A multifunctional lipid nanoparticle for co-delivery of paclitaxel and curcumin for targeted delivery and enhanced cytotoxicity in multidrug resistant breast cancer cells

The objective of the work was to develop a multifunctional nanomedicine based on a folate-conjugated lipid nanoparticles loaded with paclitaxel and curcumin. The novel system combines therapeutic advantageous of efficient targeted delivery via folate and timed-release of curcumin and paclitaxel via 2-hydroxypropyl-ß-cyclodextrin, thereby overcoming multidrug resistance in breast cancer cells (MCF-7/ADR). The faster release of curcumin from the folate-conjugated curcumin and paclitaxel-loaded lipid nanoparticles enables sufficient p-glycoprotein inhibition, which allows increased cellular uptake and cytotoxicity of paclitaxel. In western blot assay, curcumin can efficiently inhibit the expression of p-glycoprotein, conformed the enhancement of cytotoxicity by paclitaxel. Furthermore, folate-conjugated curcumin and paclitaxel-loaded lipid nanoparticles exhibited increased uptake of paclitaxel and curcumin into MCF-7/ADR cells through the folate receptor-mediated internalization. Taken together, these results indicate that folate-conjugated curcumin and paclitaxel-loaded lipid nanoparticles enables the enhanced, folate-targeted delivery of multiple anticancer drugs by inhibiting the multi-drug resistance efficiently, which may also serve as a useful nano-system for co-delivery of other anticancer drugs.

Down modulation of IL-18 expression by human papillomavirus type 16 E6 oncogene via binding to IL-18

To understand modulation of a novel immune-related cytokine, interleukin-18, by human papillomavirus type (HPV) 16 oncogenes, HaCaT, normal keratinocyte cell line, and C-33A, HPV-negative cervical cancer cell line, were prepared to establish stable cell lines expressing E6, E6 mutant (E6m), E6E7, or E7 constitutively. Expressions of various HPV oncogene transcripts were identified by RT-PCR. Expression of HPV oncogene E6 was reversely correlated to the expression of interleukin-18, a novel pro-inflammatory cytokine. The expression of E6 in C-33A, independent of E6 splicing, resulted in decreased IL-18 expression and that of IL-18 was also significantly reduced in HaCaT cells expressing E6. The level of p53 was reduced in C-33A cells expressing E6 whereas not altered in HaCaT cells expressing E6, suggesting that E6 downregulated IL-18 expression via an independent pathway of p53 degradation in HaCaT cells which have a mutated p53 form. However, E7 did not affect IL-18 expression significantly in both C-33A and HaCaT cells. Cotransfection experiments showed that E6 oncogene did not inhibit the activities of IL-18 promoter P1 and P2, suggesting that E6 oncogene indirectly inhibited IL-18 expression. Taken together, E6, E6m and E6/E7 inhibited IL-18 expression with some variation, assuming that cells expressing E6 oncogene can evade immune surveillance by downregulating the expression of immune stimulating cytokine gene, IL-18, and inhibiting the cascade of downstream effects that follow activation of the IL-18 receptor.

Effects of non-ionic surfactants as permeation enhancers towards piroxicam from the poloxamer gel through rat skins

The enhancing effects of non-ionic surfactants on the permeation of piroxicam from the poloxamer gels were evaluated using Franz diffusion cells fitted with excised rat skins. The effectiveness of penetration enhancers, the ratio of piroxicam flux in the presence or absence of enhancers, was defined as the enhancement factor. Among the various non-ionic surfactants tested, polyoxyethylene-2-oleyl ether showed the highest enhancing effects with an enhancement factor of 2.84. To elucidate the mechanisms of the action of enhancers, thermal analysis and histological examinations were carried out. Thermal analysis reveals that various surfactants have different fluidizing effects on stratum corneum. Skin pretreated with the poloxamer 407 gels containing various surfactants showed a loosely layered stratum corneum and wide intercellular space.

Ultrasound-induced mild hyperthermia as a novel approach to increase drug uptake in brain microvessel endothelial cells

PURPOSE

Drug delivery to the central nervous system (CNS) is limited by the blood-brain barrier (BBB). Thus, a noninvasive and reversible method to enhance BBB permeation of drugs is highly desirable. In the present work, we studied if ultrasound-induced mild hyperthermia (USHT, 0.4 watts (W)/cm2 at 41 degrees C) can enhance drug absorption in BBB endothelial cells, and we elucidated the mechanism of USHT on cellular accumulation.

METHODS

To accomplish these aims, we studied the effects of hyperthermia (41 degrees C), USHT, P-glycoprotein (P-gp) modulator (PSC 833), and combination of USHT and PSC 833 on accumulation of P-gp substrate (R123) and non-P-gp substrates (sucrose, 2-deoxyglucose, and antipyrine) in monolayers of primary bovine brain microvessel endothelial cells (BBMEC).

RESULTS

USHT, through its thermal effect, produces a significant (relative to controls; no USHT) and comparable increase in R123 accumulation with PSC 833. We also demonstrate that USHT increases permeability of hydrophobic (R123 and [14C]-antipyrine) and not hydrophilic molecules ([14C]-sucrose and 2-[3H]-deoxy-D-glucose). The enhanced permeability is reversible and size dependent, as USHT produces a much larger effect on cellular accumulation of [14C]-antitpyrine (molecular weight of 188 D) than that of R123 (molecular weight of 380.8 D). Although USHT increases membrane permeability, it did not affect P-gp activity or the activity of glucose transporters.

CONCLUSIONS

Our results point to the potential use of USHT as a reversible and noninvasive approach to increase BBB permeation of hydrophobic drugs, including P-gp-recognized substrates.

A polymer-supported proline-based diamine catalyst for the kinetic resolution of racemic secondary alcohols

The preparation of polymer-supported proline-based diamine catalyst 12 for the kinetic resolution of racemic mixtures of secondary alcohols is described. Not only is the catalyst effective for the resolution of a host of different alcohols, it can also be recovered and reused several times without loss of either activity or selectivity. The catalyst has been used in conjunction with a polymer-supported sequestration strategy, giving rise to an essentially pure mixture of resolved products that can be separated using flash chromatography.

Glioblastoma cell death induced by asiatic acid

Asiatic acid (AA), a triterpene, is known to be cytotoxic to several tumor cell lines. AA induces dose- and time-dependent cell death in U-87 MG human glioblastoma. This cell death occurs via both apoptosis and necrosis. The effect of AA may be cell type-specific as AA-induced cell death was mainly apoptotic in colon cancer RKO cells. AA-induced glioblastoma cell death is associated with decreased mitochondrial membrane potential, activation of caspase-9 and -3, and increased intracellular free Ca2+. Although treatment of glioblastoma cells with the caspase inhibitor zVAD-fmk completely abolished AA-induced caspase activation, it did not significantly block AA-induced cell death. AA-induced cell death was significantly prevented by an intracellular Ca2+ inhibitor, BAPTA/AM. Taken together, these results indicate that AA induces cell death by both apoptosis and necrosis, with Ca2+-mediated necrotic cell death predominating.

Physicochemical characterizations of piroxicam-poloxamer solid dispersion

To develop an efficient topical delivery system for piroxicam using poloxamer gel formulation, physicochemical behavior of piroxicam in poloxamer was studied. The gelling property of poloxamer and the solubility of piroxicam in the poloxamer were investigated. The interaction between piroxicam and poloxamer was studied by x-ray diffractometry (XRD), infrared (IR) spectroscopy and differential thermal analysis (DTA) with a solid dispersion, coprecipitate, or physical mixture. Poloxamer 407 solutions showed the property of a gel when the concentration was higher than 15% (w/w) and poloxamer 407 increased the aqueous solubility of piroxicam by about 11-fold at the concentration of 22.5% (w/w). The results of XRD did not show the crystalline from of piroxicam in the solid dispersion and results of IR spectroscopic analysis showed an association between functional groups of piroxicam and poloxamer.

Solid lipid nanoparticles of paclitaxel strengthened by hydroxypropyl-β-cyclodextrin as an oral delivery system

The objective of this study was to evaluate the potential of surface-modified paclitaxel (PTX)-incorporated solid lipid nanoparticles with hydroxypropyl-β-cyclodextrin (smPSH). The smPSH released 89.70 ± 3.99% of its entrapped PTX within 24 h when placed in dissolution medium containing sodium lauryl sulfate. The cellular uptake of PTX from smPSH in Caco-2 cells was 5.3-fold increased compared to a PTX solution based on a Taxol formulation. Moreover, smPSH showed an increased cytotoxicity compared to PTX solution. In addition, AUC (5.43 µg•h/ml) and Cmax (1.44 µg/ml) of smPSH were higher than those (1.81 µg•h/ml and 0.73 µg/ml) of PTX solution. The drug concentration of smPSH (11.12 ± 4.45 ng/mg of lymph tissue) in lymph nodes was higher than that of the PTX solution (0.89 ± 0.75 ng/mg of lymph tissue), suggesting that more PTX was transported to the lymphatic vessels in the form of smPSH. In conclusion, smPSH have a potential as an alternative delivery system for oral administration of PTX.

A novel composition of ticagrelor by solid dispersion technique for increasing solubility and intestinal permeability

The aim of this study is to improve the bioavailability of ticagrelor, BCS class 4 drug, using solid dispersion technique, and to evaluate the potential of ticagrelor loaded-solid dispersion, as a new formulation. The solid dispersion formulation was prepared via solvent evaporation method using ethanol. TPGS and Neusilin® US2 selected via screening studies were used for preparing formulation. The results of scanning electron microscopy, differential scanning calorimetry and powder X-ray diffraction showed that the crystallinity of the ticagrelor was completely transformed to an amorphous form and maintained in the solid dispersion formulation. The released amount of the optimized solid dispersion significantly increased by 2.2- and 34-fold in comparison with physical mixture (Ticagrelor:TPGS:Neusilin® US2 = 1:2:2, w/w/w) and commercial product (Brilinta®) in distilled water at 90 min, respectively. The absorptive permeability was improved (1.4-fold) and the efflux ratio was decreased (0.45-fold) by formulation containing TPGS acting as a P-gp inhibitor compared to pure drug. The solid dispersion formulation improved the peak plasma concentration (C_max) and relative bioavailability compared to that of pure drug as 238.09 ± 25.96% and 219.78 ± 36.33%, respectively, after oral administration in rats. Thus, we successfully prepared the solid dispersion formulation for enhancing oral bioavailability of ticagrelor, and then this formulation would be recommended as a practical oral pharmaceutical product.

Permeation of piroxicam from the poloxamer gels

Topical formulations of piroxicam were prepared using poloxamer 407 or poloxamer 188 by a cold method, and the permeation characteristics of piroxicam were evaluated. The permeation rate of piroxicam across the synthetic cellulose membrane and the rat skin decreased as the concentration of poloxamer increased. Though poloxamer gel exhibits reversed thermal behavior, the permeation rate of piroxicam increased with increasing temperature, indicating that the diffusional pathway of piroxicam is a water channel within the gel formulation. The pH of the gel did not affect the permeation rate of piroxicam significantly. As the concentration of piroxicam in the gel formulation increased, the permeation rate of piroxicam increased up to 1% and reached a plateau above 1%. Among various enhancers tested, polyoxyethylene-2-oleyl ether showed the highest enhancing effect, with an enhancement ratio of 2.84. Based on experimental results, the permeation rate of piroxicam can be controlled by changing the poloxamer concentration or drug concentration and by the addition of an appropriate enhancer.

Development of tretinoin gels for enhanced transdermal delivery

To develop the new gel formulations that show sustained release for a period of time, the bioadhesive carbopol gels containing tretinoin were prepared. The release characteristics of drug from the carbopol gel were studied according to temperature, receptor medium and drug concentration. For the enhancement of its percutaneous absorption, some kinds of penetration enhancer were used. As the concentration of drug increased, the release of drug from the gel increased, showing concentration dependency. The increase of temperature showed the increased drug release, depending on the activation energy of permeation. Among the enhancers used such as the glycols and the non-ionic surfactants, polyoxyethylene 2-oleyl ether showed the best enhancing effect. The carbopol gels of tretinoin containing an enhancer could be developed for the enhanced transdermal delivery of drug.

The Delivery Strategy of Paclitaxel Nanostructured Lipid Carrier Coated with Platelet Membrane

Strategies for the development of anticancer drug delivery systems have undergone a dramatic transformation in the last few decades. Lipid-based drug delivery systems, such as a nanostructured lipid carrier (NLC), are one of the systems emerging to improve the outcomes of tumor treatments. However, NLC can act as an intruder and cause an immune response. To overcome this limitation, biomimicry technology was introduced to decorate the surface of the nanoparticles with various cell membrane proteins. Here, we designed paclitaxel (PT)-loaded nanostructured lipid carrier (PT-NLC) with platelet (PLT) membrane protein because PLT is involved with angiogenesis and interaction of circulating tumor cells. After PLT was isolated from blood using the gravity-gradient method and it was used for coating PT-NLC. Spherical PT-NLC and platelet membrane coated PT-NLC (P-PT-NLC) were successfully fabricated with high encapsulation efficiency (EE) (99.98%) and small particle size (less than 200 nm). The successful coating of PT-NLC with a PLT membrane was confirmed by the identification of CD41 based on transmission electron microscopy (TEM), western blot assay and enzyme-linked immunosorbent assay (ELISA) data. Moreover, the stronger affinity of P-PT-NLC than that of PT-NLC toward tumor cells was observed. In vitro cell study, the PLT coated nanoparticles successfully displayed the anti-tumor effect to SK-OV-3 cells. In summary, the biomimicry carrier system P-PT-NLC has an affinity and targeting ability for tumor cells.

Ultrasound-Induced hyperthermia increases cellular uptake and cytotoxicity of P-glycoprotein substrates in multi-drug resistant cells

PURPOSE

Localized hyperthermia has been shown previously to augment the cytotoxicity of some lipophilic anticancer drugs. Because many of the substrates for the multi-drug resistance (MDR) transporter P-glycoprotein (P-gp) are lipophilic in nature, studies were conducted to test the hypothesis that hyperthermia induced by ultrasound could also increase cellular uptake and cytotoxicity of P-gp substrates by P-gp-expressing cells.

METHODS

To test this hypothesis, we studied the effects of hyperthermia and ultrasound on cellular accumulation of putative P-gp substrates, rhodamine 123 (R123) and doxorubicin (DOX), and cytotoxicity of DOX in the parent and MDR variants of two human cancer cell lines.

RESULTS

Treatment of cells with hyperthermia or ultrasound (20 min at 41 degrees C) both caused a significant increase over controls (no ultrasound treatment) in R123 and DOX accumulation in the parent and MDR lines of MV522 and KB cells. Ultrasound also substantially increased the antiproliferative effects of DOX in both the parent and MDR variants of MV522 and KB cell lines when compared with controls. Our results also indicated that ultrasound exerted a much greater effect on cellular accumulation of R123 and DOX and cytotoxicity enhancement of DOX in the MDR variants than putative P-gp antagonist such as verapamil.

CONCLUSION

The present results point to the potential use of ultrasound-induced hyperthermia as a much safer alternative to P-gp antagonist for reversal of MDR.

Practical preparation procedures for docetaxel-loaded nanoparticles using polylactic acid-co-glycolic acid

Background

Nanoparticles fabricated from the biodegradable and biocompatible polymer, polylactic-co-glycolic acid (PLGA), are the most intensively investigated polymers for drug delivery systems. The objective of this study was to explore fully the development of a PLGA nanoparticle drug delivery system for alternative preparation of a commercial formulation. In our nanoparticle fabrication, our purpose was to compare various preparation parameters.

Methods

Docetaxel-loaded PLGA nanoparticles were prepared by a single emulsion technique and solvent evaporation. The nanoparticles were characterized by various techniques, including scanning electron microscopy for surface morphology, dynamic light scattering for size and zeta potential, x-ray photoelectron spectroscopy for surface chemistry, and high-performance liquid chromatography for in vitro drug release kinetics. To obtain a smaller particle, 0.2% polyvinyl alcohol, 0.03% D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), 2% Poloxamer 188, a five-minute sonication time, 130 W sonication power, evaporation with magnetic stirring, and centrifugation at 8000 rpm were selected. To increase encapsulation efficiency in the nanoparticles, certain factors were varied, ie, 2–5 minutes of sonication time, 70–130 W sonication power, and 5–25 mg drug loading.

Results

A five-minute sonication time, 130 W sonication power, and a 10 mg drug loading amount were selected. Under these conditions, the nanoparticles reached over 90% encapsulation efficiency. Release kinetics showed that 20.83%, 40.07%, and 51.5% of the docetaxel was released in 28 days from nanoparticles containing Poloxamer 188, TPGS, or polyvinyl alcohol, respectively. TPGS and Poloxamer 188 had slower release kinetics than polyvinyl alcohol. It was predicted that there was residual drug remaining on the surface from x-ray photoelectron spectroscopy.

Conclusion

Our research shows that the choice of surfactant is important for controlled release of docetaxel.

Development of lidocaine gels for enhanced local anesthetic action

In relieving local pains, lidocaine, one of ester type local anesthetics, has been used. To develop the lidocaine gels of enhanced local anesthetic effects, hydroxypropyl methylcellulose (HPMC) based bioadhesive polymer gel containing an enhancer was formulated. As the drug concentration in the gels increased up to 3%, the permeation rate of drug linearly increased, thereafter reaching a plateau. As the temperature of surrounding solutions increased, the permeation of drug increased. The activation energy of drug permeation was 3.29 kcal/mol for lidocaine. The permeation rate of drug through skin was studied using various enhancers, such as glycols, non-ionic surfactants, and bile salts. Among the enhancers studied, diethylene glycol showed the greatest enhancing effects on drug permeation through skin. The analgesic activity was examined using a tail-flick analgesimeter. In the area under the efficacy curve (AUEC) of the rat-tail flick tests, lidocaine gel containing diethylene glycol showed about 3.89-fold increase in analgesic activity compared with the control. The addition of vasoconstrictor in the gels prolonged the analgesic effects. The result of this study supports that the bioadhesive gel with efficient anesthetic effect could be developed using HPMC with combination of enhancer and vasoconstrictor.

2-Hydroxypropyl-β-cyclodextrin-modified SLN of paclitaxel for overcoming p-glycoprotein function in multidrug-resistant breast cancer cells

OBJECTIVES

This study aimed to evaluate the potential of solid lipid nanoparticles (SLNs) of paclitaxel (PTX) modified with a 2-hydroxypropyl-β-cyclodextrin system to enhance cellular accumulation of PTX into p-glycoprotein (p-gp)-expressing cells.

METHODS

The PTX-loaded-SLNs consisted of lipid (stearic acid) and surfactants (lecithin and poloxamer 188) and were then modified with 2-hydroxypropyl-β-cyclodextrin by a sonication method.

KEY FINDINGS

In terms of cytotoxicity, PTX-loaded SLNs modified with 2-hydroxypropyl-β-cyclodextrin showed higher cytotoxicity than other formulations. In particular, the cellular uptake of PTX from PTX-loaded SLNs modified with 2-hydroxypropyl-β-cyclodextrin was about 5.8- and 1.5-fold higher than that from PTX solution and unmodified PTX-loaded SLNs in MCF-7/ADR cells, respectively. After a 4-h incubation, clear fluorescence images inside cells were observed over time. When PTX-loaded SLNs modified with 2-hydroxypropyl-β-cyclodextrin were incubated with MCF-7/ADR cells for 4 h, cellular uptake of PTX increased 1.7-fold versus that of PTX in the presence of verapamil.

CONCLUSIONS

These results suggest that optimized SLNs modified with 2-hydroxypropyl-β-cyclodextrin may have potential as an oral drug delivery system for PTX.

Systemic Design and Evaluation of Ticagrelor-Loaded Nanostructured Lipid Carriers for Enhancing Bioavailability and Antiplatelet Activity

Ticagrelor (TGL), a P2Y12 receptor antagonist, is classified as biopharmaceutics classification system (BCS) class IV drug due to its poor solubility and permeability, resulting in low oral bioavailability. Nanostructured lipid carriers (NLC) are an efficient delivery system for the improvement of bioavailability of BCS class IV drugs. Hence, we prepared TGL-loaded NLC (TGL-NLC) to enhance the oral bioavailability and antiplatelet activity of TGL with a systemic design approach. The optimized TGL-NLC with Box-Behnken design showed a small particle size of 87.6 nm and high encapsulation efficiency of 92.1%. Scanning electron microscope (SEM), differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD) were performed to investigate the characteristics of TGL-NLC. Furthermore, TGL-NLC exhibited biocompatible cytotoxicity against Caco-2 cells. Cellular uptake of TGL-NLC was 1.56-fold higher than that of raw TGL on Caco-2 cells. In pharmacokinetic study, the oral bioavailability of TGL-NLC was 254.99% higher than that of raw TGL. In addition, pharmacodynamic study demonstrated that the antiplatelet activity of TGL-NLC was superior to that of raw TGL, based on enhanced bioavailability of TGL-NLC. These results suggest that TGL-NLC can be applied for efficient oral absorption and antiplatelet activity of TGL.

Strategic approach to developing a self-microemulsifying drug delivery system to enhance antiplatelet activity and bioavailability of ticagrelor

Background

Ticagrelor (TCG) is used to inhibit platelet aggregation in patients with acute coronary syndrome, but its poor solubility and low bioavailability limit its in vivo efficacy. The purpose of this study was to manufacture an optimized TCG-loaded self-microemulsifying drug delivery system (SMEDDS) to enhance the oral bioavailability and antiplatelet activity of TCG.

Materials and methods

Solubility and emulsification tests were conducted to determine the most suitable oils, surfactants, and cosurfactants. Scheffé's mixture design was applied to optimize the percentage of each component applied in the SMEDDS formulation to achieve optimal physical characteristics, ie, high solubility of TCG in SMEDDS, small droplet size, low precipitation, and high transmittance.

Results

The optimized TCG-loaded SMEDDS (TCG-SM) formulation composed of 10.0% Capmul MCM (oil), 53.8% Cremophor EL (surfactant), and 36.2% Transcutol P (cosurfactant) significantly improving the dissolution of TCG in various media compared with TCG in Brilinta^® (commercial product). TCG-SM exhibited higher cellular uptake and permeability in Caco-2 cells than raw TCG suspension. In pharmacokinetic studies in rats, TCG-SM exhibited higher oral bioavailability with 5.7 and 6.4 times higher area under the concentration-time curve and maximum plasma concentration, respectively, than a raw TCG suspension. Antiplatelet activity studies exhibited that the TCG-SM formulation showed significantly improved inhibition of platelet aggregation compared with raw TCG at the same dose of TCG. And, a 10 mg/kg dose of raw TCG suspension and a 5 mg/kg dose of TCG-SM had a similar area under the inhibitory curve (907.0%±408.8% and 907.8%±200.5%⋅hours, respectively) for antiplatelet activity.

Conclusion

These results suggest that the developed TCG-SM could be successfully used as an efficient method to achieve the enhanced antiplatelet activity and bioavailability of TCG.

Ethosomes and Transfersomes for Topical Delivery of Ginsenoside Rhl from Red Ginseng: Characterization and In Vitro Evaluation

Red ginseng (the steamed root of Panax ginseng C. A. Mayer), which contains ginsenosides as its main constituents, is frequently used to treat tumor, inflammation, diabetes, stress and acquired immunodeficiency syndrome in Asian countries. Ginsenoside Rhl, a bacterial metabolite of ginsenoside Rgl, is a protopanaxatriol type of ginsenosides. Liposomes do not deeply penetrate the skin and remain confined to the stratum corneum.Thus, new vesicular colloidal carriers such as ethosomes and transfersomes have been developed as an enhanced type of liposomes, recently. The aim of this study was to improve the topical delivery of ginsenoside Rhl isolated from red ginseng employing new vesicular system of ethosomes and transfersomes compared to conventional liposome. Characterization of ginsenoside Rhl-loaded vesicles were prepared and evaluated for particle size, zeta potential, entrapment efficiency (% EE), and transmission electron microscopy (TEM) studies. In addition, skin permeation profile was obtained using frantz diffusion cells and rat dorsal skin treated with ethosome and transfersome compared with conventional iposome. The size of vesicles range from 108.5 to 322.9 nm, and negatively charged from -20.95 to -31.37 mV. The % EE of ginsenoside Rh1 was obtained between 45.0 to 65.0%. Transfersomes provided a significantly higher skin permeation of ginsenoside Rhl compared to ethosome and conventional liposome. Therefore, based on the current study, ginsenoside Rhl-loaded transfersomes can act as a topical therapeutic effects potential.

Xanthohumol inhibits IL-12 production and reduces chronic allergic contact dermatitis

Xanthohumol (XN) and its related compounds were evaluated for their effects on modulating the production of interleukin (IL)-12, the most important factor driving T helper 1 immune responses. XN showed the strongest inhibitory effect on IL-12 production in macrophages stimulated by lipopolysaccharide (LPS) or LPS/interferon-gamma. Xanthohumol 4'-O-beta-D-glucopyranoside (XNG) inhibited IL-12 production less effectively than XN. Isoxanthohumol and 8-prenylnaringenin showed comparatively lower inhibitory effects on IL-12 production than XNG. (2S)-5-methoxy-8-prenylnaringenin 7-O-beta-D-glucopyranoside did not exert any effect on IL-12 production. We then tested how these compounds affected NF-kappaB binding activity to the kappaB site in the nucleus. The compounds inhibited kappaB binding in macrophages with the same potency order as IL-12 inhibition. Furthermore, we investigated whether XN, which showed the most effective reduction of IL-12 production, attenuated skin inflammation. Chronic allergic contact dermatitis, an experimental model for psoriasis, was used to determine the anti-inflammatory effects of XN in vivo. XN treatment reduced the degree of ear thickening induced by oxazolone. Taken together, XN might be effective as an anti-inflammatory agent to reduce skin inflammation by inhibiting IL-12 production.

Protective mechanism of curcumin against Vibrio vulnificus infection

Curcumin, a natural polyphenolic flavonoid extracted from the rhizome of Curcuma longa L., has many beneficial biological activities. However, there are relatively few reports of the effects of curcumin on pathogen infections. This study examined the effect of curcumin on a Vibrio vulnificus infection. The cytotoxicity of V. vulnificus to HeLa cells was significantly inhibited by curcumin (at 10 or 30 μM). To further examine the inhibitory mechanism of curcumin against V. vulnificus-mediated cytotoxicity, the level of bacterial growth, bacterial motility, cell adhesion, RTX toxin expression and host cell reactions were evaluated. Curcumin inhibited V. vulnificus growth in HI broth. Curcumin inhibited both bacterial adhesion and RTX toxin binding to the host cells, which can be considered the major protective mechanisms for the decrease in V. vulnificus cytotoxicity. Curcumin also inhibited host cell rounding and actin aggregation, which are the early features of cell death caused by V. vulnificus. In addition, curcumin decreased the V. vulnificus-induced NF-κB translocation in HeLa cells. Finally, curcumin protected mice from V. vulnificus-induced septicemia. In conclusion, curcumin may be an alternative antimicrobial agent against fatal bacterial infections.