Biomimetic nitration of the linoleic acid metabolite 13-hydroxyoctadecadienoic acid: isolation and spectral characterization of novel chain-rearranged epoxy nitro derivatives

Horseradish peroxidase (HRP) as a tool in green chemistry

The horseradish peroxidase (HRP) potential in organic synthesis.

Modulation of nitro-fatty acid signaling: prostaglandin reductase-1 is a nitroalkene reductase

Inflammation, characterized by the activation of both resident and infiltrated immune cells, is accompanied by increased production of oxidizing and nitrating species. Nitrogen dioxide, the proximal nitrating species formed under these conditions, reacts with unsaturated fatty acids to yield nitroalkene derivatives. These electrophilic products modulate protein function via post-translational modification of susceptible nucleophilic amino acids. Nitroalkenes react with Keap1 to instigate Nrf2 signaling, activate heat shock response gene expression, and inhibit NF-κB-mediated signaling, inducing net anti-inflammatory and tissue-protective metabolic responses. We report the purification and characterization of a NADPH-dependent liver enzyme that reduces the nitroalkene moiety of nitro-oleic acid, yielding the inactive product nitro-stearic acid. Prostaglandin reductase-1 (PtGR-1) was identified as a nitroalkene reductase by protein purification and proteomic studies. Kinetic measurements, inhibition studies, immunological and molecular biology approaches as well as clinical analyses confirmed this identification. Overexpression of PtGR-1 in HEK293T cells promoted nitroalkene metabolism to inactive nitroalkanes, an effect that abrogated the Nrf2-dependent induction of heme oxygenase-1 expression by nitro-oleic acid. These results situate PtGR-1 as a critical modulator of both the steady state levels and signaling activities of fatty acid nitroalkenes in vivo.

Two new nonacosanetriols from Ginkgo biloba sarcotesta

Two new fatty alcohols named as (7S,8R,11S)-nonacosanetriol (1) and (10R,12R,15S)-nonacosanetriol (2), along with eight known compounds including ginkgolic acid (3), hydroginkgolic acid (4), sciadopitysin (5), ginkgetin (6), isoginkgetin (7), ginkgolide A (8), ginkgolide B (9) and ginkgolide C (10) have been isolated from the petroleum ether extract of Ginkgo biloba sarcotesta. Their structures were elucidated by means of chemical and extensive spectroscopic analysis. The absolute stereochemistry of compounds 1 and 2 was elucidated on the spectroscopic analysis of the R- and S-MTPA esters. Compounds 1 and 2 exhibited slight activity of antithrombin and moderate activity of antiplatelet aggregation in vitro. This was the first report regarding the anticoagulative activities of biflavonoids in G. biloba, and isoginkgetin (7) showed significant antithrombin and antiplatelet aggregation activity.