108354-13-8Relevant articles and documents
Synthesis and biological activities of the respirator chain inhibitor aurachin D and new ring versus chain analogues
Li, Xu-Wen,Herrmann, Jennifer,Zang, Yi,Grellier, Philippe,Prado, Soizic,Mueller, Rolf,Nay, Bastien
, p. 1551 - 1558 (2013)
Aurachins are myxobacterial 3-farnesyl-4(1H)-quinolone derived compounds initially described as respiratory chain inhibitors, more specifically as inhibitors of various cytochrome complexes. They are also known as potent antibiotic compounds. We describe herein the first synthesis of aurachin D through a key Conrad-Limpach reaction. The same strategy was used to reach some ring as opposed to chain analogues, allowing for the description of structure-activity relationships. Biological screening of the analogues showed antiparasitic, cytotoxic, antibacterial and antifungal activities, and depletion of the mitochondrial membrane potential. The strongest activity was found on Plasmodium falciparum with a selectivity index of 345, compared to Vero cells, for the natural product and its geranyl analogue. The loss of mitochondrial membrane potential induced by aurachins in human U-2 OS osteosarcoma cells was studied, showing the best activity for aurachin D and a naphthalene analogue, yet without totally explaining the observed cytotoxic activity of the compounds. Finally, a synthetic entry is given to the complete carboheterocyclic core of aurachin H through the N-oxidation/epoxidation of aurachin D and a shorter chain analogue, followed by subsequent biomimetic cyclization.
Biosynthesis of aurachins A-L in Stigmatella aurantiaca: A feeding study
Hoefle, Gerhard,Kunze, Brigitte
experimental part, p. 1843 - 1849 (2009/09/28)
The isolation of aurachins A-L (1-11) from Stigmatella aurantiaca strain Sg a15 is described. Their structures and relative configurations were deduced from spectroscopic data, in particular NMR. Three structural types were identified: A-type aurachins (1, 2, 6) are C-3 oxygen-substituted quinolines carrying a farnesyl residue on C-4, C-type aurachins (3, 4, 7-11) are C-4 oxygen-substituted quinolines carrying a farnesyl residue on C-3, and C-type aurachin E (5) has a [1,1a,8,d]imidazoloquinoline structure. Feeding of 13C-labeled precursors showed that the quinoline ring is constructed from anthranihc acid and acetate, and the farnesyl residue from acetate by both the mevalonate and nonmevalonate pathways. Further, feeding of labeled aurachin C (3) indicated the A-type aurachins are derived by a novel intramolecular 3,4-migration of the farnesyl residue that is induced by a 2,3-epoxidation and terminated by a reduction step. 18O-Labeling experiments indicated the new oxygen substituents originate from atomospheric oxygen. On the basis of these results a biosynthetic scheme covering all aurachins is proposed. It is further proposed that quinolones with an unorthodox substitution pattern, such as the 2-geranylquinolones from Pseudonocardia sp. and the 3-heptylquinolones from Pseudomonas sp., are formed by related rearrangement mechanisms.
Semisynthesis and antiplasmodial activity of the quinoline alkaloid aurachin E
Hoefle, Gerhard,Boehlendorf, Bettina,Fecker, Thomas,Sasse, Florenz,Kunze, Brigitte
experimental part, p. 1967 - 1969 (2009/08/14)
A one-step synthesis of the rare aurachin E (1) from the easily accessible aurachin C (2) and cyanogen bromide is described. 3-Bromocarbamoylquinoline (5) is formed in a side reaction with concomitant loss of the 3-farnesyl residue. In an alternative approach, aurachin D (3) was reacted with phosgene and sodium azide to form the imidazolone ring of 1 via n-acylation. Unexpectedly, the initial reaction occurred at the carbonyl group of 3 to give 1H-pyrrolo[3,2-c]quinoline 4. The reaction sequence represents a novel route to this type of compound. Aurachin E, contrary to other aurachins, combines a high in vitro antiplasmodial activity with low cytotoxicity and absence of mitochondrial respiratory inhibition.
