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We investigated the suppressive effects of 3-O-methylquercetin 5,7,3',4'- O-tetraacetate (QMTA), a more-potent phosphodiesterase (PDE)3/4 inhibitor than quercetin 3-O-methyl ether (3-MQ), which has been reported to have the potential for treating asthma, against ovalbumin (OVA)-induced airway hyperresponsiveness (AHR). The IC50 value of QMTA for PDE3 was significantly less than that for PDE4. According to the Lineweaver-Burk analysis, QMTA (1-10 microM) competitively inhibited PDE3 and PDE4 activities. The Ki values were 0.9+/-0.3 (n=5) and 3.9+/-0.5 (n=5) microM, respectively, which significantly differed from each other, suggesting that QMTA has higher affinity for PDE3 than for PDE4. QMTA (3-10 microM) concentration-dependently relaxed the baseline level, and significantly inhibited cumulative OVA (10-100 microg/mL)-induced contractions in isolated sensitized guinea pig trachealis suggesting that QMTA has bronchodilator and inhibiting effects on mast cell degranulation. After the secondary challenge, the AHR was measured in unrestrained OVA-sensitized mice, with nebulized methacholine (MCh, 6.25-50 mg/mL), by barometric plethysmography using a whole-body plethysmograph. In the present results, QMTA (3-10 micromol/kg, I. P.) dose-dependently attenuated the enhanced pause (Penh) value induced by MCh (25-50 mg/mL). QMTA (3-10 micromol/kg, I. P.) also significantly inhibited total inflammatory cells, macrophages, neutrophils, lymphocytes, and eosinophils in BALF after determination of Penh values. It also significantly suppressed the release of interleukin (IL)-2, IL-4, IL-5, IFN-gamma, and TNF-alpha, with the exception that 3 micromol/kg QMTA did not suppress the releases of IL-5. QMTA even at 1 micromol/kg significantly inhibited eosinophils, IL-2, and TNF-alpha. In conclusion, our results strongly suggest that QMTA has greater potential than 3-MQ for the treatment of asthma.

One new diterpene, 8(14),15-sandaracopimaradiene-2alpha,3beta,18-triol (1), two new phenylpropane derivatives, i.e., (E)-methyl 2-(3,4-methylene-dioxyphenyl)-3-methoxypropenoate (2) and (E)-2-(3,4-methylene-dioxyphenyl)-3-methoxypropenoic acid (3), and two known diterpenes, ent-8(14),15-sandaracopimaradiene-2alpha,18-diol (4) and 8(14),15-sandaracopimaradiene-2alpha,18,19-triol (5), were isolated from the heartwoods and barks of Amentotaxus formosana, respectively. The anti-inflammatory activity of the diterpenes 1, 4, and 5 was assessed in vitro by determining their inhibitory effects on the chemical mediators released from mast cells, neutrophils, macrophages, and microglial cells. Compounds 1, 4, and 5 showed significant concentration-dependent inhibitory effects on the release of beta-glucuronidase from rat neutrophils in response to formyl-Met-Leu-Phe/cytochalasin B (fMLP/CB) with IC50 values of 5.5 +/- 1.8, 8.4 +/- 2.9 and 19.2 +/- 3.3 microM, respectively. Compounds 1 and 5 also showed significant concentration-dependent inhibitory effects on superoxide anion generation in rat neutrophils stimulated with fMLP/CB and phorbol 12-myristate 13-acetate (PMA) with IC50 values of 12.6 +/- 1.2 and 9.4 +/- 1.7, and 10.7 +/- 3.3 and 12.9 +/- 0.9 microM, respectively.

Rhamnus nakaharai Hayata (Rhamnaceae) has been used as a folk medicine in Taiwan for treating constipation, inflammation, tumors, and asthma. 3-O-Methylquercetin (3-MQ), a main constituent of the plant, has been reported to inhibit total cAMP- and cGMP-phosphodiesterase (PDE) of guinea pig trachealis at low concentrations. 3-MQ has been also reported to more selectively inhibit PDE3 than PDE4 with a low K(m) value. Therefore we were interested in investigating its suppressive effects on ovalbumin (OVA)-induced airway hyperresponsiveness in vivo and in vitro. 3-MQ (3-30 micromol/kg, i. p.) significantly suppressed the enhanced pause (Penh) value induced by aerosolized methacholine (50 mg/mL) in sensitized mice after secondary allergen challenge. 3-MQ (3-30 micromol/kg, i. p.) also significantly suppressed total inflammatory cells, macrophages, neutrophils, and eosinophils, but not lymphocytes. In addition, 3-MQ (3 micromol/kg, i. p.) significantly decreased the secretion of TNF-alpha, and at the highest dose (30 micromol/kg, i. p.) even decreased the secretions of IL-4, IL-5, and TNF-alpha. 3-MQ (1-10 microM) as well as Ro 20-1724 (3-30 microM), a selective PDE4 inhibitor, significantly attenuated OVA (100 microg/mL)-induced contractions. 3-MQ (30 microM) as well as milrinone (1-10 microM), a selective PDE3 inhibitor, significantly enhanced baseline contractions in isolated guinea pig left and right atria. However, neither 3-MQ nor milrinone significantly affected baseline beating rate in the right atria. 3-MQ (3-30 micromol/kg, i. p.) did not significantly affect systolic pressure in conscious mice. In conclusion, 3-MQ has both anti-inflammatory and bronchodilating effects, and has the potential for use in the treatment of asthma at a dose without affecting blood pressure.

Rhamnus nakaharai Hayata (Rhamnaceae), has been used as a folk medicine in Taiwan for treating constipation, inflammation, tumors and asthma. 3-O-methylquercetin (3-MQ), a main constituent of the plant, has been reported to inhibit total cAMP- and cGMP-phosphodiesterase (PDE) of guinea pig trachealis. Therefore we were interested in investigating the inhibitory effect of 3-MQ on various PDE isozymes from guinea pig lungs and hearts. Isolated guinea pig lungs and hearts were homogenized and centrifuged. The supernatant was chromatographed over a column of Q-sepharose, and eluted with various concentrations of NaCl. In the following order, PDE subtypes 1, 5, 2, 4 from lungs, and 3 from hearts were separated. The IC 50 values of 3-MQ on these isozymes were 31.9, 86.9, 18.6, 28.5 and 1.6 microM, respectively. 3-MQ (10-100 microM) non-competitively inhibited PDE2, but competitively inhibited PDE4. 3-MQ (1-10 microM) also competitively inhibited PDE3. However, 3-MQ (10-100 microM) did not competitively inhibit PDE1 and 5, although it had a tendency to competitively inhibit PDE1 at concentrations of 10 - 30 microM. The present results showed that K i value of 3-MQ was similar to that of milrinone in PDE3, and was not significantly different from that of Ro 20 - 1724 in PDE4, respectively. In conclusion, 3-MQ was revealed to be a selective and competitive PDE3/PDE4 inhibitor, although its inhibitory effect on PDE4 was not potent. Therefore, 3-MQ may have a potential in the treatment of asthma beside its antiviral activity.

Two new pentaoxygenated xanthones, 2,3-dihydroxy-1,6,7-trimethoxyxanthone (1) and 3,6-dihydroxy-1,5,7-trimethoxyxanthone (2) were isolated from the leaf of Hypericum geminiflorum. The antiplatelet activities of the constituents, 2,6-dimethoxy-p-benzoquinone (3), gemichalcone A (4), gemichalcone B (5), and cycloartocarpin (6), of this plant, were assessed in vitro by determining their inhibitory effects on the aggregation of washed rabbit platelets induced by various inducers. The anti-inflammatory effects of 4 and 5 were assessed in vitro by determining their inhibitory effects on the chemical mediators released from mast cells and neutrophils. Of the compounds tested, 4 exhibited the most potent inhibition of platelet aggregation induced by arachidonic acid (AA) and 4 and 5 strongly inhibited the release of beta-glucuronidase and lysozyme in formyl-Met-Leu-Phe (fMLP)-stimulated rat neutrophils.

We investigated the mechanisms of action of 3-O-methylquercetin (3-MQ), isolated from Rhamnus nakaharai (Hayata) Hayata (Rhamnaceae) which is used as a folk medicine for treating constipation, inflammation, tumors and asthma in Taiwan. The tension changes of tracheal segments were isometrically recorded on a polygraph. 3-MQ concentration-dependently relaxed histamine (30 microM)-, carbachol (0.2 microM)- and KCl (30 mM)-induced precontractions, and inhibited cumulative histamine-, and carbachol-induced contractions in a non-competitive manner. 3-MQ also concentration-dependently and non-competitively inhibited cumulative Ca(2+)-induced contractions in depolarized (K(+), 60 mM) guinea-pig trachealis. The nifedipine (10 microM)-remaining tension of histamine (30 microM)-induced precontraction was further relaxed by 3-MQ, suggesting that no matter whether VDCCs were blocked or not, 3-MQ may have other mechanisms of relaxant action. The relaxant effect of 3-MQ was unaffected by the removal of epithelium or by the presence of propranolol (1 microM), 2',5'-dideoxyadenosine (10 microM), methylene blue (25 microM), glibenclamide (10 microM), N(omega)-nitro-L-arginine (20 microM), or alpha-chymotrypsin (1 U/ml). However, 3-MQ (7.5 - 15 microM) and IBMX (3 - 6 microM), a positive control, produced parallel and leftward shifts of the concentration-response curve of forskoline (0.01 - 3 microM) or nitroprusside (0.01 - 30 microM). 3-MQ or IBMX at various concentrations (10 - 300 microM) concentration-dependently and significantly inhibited cAMP- and cGMP-PDE activities of the trachealis. The IC50 values of 3-MQ were estimated to be 13.8 and 14.3 microM, respectively. The inhibitory effects of 3-MQ on both enzyme activities were not significantly different from those of IBMX, a non-selective PDE inhibitor. The above results reveal that the mechanisms of relaxant action of 3-MQ may be due to its inhibitory effects on both PDE activities and its subsequent reducing effect on [Ca(2+)]i of the trachealis.3-MQ:3-O-methylquercetinIBMX:3-isobutyl-1-methylxanthineVDCCs:voltage dependent calcium channelscAMP:adenosine 3',5'-cyclic monophosphatecGMP:guanosine 3',5'-cyclic monophosphatePDE:phosphodiesteraseWe investigated the mechanisms of action of 3-O-methylquercetin (3-MQ), isolated from Rhamnus nakaharai (Hayata) Hayata (Rhamnaceae) which is used as a folk medicine for treating constipation, inflammation, tumors and asthma in Taiwan. The tension changes of tracheal segments were isometrically recorded on a polygraph. 3-MQ concentration-dependently relaxed histamine (30 microM)-, carbachol (0.2 microM)- and KCl (30 mM)-induced precontractions, and inhibited cumulative histamine-, and carbachol-induced contractions in a non-competitive manner. 3-MQ also concentration-dependently and non-competitively inhibited cumulative Ca(2+)-induced contractions in depolarized (K(+), 60 mM) guinea-pig trachealis. The nifedipine (10 microM)-remaining tension of histamine (30 microM)-induced precontraction was further relaxed by 3-MQ, suggesting that no matter whether VDCCs were blocked or not, 3-MQ may have other mechanisms of relaxant action. The relaxant effect of 3-MQ was unaffected by the removal of epithelium or by the presence of propranolol (1 microM), 2',5'-dideoxyadenosine (10 microM), methylene blue (25 microM), glibenclamide (10 microM), N(omega)-nitro-L-arginine (20 microM), or alpha-chymotrypsin (1 U/ml). However, 3-MQ (7.5 - 15 microM) and IBMX (3 - 6 microM), a positive control, produced parallel and leftward shifts of the concentration-response curve of forskoline (0.01 - 3 microM) or nitroprusside (0.01 - 30 microM). 3-MQ or IBMX at various concentrations (10 - 300 microM) concentration-dependently and significantly inhibited cAMP- and cGMP-PDE activities of the trachealis. The IC50 values of 3-MQ were estimated to be 13.8 and 14.3 microM, respectively. The inhibitory effects of 3-MQ on both enzyme activities were not significantly different from those of IBMX, a non-selective PDE inhibitor. The above results reveal that the mechanisms of relaxant action of 3-MQ may be due to its inhibitory effects on both PDE activities and its subsequent reducing effect on [Ca(2+)]i of the trachealis.3-MQ:3-O-methylquercetinIBMX:3-isobutyl-1-methylxanthineVDCCs:voltage dependent calcium channelscAMP:adenosine 3',5'-cyclic monophosphatecGMP:guanosine 3',5'-cyclic monophosphatePDE:phosphodiesterase

The anti-inflammatory activities of the isolated flavonoids, quercetin 3-O-methyl ether (1), kaempferol (2), and quercetin (3), of Rhamnus nakaharai, and anthraquinone, frangulin B (4), of Rhamnus formosana, were assessed in vitro by determining their inhibitory effects on the chemical mediators released from mast cells, neutrophils, macrophages, and microglial cells. Compounds 1 - 3 strongly inhibited the release of beta-glucuronidase and lysozyme from rat neutrophils stimulated with formyl-Met-Leu-Phe/cytochalasin B (fMLP/CB). Compound 1 strongly inhibited superoxide anion formation in fMLP/CB or phorbol 12-myristate 13-acetate (PMA)-stimulated rat neutrophils. Compound 1 exhibited potent inhibitory effect on tumor-necrosis factor-alpha ( TNF-alpha) formation in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells while 1 and 4 showed potent inhibitory effects on TNF-alpha formation in LPS/IFN-gamma (interferon-gamma)-stimulated murine microglial cell lines N9.

Two new steroidal alkaloids named capsimine and isocapsicastrine were isolated from the root bark of Solanum capsicastrum. Their structures were elucidated by chemical degradation and spectral data as (22R, 25R)-22,26-epiminocholest-5-ene-3 beta, 16 alpha-diol and (22S,25S)-O(3)-beta-D-glucopyranosyl-22,26-epiminocholest-5-ene-3 beta-16 alpha-diol, respectively. Capsicastrine, capsicastrine acetate, isoteinemine acetate, and etioline exhibited strong activity against liver damage induced by CCl4.