Palladium-catalyzed C(sp3)-H nitrooxylation of masked alcohols

A palladium-catalyzed β-C(sp³)-H nitrooxylation of aliphatic alcohols with AgNO₂ is reported. An 8-formylquinoline-derived oxime is installed as an exo-type directing group for sp³ C-H activation and selectfluor acts as the oxidant. The reaction tolerates a variety of functional groups and shows good selectivity for β-C-H nitrooxylation of alcohols.

Anti-Inflammatory CeO2 Nanoparticles Prevented Cytotoxicity Due to Exogenous Nitric Oxide Donors via Induction Rather Than Inhibition of Superoxide/Nitric Oxide in HUVE Cells

The mechanism behind the cytoprotective potential of cerium oxide nanoparticles (CeO2 NPs) against cytotoxic nitric oxide (NO) donors and H2O2 is still not clear. Synthesized and characterized CeO2 NPs significantly ameliorated the lipopolysaccharide (LPS)-induced cytokines IL-1β and TNF-α. The main goal of this study was to determine the capacities of NPs regarding signaling effects that could have occurred due to reactive oxygen species (ROS) and/or NO, since NP-induced ROS/NO did not lead to toxicity in HUVE cells. Concentrations that induced 50% cell death (i.e., IC50s) of two NO donors (DETA-NO; 1250 ± 110 µM and sodium nitroprusside (SNP); 950 ± 89 µM) along with the IC50 of H2O2 (120 ± 7 µM) were utilized to evaluate cytoprotective potential and its underlying mechanism. We determined total ROS (as a collective marker of hydrogen peroxide, superoxide radical (O2•-), hydroxyl radical, etc.) by DCFH-DA and used a O2•- specific probe DHE to decipher prominent ROS. The findings revealed that signaling effects mediated mainly by O2•- and/or NO are responsible for the amelioration of toxicity by CeO2 NPs at 100 µg/mL. The unaltered effect on mitochondrial membrane potential (MMP) due to NP exposure and, again, CeO2 NPs-mediated recovery in the loss of MMP due to exogenous NO donors and H2O2 suggested that NP-mediated O2•- production might be extra-mitochondrial. Data on activated glutathione reductase (GR) and unaffected glutathione peroxidase (GPx) activities partially explain the mechanism behind the NP-induced gain in GSH and persistent cytoplasmic ROS. The promoted antioxidant capacity due to non-cytotoxic ROS and/or NO production, rather than inhibition, by CeO2 NP treatment may allow cells to develop the capacity to tolerate exogenously induced toxicity.

Identification of a novel triterpene saponin from Panax ginseng seeds, pseudoginsenoside RT8, and its antiinflammatory activity

BACKGROUND

Panax ginseng Meyer (Araliaceae) is a highly valued medicinal plant in Asian regions, especially in Korea, China, and Japan. Chemical and biological studies on P. ginseng have focused primarily on its roots, whereas the seeds remain poorly understood. This study explores the phytochemical and biological properties of compounds from P. ginseng seeds.

METHODS

P. ginseng seeds were extracted with methanol, and 16 compounds were isolated using various chromatographic methods. The chemical structures of the isolates were determined by spectroscopic data. Antiinflammatory activities were evaluated for triterpene and steroidal saponins using lipopolysaccharide-stimulated RAW264.7 macrophages and THP-1 monocyte leukemia cells.

RESULTS

Phytochemical investigation of P. ginseng seeds led to the isolation of a novel triterpene saponin, pseudoginsenoside RT8, along with 15 known compounds. Pseudoginsenoside RT8 exhibited more potent antiinflammatory activity than the other saponins, attenuating lipopolysaccharide-mediated induction of proinflammatory genes such as interleukin-1β, interleukin-6, inducible nitric oxide synthase, cyclooxygenase-2, and matrix metalloproteinase-9, and suppressed reactive oxygen species and nitric oxide generation in a dose-dependent manner.

CONCLUSION

These findings indicate that pseudoginsenoside RT8 has a pharmaceutical potential as an antiinflammatory agent and that P. ginseng seeds are a good natural source for discovering novel bioactive molecules.

A Novel Thiazolyl Schiff Base: Antibacterial and Antifungal Effects and In Vitro Oxidative Stress Modulation on Human Endothelial Cells

Schiff bases (SBs) are chemical compounds displaying a significant pharmacological potential. They are able to modulate the activity of many enzymes involved in metabolism and are found among antibacterial, antifungal, anti-inflammatory, antioxidant, and antiproliferative drugs. A new thiazolyl-triazole SB was obtained and characterized by elemental and spectral analysis. The antibacterial and antifungal ability of the SB was evaluated against Gram-positive and Gram-negative bacteria and against three Candida strains. SB showed good antibacterial activity against L. monocytogenes and P. aeruginosa; it was two times more active than ciprofloxacin. Anti-Candida activity was twofold higher compared with that of fluconazole. The effect of the SB on cell viability was evaluated by colorimetric measurement on cell cultures exposed to various SB concentrations. The ability of the SB to modulate oxidative stress was assessed by measuring MDA, TNF-α, SOD1, COX2, and NOS2 levels in vitro, using human endothelial cell cultures exposed to a glucose-enriched medium. SB did not change the morphology of the cells. Experimental findings indicate that the newly synthetized Schiff base has antibacterial activity, especially on the Gram-negative P. aeruginosa, and antifungal activity. SB also showed antioxidant and anti-inflammatory activities.

Anti-inflammatory and anti-arthritic effects of Guge Fengtong Formula: in vitro and in vivo studies

Rheumatoid arthritis (RA) is the most common inflammatory arthritis and a major cause of disability. Presently, the clinical therapeutic medicines for inflammatory and arthritic diseases are unsatisfactory due to severe adverse effects or ineffectiveness. The Guge Fengtong formula (GGFT), containing the standardized extracts of Dioscoreae Nipponicae Rhizoma, Spatholobi Caulis, and Zingiberis Rhizoma, has long been used for RA treatment by Chinese doctorsin China. However, the detailed anti-inflammatory and anti-arthritic activity of GGFT has not been reported so far. In the present work, we aimed to evaluate the anti-inflammatory and anti-arthritic effects of GGFT using three in vivo animal models, and tried to uncover its preliminarythe underlying mechanism of action mechanism in RAW 264.7 macrophages. The obtained results indicated that GGFT significantly attenuated ear edema, decreased carrageenan-induced paw edema, reduced the arthritis score, and reversed the weight loss of the complete Freund's adjuvant (CFA)CFA-injected rats. Additionally, marked decrease of in synovial inflammatory infiltration and synovial lining hyperplasia in the joints and decline of inflammatory factors (TNF-α and IL-1β) in the serum were observed in the GGFT-treated rats. In lipopolysaccharide-activated RAW264.7 macrophages, GGFT reduced the production of NO, PGE2, and IL-6, and inhibited the expression of iNOS, COX-2, and NF-κB expression. Our results demonstrated that GGFT possessed considerable anti-inflammatory activity and have had potential therapeutic effects on adjuvant induced arthritis in rats, which provided providing experimental evidences for its traditional application in the treatment of RA and other inflammatory diseases.

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(-)-myrtenol nitrate

Here we report the chemoselective synthesis of several important, climate relevant isoprene nitrates using silver nitrate to mediate a 'halide for nitrate' substitution. Employing readily available starting materials, reagents and Horner-Wadsworth-Emmons chemistry the synthesis of easily separable, synthetically versatile 'key building blocks' (E)- and (Z)-3-methyl-4-chlorobut-2-en-1-ol as well as (E)- and (Z)-1-((2-methyl-4-bromobut-2-enyloxy)methyl)-4-methoxybenzene has been achieved using cheap, 'off the shelf' materials. Exploiting their reactivity we have studied their ability to undergo an 'allylic halide for allylic nitrate' substitution reaction which we demonstrate generates (E)- and (Z)-3-methyl-4-hydroxybut-2-enyl nitrate, and (E)- and (Z)-2-methyl-4-hydroxybut-2-enyl nitrates ('isoprene nitrates') in 66-80% overall yields. Using NOESY experiments the elucidation of the carbon-carbon double bond configuration within the purified isoprene nitrates has been established. Further exemplifying our 'halide for nitrate' substitution chemistry we outline the straightforward transformation of (1R,2S)-(-)-myrtenol bromide into the previously unknown monoterpene nitrate (1R,2S)-(-)-myrtenol nitrate.