recently include locations in the Colombian Caribbean Sea. In the present study, six lipopeptides named almiramides D to H, together with the known almiramide B are identified from a mat characterized as Oscillatoria nigroviridis collected at the Island of Providence (Colombia, S.W. Caribbean Sea). The most abundant compounds, almiramides B and D were characterized by NMR and HRESIMS, while the structures of the minor compounds almiramides E to H were proposed by the analysis of their HRESIMS and MS² spectra. Almiramides B and D were tested against six human cell lines including a gingival fibroblast cell line and five human tumor cell lines (A549, MDA-MB231, MCF-7, HeLa and PC3) showing a strong but not selective toxicity.     

Lodopyridones B and C from a marine sediment-derived bacterium Saccharomonospora sp.

HPLC-UV guided isolation of the culture broth of a marine bacterium Saccharomonospora sp. CNQ-490 has led to the isolation of two new natural products, lodopyridones B and C (1 and 2) along with the previously reported lodopyridone A (3). Their chemical structures were established from the interpretation of 2D NMR spectroscopic data and the comparison of NMR data with the lodopyridone A (3). Lodopyridones B and C (1 and 2) possess the thiazole, and chloroquinoline groups which are characteristic features of these molecules. Lodopyridones A–C show weak inhibitory activities on the β-site amyloid precursor protein cleaving enzyme 1 (BACE1).     

Biogenic synthesis of gold nanoparticles by marine endophytic fungus-Cladosporium cladosporioides isolated from seaweed and evaluation of their antioxidant and antimicrobial properties

Marine endophytes are the most untapped group of microorganisms having enormous applications in pharmaceutical and cosmetra id="spar0060">Marine endophytes are the most untapped group of microorganisms having enormous applications in pharmaceutical and cosmetic industries. In the present study, we have optimized a method for biogenic synthesis of gold nanoparticles (AuNPs) from Cladosporium cladosporioides, an endophytic fungus of the seaweed, Sargassumwightii. The identity of the fungus was established by the 18 s rRNA and ITS sequence. The AuNPs synthesized using C. cladosporioides were characterized by UV–vis spectrophotometer, Field Emission Scanning Electron Microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Dynamic light scattering, Atomic force microscopy, and Energy dispersive X-ray spectroscopic studies. They were tested for free radical scavenging activity (DPPH and FRAP assay) and antimicrobial activity against a panel of pathogenic microorganisms. The AuNps were within 100 nm as confirmed by the above methods. An attempt was made to understand the mechanism of the gold nanoparticle synthesis using the fungal extract. The present study shows the involvement of NADPH-dependent reductase and phenolic compounds in the bioreduction of the gold metal salts to nanoparticles. The AuNPs showed significant antioxidant as well as the antimicrobial activity. Hence, this study has shown a great potential for the development of a cost effective antimicrobial treatment utilizing biogenic gold nanoparticles.     

Comparative sequence analysis of bacterial symbionts from the marine sponges Geodia cydonium and Ircinia muscarum

Marine sponges (Porifera) live in a symbiotic relationship with microorganisms, primarily bacteria. Recently, several studies indicated that sponges are the most prolific source of biologically-active compounds produced by symbiotic microorganisms rather than by the sponges themselves. In the present study we characterized the bacterial symbionts from two Demospongiae, Ircinia muscarum and Geodia cydonium. We amplified 16S rRNA by PCR, using specific bacterial-primers. The phylogenetic analysis revealed the presence of nine bacterial clones from I. muscarum and ten from G. cydonium. In particular, I. muscarum resulted enriched in Bacillus species and G. cydonium in Proteobacterium species. Since these bacteria were able to produce secondary metabolites with potential biotechnological and biopharmaceutical applications, we hypothesized that I. muscarum and G. cydonium could be a considered as a “gold mine” of natural products.     

Effects of N-pyrrole substitution on the anti-biofilm activities of oroidin derivatives against Acinetobacter baumannii

Bacteria of the genus Acinetobacter spp. are rapidly emerging as problematic pathogens in healthcare settings. This is exacerbated by the bacteria’s ability to form robust biofilms. Marine natural products incorporating a 2-aminoimidazole (2-AI) motif, namely from the oroidin class of marine alkaloids, have served as a unique scaffold for developing molecules that have the ability to inhibit and disperse bacterial biofilms. Herein we present the anti-biofilm activity of a small library of second generation oroidin analogues against the bacterium Acinetobacter baumannii.     

Evaluation of genotoxic biomarkers in extracts of marine sponges from Argentinean South Sea

Marine sponges are a rich source of structurally and biologically active metabolites of biomedical importance. We screened polar and non-polar samples of crude extracts obtained from marine sponges collected in different locations of Argentinean south sea coast, as a novel approach for their characterization.The evaluation was performed using cytotoxic and genotoxic biomarkers such as mitotic index (MI), cell proliferation kinetics (CPK) and sister chromatid exchanges (SCE), monitored in vitro using peripheral blood lymphocytes. Statistical analysis was performed using two-way analysis of variance (ANOVA). The extracts evaluated belonged to: Callyspongia flabellata (BURTON, 1932) (Callyspongiidae); Plicatellopsis sp.(Suberitidae); Callyspongia fortis (RIDLEY, 1881) (Callyspongiidae); Clathria (Microciona) antarctica (TOPSENT, 1917) (Microcionidae); Spongia (Spongia) magellanica (THIELE, 1905) (Spongiidae); Halicnemia papillosa (THIELE, 1905) (Axinellidae); Cliona chilensis (THIELE, 1905) (Clionidae); Haliclona sp. 1; Haliclona sp. 2(Chalinidae).Genotoxicity studies revealed that the evaluated sponge extracts did not exhibit cytotoxic activity measured from mitotic index MI and cell proliferation kinetics(CPK). In contrast, sister chromatid exchanges (SCE) showed that the non-polar extract of Callyspongia fortis and the polar extract of Cliona chilensis presented significant differences in SCE frequency (p < 0.001), when compared with control cultures. These results emphasize the need to set up a standard battery of “in vitro” genotoxicity testing for new chemicals, pharmaceutical and drugs.     

Antifouling properties of 10beta-formamidokalihinol-A and kalihinol A isolated from the marine sponge Acanthella cavernosa

Many soft-bodied sessile marine invertebrates such as sponges and soft corals defend themselves against fouling directly through the production of antifouling compounds, or indirectly through regulating the epibiotic microbes that affect larval settlement. In this study, 10beta-formamidokalihinol-A and kalihinol A were isolated and purified from the marine sponge Acanthella cavernosa (Dendy). The results indicated that both compounds inhibited the growth of bacteria isolated from the natural environment whereas kalihinol A suppressed larval settlement of a major fouling polychaete, Hydroides elegans with an EC50 of 0.5 microg ml(-1). Kalihinol A was incorporated in Phytagel that was exposed to the bacterial consortia in natural seawater for biofilm formation. Biofilms that developed on the Phytagel surfaces were analysed for bacterial abundance and bacterial species composition using a DNA fingerprinting technique, terminal restriction fragment length polymorphism (T-RFLP). The results showed that kalihinol A only slightly reduced bacterial abundance (t-test, p = 0.0497), but modified the bacterial species composition of the biofilms. Inhibition of H. elegans larval settlement was observed when biofilms developed under the influence of kalihinol A were exposed to larvae, suggesting that compounds like kalihinol A from the sponge A. cavernosa may change bacterial community composition on the sponge surface, which in turn, modulates larval settlement of fouling organisms.     

Polyenoic fatty acid isomerase from the marine alga Ptilota filicina: protein characterization and functional expression of the cloned cDNA

The recently described enzyme, polyenoic fatty acid isomerase (PFI), from the marine alga Ptilota filicina J. Argardh has been analyzed with respect to its protein structure and an associated cofactor. The enzyme was purified to homogeneity (as judged by SDS-PAGE and silver staining). By sedimentation equilibrium ultracentrifugation the mass of the native enzyme was estimated to be 125 kDa. The N-terminal peptide sequence derived from this protein was used to isolate two very similar cDNA clones encoding novel 500-amino acid proteins, both with calculated molecular masses of 55.9 kDa and pIs of 4.87. The data predict translation of a preprotein containing a signal peptide of 21 amino acids that is removed during maturation. Deglycosylation assays demonstrate that native PFI from P. filicina is a glycoprotein. The purified protein is chromophoric with a flavin-like UV spectrum and sequence analysis reveals the presence of a flavin-binding motif near the mature N-terminus. Heterologous expression of active PFI in Arabidopsis, using one of the cDNA clones, was successful as evidenced by conversion of arachidonic acid to a conjugated triene in an in vitro assay of the transgenic plant tissues.     

Investigation of bacteria with polyketide synthase genes and antimicrobial activity isolated from South China Sea sponges

Aims:  To obtain bacteria with PKS (polyketide synthase) genes and antimicrobial activity from sponges.
Methods and Results:  Eighteen bacteria with KS (ketosynthase) genes were identified by polymerase chain reaction (PCR) screening of 98 isolates from South China Sea sponges, Stelletta tenuis , Halichondria rugosa , Dysidea avara and Craniella australiensis . 16S rRNA gene-based B last analysis indicated that 15 isolates belonged to the phylum Firmicutes , among which 14 isolates were closely related to genus Bacillus , and 1 to Staphylococcus lentus . Two isolates were identified as actinomycetes, and one as Alcaligenes sp. in the phylum Proteobacteria . The 18 KS domains belong to trans-AT type I PKS and match PKS of marine bacterial symbionts. The 18 bacteria exhibited broad-spectrum antimicrobial activities against fungi, gram-positive and gram-negative bacteria. A 21·8-kb PKS gene cluster fragment containing five modules was isolated from the Staphylococcus lentus isolate A75 by screening of a fosmid library.
Conclusions:  The PKS gene diversity and different antimicrobial spectra indicate the potential of bacteria associated with South China Sea sponges for diverse polyketide production.
Significance and Impact of the Study:  Combined with bioactivity assay the PKS gene-based approach can be applied to efficient screening of strains of pharmaceutical value and the prediction of related compounds.     

Relative changes in incorporation rates of leucine and methionine during starvation survival of two bacteria isolated from marine waters

Abstract Two copiotrophic Gram-negative bacteria isolated from marine waters, S14 and Vibrio sp. DW1, were examined for changes in the rate of protein synthesis in the initial phase of energy and nutrient deprivation. The incorporation of [³H] leucine into the trichloroacetic acid (TCA)-insoluble material was examined as a method for estimating rates of protein synthesis. The incorporation of methionine was measured and compared with the results of leucine incorporation. Protein synthesis was demonstrated throughout a period of 120 h of starvation. The incorporation rate was related to the time of starvation and decreased subsequent to an initial increase during the first few hours of dormancy. Control experiments with proteinase K and chloramphenicol demonstrated that the labelled amino acids were preferentially incorporated into proteins. It was also demonstrated that the uptake of amino acids was not a rate-limiting step. During the first hours of starvation the ratio of the protein to the dry weight of the S14 cells increased parallel to the increase in the amino acid incorporation rate. The increased activity of the protein-synthesising system during the first hours of nutrient and energy depletion indicates the presence of an active cellular response to the downshift conditions. Furthermore, these findings are consistent with the increased respiratory activity during the first hours of starvation, which has previously been observed for the bacteria examined in this study.     

Modification at the C9 position of the marine natural product isoaaptamine and the impact on HIV-1, mycobacterial, and tumor cell activity

As part of an investigation to generate optimized drug leads from marine natural pharmacophores for the treatment of neoplastic and infectious diseases, a series of novel isoaaptamine analogs were prepared by coupling acyl halides to the C9 position of isoaaptamine (2) isolated from the Aaptos sponge. This library of new semisynthetic products was evaluated for biological activity against HIV-1, Mtb, AIDS-OI, tropical parasitic diseases, and cancer. Compound 4 showed potent activity against HIV-1 (EC₅₀ 0.47 μg/mL), compound 19 proved to possess remarkable activity against Mycobacterium intracellulare with an IC₅₀ and MIC value of 0.15 and 0.31 μg/mL, while compounds 4 and 17 possessed anti-leishmanial activity with IC₅₀ values of 0.1 and 0.4 μg/mL, respectively. Compounds 16 and 17 showed antimalarial activity with EC₅₀ values of 230 and 240 ng/mL, respectively, and compound 14 exhibited an EC₅₀ of 0.05 μM against the Leukemia cell line K-562.