TMC-135A and B, new triene-ansamycins, produced by Streptomyces sp

Direct stereoselective construction of cyclopropane α-amino acid with contiguous quaternary centers via [4 + 2] annulation reaction

A direct diastereoselective synthetic approach to useful cyclopropane α-amino acid was established via base-promoted [4 + 2] annulations between o-aminobenzaldehydes and alkyl 2-aroyl-1-chlorocyclopropanecarboxylates.

Copper-catalyzed regio- and enantioselective aminoboration of alkylidenecyclopropanes: the synthesis of cyclopropane-containing β-aminoalkylboranes

A Cu-catalyzed aminoboration of alkylidenecyclopropanes with B₂pin₂ and hydroxylamines produced cyclopropane-containing β-aminoalkylboranes in moderate to good yields.

SAR study of a novel triene-ansamycin group compound, quinotrierixin, and related compounds, as inhibitors of ER stress-induced XBP1 activation

Four novel triene-ansamycin group compounds, quinotrierixin, demethyltrienomycin A, demethyltrienomycin B and demethyltrienomycinol, were isolated from the culture broth of Streptomyces sp. PAE37 as inhibitors of ER stress-induced XBP1 activation. The structures of quinotrierixin, demethyltrienomycin A, demethyltrienomycin B and demethyltrienomycinol were determined on the basis of their spectroscopical and chemical properties. All of four possessed 21-membered macrocyclic lactams including triene moieties.

Trierixin, a novel Inhibitor of ER stress-induced XBP1 activation from Streptomyces sp. 1. Taxonomy, fermentation, isolation and biological activities

In the course of screening for an inhibitor of ER stress-induced XBP1 activation, we isolated a new member of the triene-ansamycin group compound, trierixin, from a culture broth of Streptomyces sp. AC 654. Trierixin was purified by column chromatography on silica gel and by HPLC. The molecular formula of trierixin is C(37)H(52)N(2)O(8)S. Trierixin inhibited thapsigargin-induced XBP1-luciferase activation in HeLa/XBP1-luc cells and endogenous XBP1 splicing in HeLa cells with an IC(50) of 14 ng/ml and 19 ng/ml, respectively. Moreover, in the process of isolating trierixin, we isolated structurally related mycotrienin II and trienomycin A as inhibitors of ER stress-induced XBP1 activation from a culture broth of a trierixin-producing strain. This study provides the first observation that triene-ansamycins have a novel inhibitory effect against XBP1 activation.

Trierixin, a novel Inhibitor of ER stress-induced XBP1 activation from Streptomyces sp. II. structure elucidation

Trierixin, a new member of the triene-ansamycin group, has been isolated from the fermentation broth of Streptomyces sp. AC654 as an inhibitor of ER stress-induced XBP1 activation. The structure of trierixin was determined on the basis of its spectroscopical and chemical properties. Trierixin possessed a 21-membered macrocyclic lactam, which contains a methylthio-benzenediol structure, and a cyclohexanecarbonylalanine moiety. Trierixin is thus elucidated as 21-thiomethylmycotrienin II.

Selective isolation and study on the global distribution of the genus Planobispora in soils

Planobispora strains, including the type strain, produced abundant sporangia on humic acid – vitamin gellan gum medium when more than 50 colonies grew on a plate. However, these strains did not produce sporangia on the aerial mycelium, a diagnostic characteristic of this genus, when fewer than 20 colonies grew on a plate. Trace salts, such as FeSO4·7H2O, MnCl2·4H2O, ZnSO4·7H2O, and NiSO4·6H2O, stimulated sporangium formation of Planobispora strains. Better sporangium formation of Planobispora strains was observed on the humic acid – trace salts gellan gum medium at pH 9.0 than at neutral pH. Moreover, an alkaline medium repressed the growth of three out of six Streptomyces strains so that this condition was effective for selective isolation of Planobispora strains. An alkaline flooding solution of skim milk, five antimicrobial agents, and dry heat treatment at 90°C for 60 min were effective for selective isolation. Using these techniques, we examined the distribution of Planobispora strains by using 1467 soil samples collected from Japan and other parts of the world. One hundred and nineteen Planobispora strains were isolated from 51 soil samples (3.5% of the samples tested) that were collected in Ecuador, Egypt, French Guiana, India, and Madagascar. Planobispora strains were recovered only in tropical and subtropical soils. To our knowledge, this is the first record that Planobispora strains have been isolated from locations other than Venezuela, Namibia, or South Africa.Key words: Planobispora, gellan gum, selective isolation, actinomycete, distribution.

Selective isolation and distribution of the genus Planomonospora in soils

For the screening of bioactive compounds and study of global distribution, a selective isolation method for Planomonospora strains by centrifugation from soil is examined. Planomonospora strains produced characteristic sporangia on the humic acid-trace salts gellan gum medium (pH 9.0) so that this genus was readily recognized on the isolation plate. High yields of motile spores were obtained by using a flooding solution containing 0.1% skim milk in 5 mM N-cyclohexyl-2-amino-ethanesulfonic acid (pH 9.0) followed by incubating the preparation at 32 degreesC for 90 min, centrifuging it at 1000 x g for 10 min, and further incubation at 32 degreesC for 60 min after centrifugation. By combining the techniques described above, we isolated 246 Planomonospora strains from 137 of the 1200 soil samples examined. Ninety-four percent of these strains were recovered from neutral to slightly alkaline soils (pH 7.0 to 9.0). Strains of P. venezuelensis group were obtained from 13 soil samples (1.1%), which were collected in Bolivia, Cyprus, Egypt, Greece, India, Japan, New Caledonia, and Turkey. Strains of this group appear widely distributed in the soil of tropical to temperate regions. To our knowledge, this is the first record that strains of this group have been isolated from a location other than Venezuela.