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Jaume Vilarrasa

Publications and source records attributed to Jaume Vilarrasa.

11 recordsLinked to original sources
PubMed2007

Collision-induced dissociation of cytidine and its derivatives.

The collision-induced dissociation of adenosine, uridine and guanosine, and their corresponding nucleobases has been published previously.1-3 Here we report the collision-induced dissociation of cytidine and the elucidation of its fragmentation pathways using stable isotope-labeled cytidines, through a quadrupole ion trap for tandem mass spectrometry up to MS(4). Furthermore, we investigated the collision-induced dissociation of five cytidine derivatives: 3-methylcytidine, N(4)-methyl-2'-deoxycytidine, 5-methylcytidine, 2-thiocytidine and N(4)-acetylcytidine. The primary fragmentation pathway was the neutral loss of ribose. MS(3) on the retained nucleobase generally resulted in an intense signal from the elimination of ammonia, but also in fragment ions characteristic of the different cytosine derivatives. On the basis of the MS(n) data, fragmentation pathways and plausible mechanisms are suggested.

Cytidine↗
PubMed2005

Evaluation of the anti-HIV activity of statins.

Recent data suggest that statins block HIV-1 replication, which may have important implications for an alternative treatment for AIDS. We tested different statins in cell culture against HIV and conducted a pilot study in HIV-positive patients receiving simvastatin. No anti-HIV activity was detected at subtoxic concentrations and simvastatin did not induce a significant change in the mean viral load or CD4 cell count in study patients. We caution on the use of statins as antiretroviral agents.

Anti-HIV Agents↗
PubMed2005

Synthesis of (-)-amphidinolide K fragment C9-C22.

[reaction: see text] The key fragment (2a or 2b) in a total synthesis of the cytotoxic macrolide (-)-amphidinolide K (1) has been achieved from synthons C9-C14 (3) and C15-C22 (4), which have both been prepared from glutamic acid in good overall yields.

Macrolides↗
PubMed2005

[N,1-(15)N2]-2'-deoxyadenosines.

[reaction: see text] An efficient route to deoxyadenosine derivatives labeled on both the amino group and nitrogen 1 is uncovered. First, 3',5'-di-O-acetyl-2'-deoxy-1-(2-nitrobenzenesulfonyl)inosine (2a) and only 1.1 equiv of (15)NH4Cl are used for labeling position 1 (1a) through the isolation of the open intermediate and its cyclization with DBU in anhydrous CH3CN. Inosine 1a is then converted to [N,1-(15)N2]-3',5'-di-O-acetyl-N6-benzoyl-2'-deoxyadenosine (5a, the precursor of 6a) via a Pd/dppf-catalyzed chloride-to-benzamide replacement, by using again only 1.1 equiv of the labeling source.

Catalysis↗
PubMed2004

Computational comparison of microtubule-stabilising agents laulimalide and peloruside with taxol and colchicine.

Microtubule-stabilising agents laulimalide and peloruside have been compared with tubulin-interacting drugs paclitaxel and colchicine by different computational approaches. Docking and QSAR-based programs point to a favourable interaction with the beta tubulin paclitaxel binding site, although an additional, preferred binding site has been found at the alpha subunit of tubulin. All together provides a plausible rationalisation of the singular binding features of these microtubule stabilisers and paves the way for future structural studies.

Binding Sites↗
PubMed2003

Control of neurotransmitter release by an internal gel matrix in synaptic vesicles.

Neurotransmitters are stored in synaptic vesicles, where they have been assumed to be in free solution. Here we report that in Torpedo synaptic vesicles, only 5% of the total acetylcholine (ACh) or ATP content is free, and that the rest is adsorbed to an intravesicular proteoglycan matrix. This matrix, which controls ACh and ATP release by an ion-exchange mechanism, behaves like a smart gel. That is, it releases neurotransmitter and changes its volume when challenged with small ionic concentration change. Immunodetection analysis revealed that the synaptic vesicle proteoglycan SV2 is the core of the intravesicular matrix and is responsible for immobilization and release of ACh and ATP. We suggest that in the early steps of vesicle fusion, this internal matrix regulates the availability of free diffusible ACh and ATP, and thus serves to modulate the quantity of transmitter released.

Acetylcholine↗
PubMed2003

Highly stereoselective aldol reactions of titanium enolates from lactate-derived chiral ketones.

[reaction: see text] Highly stereoselective titanium-mediated aldol reactions based on lactate-derived ketones are reported. The stereochemical outcome of the process depends on the protecting group (PMB or Bn) and the Lewis acid (i-PrOTiCl(3) or TiCl(4)) used in the enolization step, the corresponding anti-syn or syn-syn aldols being prepared in high yields and with diastereomeric ratios up to 99:1.

Aldehydes↗