Ana R. Rodriguez

Oxidative stress early in pregnancy and pregnancy outcome

The objectives of this study were to determine whether oxidative stress early in pregnancy influenced pregnancy outcome. A combination of assays were used for exogenous and endogenous anti-oxidants together with two well accepted biomarkers for oxidative stress, the urinary excretion of 8-iso-PGF2α (a biomarker marker for lipid oxidation, n=508) and 8-oxo-7,8 dihydro-2 deoxyguanosine (8-OHdG, a biomarker for DNA oxidation, n=487). The two biomarkers tracked different pregnancy outcomes. Isoprostanes were associated with an increased risk of pre-eclampsia and a decreased proportion of female births. In contrast, 8-OHdG tracked lower infant birthweight and shortened gestation duration. Birth defects were associated with low levels of 8-OHdG.

Selective oxidation of primary silyl ethers and its application to the synthesis of natural products

Abstract Primary TMS or TES ethers, in the presence of secondary TMS or TES ethers, are selectively oxidized to the corresponding aldehydes under Swern conditions. A short synthesis of key intermediates towards various natural products has been achieved.

Lipoxin a4 increases survival by decreasing systemic inflammation and bacterial load in sepsis.

Sepsis is characterized by systemic inflammation with release of a large amount of inflammatory mediators. If sustained, this inflammatory response can lead to multiple organ failure and/or immunoparalysis. In the latter condition, the host may be susceptible to opportunistic infections or be unable to clear existing infections. Therefore, it is potentially beneficial to resolve inflammation by reducing inflammation without compromising host defense. We examined the effect of lipoxin A4 (LXA4), a compound with inflammatory resolution properties, in the cecal ligation and puncture (CLP) model of sepsis. Cecal ligation and puncture rats were given either saline or LXA4 (40 &mgr;g/kg, i.p.) 5 h after surgery. Lipoxin A4 administration increased 8-day survival of CLP rats, which lived longer than 48 h, and attenuated tissue injury after 8 days. Therefore, we investigated the effects of LXA4 on systemic inflammation and bacterial load 48 h after CLP sepsis. Plasma IL-6, monocyte chemotactic protein 1, and IL-10 levels were reduced in LXA4-treated rats compared with CLP rats given saline vehicle. Lipoxin A4 reduced phosphorylation of the p65 subunit of nuclear factor &kgr;B (NF-&kgr;B) at serines 536 and 468 in peritoneal macrophages, suggesting that LXA4 reduced production of proinflammatory mediators through an NF-&kgr;B-mediated mechanism. Lipoxin A4 reduced blood bacterial load and increased peritoneal macrophage number without affecting phagocytic ability, suggesting that LXA4 reduced blood bacterial load by enhancing macrophage recruitment. It also suggests that LXA4 reduced systemic inflammation and NF-&kgr;B activation without compromising host defense. Increased macrophage recruitment was in part due to a direct effect of LXA4 as LXA4 increased peritoneal macrophage recruitment in sham controls and partly due to reduced production of IL-10 as LXA4 decreased macrophage IL-10 release (a known inhibitor of macrophage migration) after CLP. The results suggest that LXA4 increased survival in sepsis by simultaneously reducing systemic inflammation as well as bacterial spread.

A SELECTIVE METHOD FOR THE PREPARATION OF ALIPHATIC METHYL ESTERS IN THE PRESENCE OF AROMATIC CARBOXYLIC ACIDS

2,2-Dimethoxypropane, methanol and a catalytic amount of HCl selectively esterify aliphatic carboxylic acids, in the presence of aromatic carboxylic acids, at room temperature and in high yields.

An Efficient Asymmetric Synthesis of Prostaglandin E1

An asymmetric total synthesis of Prostaglandin E1 (5) has been achieved in a two-component coupling process. The chiral hydroxycyclopentenone 6 was readily available from furan with 96% ee. The key reaction step was a kinetic enzymatic resolution followed by an in situ inversion. A catalytic asymmetric reduction of the γ-iodo vinyl ketone 19 with the Corey CBS catalyst gave the ω-side chain 7 with >96% ee. Conjugate addition using the reaction with dilithiocyanocuprate followed by mild cleavage of the silyl protective groups and enzymatic hydrolysis of the methyl ester 22 gave (–)-PGE15in high yield.

ANTITHROMBOTIC EFFECTS OF PEROXYNITRITE : INHIBITION AND REVERSAL OF AGGREGATION IN HUMAN PLATELETS

The inhibition of platelet aggregation by peroxynitrite, a reactive oxygen species derived from the interaction of nitric oxide (NO) and superoxide, was examined in platelet-rich plasma. In this report, we have used a preparation of peroxynitrite that was free of H2O2 and MnO2. As such, peroxynitrite dose-dependently (50-200 microM) inhibited aggregation of human platelets stimulated by ADP (5 microM), collagen (0.5 microgram), thrombin (0.5U/microL) and U46619 (1 microM). In addition, peroxynitrite reversed platelet aggregation induced by collagen, ADP, and thrombin. Peroxynitrite, preincubated with platelet-poor plasma or albumin (7%) for 30 min, did not alter the inhibition of platelet aggregation. This suggested that the inhibitory action of peroxynitrite may be due to nitrosylation of proteins, which by themselves possess activity, rather than conversion to NO or NO donors. Furthermore, we show that peroxynitrite increased the cGMP level only at 200 microM concentrations, further suggesting that the action of peroxynitrite was not completely due to its conversion to NO or NO donors.

Total synthesis of 12(R)-HETE, 12(S)-HETE, 2H2-12(R)-HETE and LTB4 from racemic glycidol via hydrolytic kinetic resolution

The total synthesis of 12(R)-HETE, 12(S)-HETE (Samuelssons HETE), [14,15-2H2]-12(R)-HETE and Leukotriene B4 from racemic glycidol is described. The key steps are the hydrolytic kinetic resolution of racemic TES-glycidol with salen-Co catalyst and the selective oxidation of primary silyl ethers, in the presence of secondary ones, under Swern conditions to give a short entry to both enantiomers of 12-HETE and LTB4.

Total synthesis of aspirin-triggered 15-epi-lipoxin A4

Abstract The total synthesis of aspirin-triggered 15- epi -LXA 4 has been achieved using a chiral pool strategy for the C1–C12 fragment starting from 2-deoxy- d -ribose. Sharpless catalytic AE generated the C15 chiral center with >98% ee. The stereospecific ( Z )-reduction of the conjugated trienyne to the tetraene was achieved with Zn(Cu/Ag) in aq. CH 3 OH at rt.

Maresin conjugates in tissue regeneration biosynthesis enzymes in human macrophages

Significance We recently uncovered a family of macrophage-derived molecules, coined maresin conjugates in tissue regeneration, that regulate the system’s ability to clear bacteria as well as repair and regenerate damaged tissues. In the present study, we identified enzymes involved in the formation of these potent molecules in human macrophages. These enzymes were shared with the classic cysteinyl leukotrienes, underscoring the presence of conserved biosynthetic motifs in these two functionally distinct lipid mediator families. Inhibition of these pathways upregulated the formation of several specialized proresolving mediator (SPM) families including D- and E-series resolvins. Thus, these illustrate the dynamic nature of the SPM biosynthetic pathways and provide new targets in the resolution of inflammation and regulation of tissue repair and regeneration. Macrophages are central in coordinating immune responses, tissue repair, and regeneration, with different subtypes being associated with inflammation-initiating and proresolving actions. We recently identified a family of macrophage-derived proresolving and tissue regenerative molecules coined maresin conjugates in tissue regeneration (MCTR). Herein, using lipid mediator profiling we identified MCTR in human serum, lymph nodes, and plasma and investigated MCTR biosynthetic pathways in human macrophages. With human recombinant enzymes, primary cells, and enantiomerically pure compounds we found that the synthetic maresin epoxide intermediate 13S,14S-eMaR (13S,14S-epoxy- 4Z,7Z,9E,11E,16Z,19Z-docosahexaenoic acid) was converted to MCTR1 (13R-glutathionyl, 14S-hydroxy-4Z,7Z,9E,11E,13R,14S,16Z,19Z-docosahexaenoic acid) by LTC4S and GSTM4. Incubation of human macrophages with LTC4S inhibitors blocked LTC4 and increased resolvins and lipoxins. The conversion of MCTR1 to MCTR2 (13R-cysteinylglycinyl, 14S-hydroxy-4Z,7Z,9E,11E,13R,14S,16Z,19Z-docosahexaenoic acid) was catalyzed by γ-glutamyl transferase (GGT) in human macrophages. Biosynthesis of MCTR3 was mediated by dipeptidases that cleaved the cysteinyl-glycinyl bond of MCTR2 to give 13R-cysteinyl, 14S-hydroxy-4Z,7Z,9E,11E,13R,14S,16Z,19Z-docosahexaenoic acid. Of note, both GSTM4 and GGT enzymes displayed higher affinity to 13S,14S-eMaR and MCTR1 compared with their classic substrates in the cysteinyl leukotriene metabolome. Together these results establish the MCTR biosynthetic pathway and provide mechanisms in tissue repair and regeneration.

Total synthesis of E1 and E2 isoprostanes by diastereoselective protonation

Abstract A short total synthesis of the E-type isoprostanes has been achieved using a two-component coupling process combined with a diastereoselective protonation under reagent control . Mild cleavage of the silyl protective groups with cat. BiBr 3 or HF/Py followed by enzymatic hydrolysis of the methyl ester afforded the free E-type isoprostanes.