Guluronate and mannuronate oligomers with various degree of polymerization were prepared from polyguluronate (PG) and polymannuronate (PM) with an alginate lyase from a Pseudoalteromonas sp., and their activities to induce cytokine secretion from mouse macrophage cell line RAW264.7 cells were examined. Enzymatically depolymerized unsaturated alginate oligomers induced tumor necrosis factor (TNF)-a secretion from RAW264.7 cells in a structure-depending manner, while the activities of saturated alginate oligomers prepared by acid hydrolysis were fairly low or only trace levels. These results suggest that unsaturated end-structure of alginate oligomers was important for the TNF-a-inducing activity. Among the unsaturated guluronate (G3-G9) and mannuronate (M3-M9) oligomers, G8 and M7 showed the most potent activity, respectively. BioPlex assay revealed that interleukin (IL)-1a, IL-1b, and IL-6 secretion from RAW264.7 cells were also induced by unsaturated alginate oligomers with similar structure-activity relationship profiles as seen in TNF-a, and the most potent activities were observed with G8 and M7. These results suggest that G8 and M7 may have the most suitable molecular size or entire structural conformation as stimulant for cytokine secretion. Since antibodies to Toll-like receptor (TLR)2 and TLR4 effectively inhibited the G8-and M7-induced production of TNF-a, these alginate oligomers may stimulate innate immunity through the pattern recognition receptors on macrophages similar to microbial products.

Strain MS-02-063, gamma-proteobacterium, isolated from a coast area of Nagasaki, Japan, produced a red pigment which belongs to prodigiosin members. This pigment, PG-L-1, showed potent algicidal activity against various red tide phytoplanktons in a concentration-dependent manner. An understanding of a mechanism of PG-L-1 production by this marine bacterium may yield important new insights and strategies for preventing blooms of harmful flagellate algae in natural marine environments. Therefore, we analyzed the mechanisms of PG-L-1 production. In our previous study, the pigment production by this marine bacterium was completely inhibited at 1.56 microg/ml of erythromycin or 3.13 microg/ml of chloramphenicol, while minimal inhibitory concentrations for cell growth of erythromycin and chloramphenicol against this bacterium were >100 and 25 microg/ml, respectively. It is interesting to note that the ability of the pigment production in erythromycin-treated bacterium recovered by an addition of homoserine lactone. In fact, the pigment production was inhibited by beta-cyclodextrin that inhibits autoinducer activities by a complex with N-acyl homoserine lactones. N-acyl homoserine lactones with autoinducer activities are ubiquitous bacterial signaling molecules that regulate gene expression in a cell density dependent process known as quorum sensing. Therefore, it was suggested that PG-L-1 produced by strain MS-02-063 is controlled by the homoserine lactone quorum sensing. It is speculated that this quorum sensing is involved in the production of algicidal agents of other marine bacteria. This bacterium and other algicidal bacteria might be concerned in regulating the blooms of harmful flagellate algae through the quorum sensing system.

Global public health faces a desperate situation, due to the lack of effective antibiotics. Coordinated steps need to be taken, worldwide, to rectify this situation and protect the advances in modern medicine made over the last 100 years. Work at Japan’s Kitasato Institute has been in the vanguard of many such advances, and work is being proactively tailored to promote the discovery of urgently needed antimicrobials. Efforts are being concentrated on actinomycetes, the proven source of most modern antibiotics. We devised a novel physicochemical screening mechanism, whereby simple physico-chemical properties, in conjunction with related detection methods, such as LC/MS, LC/UV, and polarity, could be used to identify or predict new compounds in a culture broth, simply by comparing results with existing databases. New compounds are isolated, purified, and their structure determined before being tested for any bioactivity. We used lyophilized actinomycete strains from the Kitasato Microbial Library, most more than 35 years old, and found 330 strains were producers of useful bioactive substances. We also tested organisms found in fresh samples collected in the complex environments from around plant roots, as well as from sediments of mangrove forests and oceans, resulting in the discovery of 36 novel compounds from 11 actinomycete strains. A compound, designated iminimycin, containing an iminium ion in the structure was discovered from the culture broth of Streptomyces griseus OS-3601, which had been stored for a long time as a streptomycin-producing strain. This represented the first iminium ion discovery in actinomycetes. Compounds with a cyclopentadecane skeleton containing 5,6-dihydro-4-hydroxyl-2-pyrone ring and tetrahydrofuran ring, designated mangromicins, were isolated from the culture broth of Lechevalieria aerocolonigenes K10-0216 obtained from sediment in a mangrove forest. These structures are extremely unique among natural compounds. From the same culture broth, new steroid compounds, named K10-0216 KA and KB, and other new compounds having a thiazole and a pyridine ring, named pyrizomicin A and B, were discovered. New substances can be found from actinomycetes that have been exhaustively studied. Novel compounds with different skeletons can be found from a single broth of one strain. The sought after new antibiotics will arise from continued exploitation of the actinomycetes, especially rare actinomycetes. Work on new organisms and samples should be augmented by re-examination of known actinomycetes already in storage. New research should also be carried out on the manipulation of culture media, thereby stimulating actinomycete strains to produce novel chemicals. The establishment of wide-ranging international research collaborations will facilitate and expedite the efficient and timely discovery and provision of bioactive compounds to help maintain and promote advances in global public health.

Raman microspectroscopy is a minimally invasive technique that can identify molecular structure without labeling. In this study, we demonstrate in vivo detection of the bioactive compound penicillin G inside Penicillium chrysogenum KF425 fungus cells. Highly overlapped spectroscopic signatures acquired using Raman microspectroscopic imaging are analyzed using a multivariate curve resolution-alternating least squares (MCR-ALS) method to extract the pure

Recently we discovered a bacterial strain (MS‐02–063) that produces large amounts of red pigment from coastal area of Nagasaki Prefecture, Japan. Comparative 16S rDNA gene sequencing analysis revealed that strain MS‐02–063 was phylogenetically closely related to γ‐proteobacterium Hahella sp. MBIC 3957 that produces prodigiosin. However, some physiological and biochemical differences between strain MS‐02–063 and Hahella sp. MBIC 3957 were observed. The red pigment (RP‐063) produced by this isolate was highly purified from the culture supernatant. It was speculated that RP‐063 might be prodigiosin‐like pigment in physical properties and biological activities such as antibacterial and cytotoxic activity. Antibacterial activity of RP‐063 was examined by an agar dilution method. The results indicated that RP‐063 showed antibacterial activity for specific for pathogenic gram‐positive bacteria such as Staphylococcus aureus. The potency of antibacterial activity against S. aureus was nearly equal to those of tetracycline. Moreover, RP‐063 showed inhibition of the superoxide generation by 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA)‐stimulated mouse macrophage RAW 264.7 cell line. Prodigiosin members have a wide variety of biological properties, including anticancer and antimalarial, etc. Especially, potent immunosuppressive properties have been reported for prodigiosin members with the mechanism of action different from that of the other well known immunosuppressors in atopic dermatitis therapy such as cyclosporin A, FK506 and rapamycin. It is suggested that RP‐063 may be able to arrest the inflammation caused by superantigens secreted from S. aureus, which colonized skin on atopic dermatitis as well as suppression of activated lymphocyte proliferation and superoxide generation from leucocytes.

A new indole-diterpene, JBIR-03 (1), was isolated from the fungus Dichotomomyces cejpii var. cejpii NBRC 103559 and its structure was determined based on the spectroscopic data. 1 exhibited anti-MRSA (methicillinresistant Staphylococcus aureus) activity and antifungal activity against apple Valsa canker-causing fungus, Valsa ceratosperma, while it exhibited no toxicity towards human cancer cells.

No abstract

Three new natural products, designated trehangelins A, B and C, were isolated by solvent extraction, silica gel and octadecylsilyl silica gel column chromatographies and subsequent preparative HPLC from the cultured broth of an endophytic actinomycete strain, Polymorphospora rubra K07-0510. The trehangelins consisted of a trehalose moiety and two angelic acid moieties. Trehangelins A (IC50 value, 0.1 mg ml(-1)) and C (IC50 value, 0.4 mg ml(-1)), with symmetric structures, showed potent inhibitory activity against hemolysis of red blood cells induced by light-activated pheophorbide a. However, trehangelin B, with an asymmetric structure, displayed only a slight inhibition (IC50 value, 1.0 mg ml(-1)).