Magnolia extract is effective for the chemoprevention of oral cancer through its ability to inhibit mitochondrial respiration at complex I.

BACKGROUND: Magnolia extract (ME) is known to inhibit cancer growth and metastasis in several cell types in vitro and in animal models. However, there is no detailed study on the preventive efficacy of ME for oral cancer, and the key components in ME and their exact mechanisms of action are not clear. The overall goal of this study is to characterize ME preclinically as a potent oral cancer chemopreventive agent and to determine the key components and their molecular mechanism(s) that underlie its chemopreventive efficacy. METHODS: The antitumor efficacy of ME in oral cancer was investigated in a 4-nitroquinoline-1-oxide (4NQO)-induced mouse model and in two oral cancer orthotopic models. The effects of ME on mitochondrial electron transport chain activity and ROS production in mouse oral tumors was also investigated. RESULTS: ME did not cause detectable side effects indicating that it is a promising and safe chemopreventive agent for oral cancer. Three major key active compounds in ME (honokiol, magnolol and 4-O-methylhonokiol) contribute to its chemopreventive effects. ME inhibits mitochondrial respiration at complex I of the electron transport chain, oxidizes peroxiredoxins, activates AMPK, and inhibits STAT3 phosphorylation, resulting in inhibition of the growth and proliferation of oral cancer cells. CONCLUSION: Our data using highly relevant preclinical oral cancer models, which share histopathological features seen in human oral carcinogenesis, suggest a novel signaling and regulatory role for mitochondria-generated superoxide and hydrogen peroxide in suppressing oral cancer cell proliferation, progression, and metastasis. Video abstract.

A novel microbial technique for producing high-quality sophorolipids from horse oil suitable for cosmetic applications.

Horse oil contains linoleic, palmitoleic and unsaturated fatty acids that are similar to those in human skin, and may therefore be an ideal substance from which to isolate biosurfactants for cosmetic products to improve human skin quality. Herein, an innovative approach was developed to synthesise sophorolipids from horse oil by hydrolysis, followed by fermentation using the yeast Candida bombicola. The yield of sophorolipids from direct fermentation of horse oil and hydrolysed horse oil was 40.6 ± 1.3 g l-1 and 58.4 ± 1.8 g l-1 respectively. To further increase the yield, 30-40 g l-1 glucose was added in a fed-batch fermentation process to maintain the pH between 4.0 and 4.5, resulting in a conversion yield of 71.7 ± 0.8 g l-1 . The purity and structure of the synthesised sophorolipids were analysed by ultra-performance liquid chromatography-mass spectrometry and nuclear magnetic resonance. An in vitro human dermal fibroblast model was used as a surrogate for human skin to measure elastase inhibition activity. Antiwrinkle properties of isolated sophorolipids were better than those of horse oil or hydrolysed horse oil in several in vitro assays. Furthermore, no cytotoxicity was observed at a concentration of 50 µg ml-1 , and wound-healing capacity was evident in a cell culture model. Additionally, the synthesised sophorolipids attenuated lipopolysaccharide-induced expression of inflammatory cytokines in macrophages, and efficiently inhibited several strains of bacteria and yeast. In conclusion, fed-batch fermentation of hydrolysed horse oil is a novel and efficient approach for producing high-quality and high-yield sophorolipids that exhibit great potential as cosmetic ingredients.

Effect of isosecotanapartholide isolated from Artemisia princeps Pampanini on IL­33 production and STAT­1 activation in HaCaT keratinocytes.

The present study aimed to investigate the anti­inflammatory effect and mechanism of action of isosecotanapartholide (ISTP), isolated from Artemisia princeps Pampanini extract (APE). The effects of ISTP and APE on the proliferation of human keratinocytes following stimulation by tumor necrosis factor­α/interferon­Î³ were assessed. ISTP and APE downregulated the expression levels of signal transducer and activator of transcription­1 (STAT­1), and reduced interleukin­33 (IL­33) production. ISTP and APE inhibited the mRNA expression levels of thymus and activation­regulated chemokine (TARC/CCL17) in a dose­dependent manner. Western blot analysis demonstrated that ISTP and APE dose­dependently inhibited protein expression levels of intercellular adhesion molecule­1 and phosphorylation of STAT­1. The results of the present study indicate that ISTP may inhibit TARC/CCL17 production in human epidermal keratinocytes via the STAT­1 signaling pathway and may be associated with the inhibition of IL­33 production. The current study indicated that ISTP is an active component in APE and may be a potential therapeutic agent for the treatment of inflammatory skin disorders.

4-O-Methylhonokiol Protects HaCaT Cells from TGF-ß1-Induced Cell Cycle Arrest by Regulating Canonical and Non-Canonical Pathways of TGF-ß Signaling.

4-O-methylhonokiol, a neolignan compound from Magnolia Officinalis, has been reported to have various biological activities including hair growth promoting effect. However, although transforming growth factor-ß (TGF-ß) signal pathway has an essential role in the regression induction of hair growth, the effect of 4-O-methylhonokiol on the TGF-ß signal pathway has not yet been elucidated. We thus examined the effect of 4-O-methylhonokiol on TGF-ß-induced canonical and noncanonical pathways in HaCaT human keratinocytes. When HaCaT cells were pretreated with 4-O-methylhonokiol, TGF-ß1-induced G1/G0 phase arrest and TGF-ß1-induced p21 expression were decreased. Moreover, 4-O-methylhonokiol inhibited nuclear translocation of Smad2/3, Smad4 and Sp1 in TGF-ß1-induced canonical pathway. We observed that ERK phosphorylation by TGF-ß1 was significantly attenuated by treatment with 4-O-methylhonokiol. 4-O-methylhonokiol inhibited TGF-ß1-induced reactive oxygen species (ROS) production and reduced the increase of NADPH oxidase 4 (NOX4) mRNA level in TGF-ß1-induced noncanonical pathway. These results indicate that 4-O-methylhonokiol could inhibit TGF-ß1-induced cell cycle arrest through inhibition of canonical and noncanonical pathways in human keratinocyte HaCaT cell and that 4-O-methylhonokiol might have protective action on TGF-ß1-induced cell cycle arrest.

Magnolia bioactive constituent 4-O-methylhonokiol prevents the impairment of cardiac insulin signaling and the cardiac pathogenesis in high-fat diet-induced obese mice.

In obesity, cardiac insulin resistance is a putative cause of cardiac hypertrophy and dysfunction. In our previous study, we observed that Magnolia extract BL153 attenuated high-fat-diet (HFD)-induced cardiac pathogenic changes. In this study, we further investigated the protective effects of the BL153 bioactive constituent, 4-O-methylhonokiol (MH), against HFD-induced cardiac pathogenesis and its possible mechanisms. C57BL/6J mice were fed a normal diet or a HFD with gavage administration of vehicle, BL153, or MH (low or high dose) daily for 24 weeks. Treatment with MH attenuated HFD-induced obesity, as evidenced by body weight gain, and cardiac pathogenesis, as assessed by the heart weight and echocardiography. Mechanistically, MH treatment significantly reduced HFD-induced impairment of cardiac insulin signaling by preferentially augmenting Akt2 signaling. MH also inhibited cardiac expression of the inflammatory factors tumor necrosis factor-α and plasminogen activator inhibitor-1 and increased the phosphorylation of nuclear factor erythroid-derived 2-like 2 (Nrf2) as well as the expression of a Nrf2 downstream target gene heme oxygenase-1. The increased Nrf2 signaling was associated with decreased oxidative stress and damage, as reflected by lowered malondialdehyde and 3-nitrotyrosine levels. Furthermore, MH reduced HFD-induced cardiac lipid accumulation along with lowering expression of cardiac fatty acid translocase/CD36 protein. These results suggest that MH, a bioactive constituent of Magnolia, prevents HFD-induced cardiac pathogenesis by attenuating the impairment of cardiac insulin signaling, perhaps via activation of Nrf2 and Akt2 signaling to attenuate CD36-mediated lipid accumulation and lipotoxicity.

Portulaca oleracea extracts protect human keratinocytes and fibroblasts from UV-induced apoptosis.

Portulaca oleracea extracts, known as Ma Chi Hyun in the traditional Korean medicine, show a variety of biomedical efficacies including those in anti-inflammation and anti-allergy. In this study, we investigate the protective activity of the P. oleracea extracts against UVB-induced damage in human epithelial keratinocytes and fibroblasts by several apoptosis-related tests. The results suggest that P. oleracea extracts have protective effects from UVB-induced apoptosis.

The magnolia bioactive constituent 4-O-methylhonokiol protects against high-fat diet-induced obesity and systemic insulin resistance in mice.

Obesity is caused by a combination of both genetic and environmental risks. Disruption in energy balance is one of these risk factors. In the present study, the preventive effect on high-fat diet- (HFD-) induced obesity and insulin resistance in mice by Magnolia bioactive constituent 4-O-methylhonokiol (MH) was compared with Magnolia officinalis extract BL153. C57BL/6J mice were fed by normal diet or by HFD with gavage-administered vehicle, BL153, low-dose MH, and high-dose MH simultaneously for 24 weeks, respectively. Either MH or BL153 slightly inhibited body-weight gain of mice by HFD feeding although the food intake had no obvious difference. Body fat mass and the epididymal white adipose tissue weight were also mildly decreased by MH or BL153. Moreover, MH significantly lowered HFD-induced plasma triglyceride, cholesterol levels and activity of alanine transaminase (ALT), liver weight and hepatic triglyceride level, and ameliorated hepatic steatosis. BL153 only significantly reduced ALT and liver triglyceride level. Concurrently, low-dose MH improved HFD-induced hyperinsulinemia and insulin resistance. Furthermore, the infiltration of mast cells in adipose tissue was decreased in MH or in BL153 treatment. These results suggested that Magnolia bioactive constituent MH might exhibit potential benefits for HFD-induced obesity by improvement of lipid metabolism and insulin resistance.

BL153 partially prevents high-fat diet induced liver damage probably via inhibition of lipid accumulation, inflammation, and oxidative stress.

The present study was to investigate whether a magnolia extract, named BL153, can prevent obesity-induced liver damage and identify the possible protective mechanism. To this end, obese mice were induced by feeding with high fat diet (HFD, 60% kcal as fat) and the age-matched control mice were fed with control diet (10% kcal as fat) for 6 months. Simultaneously these mice were treated with or without BL153 daily at 3 dose levels (2.5, 5, and 10 mg/kg) by gavage. HFD feeding significantly increased the body weight and the liver weight. Administration of BL153 significantly reduced the liver weight but without effects on body weight. As a critical step of the development of NAFLD, hepatic fibrosis was induced in the mice fed with HFD, shown by upregulating the expression of connective tissue growth factor and transforming growth factor beta 1, which were significantly attenuated by BL153 in a dose-dependent manner. Mechanism study revealed that BL153 significantly suppressed HFD induced hepatic lipid accumulation and oxidative stress and slightly prevented liver inflammation. These results suggest that HFD induced fibrosis in the liver can be prevented partially by BL153, probably due to reduction of hepatic lipid accumulation, inflammation and oxidative stress.

Magnolia extract (BL153) protection of heart from lipid accumulation caused cardiac oxidative damage, inflammation, and cell death in high-fat diet fed mice.

Magnolia as an herbal material obtained from Magnolia officinalis has been found to play an important role in anti-inflammation, antioxidative stress, and antiapoptosis. This study was designed to investigate the effect of Magnolia extract (BL153) on obesity-associated lipid accumulation, inflammation, oxidative stress, and apoptosis in the heart. C57BL/6 mice were fed a low- (10 kcal% fat) or high-fat (60 kcal% fat) diet for 24 weeks to induce obesity. These mice fed with high-fat diet (HFD) were given a gavage of vehicle, 2.5, 5, or 10 mg/kg body weight BL153 daily. The three doses of BL153 treatment slightly ameliorated insulin resistance without decrease of body weight gain induced by HFD feeding. BL153 at 10 mg/kg slightly attenuated a mild cardiac hypertrophy and dysfunction induced by HFD feeding. Both 5 mg/kg and 10 mg/kg of BL153 treatment significantly inhibited cardiac lipid accumulation measured by Oil Red O staining and improved cardiac inflammation and oxidative stress by downregulating ICAM-1, TNF-α, PAI-1, 3-NT, and 4-HNE. TUNEL staining showed that BL153 treatment also ameliorated apoptosis induced by mitochondrial caspase-3 independent cell death pathway. This study demonstrates that BL153 attenuates HFD-associated cardiac damage through prevention of HFD-induced cardiac lipid accumulation, inflammation, oxidative stress, and apoptosis.

Pharmacokinetics and metabolism of 4-O-methylhonokiol in rats.

The purpose of this study was to characterize the pharmacokinetics and metabolism of 4-O-methylhonokiol in rats. The absorption and disposition of 4-O-methylhonokiol were investigated in male Sprague-Dawley rats following a single intravenous (2 mg/kg) or oral (10 mg/kg) dose. Its metabolism was studied in vitro using rat liver microsomes and cytosol. 4-O-Methylhonokiol exhibited a high systemic plasma clearance and a large volume of distribution. The oral dose gave a peak plasma concentration of 24.1±3.3 ng/mL at 2.9±1.9 h and a low estimated bioavailability. 4-O-Methylhonokiol was rapidly metabolized and converted at least in part to honokiol in a concentration-dependent manner by cytochrome P450 in rat liver microsomes, predicting a high systemic clearance consistent with the pharmacokinetic results. It was also shown to be metabolized by glucuronidation and sulfation in rat liver microsomes and cytosol, respectively. 4-O-Methylhonokiol showed a moderate permeability with no apparent vectorial transport across Caco-2 cells, suggesting that intestinal permeation process is not likely to limit its oral absorption. Taken together, these results suggest that the rapid hepatic metabolism of 4-O-methylhonokiol could be the major reason for its high systemic clearance and low oral bioavailability.

Inhibitory effects of Saururi chinensis extracts on melanin biosynthesis in B16F10 melanoma cells.

Saururus chinensis has been used in folk medicine in Korea for the treatment of edema, jaundice, gonorrhea, and several inflammatory diseases. Saururi chinensis extracts (SCE) have demonstrated anti-inflammatory and anti-oxidant activities, as well as anti-asthmatic, antihypertensive, anti-angiogenic, and therapeutic activities for atopic dermatitis. However, the inhibitory activity of SCE on the melanogenesis signaling pathway is not completely understood. This study examined the effects of SCE on the melanogenesis signaling pathway activated by α-melanocyte-stimulating hormone (α-MSH). We found that SCE inhibited melanin production in a dose-dependent manner without causing cytotoxicity in B16F10 cells. Interestingly, SCE decreased α-MSH-induced tyrosinase activity in B16F10 cells but did not inhibit tyrosinase activity under cell-free conditions. The results of this study indicate that SCE may reduce pigmentation by way of an indirect, nonenzymatic mechanism. We also found that SCE decreased α-MSH-induced microphthalmia-associated transcription factor (MITF) and tyrosinase expression and induced the activation of extracellular signal-regulated kinase (ERK). These results suggest that the depigmenting effect of SCE may result from downregulation of MITF and tyrosinase expression due to increased ERK activity. Thus, our results provide evidence that SCE might be useful as a potential skin-whitening agent.

Magnolia extract (BL153) ameliorates kidney damage in a high fat diet-induced obesity mouse model.

Accumulating evidence demonstrated that obesity is a risk factor for renal structural and functional changes, leading to the end-stage renal disease which imposes a heavy economic burden on the community. However, no effective therapeutic method for obesity-associated kidney disease is available. In the present study, we explored the therapeutic potential of a magnolia extract (BL153) for treating obesity-associated kidney damage in a high fat diet- (HFD-) induced mouse model. The results showed that inflammation markers (tumor necrosis factor- α and plasminogen activator inhibitor-1) and oxidative stress markers (3-nitrotyrosine and 4-hydroxy-2-nonenal) were all significantly increased in the kidney of HFD-fed mice compared to mice fed with a low fat diet (LFD). Additionally, proteinuria and renal structure changes in HFD-fed mice were much more severe than that in LFD-fed mice. However, all these alterations were attenuated by BL153 treatment, accompanied by upregulation of peroxisome proliferator-activated receptor- γ coactivator-1 α (PGC-1 α ) and hexokinase II (HK II) expression in the kidney. The present study indicates that BL153 administration may be a novel approach for renoprotection in obese individuals by antiinflammation and anti-oxidative stress most likely via upregulation of PGC-1 α and HK II signal in the kidney.

4-O-methylhonokiol attenuated memory impairment through modulation of oxidative damage of enzymes involving amyloid-ß generation and accumulation in a mouse model of Alzheimer's disease.

Accumulations of amyloid-ß (Aß) and oxidative damage are critical pathological mechanisms in the development of Alzheimer's disease (AD). We previously found that 4-O-methylhonokiol, a compound extracted from Magnolia officinalis, improved memory dysfunction in Aß-injected and presenilin 2 mutant mice through the reduction of accumulated Aß. To investigate mechanisms of the reduced Aß accumulation, we examined generation, degradation, efflux and aggregation of Aß in Swedish AßPP AD model (AßPPsw) mice pre-treated with 4-O-methylhonokiol (1.0 mg/kg) for 3 months. 4-O-methylhonokiol treatment recovered memory impairment and prevented neuronal cell death. This memory improving activity was associated with 4-O-methylhonokiol-induced reduction of Aß1-42 accumulation in the brains of AßPPsw mice. According to the reduction of Aß1-42 accumulation, 4-O-methylhonkiol modulated oxidative damage sensitive enzymes. 4-O-methylhonkiol decreased expression and activity of brain beta-site AßPP cleaving enzyme (BACE1), but increased clearance of Aß in the brain through an increase of expressions and activities of Aß degradation enzymes; insulin degrading enzyme and neprilysin. 4-O-methylhonkiol also increased expression of Aß transport molecule, low density lipoprotein receptor-related protein-1 in the brain and liver. 4-O-methylhonkiol decreased carbonyl protein and lipid peroxidation, but increased glutathione levels in the brains of AßPPsw mice suggesting that oxidative damage of protein and lipid is critical in the impairment of those enzyme activities. 4-O-methylhonokiol treatment also prevented neuronal cell death in the AßPPsw mousee brain through inactivation of caspase-3 and BAX. These results suggest that 4-O-methylhonokiol might prevent the development and progression of AD by reducing Aß accumulation through an increase of clearance and decrease of Aß generation via antioxidant mechanisms.

Anti-wrinkle activity of Platycarya strobilacea extract and its application as a cosmeceutical ingredient.

In order to investigate the potential of Platycarya strobilacea fruit extract as an active ingredient for cosmetics, we measured their free-radical scavenging activity, elastase inhibitory activity, the expression of MMP-1 (matrix metalloproteinase-1), and type I collagen synthesis in normal human fibroblast cells. To isolate the main component compounds from P. strobilacea fruit extract, we purified the extract through solvent fractionation, column chromatography, and recrystallization. The component compounds were identified as ellagic acid and 4-O-xyloside of ellagic acid (ellagic acid 4-O-xylopyranoside). P. strobilacea fruit extract and ellagic acid increased the expression of type I collagen mRNA in a dose-dependent manner (up to 37% and 41% at 20 microg/ml and 1.0 microg/ml, respectively), comparable to that of ascorbic acid (up to 39% at 500 muM). A clinical study of measurements using visual evaluation and image analysis showed a statistically significant difference (p < 0.05) between the effects of the test and placebo products. This result suggests that P. strobilacea fruit extract could be used as an active ingredient for antiaging cosmetics.

Cancer cell specific targeting of nanogels from acetylated hyaluronic acid with low molecular weight.

In order to develop a novel self-assembly as a means of cancer cell targeting, self-organized nanogels were prepared from acetylated hyaluronic acid with low molecular weight (AC-HA(LM)). Three samples were obtained (AC-HA(LM)1, 2 and 3) with degrees of acetylation, 0.8, 2.1, or 2.6 acetyl groups per unit (2 glucose rings) of HA(LM) to control their hydrophobicity. The mean diameters of AC-HA(LM)2 and 3 were less than 300 nm with unimodal size distribution, while that of AC-HA(LM)1 was above 400 nm. The critical aggregation concentrations (CAC) of the nanogels in distilled water were < 1 x 10(-1) mg/mL. The doxorubicine (DOX) loading efficiencies and loading contents of AC-HA(LM) increased as the degree of acetylation increased, in particular, the loading efficiency of AC-HA(LM)3 reached above 90%. AC-HA(LM)3 nanogels showed IC(50) at 1300 ng/mL of the DOX concentration against HeLa cells (with HA-binding receptors) similar to free DOX. For monitoring of specific interaction with a carcinoma cell line (HeLa cells with HA-binding receptors), AC-HA(LM)3 was labeled with FITC and observed with a confocal microscope. HeLa cells were strongly luminated by interactions with fluorescence-labeled AC-HA(LM)3 nanogels; however, this luminance was significantly decreased by competition inhibition of free HA. This result indicates that modified HA maintains the ability to interact with HA-binding receptors. The selective cytotoxicity and interaction of AC-HA(LM) nanogels may help reduce side effects of anti-cancer drugs in clinical use.

Inhibitory effect of ethanol extract of Magnolia officinalis and 4-O-methylhonokiol on memory impairment and neuronal toxicity induced by beta-amyloid.

The components of the herb Magnolia officinalis have exhibited antioxidant and neuroprotective activities. In this study, we investigated effects of ethanol extract of M.officinalis and its major component 4-O-methylhonokiol on memory dysfunction and neuronal cell damages caused by A beta. Oral pretreatment of ethanol extract of M. officinalis (2.5, 5 and 10mg/kg) and 4-O-methylhonokiol (1mg/kg) into drinking water for 5 weeks suppressed the intraventricular treatment of A beta(1-42) (0.5 microg/mouse, i.c.v.)-induced memory impairments. In addition, 4-O-methylhonokiol prevented the A beta(1-42)-induced apoptotic cell death as well as beta-secretase expression. 4-O-methylhonokiol also inhibited H(2)O(2) and A beta(1-42)-induced neurotoxicity in cultured neurons as well as PC12 cells by prevention of the reactive oxygen species generation. 4-O-methylhonokiol also directly inhibited beta-secretase activity and A beta fibrilization in vitro. Thus, ethanol extract of M. officinalis may be useful for prevention of the development or progression of AD, and 4-O-methylhonokiol may be a major active component.

Promotion effect of norgalanthamine, a component of Crinum asiaticum, on hair growth.

This study was conducted to evaluate the effect of Crinum asiaticum, a plant native to Jeju Island, Korea, on the promotion of hair growth. When rat vibrissa follicles were treated with a 95% ethanol (EtOH) extract of C. asiaticum, the hair-fiber lengths of the vibrissa follicles increased significantly. In addition, after daily topical application of the EtOH extract of C. asiaticum onto the back of C57BL/6 mice, anagen progression of the hair shaft was induced. Moreover, the extract increased the proliferation of immortalized vibrissa dermal papilla cells. When the vibrissa follicles in the anagen phase were treated with the extract, immunohistochemical analysis revealed that the extract was found to increase the expression of proliferating cell nuclear antigen (PCNA) in the bulb region of the 7-day cultured follicles. In particular, norgalanthamine, a principal of the extract, showed activity that increased the hair-fiber lengths of vibrissa follicles and the proliferation of dermal papilla cells. These results suggest that norgalanthamine, a principal of C. asiaticum, has the potential to promote hair growth via the proliferation of dermal papilla.

Neurite outgrowth effect of 4-O-methylhonokiol by induction of neurotrophic factors through ERK activation.

Compounds isolated from Magnolia officinalis such as magnolol, honokiol and obovatol exhibit several pharmacological effects on CNS including depressant, anxiolytic and anticonvulsant effects, as well as neuroprotective effects against chemical and heat damages. Recently, honokiol was found to have a neurotrophic effect in fetal rat cortical neurons. In the present study, we show that 4-O-methylhonokiol, a novel compound from Magnolia officinalis, promotes neurite outgrowth in a concentration- dependent manner in rat embryonic neuronal cells. In parallel with the neurite outgrowth activity, the expression of neurite outgrowth marker proteins is also increased by treatment with 4-O-methylhonokiol. We also found that 4-O-methylhonokiol promotes the release of NGF and BDNF into cell culture medium. In addition, lower concentration of 4-O-methylhonokiol (1 and 2 lM) further enhanced neurite outgrowth and expression of neurite outgrowth marker proteins in the presence of NGF (50 ng/ml) or BDNF (10 ng/ml). Subsequently, we found that 4-O-methylhonokiol activates ERK in a concentration- dependent manner. However, the neurite outgrowth activity and the NGF and BDNF release induced by 4-O-methylhonokiol are suppressed by an ERK-specific inhibitor. These results suggest that 4-O-methylhonokiol has the ability to induce neurite outgrowth via the increase of neurotrophic factor levels through ERK activation.

Anti-inflammatory effect of 4-O-methylhonokiol, compound isolated from Magnolia officinalis through inhibition of NF-kappaB [corrected].

The bioactive constituents isolated from the bark of Magnolia officinalis such as magnolol, honokiol and obovatol have anti-inflammatory properties through the inactivation of NF-kappaB which is an important factor in the regulation of inflammatory reaction. We recently isolated neolignan compound, 4-O-methylhonokiol, from M. officinalis. In the present study, we investigated whether or not 4-O-methylhonokiol inhibits inflammatory reaction through the inhibition of NF-B activity [corrected]. The results showed that 4-O-methylhonokiol (2.5-10 microM) inhibited LPS (1 microg/ml)-induced NO generation in macrophage Raw 264.7 cells in a concentration-dependent manner with IC(50) value 9.8 microM. The inhibition of NO generation by 4-O-methylhonokiol was consistent with the inhibitory effect on the expression as well as transcriptional activity of inducible nitric oxide synthase (iNOS). In addition, 4-O-methylhonokiol inhibited the LPS-induced transcriptional and DNA binding activities of NF-kappaB as well as p50 and p65 translocation into the nucleus. Topical application of 4-O-methylhonokiol (0.1-1 mg/ear) inhibited 12-O-tetradecanoylphorbol-13-acetate-induced inflammatory ear edema formation, NF-kappaB activity, and iNOS and COX-2 expression. The present results provided evidence that 4-O-methylhonokiol has anti-inflammatory properties through inhibition of the NF-kappaB pathway, and suggested that 4-O-methylhonokiol can be used as an anti-inflammatory agent.