English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Sir: Previously, we reported the isolation1) and structure determination 2) of antrimycin A*, a linear heptapeptide showing antitubercular activity (see Fig. 1). Recently, we found that Streptomyces _xauthocidicus MG125-CFI, an antrimycin-producing microorganism, produces a small amount of several minor congeners besides antrimycin A. In this communication, isolation and structure determination of antrimycins Av, Bv, B, C, Dv and D are described. An aqueous solution of a mixture of antrimycins (530 mg), obtained from a culture filtrate of Streptomyces xanthocidicus MG125-CFI by carbon, Dcwex 50 and SP-Sephadex C-25 chromatographies as described previously1), was charged on a column of Diaion HP20 (2.5 x 40 cm) and developed with a linear gradient of methanol (0%-50%). The bioactivity appeared in five separate fractions of the eluate. They were dried to give 10, 350, 15, 7 and 20 mg of colorless solid in the order of the elution. Each gave a single spot on HPTLC using silica gel developed twice with BuOH AcOH H2O (4: 1: 2), except the fourth eluate, which gave two spots. The Rf values of the five eluates were 0.16, 0.24, 0.28, two at 0.34 and 0.39, and 0.44, respectively. The second eluate was identified with antrimycin A. The fourth eluate were separated by preparative HPTLC on silica gel developed twice with the same solvent described above, to give 1.8 mg (Rf 0.34) and 3.2 mg (Rf 0.39) of solid materials. The five minor congeners thus isolated were designated antrimycins Av (Rf 0.16), B (Rf 0.28), Dv (Rf 0.34), C (Rf 0.39) and D (Rf 0.44) in relation to the structures described later. The UV and IR spectra and bioactivities of these minor congeners were close to those of antrimycin A1). The 1H NMR spectra were also similar but distinctly different from each other in the alkyl region (data are not shown). The results of amino acid analysis of the acid hydrolysates (6 N HCl, 110°C, 16 hours) are shown in Table 1. The amino acid ratio of antrimycin Av was the same as that of antrimycin A. The amino acid analysis suggested that one of two molecules of alanine in antrimycin A is replaced by butyrine in antrimycin B, by norvaline in antrimycin C, and by leucine in antrimycins Dv and D. The presence of one mole each of BHMG, DABA and THPC in all antrimycins was indicated by their specific signals (o 3.58 for BHMG, o 5.63 for DABA and o 7.20 for THPC, see Fig. 2 in reference 2) in the 1H NMR spectra. The presence of a 2,3-didehydroisoleucine (d-Ile) moiety in antrimycins B, C and D was also indicated by the ethyl signals [o 1.08 (t) and 2.46 (q)], which were not present in the spectra of antrimycins Av and

Minor congeners of antrimycin: application of secondary ion mass spectrometry (SIMS) to structure determination.