The succinoxidase system of Aspergillzrs niger differs from that of avian and mammalian tissues in its greater lability during preparation and storage but is similar in its sensitivity to malonate, cyanide, azide, and B.A.L., its association with cell particles, and its single pH optimum a t pH 7.3. T h e system is not inhibited by arsenite in concentrations up to 0.01 M. MethodsAspergillus niger, N.R.C. 233, was grown in 200 ml. lots of a medium containing 3% malt extract, 0.5Yo yeast extract, and ly0 glucose in 1-liter shake flaslts a t 26'. The growth (15-20 gm.) from two 18 to 20 hr. cultures was washed with water by filtration and the pressed pad of mold was then frozen in powdered dry ic% When completely frozen, the pad was ground for 30 min. in a mortar paclted in dry ice, with twice its weight of acid-washed Manzucript
High-throughput natural products chemistry methods have facilitated the isolation of eight new (1-8) and two known (9 and 10) beilschmiedic acid derivatives from the leaves of a Gabonese species of Beilschmiedia. Compounds 3-10 were isolated in microgram quantities, and the NMR data for structure elucidation and dereplication were acquired utilizing a Bruker BioSpin TCI 1.7 mm MicroCryoProbe. All of the compounds were screened for cytotoxic and antibacterial activity against NCI-H460 human lung cancer cells and a clinical isolate of methicillin-resistant Staphylococcus aureus, respectively. This is the first report of cytotoxic activity for the endiandric/ beilschmiedic acid class of compounds.A few species of Beilschmiedia and one species of Endiandra have been found to produce a remarkable series of polycyclic fatty acids known as beilschmiedic and endiandric acids. [1][2][3][4][5][6][7][8][9][10][11][12][13] These complex fatty acids, typically isolated as racemic mixtures, were proposed by Black to be the result of a series of consecutive nonenzymatic cyclizations (8πe, 6πe, and DielsAlder) of a polyunsaturated fatty acid precurser. 14 Support for such a mode of biosynthesis was provided by a biomimetic synthesis carried out by Nicolaou. 15 To date, 29 of these compounds have been reported in the literature as natural products, with 31 additional compounds resulting from derivatization and synthesis. Recent publications have reported antibacterial and anti-inflammatory activity. 9,10,13 Additionally, one analogue was the subject of a patent that claimed it was useful in the treatment of asthma. 7 Given the unique chemical space occupied by these compounds, and the lack of biological activity reported, we checked our plant library to see if any material was available that could yield similar compounds. We found that our library contained two collections of Beilschmiedia from Gabon. One had previously been screened for cytotoxic activity and was found to be active. Further examination of that hit resulted in the isolation of the known beilschmiedic acids A (9) and C (10), 9 as well as eight new beilschmiedic acids H -O (1-8). Compounds 4, 5, 7, and 8 represent new frameworks as described by Lipkus, et al. 16,17 Several of the compounds demonstrated moderate cytotoxic activity in the NCI-H460 human lung cancer cell line. The second collection contained no evidence of beilschmiedic acids as indicated by thorough HPLC and NMR analysis. , COSY correlations could be followed through the entirety of compound 1 (Figure 1) with the only exceptions being the three quaternary carbons. Those were assigned based on HMBC correlations (Figure 1). In particular, HMBC correlations from H-5 (δ H 6.91) to CO 2 H (δ C 170.4) and from H-4 (δ H 4.14) to C-6 (δ C 136.5) confirmed the presence of the α/β-unsaturated carboxylic acid. Likewise, HMBC correlations from H-6′ (δ H 6.78) to C-8′ (δ C 139.8) and from H-9′/13′ (δ H 7.38) to C-7′ (δ C 131.3) confirmed the location of the phenyl moiety. Finally, HMBC correlations from ...
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