Rubromycine, II

Abstract

Die Isolierung der roten Antibiotica β‐Rubromycin und γ‐Rubromycin wird beschrieben. – β‐Rubromycin isomerisiert sich in siedendem Pyridin quantitativ zu α‐Rubromycin und wird durch verd. Mineralsäuren unter Verseifung eines Methoxyls in γ‐Rubromycin verwandelt. γ‐iso‐Rubromycin entsteht: 1. Aus γ‐Rubromycin durch Erhitzen mit Pyridin oder konz. Schwefelsäure, 2. aus α‐Rubromycin durch Chlorwasserstoff in Chloroform. – β‐Rubromycin (11) enthält als Chromophor 8‐Hydroxy‐5.7‐dimethoxy‐naphthochinon‐(1.2), das über Sauerstoff an C‐4 und eine Methylengruppe an C‐3 mit dem Rest des Moleküls verbunden ist. – Chromophor der drei anderen Rubromycine (12, 13, 14a) ist 5.8‐Dihydroxy‐2(bzw. 7)‐methoxy‐naphthochinon‐(1.4) – in α‐Rubromycin am 5‐Hydroxyl methyliert –, an dem über Sauerstoff an C‐7 (bzw. C‐2) und Kohlenstoff an C‐6 (bzw. C‐3) der Rest des Moleküls hängt.

Structural and Biosynthetic Investigations of the Rubromycins

“…Besides β-rubromycin (6) the strain A1 produces the equally known γ-rubromycin (3) [2] and the structurally new secondary metabolites δ-rubromycin (4) and 3Ј-hydroxy-β-rubromycin (7). The yields of the single compounds as shown in Table 2 are highly dependent of the type of the medium which was chosen.…”

“…Furthermore, we compile the known data about the biological activities of the rubromycins and supplement them with new facts. In addition to the described rubromycin-producing strains [2] [5] and large amounts of β-rubromycin from H. Brockmann et al, we used a new strain. This strain was isolated from enrichment cultures prepared from orange grove soil samples from Israel.…”

“…Due to the fact that this derivative was hardly soluble in organic solvents and water it was acetylated with acetic anhydride/sodium acetate to its more lipophilic diacetate. [2] The evaluation of the one-and two-dimensional NMR spectra of this derivative led to structure 10, from which structure 9, the structure of the product of the transformation with o-phenylenediamine, could be derived. The established structures 9 and 10 harmonize with the fact that the CD spectrum of 10 shows minima at 266 and 312 nm, and maxima at 278 and 348 nm.…”

“…For this purpose it was intended to synthesize di-O-acetyl-di-O-mesyl-dihydro-β-rubromycin by the reaction of di-O-acetyl-β-rubromycin [2] with palladium/pyridine/methanesulfonic anhydride under H 2 in THF. The following hydrogenation in the presence of Pd/C in methanol should yield a pentasubstituted naphthalene derivative, after reductive removal of the O-mesylate protecting groups.…”

Atacamycins A–C, 22-membered antitumor macrolactones produced by Streptomyces sp. C38

“…12 Nearly all of the Streptomyces isolates were potent producers of diverse antibiotics including the anthelmintic LL-F28249a (nemadectin a), 13 a member of the oligomycin group of macrocyclic lactones related to milbemycins and avermectins, and LL-F28249o (nemadectin o, 21-hydroxy-oligomycin A). 14 Other Streptomyces isolates produced the anthraquinone antibiotic b-rubromycin, 15 and an uncharacterized tetraene-polyene antibiotic.…”