angucyclinone and ochromycinone

Three new angucyclinones, saccharosporones A, B and C, together with (+)-ochromycinone, (+)-rubiginone B2, tetrangulol methyl ether and fujianmycin A, were obtained from fermentation of the terrestrial actinomycete of the genus Saccharopolyspora BCC 21906 isolated from a soil collected in Chanthaburi Province, Thailand. Structures of the new compounds and their relative configurations were assigned by NMR spectral data interpretation. Saccharosporones A and B exhibited antimalarial activity against Plasmodium falciparum K1 with IC50 values of 4.1 and 3.9 μM. Both metabolites also possessed cytotoxic activities against cancer cell lines (KB, MCF-7 and NCI-H187) and nonmalignant Vero cell, while saccharosporone C only showed cytotoxic activity against NCI-H187.

Topics: Animals; Anthraquinones; Anti-Bacterial Agents; Antibiotics, Antineoplastic; Antifungal Agents; Antimalarials; Bacillus cereus; Benz(a)Anthracenes; Candida albicans; Chlorocebus aethiops; Fermentation; Humans; Inhibitory Concentration 50; KB Cells; Magnetic Resonance Spectroscopy; MCF-7 Cells; Microbial Sensitivity Tests; Molecular Conformation; Mycobacterium tuberculosis; Plasmodium falciparum; Saccharopolyspora; Soil Microbiology; Thailand; Vero Cells

Six new angucyclinone polyketides named panglimycins A-F were isolated together with the three known metabolites (+)-fujianmycin A, (+)-ochromycinone, and emycin C from the bioassay-guided fractionation of the extract of the Indonesian Streptomyces strain ICBB8230. The new compounds are highly oxygenated angucyclinones that appear to be biosynthetically derived from ochromycinone or fujianmycin. Their structures were determined by X-ray crystal analysis, interpretation of 1D- and 2D-NMR spectra, and comparison of the data with those of structurally related known natural products. Despite structural similarities to angucyclinones with antibiotic activities, the panglimycins did not exhibit any growth inhibition when tested against several bacteria and fungi.

Topics: Anthraquinones; Bacteria; Crystallography, X-Ray; Fungi; Indonesia; Microbial Sensitivity Tests; Molecular Conformation; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Stereoisomerism; Streptomyces

A concise and highly enantioselective route has been developed for the synthesis of angucyclinone-type natural products. Utilizing this strategy, total syntheses of five natural products YM-181741, (+)-ochromycinone, (+)-rubiginone B2, (-)-tetrangomycin, and MM-47755 have been accomplished in 22%, 23%, 19%, 18%, and 12% overall yields, respectively. Our approach for the synthesis of these natural products having the benz[a]anthraquinone skeleton is based on a sequential intramolecular enyne metathesis, intermolecular Diels-Alder reaction (DAR), and aromatization. The intramolecular enyne metathesis reaction was employed for the synthesis of enantiopure 1,3-dienes in excellent yields. Furthermore, the synthesis of YM-181741 as well as structurally similar angucyclinones such as (+)-ochromycinone and (+)-rubiginone B2 was achieved via asymmetric enolate alkylation of an oxazolidinone in excellent de. The related angucyclinones (-)-tetrangomycin and MM-47755, bearing a labile tertiary alcohol, were synthesized via Sharpless asymmetric epoxidation of a known allylic alcohol followed by opening the epoxide with Red-Al. The introduction of oxygen functionality at C-1 in all these natural products was accomplished by photooxygenation under a positive pressure of oxygen.

Topics: Anthraquinones; Anti-Bacterial Agents; Benz(a)Anthracenes; Chemistry, Organic; Chemistry, Pharmaceutical; Drug Design; Models, Chemical; Oxygen; Stereoisomerism

[reaction: see text] An efficient synthetic approach to angucyclinone antibiotics, (+)-ochromycinone and (+)-rubiginone B(2), is reported. The key step involves the facile formation of 2,3-dihydrophenantren-4(1H)-one skeleton, an important framework of angucyclinone natural products, by using gold-catalyzed intramolecular [4 + 2] benzannulation reaction.

Topics: Anthraquinones; Anti-Bacterial Agents; Benzene; Catalysis; Gold; Molecular Structure; Naphthalenes; Stereoisomerism