Suppression of intracellular calcium levels and inhibition of degranulation in RBL-2H3 mast cells by the sesquiterpene lactone parthenolide.

Pretreatment with parthenolide for 60 min inhibited the antigen-induced degranulation of RBL-2H3 mast cells; the IC(50) value being 4.5 ± 0.4 µM. The inhibition was not due to suppression of the phosphatidylinositol 3-kinase pathway because the antigen-induced phosphorylation of Akt was not inhibited by parthenolide. The antigen-induced increase in intracellular calcium levels was prevented by parthenolide, suggesting that parthenolide inhibited the antigen-induced degranulation by suppressing an increase in intracellular calcium levels. In support of this, parthenolide was found to prevent ionomycin-induced degranulation by inhibiting an increase in intracellular calcium levels. Therefore, parthenolide inhibits the degranulation of mast cells by preventing an increase in intracellular calcium levels.

Suppression of the antigen-stimulated RBL-2H3 mast cell activation by Artekeiskeanol A.

Effects of artekeiskeanol A, a newly isolated coumarin derivative from Artemisa keiskeana Miq. (Compositae), the extract of which is used for treatment of rheumatoid arthritis as a folk medicine, on the antigen-induced activation of RBL-2H3 cells were examined. RBL-2H3 cells were sensitized with dinitrophenol (DNP)-specific IgE, and then stimulated with the antigen DNP-conjugated human serum albumin (DNP-HSA). Artekeiskeanol A at 10 to 100 microM inhibited the antigen-induced degranulation in a concentration-dependent manner, the IC(50) value being 38.0 + or - 0.2 microM. Degranulation induced by thapsigargin or A23187 also was inhibited by artekeiskeanol A at 10 to 100 microM. The antigen-induced increase in the levels of mRNA for tumor necrosis factor (TNF)-alpha and interleukin (IL)-13 and phosphorylations of Akt, p38 mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK) and p44/42 MAPK were also suppressed by artekeiskeanol A. Our findings suggested that the effectiveness of the extract of A. keiskeana might partly be due to the inhibition of mast cell activation by artekeiskeanol A.

Lead compounds for anti-inflammatory drugs isolated from the plants of the traditional oriental medicine in Korea.

Effects of compounds isolated from medicinal plants in Korea on prostaglandin E2 (PGE2) production in rat peritoneal macrophages were examined, and mechanism of action of the active constituents was analyzed. The active constituents were as follows; tectorigenin and tectoridin isolated from the rhizomes of Belamcanda chinensis, platycodin D isolated from the roots of Platycodon grandiflorum, imperatorin isolated from the roots of Angelica dahurica, and hyperin isolated from the roots of Acanthopanax chiisanensis. These compounds inhibit the induction of cyclooxygenase-2 (COX-2), thus inhibiting PGE2 production. The chemically synthesized chalcone derivative, 2'-hydroxy-4'-methoxychalcone, also inhibits PGE2 production by suppressing COX-2 induction. In contrast, taiwanin C isolated from the roots of Acanthopanax chiisanensis inhibited PGE2 production by direct inhibition of COX-1 and COX-2.

Effects of hyperin, isoquercitrin and quercetin on lipopolysaccharide-induced nitrite production in rat peritoneal macrophages.

The extract of the root of Acanthopanax chiisanensis Nakai is used for the treatment of inflammation. To analyse the action mechanism of this extract, the effect of hyperin (quercetin-3-O-beta-d-galactose) isolated from the ethyl acetate fraction of the root of A. chiisanensis on nitrite production and induction of inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS, 1 microg/mL)-stimulated rat peritoneal macrophages were examined. The effect of the structurally related compounds, isoquercitrin (quercetin-3-O-beta-d-glucose) and quercetin (an aglycone of the two compounds) isolated from the extract of the leaves of Vaccinium koreanum Nakai was also examined to compare the effect. It was shown that hyperin inhibited the LPS-induced iNOS expression and nitrite production. Of the three compounds, quercetin showed the most potent inhibitory activity. The phosphorylation of p44/42 mitogen activated protein kinase (MAPK), p38 MAPK and c-Jun N-terminal kinase (JNK) were also inhibited by these compounds. These findings suggested that hyperin in the extract of the root of A. chiisanensis inhibits nitric oxide (NO) production through inhibition of the expression of iNOS by attenuation of p44/p42 MAPK, p38 MAPK and JNK, and thus participates in the antiinflammatory activity of the extract.

Inhibition of bone resorption in cultures of mouse calvariae by apicularen A.

Apicularens A and B were isolated from the myxobacterial genus Chondromyces apiculatus JW184. Apicularen A inhibited bafilomycin A1-sensitive ATP-dependent proton transport into microsome vesicles more potently than apicularen B. Bone resorption in cultures of mouse calvariae induced by human parathyroid hormone (PTH) or interleukin-1beta (IL-1beta) was inhibited by apicularen A at 10 and 100 nM, while apicularen B had no effect. The bisphosphonate incadronate inhibited bone resorption at 100 nM, being less effective than apicularen A. Our findings indicate that apicularen A inhibits bone resorption induced by PTH or IL-1beta more potently than apicularen B, probably due to inhibition of the V-ATPase.

Inhibitory effects of isorhamnetin-3-O-beta-D-glucoside from Salicornia herbacea on rat lens aldose reductase and sorbitol accumulation in streptozotocin-induced diabetic rat tissues.

The inhibitory effects of compounds from Salicornia herbacea (Chenopodiaceae) on rat lens aldose reductase (RLAR) and sorbitol accumulation in streptozotocin-induced diabetic rat tissues were investigated. The various fractions from the MeOH extract of S. herbacea were tested for their effects on RLAR in vitro. Among them, the EtOAc fraction was found to exhibit a potent RLAR inhibition (IC(50)=0.75 microg/ml), from which an active principle as a potent AR inhibitor was isolated and its chemical structure was elucidated as isorhamnetin-3-O-beta-D-glucoside (1) by spectral analysis. Compound 1 exhibited a potent RLAR inhibition in vitro, its IC(50) being 1.4 microM. Compound 1, when administered orally at 25 mg/kg in streptozotocin (STZ)-induced diabetic rats, caused not only a significant inhibition of serum glucose concentration but also sorbitol accumulation in the lenses, red blood cells (RBC), and sciatic nerves. These results indicate that compound 1 from S. herbacea is a leading compound for further study as a new drug for the prevention and/or treatment of diabetes and its complications.

Induction of apoptosis by apicularen A in human promyelocytic leukemia cell line HL-60.

Apicularen A, a macrolide isolated from the myxobacterial genus Chondromyces, suppressed the proliferation of human promyelocytic leukemia cells (HL-60 cells), increased the release of lactate dehydrogenase and induced condensation and fragmentation of chromatin at 1 to 100 nM. In addition, it induced the DNA fragmentation, increased the percentage of annexin V-stained cells, and cleaved poly(ADP-ribose) polymerase (PARP), a substrate of caspase. In contrast, apicularen B, an N-acetylglucosamine glycoside of apicularen A, had no such effects at 100 nM. These findings indicated that apicularen A induces apoptosis in HL-60 cells by activating caspases. Phosphorylation of p44/42 MAPK, p38 MAPK and Akt was not induced by apicularen A at 100 nM, suggesting that the apicularen A-induced apoptosis in HL-60 cells is not regulated by the activation of p44/42 MAPK, p38 MAPK or Akt. Furthermore, by acridine orange staining of the cells, it was suggested that apicularen A but not apicularen B inhibits vacuolar-type H+-ATPase.

Lignans from Acanthopanax chiisanensis having an inhibitory activity on prostaglandin E2 production.

The chloroform and the ethyl acetate fractions from the roots of Acanthopanax chiisanensis exhibited the significant inhibition of TPA-induced prostaglandin E(2) (PGE(2)) production in rat peritoneal macrophages. Five lignans were isolated from the chloroform fraction and their structures were elucidated as l-sesamin, helioxanthin, savinin, taiwanin C, and 3-(3,4-dimethoxybenzyl)-2-(3,4-methylenedioxybenzyl)butyrolactone. Among the lignans tested, taiwanin C showed the most potent inhibitory activity (IC(50) = 0.12 microM) on PGE(2) production with the relative order of potency, taiwanin C >> 3-(3,4-dimethoxybenzyl)-2-(3,4-methylenedioxybenzyl)butyrolactone > savinin = helioxanthin. l-Sesamin showed no inhibitory activity at 30 microM.

Antiinflammatory activity of hyperin from Acanthopanax chiisanensis roots.

The chloroform and the ethyl acetate fractions from the roots of Acanthopanax chiisanensis exhibited a significant inhibition of prostaglandin E2 (PGE2) production in rat peritoneal macrophages stimulated by the protein kinase C activator, 12-O-tetradecanoylphorbol 13-acetate (TPA). Hyperin was isolated as an active principle from the ethyl acetate fraction. It suppressed not only PGE2 production but also nitric oxide (NO) production in vitro in a concentration dependent manner, their IC50, being 24.3 and 32.9 microM, respectively. Hyperin also caused a significant inhibition of increase in acetic acid-induced vascular permeability in mice in vivo.

Anti-angiogenic and anti-tumor activities of isoflavonoids from the rhizomes of Belamcanda chinensis.

The present study was carried out to clarify whether tectorigenin and tectoridin isolated from the rhizomes of Belamcanda chinensis (Iridaceae) inhibit angiogenesis by the experimental methods in vitro and in vivo. Tectorigenin and tectoridin decreased angiogenesis of both chick embryos in the chorioallantoic membrane assay and basic fibroblast growth factor-induced vessel formation in the mouse Matrigel plug assay. Both compounds also reduced the proliferation of calf pulmonary arterial endothelial (CPAE) cells and found to possess relatively weak gelatinase/collagenase inhibitory activity in vitro. Tectorigenin exhibited a much stronger anti-proliferative activity than its glycoside, tectoridin and was almost equipotent to that of genistein, a reference drug. Tectorigenin, when administered subcutaneously at the dose of 30 mg/kg for 20 days to mice implanted with murine Lewis lung carcinoma (LLC), caused a significant inhibition of tumor volume by 30.8 %. Tectorigenin and tectoridin, when treated i. p. at the same dosage for 10 days to ICR mice bearing sarcoma 180, caused a significant suppression in tumor weight by 44.2 and 24.8 %, respectively.

Inhibitory effects of furanocoumarins isolated from the roots of Angelica dahurica on prostaglandin E2 production.

We have isolated five furanocoumarins, byakangelicin, phellopterin, imperatorin, isoimperatorin, and oxypeucedanin methanolate, from the roots of Angelica dahurica (Umbelliferae) and prepared five semi-synthesized compounds by the partial reduction of each isolated furanocoumarin, and the effects of these compounds on lipopolysaccharide (LPS)-induced prostaglandin E2 (PGE2 ) production in rat peritoneal macrophages were examined. Among these compounds, imperatorin showed the most potent inhibitory activity on the LPS-induced PGE2 production. It also inhibited the LPS-induced expressions of cyclooxygenase (COX)-2 and microsomal prostaglandin E synthase (mPGES). These findings suggest that the inhibitory effect of furanocoumarins on the LPS-induced PGE2 production is due to the inhibition of the expression of COX-2 and mPGES.

Inhibition of prostaglandin E(2) production by taiwanin C isolated from the root of Acanthopanax chiisanensis and the mechanism of action.

Five lignans, l-sesamin, savinin, helioxanthin, taiwanin C, and cis-dibenzylbutyrolactone, were isolated from the root of Acanthopanax chiisanensis (Araliaceae), a Korean medicinal plant, and their inhibitory effects on the production of prostaglandin (PG) E(2) stimulated by 12-O-tetradecanoylphorbol 13-acetate (TPA) in rat peritoneal macrophages were examined. Among the five lignans, taiwanin C was the most potent (IC(50)=0.12 microM), followed by helioxanthin, cis-dibenzylbutyrolactone, and savinin. l-Sesamin had no effect. Taiwanin C showed no inhibitory effect on the TPA-induced release of radioactivity from [3H]arachidonic acid-labeled macrophages, nor did it inhibit the expression of cyclooxygenase (COX)-2 protein induced by TPA. However, the activities of isolated COX-1 and COX-2 were inhibited by taiwanin C (IC(50)=1.06 and 9.31 microM, respectively), reflecting the inhibition of both COX-1- and COX-2-dependent PGE(2) production in the cell culture system. These findings suggest that the mechanism of action of taiwanin C in the inhibition of PGE(2) production is the direct inhibition of COX enzymatic activity.

Plasma extravasation induced by dietary supplemented histamine in histamine-free mice.

Histidine decarboxylase (HDC) synthesizes endogenous histamine from histidine in mammals. To evaluate the role of histamine in skin allergic reaction, we used HDC gene knockout mice lacking histamine. No plasma extravasation reaction was observed in HDC-/- mice after passive cutaneous anaphylaxis (PCA) test. Compound 48/80, a mast cell granule depletor, produced plasma extravasation inHDC+/+ mice but no extravasation in HDC-/- mice. Interestingly, orally administered histamine was distributed in the skin in HDC-/- mice and in these histamine-supplemented mice the plasma extravasation reaction was observed after the injection of compound 48/80 and the PCA test. Cultured bone marrow-derived mast cells of HDC-/- mice took up histamine from the histamine-supplemented medium into the secretory granules. The absorbed histamine was released in response to the same antigen and antibody combination used as in PCA test. In contrast to the immediate-type response, the delayed-type hypersensitive response, observed as a thickening of the ear skin after trinitrochlorobenzene challenge (following sensitization), showed no differences between HDC+/+ and HDC-/- mice. Therefore, among the allergic skin reactions, histamine is revealed to be an important mediator especially for the plasma extravasation in an immediate-type allergy model.

Effect of the essential oil from the flowers of Magnolia sieboldii on the lipopolysaccharide-induced production of nitric oxide and prostaglandin E2 by rat peritoneal macrophages.

The essential oil from the flowers of Magnolia sieboldii was tested for its effects on lipopolysaccharide (LPS)-induced production of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) by rat peritoneal macrophages. It was shown to induce the production of NO and PGE 2 in a concentration-dependent manner (3 - 30 microg/ml). Gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) led to the identification of sixty compounds, of which beta-elemene (18.0 %), alpha-terpinene (14.83 %) and beta-myrcene (12.72 %) were the major constituents. Among these three compounds, alpha-terpinene was found to be the most effective one with inhibitory activity on NO and PGE(2) production by LPS-stimulated rat peritoneal macrophages.

Effects of naturally occurring isoflavones on prostaglandin E2 production.

Previously, we reported that the isoflavones tectorigenin and tectoridin, a glycosylated tectorigenin, isolated from the rhizomes of Belamcanda chinensis have an activity to inhibit prostaglandin (PG) E2 production in 12-O-tetradecanoylphorbol 13-acetate (TPA)-stimulated rat peritoneal macrophages. The inhibitory effect of tectorigenin is more potent than that of tectoridin. In this study, we investigated the structure-activity relationship of various isoflavones in the inhibition of PGE2 production in TPA-stimulated rat peritoneal macrophages. The isoflavones examined were isolated from the rhizomes of B. chinensis, and the flowers and the rhizomes of Pueraria thunbergiana. The order of potency to inhibit PGE2 production was as follows; irisolidone, tectorigenin > genistein > tectoridin (tectorigenin 7-glucoside), glycitein > daidzein. Kakkalide (irisolidone 7-xylosylglucoside), glycitin (glycitein 7-glucoside), daidzin (daidzein 7-glucoside), puerarin (daizein 8-glucoside), and genistin (genistein 7-glucoside) showed no significant inhibition. These findings indicated that 6-methoxylation and 5-hydroxylation increase the potency to inhibit PGE2 production and 7-O-glycosylation decreases the inhibitory activity.