A new family of antibacterial antibiotics has been isolated from Micromonospora citrea. The compounds, designated citreamicins a, /?, y, £ and rj are of the polycyclic xanthone structure type. Their isolation, characterization and structure determination are presented.The citreamicin antibiotic complex is produced by a recently described subspecies of Micromonospora citrea1]. As antimicrobial agents, these compoundsare effective in vitro against a spectrum of Gram-positive aerobic and anaerobic bacteria. Citreamicin rj is the most potent congener with in vitro MICvalues < 0.015 //g/ml against several Gram-positive strains. The compoundsare structurally related to a small family of antibiotics including cervinomycin2), simaomicin3), lysolipin4), and actinoplanone5). The citreamicins are the first examples of this class to be reported from Micromonospora,and are only the second example of the structure type to have a quinone ring fused to the pyrone. In this report are presented the isolation, characterization, and structure determination of citreamicins a, p, y, £ and rj (l~5)n. Materials and Methods NMR ExperimentsThe carbon detected long range heteronuclear correlation experiment (CSCMLR)7) was performed on a GE500 MHzspectrometer. Initial spectral acquisition parameters were: 25,641 Hz sweep width in the F2 dimension; 512 spectra (44 scans each) were accumulated with a 1.0-second relaxation delay and 0.250msecond increments starting with a 0.125-msecond delay, with 12.52Hz/pt resolution in the F2 dimension and 7.8 Hz/pt in the Ft dimension.f These compounds were previously designated the LL-E19085 antibiotics. * f The structure ofcitreamicin a represents a revision of the original structure disclosed in our previous reports* à"6).

Culture LL-F42248, preliminarily identified as an unusual Streptomyces species, was found to produce the novel antibiotic 1, designated LL-F42248a. This compound, which is related to the coproduced pyrrolomycin C (2)i:) is the first tricyclic member of this family and is the only chiral pyrrolomycin reported to date.2) The culture was grown in a 30-liter tank fer

The nitro group of dioxapyrrolomycin (1) was shown to be introduced via direct biochemical nitration in cultures of the producing organism Streptomyces fumanus containing K'5N'803 as the sole source of nitrogen; the nitro group of dioxapyrrolomycin produced under these conditions contained the same ratio of 1 8 0 to 15N as was present in the labelled nitrate precursor, the extent of 1 8 0 enrichment of the nitro group being determined by negative electron impact mass spectrometry and 15N n.m.r. spectroscopy. 353

A new family of antiparasitic macrolides has been isolated from Streptomyces cyaneogriseus sp. noncyanogenus. The compounds, designated LL-F28249 a, & T and 1, possess potent antiparasitic activity. The isolation, purification and structure determination by spectroscopic methods are presented.

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Whenthe citreamicin-producing organism Micromonospora citrea NRRL1 8935 1 was incubated in the presence of the methylation inhibitors sinefungin or aminopterin, biosynthesis of the { component was stimulated approximately 20 to 200-fold above the level normally produced. Inhibition of a second methylation reaction, which is superficially very similar to the first, was not detected. Other known methylation inhibitors failed to yield any change in the natural pattern of citreamicins produced. This approach is an excellent route for preparing citreamicin f, which can be used as a substrate for semi-synthesis or for further biosynthetic studies.

No abstract

In Figure 1, on p. 1788, ET values are given without reference to a specific temperature (ET= 30°C originally referred to a specific dye, see reference 10 and references cited therein).Figure 3 contains k values and not log k values.