Metacytofilin has potent anti-malarial activity.

Metacytofilin (MCF) was isolated from the fungus Metarhizium sp. TA2759. Although MCF possesses anti-Toxoplasma activity, the effects of this compound against other parasites are unknown. Here, we evaluated the in vitro anti-malarial activity of MCF against the 3D7 strain and the chloroquine-resistant K1 strain of Plasmodium falciparum. The half maximal inhibitory concentrations (IC50) of MCF against the 3D7 and K-1 strains following culture for 48 h were 666 nM and 605 nM, respectively. Artemisinin was more potent than MCF against both strains (3D7 IC50: 17.4 nM; K-1 IC50: 18.3 nM), while chloroquine was ineffective against the chloroquine-resistant strain (3D7 IC50: 39.1 nM; K-1 IC50: 1.62 µM). MCF affected the ring stage of the parasites, resulting in their death as shown by spots within red blood cells. MCF also inhibited parasite growth following culture for 72 h (3D7 IC50, 285 nM). Four optical isomers of cyclo[Leu-Phe]-diketopiperazine derivatives with modified methoxy and/or hydroxyl groups lost anti-malarial activity, suggesting that the spatial positions of the methoxy and hydroxyl groups in MCF play an important role in its anti-malarial effects. Together, these data suggest that MCF may represent a promising lead compound for treatment of drug-resistant malarial parasites.

Description of Gelidibacter japonicus sp. nov., isolated from the Inland Sea (Setonaikai) in Japan.

A novel Gelidibacter strain, JCM 31967T, was isolated from seawater collected from the Inland Sea (Setonaikai) in Japan. It was characterized as a Gram-negative, halophilic, oxidase-negative, catalase-positive, aerobic, nonmotile, but gliding, rod-shaped bacterium without flagella. Based on 16S rDNA gene identity, strain JCM 31967T is closely related to Gelidibacter mesophilus (DSM 14095T, 96.6% identity), G. gilvus (IC158T, 96.4%), G. algens (DSM 12408T, 96.1%), G. sediminis (S11-41T, 94.7%), and G. salicanalis (IC162T, 94.7%). The G + C content of strain JCM 31967T DNA was found to be 39.1%. The average nucleotide identity (ANI) values of JCM 31967T against G. algens DSM 12408T and G. mesophilus DSM 14095T were 79.1% and 80.9%, respectively. Strain JCM 31967T phenotypically differed from the closest related Gelidibacter species in its utilization of methyl α-D-mannopyranoside, methyl α-D-glucopyranoside, and D-ribose and in its lack of utilization of L-arginine and D-arabinose. It was further differentiated based on its fatty acid composition, specifically properties of C18:0 and C20:2 ω6c, 9c, which were significantly different from those of G. algens, G. gilvus, G. mesophilus, G. salicanalis, and G. sediminis type strains. Overall, the results of DNA-DNA hybridization and physiological and biochemical analyses differentiated strain JCM 31967T from a previously described species of Gelidibacter. Based on these polyphasic taxonomic findings, it was concluded that strain JCM 31967T is a novel Gelidibacter species, for which the name Gelidibacter japonicus sp. nov. is proposed, with JCM 31967T (= LMG 30063T) as the type strain.

Leucinostatin Y: A Peptaibiotic Produced by the Entomoparasitic Fungus Purpureocillium lilacinum 40-H-28.

Leucinostatin Y, a new peptaibiotic, was isolated from the culture broth of the entomoparasitic fungus Purpureocillium lilacinum 40-H-28. The planar structure was elucidated by detailed analysis of its NMR and MS/MS data. The absolute configurations of the amino acids were partially determined by an advanced Marfey's method. The biological activities of leucinostatin Y were assessed using human pancreatic cancer cells, revealing the importance of the C-terminus of leucinostatins for preferential cytotoxicity to cancer cells under glucose-deprived conditions and inhibition of mitochondrial function.

Vibrio japonicus sp. nov., a novel member of the Nereis clade in the genus Vibrio isolated from the coast of Japan.

A novel Vibrio strain, JCM 31412T, was isolated from seawater collected from the Inland Sea (Setonaikai), Japan, and characterized as a Gram-negative, oxidase-positive, catalase-negative, facultatively anaerobic, motile, ovoid-shaped bacterium with one polar flagellum. Based on 16S rDNA gene identity, strain JCM 31412T showed a close relationship with type strains of Vibrio brasiliensis (LMG 20546T, 98.2% identity), V. harveyi (NBRC 15634T, 98.2%), V. caribbeanicus (ATCC BAA-2122T, 97.8%) and V. proteolyticus (NBRC 13287T, 97.8%). The G+C content of strain JCM 31412T DNA was 46.8%. Multi-locus sequence analysis (MLSA) of eight loci (ftsZ, gapA, gyrB, mreB, pyrH, recA, rpoA and topA; 5535bp) further clustered strain JCM 31412T in the Nereis clade, genus Vibrio. Phenotypically, strain JCM 31412T differed from the closest related Vibrio species in its utilization of melibiose and raffinose, and its lack of casein and gelatin hydrolysis. It was further differentiated based on its fatty acid composition, specifically properties of C12:03OH and summed features, which were significantly different from those of V. brasiliensis, V. nigripulchritudo and V. caribbeanicus type strains. Overall, the results of DNA-DNA hybridization, and physiological and biochemical analysis differentiated strain JCM 31412T from other described species of the genus Vibrio. Based on these polyphasic taxonomic findings, it was therefore concluded that JCM 31412T was a novel Vibrio species, for which the name Vibrio japonicus sp. nov. was proposed, with JCM 31412T (= LMG 29636T = ATCC TSD-62T) as the type strain.

Asteltoxins from the Entomopathogenic Fungus Pochonia bulbillosa 8-H-28.

New asteltoxins C (3) and D (4) were found in the extract of the entomopathogenic fungus Pochonia bulbillosa 8-H-28. Compound 2, which was spectroscopically identical with the known asteltoxin B, was isolated, and structural analysis led to a revision of the structure of asteltoxin B. Compounds 2 and 4 have a novel tricyclic ring system connected to a dienyl α-pyrone structure. Compound 3 has a 2,8-dioxabicyclo[3.3.0]octane ring similar to that of asteltoxin (1). Compound 3 showed potent antiproliferative activity against NIAS-SL64 cells derived from the fat body of Spodoptera litura larvae, while 2 and 4 were inactive.

A new cell line from the fat body of Spodoptera litura (Lepidoptera, Noctuidae) and detection of lysozyme activity release upon immune stimulation.

A new cell line, designated NIAS-SL64, was established from the fat body of the fifth instar larvae of the common cutworm Spodoptera litura. NIAS-SL64 cells grew as spindle-shaped and non-adherent cells in the insect-specific cell culture medium MGM-450 supplemented with 10% fetal bovine serum. Criterions for the establishment of the NIAS-SL64 cell line is spindle shape and length (30~90 µm) stabilized after 100 passages. The doubling time of the cells was 24 h at 25°C. Lipopolysaccharide significantly stimulated the release of lysozyme activity by NIAS-SL64 cells. Lysozyme is one of the components of the innate immunity and plays important role as lytic enzyme in infection. Lysozyme activity released from NIAS-SL64 would be a marker for immune response. The released lysozyme activity critically depends on morphology of the cells and would be a criterion of the establishment of the cell line. Lysozyme activity was suppressed in a dose-dependent manner by the immunosuppressive agent cyclosporin A.

Inhibitory activity of the hypoxia-inducible factor-1 pathway by tartrolone C.

Hypoxia-inducible factor-1 (HIF-1) is a central mediator of cellular responses to low oxygen and has recently become an important therapeutic target for solid tumor therapy. To identify small molecule inhibitors of the HIF-1 transcriptional activation, we have established a high through-put assay system using a stable transformant of mammalian cells that express a luciferase reporter gene construct containing a HIF-1 binding site. Using this system, we screened 5000 cultured broths of microorganisms, and we found that fermentation broth produced by Streptomyces strain 1759-27 showed significant inhibition of the reporter activity induced by hypoxic conditions. The active substance NBRI759-27 was purified and determined to be tartrolone C by several methods including X-ray crystallography. In the reporter gene assay, tartrolone C inhibited the HIF-1 transcriptional activity under hypoxic conditions with an IC50 value of 0.17 microg/ml.

Alkaline serine protease produced by Streptomyces sp. degrades PrP(Sc).

A PrP(Sc)-degrading enzyme was isolated from the culture medium of Streptomyces sp. using perchloric acid-soluble protein (PSP) as a substrate. The media of 500 microbial species were screened to obtain the PSP-degrading enzyme. The medium containing the protease secreted from strain 99-GP-2D-5 showed the highest PSP-degrading activity. Strain 99-GP-2D-5 was assigned as the genus Streptomyces by its morphological and chemotaxonomic characteristics. When scrapie prion was used as the substrate, it was completely digested by the enzyme. The amino acid sequence of the enzyme was identical to that of the C-terminal region of alkaline serine protease (ASP) I. ASP I may be the precursor of the enzyme, and the enzyme seems to be the mature type of ASP I. The maximal activity of the enzyme was observed at 60 degrees C and pH 11, and the scrapie prion was degraded within 3 min under the optimum conditions.

Synergistic effect of CMP/KDO synthase inhibitors with antimicrobial agents on inhibition of production and release of Vero toxin by enterohaemorrhagic Escherichia coli O157:H7.

Synergistic effect of CMP/KDO synthase inhibitors in LPS biosynthesis of Gram-negative bacteria with kanamycin (KM) and fosfomycin (FOM) on the production and release of Vero toxins (VTs) by Escherichia coli O157 was evaluated in vitro. While CMP/KDO synthase inhibitors, KM and FOM showed no inhibitory effect on the production/release of VTs by themselves alone, both KM and FOM showed the remarkable inhibition of VT2 release through synergistic collaboration with CMP:KDO synthase inhibitor.

Recombinant alkaline serine protease II degrades scrapie isoform of prion protein.

An efficient Escherichia coli expression system for the production of mature-type alkaline serine protease II (mASP II) has been constructed. Complementary deoxyribonucleic acid-encoding mASP II was inserted into the inducible bacterial expression vector pGE-30. After introduction into E. coli, the plasmid was expressed by isopropyl-1-thio-beta-D-galactopyranoside, and the recombinant product was purified using a Ni-nitrilotriacetic acid column. The purified product had the expected NH2-terminal sequence and showed a scrapie isoform of prion protein-degrading activity using hamster scrapie 263K prions as a substrate.