Secoiridoid Glucosides and Anti-Inflammatory Constituents from the Stem Bark of Fraxinus chinensis.

Qin Pi (Fraxinus chinensis Roxb.) is commercially used in healthcare products for the improvement of intestinal function and gouty arthritis in many countries. Three new secoiridoid glucosides, (8E)-4''-O-methylligstroside (1), (8E)-4''-O-methyldemethylligstroside (2), and 3'',4''-di-O-methyl-demethyloleuropein (3), have been isolated from the stem bark of Fraxinus chinensis, together with 23 known compounds (4-26). The structures of the new compounds were established by spectroscopic analyses (1D, 2D NMR, IR, UV, and HRESIMS). Among the isolated compounds, (8E)-4''-O-methylligstroside (1), (8E)-4''-O-methyldemethylligstroside (2), 3'',4''-di-O-methyldemethyloleuropein (3), oleuropein (6), aesculetin (9), isoscopoletin (11), aesculetin dimethyl ester (12), fraxetin (14), tyrosol (21), 4-hydroxyphenethyl acetate (22), and (+)-pinoresinol (24) exhibited inhibition (IC50 ≤ 7.65 µg/mL) of superoxide anion generation by human neutrophils in response to formyl-L-methionyl-L-leuckyl-L-phenylalanine/cytochalasin B (fMLP/CB). Compounds 1, 9, 11, 14, 21, and 22 inhibited fMLP/CB-induced elastase release with IC50 ≤ 3.23 µg/mL. In addition, compounds 2, 9, 11, 14, and 21 showed potent inhibition with IC50 values ≤ 27.11 µM, against lipopolysaccharide (LPS)-induced nitric oxide (NO) generation. The well-known proinflammatory cytokines, tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6), were also inhibited by compounds 1, 9, and 14. Compounds 1, 9, and 14 displayed an anti-inflammatory effect against NO, TNF-α, and IL-6 through the inhibition of activation of MAPKs and IκBα in LPS-activated macrophages. In addition, compounds 1, 9, and 14 stimulated anti-inflammatory M2 phenotype by elevating the expression of arginase 1 and Krüppel-like factor 4 (KLF4). The above results suggested that compounds 1, 9, and 14 could be considered as potential compounds for further development of NO production-targeted anti-inflammatory agents.

Isolation of Terpenoids from the Stem of Ficus aurantiaca Griff and their Effects on Reactive Oxygen Species Production and Chemotactic Activity of Neutrophils.

Three new triterpenoids; namely 28,28,30-trihydroxylupeol (1); 3,21,21,26-tetrahydroxy-lanostanoic acid (2) and dehydroxybetulinic acid (3) and seven known compounds; i.e., taraxerone (4); taraxerol (5); ethyl palmitate (6); herniarin (7); stigmasterol (8); ursolic acid (9) and acetyl ursolic acid (10) were isolated from the stem of Ficus aurantiaca Griff. The structures of the compounds were established by spectroscopic techniques. The compounds were evaluated for their inhibitory effects on polymorphonuclear leukocyte (PMN) chemotaxis by using the Boyden chamber technique and on human whole blood and neutrophil reactive oxygen species (ROS) production by using a luminol-based chemiluminescence assay. Among the compounds tested, compounds 1-4, 6 and 9 exhibited strong inhibition of PMN migration towards the chemoattractant N-formyl-methionyl-leucyl-phenylalanine (fMLP) with IC50 values of 6.8; 2.8; 2.5; 4.1; 3.7 and 3.6 µM, respectively, comparable to that of the positive control ibuprofen (6.7 µM). Compounds 2-4, 6, 7 and 9 exhibited strong inhibition of ROS production of PMNs with IC50 values of 0.9; 0.9; 1.3; 1.1; 0.5 and 0.8 µM, respectively, which were lower than that of aspirin (9.4 µM). The bioactive compounds might be potential lead molecules for the development of new immunomodulatory agents to modulate the innate immune response of phagocytes.

Limonoids from the Seeds of Swietenia macrophylla and Their Anti-Inflammatory Activities.

A new limonoid, swietemacrophin (1), was isolated from the seeds of Swietenia macrophylla, together with five known compounds 2-6. The structure of 1 was determined through extensive 1D/2D-NMR and mass-spectrometric analyses. Swietemacrophin (1), humilinolide F (2), 3,6-O,O-diacetylswietenolide (3), 3-O-tigloylswietenolide (4), and swietemahonin E (5) exhibited inhibition (IC50 values≤45.44 µM) of superoxide anion generation by human neutrophils in response to formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP). Compounds 1, 4, 5, and swietenine (6) showed potent inhibition with IC50 values≤36.32 µM, against lipopolysaccharide (LPS)-induced nitric oxide (NO) generation.

Appraisal of the antichemotactic activity of flavonoids on polymorphonuclear neutrophils.

Flavonoids are polyphenols that are ubiquitous in plants and frequently consumed in the diet. They are suggested to have many beneficial actions on human health, including anti-inflammatory activity. Their properties have been studied in a number of cell types, but little is known about their effects on neutrophil biology. Consequently, we selected 25 flavonoids with different structural features to evaluate their in vitro inhibition of rat polymorphonuclear neutrophil (PMN) chemotaxis, employing a modified Boyden chamber. Migratory activity was measured towards a chemotactic stimulant, formyl-Met-Leu-Phe or lipopolysaccharide. Furthermore, the cytotoxic effect of flavonoids on PMNs was determined by the release of cytosolic lactate dehydrogenase (LDH). Ten flavonoids significantly retarded the migration of PMNs with at least one of the concentrations tested in a range between 0.625 and 100 µM; the best antichemotactic agents were flavone, flavonol, quercetin and rutin. None of the flavanones evaluated presented any significant inhibition of migration in this assay. Our findings indicated that non-hydroxylated flavones possess a better antichemotactic activity when compared to flavones with hydroxy groups. The presence of a sugar moiety in rutin did not produce any increase in this effect, when compared to the respective aglycone analogue. Finally, none of the flavonoids exhibited cell toxicity and for many of these flavonoids this is the first report of the inhibition of PMN chemotaxis.

Concentration-dependent activity of mometasone furoate and dexamethasone on blood eosinophils isolated from atopic children: modulation of Mac-1 expression and chemotaxis.

Treatment of asthma with corticosteroids results in downregulation of eosinophilic airway inflammation. We evaluated in vitro the activity of an "inhaled" corticosteroid, mometasone furoate (MF), and of a "systemic" corticosteroid, dexamethasone (DEX), on eosinophil functions, i.e. adhesion molecule expression and cell chemotaxis. Partially purified blood eosinophils were obtained from 18 asthmatic subjects sensitized to house dust mites. The expression of the macrophage antigen (Mac)-1 (CD11b/CD18) was measured by specific monoclonal antibody (mAb) staining and flow cytometry analysis at baseline or after stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP) or with recombinant human (rh) granulocyte macrophage-colony stimulating factor (GM-CSF) plus a mAb anti-human (ah) IgE low affinity receptor [FcepsilonRII or CD23]. Cell chemotaxis toward the complement fragment 5a (C5a) or rh interleukin (IL)-5 was evaluated in Boyden microchambers by light microscopy. Eosinophils showed a significant increase in Mac-1 expression after activation with fMLP or with rh GM-CSF plus ah CD23 mAbs (p<0.05, each comparison) and a remarkable chemotactic response to both C5a or rh IL-5 (p<0.001, each comparison). To test the inhibitory activity of MF and DEX on eosinophil functions, the cells were preincubated for 3 h with four concentrations (0.1, 1, 10 and 100 nM) of each of the two drugs, before being activated by fMLP or by rh GM-CSF plus ah CD23 mAbs or tested with C5a or with rh IL-5. Independently of the stimulus used, both Mac-1 expression and eosinophil migration were effectively downregulated by preincubation with MF or DEX at 1, 10 and 100 nM (p<0.05). The inhibitory activity on cell chemotaxis in response to both C5a or with rh IL-5 was higher for MF than DEX, but only at the highest concentration tested (p<0.05, each comparison). These data demonstrate that concentrations of MF similar to those obtained in vivo are highly effective in inhibiting eosinophil functions involved in airway inflammation.

A Chinese traditional medicine, juzentaihoto, inhibits the O2- generation by macrophages.

Guinea pig peritoneal macrophages generate superoxide anion (O2-), when stimulated with N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), phorbol-myristate acetate (PMA) or ovalbumin complex of guinea pig IgG2 antibody (OA gamma 2). These responses were found to be inhibited by a Chinese traditional medicine, Juzentaihoto (JT). When the inhibition was assayed by the use of fMLP as a stimulant, at least one of the substances responsible for the inhibitory activity of JT was identified to be cinnamic acid. An authentic sample of cinnamic acid also inhibited the O2- generation by fMLP-stimulated macrophages. Cinnamic acid, however, did not inhibit the O2- generation, when macrophages were stimulated with PMA and OA gamma 2. These results indicate that a certain cinnamic acid-inhibitable factor may be involved in the intracellular triggering event(s) initiated by fMLP, leading to activation of the respiratory burst reduced nicotinamide adenine dinucleotide phosphate oxidase, but not in those by PMA and OA gamma 2.

Inhibition of superoxide anion radical production by ebselen (PZ51) and its sulfur analogue (PZ25) in guinea pig alveolar macrophages.

The production of superoxide anion radicals by guinea pig alveolar macrophages is stimulated by the chemotactic peptide N-formylmethionyl-leucylphenylalanine and the protein kinase C activator phorbol-12-myristate-13-acetate. Both stimulations are completely and equipotently (IC50 = 20 microM) inhibited by the seleno-organic compound ebselen. As the sulfur containing analogue, which is devoid of glutathione peroxidase-like activity, shows the same inhibitory activity towards superoxide anion radical production the observed effect of ebselen can not be explained by the described glutathione peroxidase-like activity. The observed inhibition is probably caused by an inhibition of protein kinase C or inhibition at a level distal to protein kinase C activation.