Dynamics of antibacterial activity in three species of Caribbean marine algae as a function of habitat and life history

Antibacterial activity of lipid extracts from three species of Caribbean marine algae, Spyridia filamentosa, S. hypnoides and Wrangelia bicuspidata was evaluated monthly for one year. Activities were tested for whole plant extracts and TLC-separable zones. Whole plant extracts demonstrated monthly variability in activity with respect to both habitat and life history phase in addition to periods of similarity. No consistency was seen regarding activity against different microorganisms. TLC analyses of the extracts led to the identification of twenty-seven chromatographically distinct regions (TLC zones) each from both S. filamentosa and S. hypnoides and twenty-five from W. bicuspidata, which demonstrated antimicrobial activity. Between these species, twenty-one active TLC zones appeared to be shared based on their similar chromatographic characteristics. Individual TLC zones also demonstrated variable activity throughout the sampling period with respect to habitat and life history phase as well as periods of similarity. Algal antibiosis in these species is recognized as being highly complex, involving numerous chemical compounds, each of which is highly variable in terms of its presence and/or probable concentration.     

Antibiotic activity of lectins from marine algae against marine vibrios

Saline and aqueous ethanol extracts of marine algae and the lectins from two red algal species were assayed for their antibiotic activity against marine vibrios. Experimental studies were also carried out on the influence of environmental factors on such activity, using batch cultures. The results indicated that many of the saline extracts of the algal species were active and that the activity was selective against those vibrios assayed. The algal extracts were active against Vibrio pelagius and the fish pathogen V. vulnificus, but inactive against V. neresis. Algal lectins from Eucheuma serra (ESA) and Galaxaura marginata (GMA) strongly inhibited V. vulnificus but were inactive against the other two vibrios. The antibacterial activity of algal extracts was inhibited by pretreatment with various sugars and glycoprotein. Extracts of the two red algae, E. serra and Pterocladia capillacea, in saline and aqueous ethanol, inhibited markedly the growth rate of V. vulnificus at very low concentrations. Culture results indicated that metabolites active against V. vulnificus were invariably produced in P. capillacea over a wide range of temperature, light intensity, and nutritional conditions. Enhanced antibacterial activity occurred when P. capillacea was grown under higher irradiance, severe nutrient stress and moderate temperature (20 °C), reflecting the specific antibiotic characteristics of this alga. The strong antibiotic activity of lectins towards fish pathogenic bacteria reveals one of the important roles played by algal lectins, as well as the potential high economic value of those marine algae assayed for aquaculture and for biomedical purposes.     

Antitumor activity of marine algae

Powdered tissue from 46 species of air-dried marine algae (four green, 21 brown and 21 red algae) were screened for antitumor activity. Significant activity against Ehrlich carcinoma was found in the brown algae Scytosiphon lomentaria (69.8% inhibition), Lessonia nigrescens (60.0%), Laminaria japonica (57.6%), Sargassum ringgoldianum (46.5%), the red algae Porphyra yezoensis (53.2%) and Eucheuma gelatinae (52.1%) and the green alga Enteromorpha prolifera (51.7%). Five brown and four red algae showed appreciable antitumor activity against Meth-A fibrosarcoma. To identify specific molecules with antitumor activity, 15 kinds of polysaccharide preparations of seaweed origin and 24 kinds of lipid fractions extracted from various seaweeds were tested. Appreciable inhibition of Ehrlich carcinoma was found for fucoidan preparations from Undaria pinnatifida and Sargassum ringgoldianum, for carrageenans and for porphyran. Several glycolipid and phospholipid fractions from brown and red algae were effective against Meth-A fibrosarcoma.     

Telomerase inhibiting activity in vitro from natural resources, marine algae extracts

We attempted to screen for telomerase inhibitingactivity in vitro from a total of 304 marine algae samples which were collected from various Japancoasts by nonradioisotope telomeric repeatamplification protocol (Non-RI TRAP) assay using humanleukemia MOLT-4 cells. Ten of the MeOH extracts andtwo of the PBS extracts from those algal samplesshowed telomerase inhibiting activity. In particular,the MeOH extract from a green alga, Caulerpasertularioides strongly inhibited telomerase activitywhen added to MOLT-4 cell culture at a level of 1.25%(v/v), suggesting that it may be possible to developa novel anti-cancer agent in view of its specificanti-telomeric property.     

Ichtyotoxic activity of extracts from Mexican marine macroalgae

Seventy-three species of macroalgae from the Mexican Pacific, Atlantic and Caribbean coast were screened for ichtyotoxic activity. Ethanolic, acetonic and aqueous extracts were prepared and tested against the fish Carassius auratus. The extracts were classified on the basis of their effects as: toxic if the fish died in two hours or less; moderately toxic, if the organism behaved abnormally but death did notoccur, and non-toxic if the fish did not display any change. 79% species were ichtyotoxic to some degree. Extracts of 39 species were toxic, with at least one extract with lethal effects, 19 were moderately toxic and 15 species were non-toxic. Only the extracts ofDictyota bartayresiana, Dictyota cervicornis,Lobophora variegata, Bryothamnion triquetrum and Laurencia obtusa were toxic in all three solvents. The acetone and ethanol extracts were more active, and therefore are more suitable for extraction of toxic substances. This revised version was published online in August 2006 with corrections to the Cover Date.     

Antiviral carbohydrates from marine red algae

The solubility of the O₂ in the Dead Sea brine was determined over the temperature range 5 °C–50 °C using a modified Winkler titration, volumetric analysis, and a polarographic sensor. The solubility at room temperature and 1 atmosphere pressure was ca. 1 mg l^–1, and the temperature coefficient 0.006 mg 1^–1° C^–1 . The data are nearly consistent with sea water solubility extrapolated to Dead Sea brine salinity.     

Antibiotic activity of Leu-Lys rich model peptides

To develop novel antibiotic peptides useful as therapeutic drugs, short model peptides rich in Leu and Lys were designed by changing not only the net positive charge by Lys-deletion but also in the hydrophobic helix region by Leu-deletion from a peptide analogue of cecropin A (1–8)-magainin 2 (1–12) (CA-MA) known as P5. In particular, one peptide (P6), which was obtained by deleting Lys residues (positions 1, 3, 5, 9, 10, 13, 14) and Leu residues (positions 4, 7, 8, 11, 12, 15) and keeping Pro (position 6) and Trp (position 2), showed a strong antimicrobial and antitumor activity at 0.2–3.1 M without hemolytic activity against human erythrocyte cells. Furthermore, P6 causes significant morphological alterations of the bacterial surfaces at 3.1 M as shown by scanning electron microscopy.     

Antibacterial and antifungal activity of ethanolic extracts from eleven spice plants

Eleven ethanolic extracts from spices of Melissa officinalis, Mentha piperita, Laurus nobilis, Rhus coriaria, Dianthus coryophyllum, Piper nigrum, Capsicum annum, Juniperus oxycedrus, Erica arborea, Colutea arborescens, and Cuminum cyminum collected from various regions of Turkey and local markets were assayed for the in vitro antibacterial activity against 3 Gram-positive (Bacillus subtilis, Staphylococcus aureus and S. epidermidis) and 2 Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), using agar dilution methods. In addition, their possible toxicity to Candida albicans and Aspergillus niger was determined, using both agar dilution and disc-diffusion methods. The minimum inhibition concentration (MIC) of the M. piperita, L. nobilis and J. oxycedrus ethanolic extracts was 5 mg/mL for all the microorganisms tested. P. aeruginosa was the most sensitive bacterial strain to P. nigrum and E. arborea extracts among both Gram-positive and Gram-negative bacteria tested with MIC of 5 mg/mL. The extracts of L. nobilis, D. coryophyllum, J. oxycedrus and C. arborescens showed higher inhibitory activity against the yeast C. albicans and the fungus A. niger than the standard antifungal nystatin.     

Anti-bacterial activity of extracts from the brown seaweed Stoechospermum marginatum

The methanol extract of the brown seaweed Stoechospermum marginatum was found to inhibit the growth of Staphylococcus aureus. The active constituents were found to be a mixture of diterpenoid monoacetates having the spatane skeleton.     

Phosphatase activity of benthic marine algae. An overview

This review provides an account of the phosphatase activities of benthicmarine algae and is based on reports for more than a hundred species, includingcyanobacteria, red, brown and green algae. Particular emphasis is given to theuse of phosphomonoesterase activity as a rapid means of assessing thephosphorusstatus of the alga and thus indirectly that of the environment. Anunderstandingof the influence of environmental factors and the growth pattern of theparticular alga is important in carrying out assays. For instance, the responseto light differs markedly between species, especially in short-term assays,whenthe effect can be obvious or none. Considerations about the methodology formeasuring "alkaline phosphatase activity" are discussed, particularly whethertosimulate field conditions or to use optimum conditions. Recommendations aresuggested concerning the best methodology for routine use, followed by adiscussion of the future prospects for the method.     

Diversity and antimicrobial activity of Pseudovibrio spp. from Irish marine sponges

Aims: To evaluate the diversity and antimicrobial activity present among Pseudovibrio spp. isolated from marine sponges. Methods and Results: Seventy‐three bacterial isolates from the marine sponges Polymastia boletiformis, Axinella dissimilis and Haliclona simulans were identified as Pseudovibrio spp. using phylogenetic analysis of 16S rRNA gene sequences. Genetic diversity among these isolates was estimated using random amplification of polymorphic DNA (RAPD), and 33 RAPD types were identified among the 73 Pseudovibrio isolates. These Pseudovibrio spp. were assayed for the production of compounds with antimicrobial activity against various clinically relevant pathogens. Sixty‐two (85%) of the isolates showed activity against at least one of the pathogens tested, including Escherichia coli, Salmonella enterica serotype Typhimurium, methicillin‐resistant Staphylococcus aureus (MRSA), and Clostridium difficile. PCR screens of the Pseudovibrio isolates also revealed the presence of potential antibiotic‐producing polyketide synthase genes. Conclusions: Marine sponges harbour a diverse population of Pseudovibrio spp., the majority of which demonstrate antimicrobial activity. The identification of several different antimicrobial activity spectra suggests that the Pseudovibrio isolates may produce a suite of antimicrobial compounds. Significance and Impact of the Study: This is the first study in which an extended population of Pseudovibrio isolates from marine sponges has been analysed and establishes the little‐studied Pseudovibrio as a potentially important genus in the search for antimicrobial compounds of clinical relevance.     

Antiinfluenza virus effect of extracts from marine algae and invertebrates

Sixty products, derived from marine organisms, typical of the Bulgarian Black Sea coast, were examined for inhibitory activity on the reproduction of influenza viruses in tissue cultures. The antiviral effect was investigated by the reduction of virus infectivity. Using representative strains of influenza virus it was shown that apparently the inhibitory effect was strain-specific. The most effective products were further studied in fertile hen's eggs and in experimental influenza infection in white mice.