bisorbicillinol and sorbicillin

Natural products are a virtually inexhaustible source of small molecules with spectacular molecular architectures and biomedical potential. Their structural complexity generates formidable challenges to total synthesis but often also precludes time- and resource-efficient, stereoselective synthetic access. Biosynthetically, nature frequently uses dimerization and oligomerization reactions to produce highly challenging frameworks from simple starting materials. Impressive examples are the bisorbicillinoids, a family of fungal natural products thought to originate from the polyketide precursor sorbicillin. Utilizing the recombinant oxidoreductase SorbC from the sorbicillin biosynthetic gene cluster, a robust, fully stereoselective synthesis of bisorbicillinoid natural products and unnatural side-chain analogues was developed.

Topics: Biocatalysis; Biological Products; Bridged-Ring Compounds; Dimerization; Fungi; Oxidation-Reduction; Oxidoreductases; Recombinant Proteins; Resorcinols; Stereoisomerism

In our screening of microorganisms for new natural products, the fungus Penicillium notatum delivered further members of the sorbicillin family, namely, the sohirnones A [3, 1-(2,4-dihydroxy-5-methylphenyl)hex-4-en-1-one], B [4a, 1-(2,4,5-trihydroxy-3,6-dimethylphenyl)hexa-2,4-dien-1-one], and C [5, 1-(2,4,5-trihydroxy-3,6-dimethylphenyl)hex-4-en-1-one]. A stable tautomer of oxosorbicillinol (7) was characterized as 6, and the recently described 7-deacetoxyyanuthone (8) was reisolated. The additionally isolated rezishanones A-D (12-13c) are the first natural Diels-Alder products of sorbicillinol (1) with dienophiles not related with 1. The monomers and dimers showed weak antibacterial activity, but were inactive against fungi and algae. The structures were determined by spectroscopic methods and by comparison of the NMR data with those of the structurally related 2',3'-dihydrosorbicillin (2) and, in the case of 4a, by transformation into the known sorrentanone (4b).

Topics: Anti-Bacterial Agents; Cyclohexanones; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Penicillium chrysogenum; Resorcinols

An incorporation study of [1-(13)C] and [1,2-(13)C2] labeled sodium acetates into sorbicillinol 1 established a ring closure system between C-1 and C-6 and the positions that were oxidized and/or methylated on a hexaketide chain. Subsequent investigations, using 13C-labeled 1 prepared from [1-(13)C] labeled sodium acetate, clearly demonstrated that both bisorbicillinol 2 and sorbicillin 6 incorporated 13C-labeled 1 into their carbon skeletons. 13C-labeled bisorbicillinols 2 derived from [1-(13)C]- and [2-(13)C]-labeled sodium acetates clearly indicate that these were on the biosynthetic route from 1 to bisorbibutenolide (bislongiquinolide) 3 and bisorbicillinolide 4 via 2 as a branching point in the fungus.

Topics: 4-Butyrolactone; Acetylation; Bridged Bicyclo Compounds; Bridged-Ring Compounds; Cyclohexanones; Fermentation; Magnetic Resonance Spectroscopy; Models, Molecular; Resorcinols; Trichoderma