Aceriphyllum rossii Extract and Its Active Compounds, Quercetin and Kaempferol Inhibit IgE-mediated Mast Cell Activation and Passive Cutaneous Anaphylaxis

Aceriphyllum rossii contains an abundant source of natural flavonoids with potential antioxidant, anticancer and anti-inflammatory properties. However, the effect of A. rossii extract (ARE) on immunoglobulin E­(IgE)-mediated allergic responses remains unknown. In the present study, the effects of ARE and its active compounds, quercetin and kaempferol, on IgE-mediated rat basophilic leukemia mast cell activation and passive cutaneous anaphylaxis (PCA) were investigated. ARE, quercetin, and kaempferol inhibited secretion of β-hexosaminidase and histamine, and reduced the production and mRNA expression of interleukin-4 and tumor necrosis factor-α. ARE also decreased the production of prostaglandin E₂ and leukotriene B₄ and expression of cyclooxygenase 2 and 5-lipoxygenase. Furthermore, ARE, quercetin, and kaempferol inhibited IgE-mediated phosphorylation of Syk, phospholipase Cγ, protein kinase C (PKC)­μ, and the mitogen-activated protein kinases, extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase. ARE, quercetin, and kaempferol markedly suppressed mast cell-dependent PCA in IgE-sensitized mice. These results indicate that ARE and its active constituents, quercetin and kaempferol, may be a useful therapy for immediate-type hypersensitivity

Asymmetric Ene-Reduction of α,β-Unsaturated Compounds by F₄₂₀-Dependent Oxidoreductases A Enzymes from Mycobacterium smegmatis

The stereoselective reduction of alkenes conjugated to electron-withdrawing groups by ene-reductases has been extensively applied to the commercial preparation of fine chemicals. Although several different enzyme families are known to possess ene–reductase activity, the old yellow enzyme (OYE) family has been the most thoroughly investigated. Recently, it was shown that a subset of ene-reductases belonging to the flavin/deazaflavin oxidoreductase (FDOR) superfamily exhibit enantioselectivity that is generally complementary to that seen in the OYE family. These enzymes belong to one of several FDOR subgroups that use the unusual deazaflavin cofactor F420. Here, we explore several enzymes of the FDOR-A subgroup, characterizing their substrate range and enantioselectivity with 20 different compounds, identifying enzymes (MSMEG_2027 and MSMEG_2850) that could reduce a wide range of compounds stereoselectively. For example, MSMEG_2027 catalyzed the complete conversion of both isomers of citral to (R)-citronellal with 99% ee, while MSMEG_2850 catalyzed complete conversion of ketoisophorone to (S)-levodione with 99% ee. Protein crystallography combined with computational docking has allowed the observed stereoselectivity to be mechanistically rationalized for two enzymes. These findings add further support for the FDOR and OYE families of ene-reductases displaying general stereocomplementarity to each other and highlight their potential value in asymmetric ene-reduction

Leaves of Persimmon (Diospyros kaki Thunb.) Ameliorate <i>N</i>‑Methyl‑<i>N</i>‑nitrosourea (MNU)-Induced Retinal Degeneration in Mice

The purpose of the study was to investigate the protective effects of the ethanol extract of Diospyros kaki (EEDK) persimmon leaves to study <i>N</i>-methyl-<i>N</i>-nitrosourea (MNU)-induced retinal degeneration in mice. EEDK was orally administered after MNU injection. Retinal layer thicknesses were significantly increased in the EEDK-treated group compared with the MNU-treated group. The outer nuclear layer was preserved in the retinas of EEDK-treated mice. Moreover, EEDK treatment reduced the MNU-dependent up-regulation of glial fibrillary acidic protein (GFAP) and nestin expression in Müller and astrocyte cells. EEDK treatment also inhibited MNU-dependent down-regulation of rhodopsin expression. Quercetin exposure significantly attenuated the negative effects of H₂O₂ in R28 cells, suggesting that quercetin can act in an antioxidative capacity. Thus, EEDK may be considered as an agent for treating or preventing degenerative retinal diseases, such as retinitis pigmentosa and age-related macular degeneration