Publicaciones 2011-2020

@article{RN174,
title = {Determination and Co-Estimate of the Chlormadinone Acetate and 17 Alpha-Ethinyl Estradiol in Pharmaceutical Formulation and Drinking Water Samples by Digital Derivative Spectophotometry},
author = { C. Soto and R. Otipka and M.I. Toral and D. Pino and D. Contreras and J. Yanez},
url = {/brokenurl#<Go to ISI>://WOS:000342613100019},
doi = {10.4067/S0717-97072014000200019},
issn = {0717-9707},
year = {2014},
date = {2014-01-01},
journal = {Journal of the Chilean Chemical Society},
volume = {59},
number = {2},
pages = {2485-2489},
abstract = {In this work are presented two methods for the simultaneous determination of 17 alpha-ethinylestradiol (EEL) and chlormadinone acetate (CMA) by second order derivative spectrophotometry., The first analytical method proposed is based in the dissolution and extraction of both drugs in acetonitrile. The solution was directly evaluated by second order derivative spectrophotometry with a smoothing factor of 8,000 and a scale factor of 10,000. The determination of EEL and CMA was carried out to 296,6 and 291.8 nm, respectively. The detection limits (3.3 sigma criterion) for EEL and CMA were 6.9 x 10(-7) and 9.8 x 10(-8) mol/L, respectively., Furthermore, a study of the effect of the excipients containing in the pharmaceutical formulation was included. Polyvidone presents greater tendency to produce interference, but its spectral bands are located between 215 and 240 nm, so these bands do not interferes spectrally in the simultaneous determination of EEL and CMA. Both drugs were extracted from the pharmaceutical formulation with acetonitrile, obtaining a good recovery relative to the nominal content., The second method is a screening method and was applied in fortified drinking water. In this method, drugs were extracted in chloroform, which was then removed with N-2 and the residue was redissolved in acetonitrile. Due to the difference in the procedure in relation to the pharmaceutical formulation a new analytical parameters were obtained. For EEL this parameters were very similar to those obtained directly in solution, however these were higher for CMA, which could be attributed to that under these conditions was found a higher standard deviation of the blank. Recoveries of fortified samples were 81.8 +/- 1.5% and 101.1 +/- 0.73% for EEL and CMA, respectively.},
keywords = {alpha-ethinyl chlormadinone derivative electrode estradiol, ethinylestradiol, formulations, gestodene, human least-squares, liquid-chromatography, mass-spectrometry, method, oral-contraceptives, performance pharmaceutical plasma, screening spectrophotometry, tandem},
pubstate = {published},
tppubtype = {article}
}

@article{RN30d,
title = {Motifs in the C-Terminal Region of the Penicillium Chrysogenum Acv Synthetase Are Essential for Valine Epimerization and Processivity of Tripeptide Formation},
author = { X.B. Wu and C. Garcia-Estrada and I. Vaca and J.F. Martin},
url = {/brokenurl#<Go to ISI>://WOS:000300270900010},
doi = {10.1016/j.biochi.2011.08.002},
issn = {0300-9084},
year = {2012},
date = {2012-01-01},
journal = {Biochimie},
volume = {94},
number = {2},
pages = {354-364},
publisher = {2011 Elsevier Masson SAS.},
abstract = {The first step in the penicillin biosynthetic pathway is the non-ribosomal condensation of L-alpha-aminoadipic acid, L-cysteine and L-valine into the tripeptide delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (ACV). This reaction is catalysed by the multienzyme ACV synthetase (ACVS), which is encoded in the filamentous fungus Penicillium chrysogenum by the pcbAB gene. This enzyme contains at least ten catalytic domains. The precise role of the C-terminal domain of this multidomain NRPS still remains obscure. The C-terminal region of ACVS bears the epimerase and the thioesterase domains and may be involved in the epimerization of LLL-ACV to LLD-ACV and in the hydrolysis of the thioester bond. In this work, the conserved motifs (3371)EGHGRE(3376) (located in the putative epimerase domain) and (3629)GWSFG(3633) (located in the thioesterase domain) were changed by site-directed-mutagenesis to LGFGLL and GWAFG, respectively. In addition, the whole thioesterase domain (230 amino acids) and the different parts of this domain were deleted. The activity of these mutant enzymes was assessed in vivo by two different procedures: i) through the quantification of bisACV produced by the fungus and ii) by quantifying the benzylpenicillin production using tailored strains of P. chrysogenum, which lack the pcbAB gene, as host strains. All indicated mutant enzymes showed lower or null activity than the control strain confirming that E3371, H3373, R3375 and E3376 belong to the epimerase active centre. Different fragments included in the C-terminal region of ACVS control thioester hydrolysis. Overexpression of the sequence encoding the ACVS integrated thioesterase domain as a separate (stand-alone) transcriptional unit complemented mutants lacking the integrated thioesterase domain, although with low ACV releasing activity, suggesting that the stand-alone thio-esterease interacts with the other ACVS domains.},
keywords = {biosynthesis, biosynthetic cephalosporin cluster, enzyme, epimerase, functional genes, isopenicillin-n, l-valine non-ribosomal nonribosomal penicillin penicillin, peptide peptide-synthesis, repeats, syntethase, synthetase, synthetases, tandem},
pubstate = {published},
tppubtype = {article}
}