Clark, Benjamin R.
Clark, Benjamin R.
Clark, Benjamin R.
Now showing 1 - 8 of 8
- PublicationBiosynthesis of pyrrolylpolyenes in Auxarthron umbrinum(RSC Publishing, 2009)
;The biosynthesis of the pyrrolylpolyene rumbrin (1) in the fungus Auxarthron umbrinum was elucidated using feeding studies with labelled precursors. Incorporation of stable isotopes from [15N]-proline, [13C]-methionine and [13C]-acetate confirmed that these were the precursors of the pyrrole moiety, methyl groups, and backbone of rumbrin, respectively. Label-dilution experiments with pyrrole-2-carboxylate confirmed it was a direct precursor in the biosynthesis of rumbrin. Both 3- and 4-chloropyrrolecarboxylates were also accepted as precursors in polyene production. 1323Scopus© Citations 16
- PublicationProduction of anticancer polyenes through precursor-directed biosynthesis(RSC Publishing, 2011-09)
; ; ; ;The biosynthesis of the pyrrolyl moiety of the fungal metabolite rumbrin originates from pyrrole-2-carboxylic acid. In an effort to produce novel derivatives with enhanced biological activity a series of substituted pyrrole-2-carboxylates were synthesised and incubated with the producing organism, Auxarthron umbrinum. Several 4-halo-pyrrole-2-carboxylic acids were incorporated into the metabolite yielding three new derivatives: 3-fluoro-, 3-chloro- and 3-bromo-isorumbrin, which were generated in milligram quantities enabling cytotoxicity assays to be conducted. The 3-chloro- and 3-bromo-isorumbrins had improved activity against HeLa cells compared with rumbrin; 3-bromoisorumbrin also showed dramatically improved activity towards a lung cancer cell line (A549). 435Scopus© Citations 16
- PublicationBiosynthesis of pyrrolylpolyenes in Auxarthron umbrinum(Royal Society of Chemistry, 2008-10-31)
;The biosynthesis of the pyrrolylpolyene rumbrin (1) in the fungus Auxarthron umbrinum was elucidated using feeding studies with labelled precursors. Incorporation of stable isotopes from [15N]-proline, [13C]-methionine and [13C]-acetate confirmed that these were the precursors of the pyrrole moiety, methyl groups, and backbone of rumbrin, respectively. Label-dilution experiments with pyrrole-2-carboxylate confirmed it was a direct precursor in the biosynthesis of rumbrin. Both 3- and 4-chloropyrrolecarboxylates were also accepted as precursors in polyene production. 464Scopus© Citations 16
- PublicationPrecursor-directed biosynthesis of fluorinated iturin A in Bacillus spp.(RSC Publishing, 2009)
; ; ;Some iturin A-producing strains of Bacillus subtilis will elaborate the novel fluorinated analogue when incubated with 3-fluoro-L-tyrosine. The activity of iturin A is dependent on the D-tyrosine residue and the presence of fluorotyrosine may result in an improvement of the biological properties of this lipopeptide. The fluorinated iturin might also be used as a probe for studying its interaction with biological membranes. 1549Scopus© Citations 30
- PublicationMetabolism of fluoroorganic compounds in microorganisms: Impacts for the environment and the production of fine chemicals(Springer, 2009-09)
; ;Incorporation of fluorine into an organic compound can favourably alter its physicochemical properties with respect to biological activity, stability and lipophilicity. Accordingly, this element is found in many pharmaceutical and industrial chemicals. Organofluorine compounds are accepted as substrates by many enzymes, and the interactions of microorganisms with these compounds are of relevance to the environment and the fine chemicals industry. One the one hand the microbial transformation of fluorinated compounds can lead to the generation of toxic compounds that are of environmental concern, yet similar biotransformations can yield difficult-to-synthesise products and intermediates, in particular derivatives of biologically active secondary metabolites. In this paper we review the historical and recent developments of organofluorine biotransformation in microorganisms, and highlight the possibility of using microbes as models of fluorinated drug metabolism in mammals. 934Scopus© Citations 47
- PublicationProduction of the Novel Lipopeptide Antibiotic Trifluorosurfactin via Precursor-Directed Biosynthesis(Elsevier, 2012-11)
; ; ;Incorporation of fluorine into antibiotics can moderate their biological activity, lipophilicity and metabolic stability. The introduction of fluorine into an antimicrobial lipopeptide produced by Bacillus sp. CS93 via precursor-directed biosynthesis is described. The lipopeptide surfactin is synthesised non-ribosomally by various Bacillus species and is known for its biological activity. Administering 4,4,4-trifluoro-dl-valine to cultures of Bacillus sp. CS93 results in the formation of trifluorosurfactin in quantities sufficient for detection by LC–MS/MS. 19F NMR analysis of the culture supernatant revealed that the bulk of the fluorinated amino acid was transformed and thus was unavailable for incorporation into surfactin. Detection of ammonia, and MS analysis indicated that the transformation proceeds with deamination and reduction of the keto acid, yielding 4,4,4-trifluoro-2-hydroxy-3-methylbutanoic acid. 524Scopus© Citations 6
- PublicationBiodegradation of polyfluorinated biphenyl in bacteria(Springer, 2011-07)
; ;Fluorinated aromatic compounds are significant environmental pollutants, and microorganisms play important roles in their biodegradation. The effect of fluorine substitution on the transformation of fluorobiphenyl in two bacteria was investigated. Pseudomonas pseudoalcaligenes KF707 and Burkholderia xenovorans LB400 used 2,3,4,5,6-pentafluorobiphenyl and 4,4′-difluorobiphenyl as sole sources of carbon and energy. The catabolism of the fluorinated compounds was examined by gas chromatography–mass spectrometry and fluorine-19 nuclear magnetic resonance spectroscopy (19F NMR), and revealed that the bacteria employed the upper pathway of biphenyl catabolism to degrade these xenobiotics. The novel fluorometabolites 3-pentafluorophenyl-cyclohexa-3,5-diene-1,2-diol and 3-pentafluorophenyl-benzene-1,2-diol were detected in the supernatants of biphenyl-grown resting cells incubated with 2,3,4,5,6-pentafluorobiphenyl, most likely as a consequence of the actions of BphA and BphB. 4-Fluorobenzoate was detected in cultures incubated with 4,4′-difluorobiphenyl and 19F NMR analysis of the supernatant from P. pseudoalcaligenes KF707 revealed the presence of additional water-soluble fluorometabolites. 654Scopus© Citations 17
- PublicationBacterial production of hydroxylated and amidated metabolites of flurbiprofen(Elsevier, 2011-11)
; ; ;Several Streptomyces and Bacillus strains were examined for their ability to transform the anti-inflammatory drug flurbiprofen 1 to the hydroxylated metabolites that are found in humans after ingestion of this compound. Of the seven Streptomyces spp. examined, all but one transformed flurbiprofen to the main mammalian metabolite 4′-hydroxyflurbiprofen 2, and the majority also produced 3′,4′-dihydroxyflurbiprofen 3. Three strains, Streptomyces griseus DSM40236 and ATCC13273, and Streptomyces subrutilis DSM40445, also elaborated 3′-methoxy, 4′-hydroxy-flurbiprofen 4. None of the Bacillus spp. examined yielded these metabolites. Examination of the extracted supernatants of Streptomyces lavenduligriseus and Streptomyces rimosus by fluorine-19 nuclear magnetic resonance (19F NMR), indicated new resonances and these new fluorometabolites were purified by HPLC and revealed to be flurbiprofenamide 5 and 7-hydroxyflurbiprofenamide 6 after MS and NMR analyses. Subsequent re-examination of the culture supernatants from Bacillus subtilis IM7, Bacillus megaterium NCIMB8291 and B. megaterium ATTC14581 showed that these strains also produced 5 and 6. Resting cell investigations suggested that the amidation reaction employed nitrogen from an as yet unidentified amino acid. 517Scopus© Citations 15