Screening for free radical scavenging and cell aggregation inhibitory activities by secondary metabolites from Turkish Verbascum species

Free radical scavenging and cell aggregation inhibitory activities of 36 secondary metabolites isolated from the methanolic extracts of Verbascum cilicicum Boiss., V. lasianthum Boiss. ex Bentham, V pterocalycinum var. mutense Hub.-Mor., and V. salviifolium Boiss. (Scrophulariaceae) were investigated. The isolated compounds, 6-O-vaniloyl ajugol (1), ilwensisaponin A (2), ilwensisaponin C (3), verbascoside (4), beta-hydroxyacteoside (5), martynoside (6), poliumoside (7), forsythoside B (8), angoroside A (9), dehydrodiconiferyl alcohol-9-O-beta-D-glucopyranoside (10), dehydrodiconiferyl alcohol-9'-O-beta-D-glucopyranoside (11), apigenin 7-O-beta-glucopyranoside (12), luteolin 7-O-beta-glucopyranoside (13), luteolin 3'-O-beta-glucopyranoside (14) and chrysoeriol 7-O-beta-glucopyranoside (15), exhibited a dose-dependent inhibition of bioautographic and spectrophotometric DPPH activities. Verbascoside (4) was the most active (IC50 4.0 microg/ml) comparing it to vitamin C (IC50 4.4 microg/ml) to inhibit phorbol 12-myristate 13-acetate (PMA)-induced peroxide-catalyzed oxidation of 2',7'-dichlorofluorescein (DCFH) by reactive oxygen species (ROS) within human promyelocytic HL-60 cells. Ilwensisaponin A (2) (MIC 6.9 microg/ml) showed moderate in vitro activity on lymphocyte-associated antigen-1 (LFA-1)/intercellular adhesion molecule-1 (ICAM-1)-mediated aggregation using the HL-60 cell line [positive control was cytochalasin B (MIC 2.3 microg/ml)]. None of the other compounds showed free radical scavenging and cell aggregation inhibitory activities.     

In vivo activity of pseudoguaianolide sesquiterpene lactones in acute and chronic inflammation

The pseudoguaianolide sesquiterpene lactones 4-alpha-O-acetyl-pseudoguaian-6beta-olide (1), hymenin (2), ambrosanolide (3), tetraneurin A (4), parthenin (5), hysterin (6) and confertdiolide (7) were evaluated for their ability to affect the inflammation responses induced by different agents. All the compounds showed activity against the 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced mouse ear edema. The ethyl phenylpropiolate (EPP)-induced mouse ear edema was inhibited by compounds 3, 5 and 7. However, when sesquiterpene-lactones were assayed on the arachidonic acid (AA)-induced mouse ear edema, none of them were active. The only sesquiterpene lactone orally active against the paw mouse edema induced by carrageenan was 7, which gave a 46% edema inhibition after 3 h. On the other hand, compounds 3, 5 and 7 reduced the serotonin-induced paw edema in mice, although compound 7 was inactive in presence of cycloheximide. In addition, the sesquiterpene lactones were assayed against the chronic inflammation induced by repeated application of TPA on mouse ear. Confertdiolide was the most active compound; it reduced the edema by 87% and had a more moderate effect against the leukocyte recruitment (36% reduction in myeloperoxidase (MPO) levels). A histological study of ear the samples treated with 7 presented no detectable morphological lesions such as those treated with dexamethasone. On the oxazolone-induced delayed type hypersensitivity (DTH) only compounds 4 and 5 were active 24 h after the challenge. Compound 5 affected polymorphonuclear leukocyte infiltration (69% reduction in MPO levels). The results suggest that the especial chemical structure and spatial conformation of confertdiolide may facilitate its anti-inflammatory effect.     

In vivo anti-inflammatory and antinociceptive activity evaluation of phenolic compounds from Sideritis stricta

An acetone extract obtained from aerial parts of S. stricta Boiss. & Heldr. apud Bentham, its fractions and phenolic compounds were investigated for their in vivo anti-inflammatory and antinociceptive activities. For the anti-inflammatory activity and for the antinociceptive activity assessment, carrageenan-induced hind paw edema and p-benzoquinone-induced abdominal constriction tests were used, respectively. The acetone extract of the plant and its phenolic fraction exhibited potent inhibitory activity against both bioassay models in mice. From the active phenolic fraction a well-known phenylethanoid glycoside, verbascoside (acteoside) (1), and two flavonoid glycosides, isoscutellarein 7-O-[6"'-O-acetyl-beta-D-allopyranosyl-(1-->2)]-beta-D-glucopyranoside (2) and isoscutellarein 7-O-[6"'-O-acetyl-beta-D-allopyranosyl-(1-->2)]-6"-O-acetyl-beta-D-glucopyranoside (3), were isolated. During phytochemical studies we also isolated a methoxyflavone, xanthomicrol (4), from the non-polar fraction. The structures of the isolated compounds were established by spectroscopic evidence (UV, IR, 1D- and 2D-NMR, MS). Although antinociceptive and anti-inflammatory activities of the phenolic components were found not significant in the statistical analysis, compounds 1 to 3 showed a notable activity without inducing any apparent acute toxicity as well as gastric damage. Furthermore, a mixture of flavonoid glycosides (2 + 3) exhibited a significant inhibitory effect in both models at a higher dose.     

Anti-inflammatory and antinociceptive activity of flavonoids isolated from Viscum album ssp. album

Viscum album L. has been used in the indigenous systems of medicine for treatment of headache and some inflammatory diseases. In order to evaluate this information, antinociceptive and anti-inflammatory activities of the five flavonoids (5,7-dimethoxy naringenin or 4',6'-dimethoxy chalcononaringenin) derivatives, isolated from the ethyl acetate fraction of the extract from V. album ssp. album, were investigated, namely 5,7-dimethoxy-flavanone-4'-O-beta-D-glucopyranoside (1), 2'-hydroxy-4',6'-dimethoxy-chalcone-4-O-beta-D-glucopyranoside (2), 5,7-dimethoxy-flavanone-4'-O-[2"-O-(5"'-O-trans-cinnamoyl)-beta-D-apiofuranosyl]-beta-D-glucopyranoside (3), 2'-hydroxy-4',6'-dimethoxy-chalcone-4-O-[2"-O-(5"'-O-trans-cinnamoyl)-beta-Dapiofuranosyl]-beta-D-glucopyranoside (4), 5,7-dimethoxy-flavanone-4'-O-[beta-D-apiofuranosyl-(1 --> 2)]-beta-D-glucopyranoside (5). For the antinociceptive activity assessment the p-benzoquinone-induced writhing test and for the anti-inflammatory activity the carrageenan-induced hind paw edema model in mice were used. The ethyl acetate fraction in a dose of 250 mg/kg as well as compounds 2 and 5 in a 30 mg/kg dose were shown to possess remarkable antinociceptive and anti-inflammatory activities per os without inducing any apparent acute toxicity as well as gastric damage.     

Antinociceptive and anti-inflammatory effects of saponin and iridoid glycosides from Verbascum pterocalycinum var. mutense Hub.-Mor

The anti-inflammatory and antinociceptive properties of four major compounds from the flowers of Verbascum pterocalycinum var. mutense were investigated. Saponin glycosides called ilwensisaponin A and C and iridoid glycosides known as ajugol and picroside IV were isolated from the methanolic extract. A dose-related anti-inflammatory and antinociceptive response were obtained in this study at doses of 100 and 200 mg/kg. The results of the evaluation of the anti-inflammatory activity induced by carrageenan and PGE1 showed that this species possesses active constituents that could diminish the cyclooxygenase activitiy. No effects were observed in the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ear edema model. Our results support the anti-inflammatory and analgesic effects of Verbascum pterocalycinum var. mutense. Ilwensisaponins A and C could explain in part the anti-inflammatory and analgesic activities of this species. Although antinociceptive and anti-inflammatory activities of ajugol and picroside IV were found insignificant in the statistical analysis, ilwensisaponin A and C showed notable activity without inducing any apparent acute toxicity as well as gastric damage.     

Analgesic,anti-inflammatory and anti-ulcer properties of Thai Perilla frutescence fruit oil in animals

Perilla frutescens fruit oil (PFO) is rich in α-linolenic acid (ALA) and exhibits biological activities. We aimed to investigate analgesic, anti-inflammatory and anti-ulcer activities of PFO and PFO-supplemented soybean milk (PFO-SM) in animal models. Analgesic activity was assessed in acetic acid-induced writhing in mice, while anti-inflammatory activity was performed in ethyl phenylpropiolate (EPP)-induced ear edema and carrageenan-induced hind paw edema in rats. Anti-ulcer effects were conducted in water immersion stress, HCl/ethanol and indomethacin-induced gastric ulcer in rats. Distinctly, PFO, containing 6.96 mg ALA and 2.61 mg LA equivalence/g, did not induce acute toxicity (LD₅₀ > 10 mL/kg) in mice. PFO (2.5 and 5 mL/kg) and PFO-SM (0.05 mL PFO equivalence/kg) inhibited incidences of writhing (16.8, 18.0 and 32.3%, respectively) in acetic acid-induced mice. In addition, topical applications of PFO (0.1 and 1 mL/ear) significantly inhibited EPP-induced ear edema (59.3 and 65.7%, respectively) in rats, while PFO-SM slightly inhibited ear edema (25.9%). However, PFO and PFO-SM did not inhibit carrageenan-induced hind paw edema in rats. Indeed, PFO (2.5 and 5 mL/kg) significantly inhibited gastric ulcers in rats that induced by water immersion stress (92.4 and 96.6%, respectively), HCl/ethanol (74.8 and 73.3%, respectively) and indomethacin (68.8 and 88.9%, respectively), while PFO-SM did not. PFO displayed potent analgesic, anti-inflammatory and anti-ulcer properties, while PFO-SM exerted only analgesic properties. Thus, Thai PFO and its functional drink offer potential benefits in treatment of analgesic, inflammatory diseases and gastric ulcer.     

A new hepatoprotective flavone glycoside from the flowers of Onopordum alexandrinum growing in Egypt

A bioactivity-guided fractionation of the ethyl acetate fraction of the flowers of Onopordum alexandrinum L. (Asteraceae) yielded a new flavonoidal glycoside designated as acacetin-7-O-galacturonide (9), alongside with nine known flavonoids; 6-methoxy-apigenin (hispidulin) (1), acacetin (2), apigenin (3), luteolin (4), kaempferol (5), eriodictyol (6), apigenin-7-O-glucoside (7), luteolin-7-O-glucoside (8), and kaempferol-3-O-rutinoside (10). The compounds were assayed for their hepatoprotective activity against CCl4-induced hepatic cell damage in rats and free radical scavenging activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH). Compounds 4, 6, 9, and 10 have not been previously reported from flowers of O. alexandrinum L., and this is the first report of acacetin-7-O-galacturonide (9) in nature which has also shown significant hepatoprotective and free radical scavenging effects. The isolated compounds were identified using different spectroscopic methods (UV, 1H NMR, 13C NMR, HMQC, HMBC, and COSY).     

Anti-inflammatory activity of licochalcone A isolated from Glycyrrhiza inflata

Licochalcone A was isolated from the roots of Glycyrrhiza inflata and evaluated for its anti-inflammatory activity in xylene-induced mice ear edema and carrageenan-induced paw edema tests. At the same time, the inhibition of prostaglandin biosynthesis by licochalcone A was also studied in lipopolysaccharide (LPS)-induced mouse macrophage cells. At 5 mg/ ear, licochalcone A showed remarkable effects against acute inflammation induced by xylene, and at the doses of 2.5, 5, 10 mg/kg (p.o.), licochalcone A reduced significantly paw edema induced by carrageenan compared to the control at the fourth hour. Both COX-2 activity and expression were significantly inhibited by licochalcone A at all the test doses. Therefore, licochalcone A could be a useful compound for the development of new anti-inflammatory agents.     

Evaluation of the anti-inflammatory and analgesic activity of Me-UCH9, a dual cyclooxygenase-2/5-lipoxygenase inhibitor

Recently, we reported the dual inhibition of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LO) activity by some phenylsulphonyl urenyl chalcone derivatives. 2,4-dichloro-4'N[N'(4'methylphenylsulphonyl)urenyl] chalcone (Me-UCH9), was selected in the present study to determine its potential anti-inflammatory and analgesic effect after oral administration in several animal models related to the activation of COX-2 and 5-LO pathways. In the zymosan stimulated mouse air pouch model, Me-UCH9, reduced in a dose-dependent manner leukotriene B(4) (LTB(4)) levels in pouch exudates obtained at 4 h, as well as prostaglandin E(2) (PGE(2)) generated through COX-2 activation at 24 h. Tumor necrosis factor alpha (TNF-alpha) and myeloperoxidase activity were also strongly inhibited in this model. Me-UCH9 significantly reduced granuloma size and vascular index determined in the murine air pouch granuloma model of angiogenesis. In the carrageenan-induced paw edema, this compound inhibited inflammatory response and pain, as well as PGE(2) and LTB(4) content in paw edematous fluid. Analgesic properties were corroborated in the murine phenyl-p-benzoquinone-induced writhing test. Finally, Me-UCH9 exerted anti-inflammatory effects in the chronic model of rat adjuvant-induced arthritis, both inhibiting paw swelling and reducing PGE(2) content. Our findings confirm that Me-UCH9 can modulate inflammatory and nociceptive responses in relation to the dual inhibition of COX-2 and 5-LO activities presented by this compound.     

Anti-inflammatory activities of inotilone from Phellinus linteus through the inhibition of MMP-9, NF-κB, and MAPK activation in vitro and in vivo

Inotilone was isolated from Phellinus linteus. The anti-inflammatory effects of inotilone were studied by using lipopolysaccharide (LPS)-stimulated mouse macrophage RAW264.7 cells and λ-carrageenan (Carr)-induced hind mouse paw edema model. Inotilone was tested for its ability to reduce nitric oxide (NO) production, and the inducible nitric oxide synthase (iNOS) expression. Inotilone was tested in the inhibitor of mitogen-activated protein kinase (MAPK)?[extracellular signal-regulated protein kinase (ERK), c-Jun NH(2)-terminal kinase (JNK), p38], and nuclear factor-κB (NF-κB), matrix-metalloproteinase (MMP)-9 protein expressions in LPS-stimulated RAW264.7 cells. When RAW264.7 macrophages were treated with inotilone together with LPS, a significant concentration-dependent inhibition of NO production was detected. Western blotting revealed that inotilone blocked the protein expression of iNOS, NF-κB, and MMP-9 in LPS-stimulated RAW264.7 macrophages, significantly. Inotilone also inhibited LPS-induced ERK, JNK, and p38 phosphorylation. In in vivo tests, inotilone decreased the paw edema at the 4(th) and the 5(th) h after Carr administration, and it increased the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx). We also demonstrated that inotilone significantly attenuated the malondialdehyde (MDA) level in the edema paw at the 5(th) h after Carr injection. Inotilone decreased the NO and tumor necrosis factor (TNF-α) levels on serum at the 5(th) h after Carr injection. Western blotting revealed that inotilone decreased Carr-induced iNOS, cyclooxygenase-2 (COX-2), NF-κB, and MMP-9 expressions at the 5(th) h in the edema paw. An intraperitoneal (i.p.) injection treatment with inotilone diminished neutrophil infiltration into sites of inflammation, as did indomethacin (Indo). The anti-inflammatory activities of inotilone might be related to decrease the levels of MDA, iNOS, COX-2, NF-κB, and MMP-9 and increase the activities of CAT, SOD, and GPx in the paw edema through the suppression of TNF-α and NO. This study presents the potential utilization of inotilone, as a lead for the development of anti-inflammatory drugs.     

Changes in prostaglandin E2 (PGE2) levels in paw exudate, stomach and kidney of arthritic rats: effects of flosulide

To further examine the organ-specific toxic effects of selective and non-selective COX-2 inhibitors in adjuvant arthritis (CAA), we assessed the PGE2 concentration in various organs. AA was induced by intradermal injection of Mycobacterium butyricum. Fourteen days after inoculation, AA rats were selected and treated orally every day for two weeks with the selective COX-2 inhibitor, flosulide, or the COX-1-COX-2 inhibitor, indomethacin. The time-course of paw swelling was determined. At the end of treatments, PGE2 was extracted from paw, stomach (wall and mucosa) and kidney and its concentration was determined by ELISA. Paw edema increase was accompanied by a rise in PGE2 concentration. PGE2 also increased in stomach (mucosa and wall) and kidney. The anti-inflammatory treatment with flosulide (5 mg/kg x day), and indomethacin (1 mg/kg x day), reduced plantar edema by 98.0% and 74.4% respectively. Both drugs greatly decreased PGE2 levels in paw (73.7-53.2%), stomach wall (84.5-80.3%), stomach mucosa (109.9-110.9%) and kidney (92.9-97.5% respectively). However, PGE2 reductions in AA rats did not fall significantly below control values.     

A hydroxyl group of flavonoids affects oral anti-inflammatory activity and inhibition of systemic tumor necrosis factor-alpha production

We previously reported that oral administration of luteolin can inhibit serum tumor necrosis factor (TNF)-alpha production and several inflammatory and allergic models. We investigated here the effect of various flavonoids which resemble luteolin in structure. Lipopolysaccharide (LPS)-induced TNF-alpha production from macrophages was inhibited by treatment with flavone (luteolin, apigenin, and chrysin), flavonol (quercetin and myricetin), flavanonol (taxifolin), and anthocyanidin (cyanidin chloride) in vitro. Most of these, however, did not affect mice when administered orally. Serum TNF-alpha production was inhibited only by luteolin or apigenin, and only luteolin or quercetin inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ear edema. These results suggest that the structure of luteolin: 3',4',5,7-tetrahydroxyflavone, is most suitable for the oral anti-inflammatory activity and that existence or disappearance of a hydroxy group may cause a loss of efficiency.     

Anti-inflammatory activity of Urera baccifera (Urticaceae) in Sprague-Dawley rats

On a preliminary test, anti-inflammatory and analgesic dose-related activities on rats were observed for the aqueous fraction of Urera baccifera; this extract was bioassay-guided fractionated and the final aqueous fraction was used according the ethnobotanical use. Carrageenan-induced edema (n = 6), was used as an assay in the fractionating process. The anti-inflammatory and antinociceptive properties of the final aqueous fraction were studied using in vivo models. For the anti-inflammatory activity rat paw edema (n = 6), pleurisy induced by carrageenan (n = 6) and ear edema induced by topical croton oil (n = 6) models were used, and tail-flick test (n = 6), abdominal constrictions induced by acetic acid (n = 6), and formalin test (n = 6), were used for the antinociceptive activity. The tests performed showed an inhibition effect on leukocyte migration, and a reduction on pleural exudate, as well as dose-dependant peripheral analgesic activity, at a range of 25-100 mg/kg i.p. The final aqueous fraction contains most of the anti-inflammatory activity of the plant U. baccifera. A possible mechanism of action is discussed and based on the results we conclude that this plant has a potential for both anti-inflammatory and analgesic activity at the clinical level.     

Topical anti-inflammatory activity of flavonoids and a new xanthone from Santolina insularis

Bioactivity-guided fractionation of the methanol extract from the leaves of Santolina insularis led to the isolation of one new xanthone, (E)-3-(6-[(E)-3-hydroxy-3-oxo-1-propenyl]-9-oxo-9H-xanthen-2-yl)-2-propenoic acid, together with six known flavonoids: hispidulin, nepetin, cirsimaritin, rhamnocitrin, luteolin and luteolin 7-O-beta-D-glucopyranoside. The structures were elucidated by means of 1D-, 2D-NMR spectroscopy and mass spectrometry. The topical anti-inflammatory activity of all isolated compounds and extracts was investigated employing the croton oil-induced dermatitis in mouse ear. The most active compound, luteolin, showed an ID50 of 0.3 micromol/cm(2) and prevented ear oedema more effectively than an equimolar dose of indomethacin within 24 h.     

Luteolin and luteolin-7-O-glucoside from dandelion flower suppress iNOS and COX-2 in RAW264.7 cells

Both reactive oxygen- and nitrogen-derived reactive species play important roles in physiological and pathophysiological conditions. Flavones, luteolin and luteolin-7-O-glucoside along with a rich plant source of both flavones, namely dandelion (Taraxacum officinale) flower extract were studied for antioxidant activity in different in vitro model systems. In this current study, luteolin and luteolin-7-O-glucoside at concentrations lower than 20 microM, significantly (p < 0.05) suppressed the productions of nitric oxide and prostaglandin E2 (PGE2) in bacterial lipopolysaccharide activated-mouse macrophage RAW264.7 cells without introducing cytotoxicity. The inhibitory effects were further attributed to the suppression of both inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expression, and not reduced enzymatic activity. Similar suppression for both inducible enzymes was also found with the presence of dandelion flower extract, specifically, the ethyl acetate fraction of dandelion flower extract which contained 10% luteolin and luteolin-7-O-glucoside.     

两粤黄檀乙醇提取物化学成分分析及抗炎活性研究

为了研究壮药两粤黄檀的化学成分及其抗炎活性,阐明其药理作用机制,该研究采用小鼠二甲苯致炎耳廓肿胀法、角叉菜胶致炎足肿胀急性炎症模型,观察不同剂量两粤黄檀乙醇提取物对小鼠耳廓肿胀度、肿胀率及足肿胀度的影响,并利用液相色谱-质谱(LC-MS)、热裂解气相色谱-质谱(PY-GC/MS)等技术分析提取物的化学成分,结合网络药理...     

Anti-inflammatory activities of furanoditerpenoids and other constituents from Fibraurea tinctoria

Five new furanoditerpenoids, epi-8-hydroxycolumbin (1), fibaruretin B (2), C (3), E (5), and F (6), were isolated from the stems of Fibraurea tinctoria, as well as fibaruretin D (4) from the natural source for the first time, and 39 known compounds. The structures (1-6) were elucidated on the basis of spectroscopic analysis. All the isolated furanoditerpenoids (1-16) were examined for their in vitro activity and some were in vivo anti-inflammatory activity. Compounds 8 and 9 showed significant anti-inflammatory action administered at a dose of 100mg/kg of reducing carrageenan mice paw edema, whereas compound 7, 9, 10, 14, and 16 were more potent to inhibit NO production. The inhibitory effects of these compounds are dose-dependent (1-4 microg/ml).     

Effect of simulated microgravity on PGE2-induced edema and hyperalgesia in rat paws: pharmacological data and biochemical correlates

The aim of the present study has been to investigate the effect of conditions of modeled microgravity using a three-dimensional clinostat (Random Positioning Machine, RPM) on edema and thermal hyperalgesia induced by prostaglandin E2 (PGE2) in the hind paw of rat. Our results showed that RPM reduced PGE2-evoked edema associated to a significant decrease in hyperalgesia compared to ground control animals. To further characterize the mechanisms by which RPM induces anti-inflammatory and anti-hyperalgesic action, we performed biochemical assays of PGE2 and Western immunoblot experiments to assess whether the intraplantar administration of exogenous PGE2 modifies the expression of the iNOS. These results showed that RPM diminished the levels of PGE2 in exudates of paws previously treated with PGE2, but did not influence the iNOS expression.     

Anti-inflammatory and cytotoxic activities of chichipegenin, peniocerol, and macdougallin isolated from Myrtillocactus geometrizans (Mart. ex Pfeiff.) Con

The oleanane-type triterpene chichipegenin and the sterols peniocerol and macdougallin, isolated from Myrtillocactus geometrizans, showed anti-inflammatory activities in both the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse ear edema model and the carrageenan-induced rat paw edema model. All tested compounds inhibited the TPA-induced edema in a dose-dependent manner, with ED50 values less than or equal to that shown by indomethacin. Among them, peniocerol was the most active compound. However, only peniocerol and macdougallin reduced carrageenan-induced rat paw edema. On the other hand, peniocerol and macdougallin showed cytotoxicity against several human cancer cell lines. These results indicate that compounds isolated from M. geometrizans possess antiinflammatory and cytotoxic properties, and the presence of chichipegenin in the aerial parts could justify the medicinal uses attributed to the plant.     

Effects of naturally occurring dihydroflavonols from Inula viscosa on inflammation and enzymes involved in the arachidonic acid metabolism

The anti-inflammatory properties of three flavanones isolated from Inula viscosa, sakuranetin, 7-O-methylaromadendrin, and 3-acetyl-7-O-methylaromadendrin, have been tested both in vitro and in vivo. Acute inflammation in vivo was induced by means of topical application of 12-O-tetradecanoylphorbol 13-acetate (TPA) to mouse ears or by subcutaneous injection of phospholipase A(2) (PLA(2)) into mouse paws. The test compounds were evaluated in vitro for their effect on both the metabolism of arachidonic acid and on the release and/or activity of enzymes involved in the inflammatory response such as elastase, myeloperoxidase (MPO), and protein kinase C (PKC). The most active compounds in vivo against PLA(2)-induced paw oedema were 7-O-methylaromadendrin (ED(50)=8 mg/kg) and sakuranetin (ED(50)=18 mg/kg). In contrast, the most potent compound against TPA-induced ear oedema was 3-acetyl-7-O-methylaromadendrin (ED(50)=185 microg/ear), followed by sakuranetin (ED(50)=205 microg/ear). In vitro, the latter compound was the most potent inhibitor of leukotriene (LT) B(4) production by peritoneal rat neutrophils (IC(50)=9 microM) and it was also the only compound that directly inhibited the activity of 5-lipoxygenase (5-LOX). 3-Acetyl-7-O-methylaromadendrin also inhibited LTB(4) production (IC(50)=15 microM), but had no effect on 5-LOX activity. The only flavanone that inhibited the secretory PLA(2) activity in vitro was 7-O-methylaromadendrin. This finding may partly explain the anti-inflammatory effect observed in vivo, although other mechanisms such as the inhibition of histamine release by mast cells may also be implicated. Sakuranetin at 100 microM was found to inhibit elastase release, although this result is partly due to direct inhibition of the enzyme itself. At the same concentration, 7-O-methylaromadendrin only affected the enzyme release. Finally, none of the flavanones exhibited any effect on MPO or PKC activities. Taken together, these findings indicate that sakuranetin may be a selective inhibitor of 5-LOX.