Dihydrolipoic acid inhibits skin tumor promotion through anti-inflammation and anti-oxidation

Liquid crystalline nanodispersion functionalized with cell-penetrating peptides improves skin penetration and anti-inflammatory effect of lipoic acid after in vivo skin exposure to UVB radiation

In this study, the development and the performance of a new targeted liquid crystalline nanodispersion (LCN) by the attachment of cell-penetrating peptides (CPP) onto their surfaces to improve skin delivery of lipoic acid (LA) were evaluated. For that, the synthesis and characterization of this new platform as well as its spatiotemporal analysis from in vitro and in vivo topical application were explored and extensively discussed in this paper. The TAT or D4 peptides were chosen as CPP due to specific target strategies by the charge grouping on the skin surface or target the overexpressed epidermal growth factor receptor (EGFR) of cell membrane of keratinocytes, respectively. Thus, the nanoparticle characterization results when taken together suggested that designed LCNs maintained their hexagonal phase structure, nanoscale particle size, and low polydispersity index even after drug, lipopolymers, and peptide additions, which are proved to be favorable for topical skin delivery. There were no statistical differences among the LCNs investigated, except for superficial charge of LCN conjugated with TAT which may have altered the LCN zeta potential due to cationic charge of TAT amino acid sequence compared with D4. The cumulative amounts of LA retained into the skin were determined to be even higher coming from the targeted LCNs. Moreover, the exogenous antioxidant application of the LA from the LCNs can prevent ROS damage, which was demonstrated by this study with the less myeloperoxidase (MPO) activity and decrease in cytokine levels (TNF-alpha and IL-1β) generated by the oxidative stress modulation. Together, the data presented highlights the potential of these targeted LCNs, and overall, opens new frontiers for preclinical trials.

Dihydrolipoic acid protects against lipopolysaccharide-induced behavioral deficits and neuroinflammation via regulation of Nrf2/HO-1/NLRP3 signaling in rat

Background

Recently, depression has been identified as a prevalent and severe mental disorder. However, the mechanisms underlying the depression risk remain elusive. The neuroinflammation and NLRP3 inflammasome activation are known to be involved in the pathology of depression. Dihydrolipoic acid (DHLA) has been reported as a strong antioxidant and exhibits anti-inflammatory properties in various diseases, albeit the direct relevance between DHLA and depression is yet unknown. The present study aimed to investigate the preventive effect and potential mechanism of DHLA in the lipopolysaccharide (LPS)-induced sickness behavior in rats.

Methods

Adult male Sprague–Dawley rats were utilized. LPS and DHLA were injected intraperitoneally every 2 days and daily, respectively. Fluoxetine (Flu) was injected intraperitoneally daily. PD98059, an inhibitor of ERK, was injected intraperitoneally 1 h before DHLA injection daily. Small interfering ribonucleic acid (siRNA) for nuclear factor erythroid 2-like (Nrf2) was injected into the bilateral hippocampus 14 days before the DHLA injection. Depression-like behavior tests were performed. Western blot and immunofluorescence staining detected the ERK/Nrf2/HO-1/ROS/NLRP3 pathway-related proteins.

Results

The DHLA and fluoxetine treatment exerted preventive effects in LPS-induced sickness behavior rats. The DHLA treatment increased the expression of ERK, Nrf2, and HO-1 but decreased the ROS generation levels and reduced the expression of NLRP3, caspase-1, and IL-1β in LPS-induced sickness behavior rats. PD98059 abolished the effects of DHLA on preventive effect as well as the levels of Nrf2 and HO-1 proteins. Similarly, Nrf2 siRNA reversed the preventive effect of DHLA administration via the decreased expression of HO-1.

Conclusions

These findings suggested that DHLA exerted a preventive effect via ERK/Nrf2/HO-1/ROS/NLRP3 pathway in LPS-induced sickness behavior rats. Thus, DHLA may serve as a potential therapeutic strategy for depression.

Dihydrolipoic Acid-Gold Nanoclusters Regulate Microglial Polarization and Have the Potential To Alter Neurogenesis

Microglia-mediated neuroinflammation is one of the most significant features in a variety of central nervous system (CNS) disorders such as traumatic brain injury, stroke, and many neurodegenerative diseases. Microglia become polarized upon stimulation. The two extremes of the polarization are the neuron-destructive proinflammatory M1-like and the neuron-regenerative M2-like phenotypes. Thus, manipulating microglial polarization toward the M2 phenotype is a promising therapeutic approach for CNS repair and regeneration. It has been reported that nanoparticles are potential tools for regulating microglial polarization. Gold nanoclusters (AuNCs) could penetrate the blood-brain barrier and have neuroprotective effects, suggesting the possibility of utilizing AuNCs to regulate microglial polarization and improve neuronal regeneration in CNS. In the current study, AuNCs functionalized with dihydrolipoic acid (DHLA-AuNCs), an antioxidant with demonstrated neuroprotective roles, were prepared, and their effects on polarization of a microglial cell line (BV2) were examined. DHLA-AuNCs effectively suppressed proinflammatory processes in BV2 cells by inducing polarization toward the M2-like phenotype. This was associated with a decrease in reactive oxygen species and reduced NF-kB signaling and an improvement in cell survival coupled with enhanced autophagy and inhibited apoptosis. Conditioned medium from DHLA-AuNC-treated BV2 cells was able to enhance neurogenesis in both the neuronal cell line N2a and in an ex vivo brain slice stroke model. The direct treatment of brain slices with DHLA-AuNCs also ameliorated stroke-related tissue injury and reduced astrocyte activation (astrogliosis). This study suggests that by regulating neuroinflammation to improve neuronal regeneration, DHLA-AuNCs could be a potential therapeutic agent in CNS disorders.

The Effects of a Novel Series of KTTKS Analogues on Cytotoxicity and Proteolytic Activity

KTTKS is a matrikine that originates from the proteolytic hydrolysis of collagen. This peptide stimulates ECM production and types I and III collagen expression in vitro. A more stable form of KTTKS is pal-KTTKS, known as Matrixyl^® or palmitoyl pentapeptide-3. A series of novel pentapeptides, analogues of KTTKS with the general formula X-KTTKS-OH(NH₂), where X = acetyl, lipoyl, palmitoyl residues, was designed and synthesized. Their effect on amidolytic activity of urokinase, thrombin, trypsin, plasmin, t-PA, and kallikrein were tested. Cytotoxic tests on fibroblasts, as well as collagen and DNA biosynthesis tests for selected peptides, were also carried out. The test results showed that the most active plasmin inhibitors were palmitoyl peptides, whether in acid or amide form. No biological effects of lysine modification to arginine in the synthesized peptides were found. None of the synthesized peptides was not cytotoxic on fibroblasts, and three of them showed cell growth. These three compounds showed no concentration-activity relationship in the collagen and DNA biosynthesis assays.

Protection by mTOR Inhibition on Zymosan-Induced Systemic Inflammatory Response and Oxidative/Nitrosative Stress: Contribution of mTOR/MEK1/ERK1/2/IKKβ/IκB-α/NF-κB Signalling Pathway

Mammalian target of rapamycin (mTOR), a serine/threonine kinase regulate variety of cellular functions including cell growth, differentiation, cell survival, metabolism, and stress response, is now appreciated to be a central regulator of immune responses. Because mTOR inhibitors enhanced the anti-inflammatory activities of regulatory T cells and decreased the production of proinflammatory cytokines by macrophages, mTOR has been a pharmacological target for inflammatory diseases. In this study, we examined the role of mTOR in the production of proinflammatory and vasodilator mediators in zymosan-induced non-septic shock model in rats. To elucidate the mechanism by which mTOR contributes to non-septic shock, we have examined the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system caused by mTOR/mitogen-activated protein kinase kinase (MEK1)/extracellular signal-regulated kinase (ERK1/2)/inhibitor κB kinase (IKKβ)/inhibitor of κB (IκB-α)/nuclear factor-κB (NF-κB) signalling pathway activation. After 1 h of zymosan (500 mg/kg, i.p.) administration to rats, mean arterial blood pressure (MAP) was decreased and heart rate (HR) was increased. These changes were associated with increased expression and/or activities of ribosomal protein S6, MEK1, ERK1/2, IKKβ, IκB-α and NF-κB p65, and NADPH oxidase system activity in cardiovascular and renal tissues. Rapamycin (1 mg/kg, i.p.), a selective mTOR inhibitor, reversed these zymosan-induced changes in these tissues. These observations suggest that activation of mTOR/MEK1/ERK1/2/IKKβ/IκB-α/NF-κB signalling pathway with proinflammatory and vasodilator mediator formation and NADPH oxidase system activity contributes to systemic inflammation in zymosan-induced non-septic shock. Thus, mTOR may be an optimal target for the treatment of the diseases characterized by the severe systemic inflammatory response.

An endogenous DNA adduct as a prognostic biomarker for hepatocarcinogenesis and its prevention by Theaphenon E in mice

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths worldwide, mainly because of its poor prognosis. A valid mechanism-based prognostic biomarker is urgently needed. γ-hydroxy-1,N² -propanodeoxyguanosine (γ-OHPdG) is an endogenously formed mutagenic DNA adduct derived from lipid peroxidation. We examined the relationship of γ-OHPdG with hepatocarcinogenesis in two animal models and its potential role as a prognostic biomarker for recurrence in HCC patients. Bioassays were conducted in xeroderma pigmentosum group A knockout mice and diethylnitrosamine-injected mice, both prone to HCC development. γ-OHPdG levels in the livers of these animals were determined. The effects of antioxidant treatments on γ-OHPdG and hepatocarcinogenesis were examined. Using two independent sets of HCC specimens from patients, we examined the relationship between γ-OHPdG and survival or recurrence-free survival. γ-OHPdG levels in liver DNA showed an age-dependent increase and consistently correlated with HCC development in all three animal models. Theaphenon E treatment significantly decreased γ-OHPdG levels in the liver DNA of xeroderma pigmentosum group A knockout mice and remarkably reduced HCC incidence in these mice to 14% from 100% in the controls. It also effectively inhibited HCC development in the diethylnitrosamine-injected mice. Using clinical samples from two groups of patients, our study revealed that higher levels of γ-OHPdG are strongly associated with low survival (P < 0.0001) and low recurrence-free survival (P = 0.007).

CONCLUSION

These results support γ-OHPdG as a mechanism-based, biologically relevant biomarker for predicting the risk of HCC and its recurrence. (Hepatology 2018;67:159-170).

Molecular hepatoprotective effects of lipoic acid against carbon tetrachloride-induced liver fibrosis in rats: Hepatoprotection at molecular level

BACKGROUND

Liver fibrosis is a noteworthy well-being issue that can prompt the progression of liver cirrhosis and hepatocellular carcinoma. Prominently, many antioxidants have been shown to have defensive impacts against liver fibrosis.

AIM

Subsequently, in the present study, the viability of alpha-lipoic acid (α-LA) in ensuring against carbon tetrachloride (CCl₄)-actuated liver fibrosis and the mechanism(s) involved in this defensive impact were considered in rats.

RESULTS

The present results uncovered that in the CCl₄-treated group, the expression of antioxidant enzymes and matrix metalloproteinase-13 (MMP-13) messenger RNA (mRNA) was downregulated ( p < 0.05), and the levels of lipid peroxide and nitric oxide were increased ( p < 0.05) in the treated rat livers along with increased collagen deposition compared to that of the control group. Also, the gene expression levels of the proinflammatory factors interleukin-6 and tumor necrosis factor-alpha, nuclear factor-kappa B (NF-κB) p65, transforming growth factor-alpha, and inducible nitric oxide synthase (iNOS) were upregulated significantly ( p < 0.05) in the CCl₄ group. These negative impacts were all restrained by α-LA.

CONCLUSIONS

These outcomes show that α-LA might be compelling at forestalling collagen deposition and hepatic oxidative stress as well as downregulating the expression of hepatic proinflammatory cytokines, iNOS, and NF-κB and upregulating MMP-13 expression.

Grape-seed proanthocyanidins inhibit the lipopolysaccharide-induced inflammatory mediator expression in RAW264.7 macrophages by suppressing MAPK and NF-κb signal pathways

Grape-seed proanthocyanidins (GSPs) have been shown to function as an anti-oxidant and anti-inflammatory agent with little toxicity in vivo and in vitro. However, little is known about their anti-inflammatory properties and mechanisms of action. The specific focus being its effects on the MAP kinases and nuclear factor-kappaB (NF-κB) signal transduction pathways in lipopolysaccharide (LPS) -stimulated RAW264.7 cells. GSPs extract has been found to suppress the mRNA expression of pro-inflammatory cytokines like tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and inflammatory molecule of cyclooxygenase-2 (COX-2) while mRNA level of IL-10 was greatly promoted. Furthermore, GSPs extract inhibited the expression of phosphorylated ERK, JNK and P38, as well as phosphorylated IKKα/β and NF-κB p65 subunit. In conclusion, our results show that GSPs extract showed its anti-inflammatory and immunomodulatory properties by suppressing the activation of MAP kinases and NF-κB signal transduction pathways.

Molecular Mechanisms of Lipoic Acid Protection against Aflatoxin B₁-Induced Liver Oxidative Damage and Inflammatory Responses in Broilers

Alpha-lipoic acid (α-LA) was evaluated in this study for its molecular mechanisms against liver oxidative damage and inflammatory responses induced by aflatoxin B₁ (AFB₁). Birds were randomly allocated into four groups with different diets for three weeks: a basal diet, a 300 mg/kg α-LA supplementation in a basal diet, a diet containing 74 μg/kg AFB₁, and 300 mg/kg α-LA supplementation in a diet containing 74 μg/kg AFB₁. In the AFB₁ group, the expression of GSH-P_X mRNA was down-regulated (p < 0.05), and the levels of lipid peroxide and nitric oxide were increased (p < 0.05) in the chicken livers compared to those of the control group. Additionally, the mRNA level of the pro-inflammatory factor interleukin-6 was up-regulated significantly (p < 0.05), the protein expressions of both the nuclear factor kappa B (NF-κB) p65 and the inducible nitric oxide synthase were enhanced significantly (p < 0.05) in the AFB₁ group. All of these negative effects were inhibited by α-LA. These results indicate that α-LA may be effective in preventing hepatic oxidative stress, down-regulating the expression of hepatic pro-inflammatory cytokines, as well as inhibiting NF-κB expression.

Anti-inflammatory effect of 3-O-[(6'-O-palmitoyl)-β-D-glucopyranosyl sitosterol] from Agave angustifolia on ear edema in mice

In Mexico Agave angustifolia has traditionally been used to treat inflammation. The aim of this study was to measure the anti-inflammatory effect of the extract of A. angustifolia, the isolation and identification of active compounds. From the acetone extract two active fractions were obtained, (AsF13 and AaF16). For the characterization of pharmacological activity, the acute inflammatory model of mouse ear edema induced with TPA was used. The tissue exposed to TPA and treatments were subjected to two analysis, cytokine quantification (IL-1β, IL-6, IL-10 and TNF-α) and histopathological evaluation. The active fraction (AaF16) consisted principally of 3-O-[(6'-O-palmitoyl)-β-D-glucopyranpsyl] sitosterol. In AaF13 fraction was identified β-sitosteryl glucoside (2) and stigmasterol (3). The three treatments tested showed a concentration-dependent anti-inflammatory effect (AaAc Emax = 33.10%, EC50 = 0.126 mg/ear; AaF13 Emax = 54.22%, EC50 = 0.0524 mg/ear; AaF16 Emax = 61.01%, EC50 = 0.050 mg/ear). The application of TPA caused a significant increase on level of IL-1β, IL-6 and TNFα compared with basal condition, which was countered by any of the experimental treatments. Moreover, the experimental treatments induced a significant increase in the levels of IL-4 and IL-10, compared to the level observed when stimulated with TPA. Therefore, the anti-inflammatory effect of Agave angustifolia, is associated with the presence of 3-O-[(6'-O-palmitoyl)-β-D-glucopyranosyl] sitosterol.

In vivo detection of a novel endogenous etheno-DNA adduct derived from arachidonic acid and the effects of antioxidants on its formation

Previous studies showed that 7-(1',2'-dihydroxyheptyl)-substituted etheno DNA adducts are products of reactions with the epoxide of (E)-4-hydroxy-2-nonenal, an oxidation product of ω-6 polyunsaturated fatty acids (PUFAs). In this work, we report the detection of 7-(1',2'-dihydroxyheptyl)-1,N(6)-ethenodeoxyadenosine (DHHedA) in rodent and human tissues by two independent methods: a (32)P-postlabeling/HPLC method and an isotope dilution liquid chromatography-electrospray ionization-tandem mass spectrometry method, demonstrating for the first time that DHHedA is a background DNA lesion in vivo. We showed that DHHedA can be formed upon incubation of arachidonic acid with deoxyadenosine, supporting the notion that ω-6 PUFAs are the endogenous source of DHHedA formation. Because cyclic adducts are derived from the oxidation of PUFAs, we subsequently examined the effects of antioxidants, α-lipoic acid, Polyphenon E, and vitamin E, on the formation of DHHedA and γ-hydroxy-1,N(2)-propanodeoxyguanosine (γ-OHPdG), a widely studied acrolein-derived adduct arising from oxidized PUFAs, in the livers of Long Evans Cinnamon (LEC) rats. LEC rats are afflicted with elevated lipid peroxidation and prone to the development of hepatocellular carcinomas. The results showed that although the survival of LEC rats was increased significantly by α-lipoic acid, none of the antioxidants inhibited the formation of DHHedA, and only Polyphenon E decreased the formation of γ-OHPdG. In contrast, vitamin E caused a significant increase in the formation of both γ-OHPdG and DHHedA in the livers of LEC rats.

Influence of lipoic acid on testicular toxicity induced by bi-n-butyl phthalate in rats

Bi-n-butyl phthalate (BNBP) is an environmental pollutant. The aim of this study was to evaluate the protective effect of lipoic acid (LA) against testicular dysfunction associated with the intake of to BNBP- intoxicated rats. Adult male Wistar rats were divided into 4 groups of 6 animals each, and received medication orally for 14 days. Group I rats received 0.5 ml corn oil. Group II rats received LA (20 mg/kg B.W./day). Group III rats received BNBP (250 mg/kg B.W./day). Group IV rats received LA 24h prior to BNBP intake. Testes weight, cauda sperm count and sperm motility were decreased significantly by 18.15%, 13.83% and 13.5%, respectively, after BNBP treatment. Significant increase by 12.1%, 10.20% and 11.51%, respectively, was observed in LA-BNBP rats. Significant increase by 1.53%, 1.5% and 1.8%, for serum follicle stimulating hormone, testosterone and total antioxidant status, respectively, were observed in LA-BNBP rats. Testicular lipid peroxides and lactate dehydrogenase enzyme were significantly decreased by 1.5 and 1.6 folds, respectively, in LA-BNBP rats were decreased after BNBP treatment. Testicular superoxide dismutase, catalase and glutathione reductase enzymes were significantly increased in LA-BNBP rats. LA-BNBP rats, decreased the damage to seminiferous tubules produced by BNBP intake. In conclusion, LA mitigated BNBP-induced testicular toxicity through antioxidant mechanism and by direct free radical scavenging activity.

Stability of a liposomal formulation containing lipoyl or dihydrolipoyl acylglycerides

CONTEXT

The acylglycerides of lipoic and dihydrolipoic acids may serve as slow-release sources for cutaneous delivery of these antioxidants when formulated in a liposomal vehicle.

OBJECTIVE

Testing was conducted to determine the storage stability of lipoyl glycerides in phospholipid-based liposomes.

MATERIALS AND METHODS

Lipoyl glycerides prepared by transesterification of lipoic acid with high oleic sunflower oil were incorporated into unilamellar liposomes comprised of soy phosphatidylcholine (soyPC) or dioleoylphosphatidylcholine (DOPC).

RESULTS

Lipoyl glycerides were stable in soyPC at 4 °C (90% remaining after five weeks) and decayed with a half-life (t(½)) of 14 d at 40 °C. In contrast, lipoyl glycerides embedded in DOPC were completely stable for four weeks at 40 °C. Dihydrolipoyl glycerides in soyPC converted to lipoyl glycerides at 4 °C (t(½) = 14 d) over four weeks, and much more rapidly so at 40 °C (t(½) = 1 d). A hydroperoxide accumulation analysis indicated that lipoyl glycerides and dihydrolipoyl glycerides were modified or degraded while suppressing autoxidation of the polyunsaturated fatty acids present in soyPC. Dynamic light scattering measurements found that liposomes containing lipoyl glycerides or dihydrolipoyl glycerides did not undergo significant size changes for at least 48 d, indicating that inclusion of the lipoic acid derivatives did not induce vesicle aggregation.

DISCUSSION/CONCLUSION

Substitution of the soyPC with DOPC, which is not readily subject to autoxidation, provided a much more stable storage environment for lipoyl glycerides. These findings confirm the expectation that phospholipid liposomes need to be oxidatively stable vehicles for dermal delivery of lipoic acid derivatives.

The preventive role of breadfruit against inflammation-associated epithelial carcinogenesis in mice

Artocarpus communis has been identified as a rich source of flavonoids and has been gaining attention for its potential chemopreventive abilities. In this study, methanol extracts from the fruit of A. communis (MEFA) and leaf of A. communis (MELA) were prepared, and their effects on inflammation-associated skin tumorigenesis were assessed using mouse models, including 12-O-tetradecanoylphorbol-13-acetate (TPA) induced cutaneous inflammation as well as 7,12-dimethylbenz[α]anthracene (DMBA) initiated and TPA-promoted skin tumorigenesis. According to the results, both MEFA and MELA decreased the intensity of leukocyte infiltration in mouse dorsal skin and cutaneous edema induced by TPA, which appeared to be mediated by inhibition of proinflammatory genes (inducible nitric oxide synthase, cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), IL-1β, and IL-6) and proinflammatory mediators (TNF-α, IL-1β, and Prostaglandin E2 ). In addition, topical application with MEFA or MELA effectively attenuated tumor incidence, multiplicity, volume, malignancy as well as angiogenesis of TPA-stimulated skin tumor promotion in DMBA-initiated mice. Notably, immunohistochemical stain showed that MEFA and MELA attenuated COX-2 expression of both skin and tumor tissues in different animal tests, which may be closely related to the suppression of nuclear factor kappa B/activator protein signaling networks. These findings first demonstrate that flavonoid-rich A. communis may exert potent anti-inflammatory activity through modulation of COX-2 in TPA-activated skin and tumor tissues.

Dihydroasparagusic acid: antioxidant and tyrosinase inhibitory activities and improved synthesis

Dihydroasparagusic acid (DHAA) is the reduced form of asparagusic acid, a sulfur-containing flavor component produced by Asparagus plants. In this work, DHAA was synthetically produced by modifying some published protocols, and the synthesized molecule was tested in several in vitro assays (DPPH, ABTS, FRAP-ferrozine, BCB, deoxyribose assays) to evaluate its radical scavenging activity. Results show that DHAA is endowed with a significant in vitro antioxidant activity, comparable to that of Trolox. DHAA was also evaluated for its inhibitory activity toward tyrosinase, an enzyme involved, among others, in melanogenesis and in browning processes of plant-derived foods. DHAA was shown to exert an inhibitory effect on tyrosinase activity, and the inhibitor kinetics, analyzed by a Lineweaver-Burk plot, exhibited a competitive mechanism. Taken together, these results suggest that DHAA may be considered as a potentially active molecule for use in various fields of application, such as pharmaceutical, cosmetics, agronomic and food.

Pesticide-induced decrease in rat testicular steroidogenesis is differentially prevented by lipoate and tocopherol

We have previously demonstrated that the sub-chronic administration of low doses of Toc or α-Toc, glyphosate and zineb to rats (i.p. 1/250 LD50, three times a week for 5 weeks) provoked severe oxidative stress (OS) in testicles. These effects were also reflected in plasma. Lipoic acid (LA) and α-tocopherol are considered as antioxidants due to their ability to neutralize reactive oxygenated species (ROS) and reset endogenous antioxidant levels. To investigate the possible protective effect on reproductive function, LA and Toc (i.p. 25, 50 and 100mg/kg) were administered simultaneously with the pesticide mixture (PM) for 5 weeks. Both drugs prevented OS and the damage to proteins and lipids caused by PM in a dose-dependent manner. The PM-induced increase levels of prostaglandins E2 and F2α was completely restored by LA but not by Toc. Similarly, only LA was able to restore the inhibition of testosterone production, the decrease of 3β- and 17β-hydroxysteroid dehydrogenases activities, and the elevation of gonatropins (FSH and LH) levels produced by PM. Furthermore, LA was more efficient than Toc in normalizing the histological alterations produced by PM administration, suggesting that pesticides act though other mechanisms that generate oxidative stress. In our experimental model LA displayed a higher protective role against pesticide-induced damage than that observed by Toc administration. Our results suggest that LA administration is a promising therapeutic strategy for coping with disorders suspected to be caused by OS generators - such as pesticides - in male reproductive system.

Inhibitory effect of echinocystic acid on 12-O-tetradecanoylphorbol-13-acetate-induced dermatitis in mice

The rhizome of Codonopsis lanceolata (family Campanulaceae), which contains lancemaside A as a main constituent, is frequently used in the traditional Chinese medicine for the treatment of inflammatory diseases. Lancemaside A exhibits anti-inflammatory effect in vitro and in vivo. However, orally administered lancemaside A is metabolized to echinocystic acid by the intestinal microflora and the metabolite is absorbed into the blood. Therefore, to understand whether echinocystic acid is effective against skin inflammatory diseases, we assessed its inhibitory effect against 12-O-tetra decanoylphorbol-13-acetate (TPA)-induced ear inflammation in mice. Topically administered echinocystic acid potently suppressed TPA-induced ear swelling. The suppression rates at 0.05 and 0.10 % concentrations were 65 and 73 %, respectively. Echinocystic acid also inhibited TPA-induced myeloperoxidase activity, as well as COX-2, iNOS, TNF-α and IL-1β expressions. Echinocystic acid inhibited NF-κB in TPA-treated mouse ears, as well as in lipopolysaccharide-stimulated peritoneal macrophages. Its potency is comparable with that of dexamethasone. These findings indicate that echinocystic acid may ameliorate inflammatory diseases, such as dermatitis.

Antigenotoxic effect of lipoic acid against mitomycin-C in human lymphocyte cultures

Antitumor agents are used in therapy against many forms of human cancer. One of these is mitomycin-C (MMC). As with many agents, it can interact with biological molecules and can induce genetic hazards in non-tumor cells. One of the possible approaches to protect DNA from this damage is to supply antioxidants that can remove free radicals produced by antitumor agents. Lipoic acid (LA) is known as one of the most powerful antioxidants. The aim of this study was to investigate antigenotoxic effects of LA against MMC induced chromosomal aberrations (CA), sister chromatid exchanges (SCE) and micronucleus (MN) formation in human lymphocytes. Lymphocytes were treated with 0.2 μg MMC/heparinized mL for 48 h. Three different concentrations (0.5, 1, 2 μg/mL) of LA were used together with MMC in three different applications; 1 h pre-treatment, simultaneous treatment and 1 h post-treatment. A negative, a positive and a solvent control were also included. In all the cultures treated with MMC + LA, the frequency of abnormal cells and CA/cell significantly decreased compared to MMC. Statistically significant reduction was also observed in SCE/cell and MN frequencies in all treatments. These results demonstrated anticlastogenic and antimutagenic effects of LA against MMC induced genotoxicity. LA showed the most efficient effect during 1 h pretreatment. On the other hand, MMC + LA treatments induced significant reduction in mitotic index than that of MMC treatment alone. These results are encouraging that LA can be a possible chemopreventive agent in tumorigenesis in both cancer patients and in health care persons handling anti-cancer drugs.

The melanocortin 1 receptor (MC1R) inhibits the inflammatory response in Raw 264.7 cells and atopic dermatitis (AD) mouse model

The alpha melanocyte stimulating hormone receptor (MC1R) is one of five G-protein coupled receptors belonging to the melanocortin subfamily, MC1R gene has been known to play a major role in regulating of fur color in mammals, and α-MSH and ACTH are endogenous nonselective agonists for MC1R. However, we found that MC1R was highly expressed in Raw 264.7 cells which were important inflammatory cells involved in the initiation of inflammatory responses. In addition, Cyclic AMP is not only a key molecule in the MC1R signal transduction pathway, but dampen innate immune-mediated responses. These intriguing biological results triggered the further conformation studies; it suggested that MC1R was very likely to be an important role in immunoregulation. In this study, we were to investigate the immunosuppressive effects of MC1R on inflammation in lipopolysaccharide (LPS) stimulated Raw 264.7 cells and LPS induced vivo 2-chloro-1,3,5-trinitrobenzene (TNCB)-induced atopic dermatitis (AD) model. The effects of the MC1R antagonist psoralen on pro-inflammatory cytokines and signaling pathways were analyzed by enzyme-linked immunosorbent assay, western blot, real-time fluorescence quantitative PCR and Histological analysis. Our results show a consistent and marked effect of high concentrations of MC1R antagonist psoralen increased the level of MC1R mRNA in Raw 264.7 cells by cumulative feedback regulation through preferential binding of MC1R. Moreover, as evidenced by inhibiting the LPS-induced TNF-α, IL-6 and enhancing the expression level of cyclic AMP protein in vitro. In vivo study it was also observed that psoralen promoted on histopathologic changes in the skin tissue of TNCB-induced AD mice. Taken together, our results suggest that MC1R decrease the inflammation in vitro and vivo, and might be a therapeutic signaling pathway to against inflammatory diseases.

Effect of Rhizoma Polygonati on 12-O-tetradecanoylphorbol-acetate-induced ear edema in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Rhizoma Polygonati is originated from the dried rhizomes of Polygonatum sibircum Red. It has long been used in traditional Chinese medicine for the treatment of inflammatory disorders.

AIM OF THE STUDY

The present study aims to investigate the anti-inflammatory effect of aqueous extract of Rhizoma Polygonati (ERP) in a mouse model of inflammation induced by 12-O-tetradecanoylphorbol-acetate (TPA).

MATERIALS AND METHODS

The anti-inflammatory effect was evaluated by measuring the ear thickness and activity of myeloperoxidase (MPO). The anti-inflammatory mechanism was explored by determining the protein and mRNA levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6.

RESULTS

The results showed that ERP significantly decreased the ear thickness and MPO activity in mouse model of inflammation induced by TPA. In addition, ERP also remarkably inhibited the protein and mRNA levels of iNOS, COX-2, TNF-α, IL-1β, and IL-6.

CONCLUSIONS

These results indicate that ERP has potential anti-inflammatory effect on TPA-induced inflammatory in mice, and the anti-inflammatory effect may be mediated, at least in part, by inhibiting the mRNA expression of a panel of inflammatory mediators including iNOS, COX-2, TNF-α, IL-1β, and IL-6.

Anti-inflammatory effects of Tat-Annexin protein on ovalbumin-induced airway inflammation in a mouse model of asthma

Chronic airway inflammation is a key feature of bronchial asthma. Annexin-1 (ANX1) is an anti-inflammatory protein that is an important modulator and plays a key role in inflammation. Although the precise action of ANX1 remains unclear, it has emerged as a potential drug target for inflammatory diseases such as asthma. To examine the protective effects of ANX1 protein on ovalbumin (OVA)-induced asthma in animal models, we used a cell-permeable Tat-ANX1 protein. Mice sensitized and challenged with OVA antigen had an increased amount of cytokines and eosinophils in their bronchoalveolar lavage (BAL) fluid. However, administration of Tat-ANX1 protein before OVA challenge significantly decreased the levels of cytokines (interleukin (IL)-4, IL-5, and IL-13) and BAL fluid in lung tissues. Furthermore, OVA significantly increased the activation of mitogen-activated protein kinase (MAPK) in lung tissues, whereas Tat-ANX1 protein markedly reduced phosphorylation of MAPKs such as extracellular signal-regulated protein kinase, p38, and stress-activated protein kinase/c-Jun N-terminal kinase. These results suggest that transduced Tat-ANX1 protein may be a potential protein therapeutic agent for the treatment of lung disorders including asthma.

Comparison on the anti-inflammatory effect of Cortex Phellodendri Chinensis and Cortex Phellodendri Amurensis in 12-O-tetradecanoyl-phorbol-13-acetate-induced ear edema in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Cortex Phellodendri is derived from the dried bark of Phellodendron chinense Schneid. or Phellodendron amurense Rupr. Traditionally, Cortex Phellodendron Chinensis (CPC) and Cortex Phellodendron Amurensis (CPA) are used interchangeably under the name "Huang Bai" for the treatment of gastroenteritis, abdominal pain or diarrhea. The present study aims to compare the anti-inflammatory effect of ethanol extracts of Cortex Phellodendri Chinensis (ECPC) and Cortex Phellodendri Amurensis (ECPA) in a mouse model of inflammation induced by 12-O-tetradecanoylphorbol-acetate (TPA).

MATERIALS AND METHODS

The anti-inflammatory effect was evaluated by measuring the ear thickness, activity of myeloperoxidase (MPO) and the production reactive oxygen species (ROS). The anti-inflammatory mechanism was explored by determining the protein and mRNA levels of cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6.

RESULTS

The results showed that both ECPC and ECPA significantly decreased the ear thickness, MPO activity and the ROS level in mouse model of inflammation induced by TPA. In addition, ECPC and ECPA also remarkably inhibited the protein and mRNA levels of TNF-α, IL-1β, IL-6 and COX-2. Interestingly, ECPC has better anti-inflammatory effect than that of ECPA.

CONCLUSIONS

These results indicate that both ECPC and ECPA have potential anti-inflammatory effect on TPA-induced inflammatory in mice, and ECPC is more effective than ECPA. The anti-inflammatory effect of the herbal drugs may be mediated, at least in part, by down-regulating the mRNA expression of a panel of inflammatory mediators including TNF-α, IL-1β, IL-6 and COX-2.

α-Lipoic acid inhibits liver fibrosis through the attenuation of ROS-triggered signaling in hepatic stellate cells activated by PDGF and TGF-β

Reactive oxygen species (ROS) have been implicated in hepatic stellate cell activation and liver fibrosis. We previously reported that α-lipoic acid (LA) and its reduced form dihydrolipoic acid (DHLA) inhibited toxicant-induced inflammation and ROS generation. In the present study, we further examined the effects of LA/DHLA on thioacetamide (TAA)-induced liver fibrosis in rats and the possible underlying mechanisms in hepatic stellate cells in vitro. We found that co-administration of LA to rats chronically treated with TAA inhibited the development of liver cirrhosis, as indicated by reductions in cirrhosis incidence, hepatic fibrosis, and AST/ALT activities. We also found that DHLA inhibited TGF-β/PDGF-stimulated HSC-T6 activation and ROS generation. These effects could be mediated by the MAPK and PI3K/Akt pathways. According to our current results, LA may have a beneficial role in the treatment of chronic liver diseases caused by ongoing hepatic damage.

Regulation of cell cycle transition and induction of apoptosis in HL-60 leukemia cells by lipoic acid: role in cancer prevention and therapy

Background

Lipoic acid (LA), a potent antioxidant, has been used as a dietary supplement to prevent and treat many diseases, including stroke, diabetes, neurodegenerative and hepatic disorders. Recently, potent anti-tumorigenic effects induced by LA were also reported and evident as assayed by suppression of cell proliferation and induction of apoptosis in malignant cells. However, the mechanism by which LA elicits its chemopreventive effects remains unclear.

Methods and Results

Herein, we investigated whether LA elicits its anti-tumor effects by inducing cell cycle arrest and cell death in human promyelocytic HL-60 cells. The results showed that LA inhibits both cell growth and viability in a time- and dose-dependent manner. Disruption of the G₁/S and G₂/M phases of cell cycle progression accompanied by the induction of apoptosis was also observed following LA treatment. Cell cycle arrest by LA was correlated with dose-dependent down regulation of Rb phosphorylation, likely via suppression of E2F-dependent cell cycle progression with an accompanying inhibition of cyclin E/cdk2 and cyclin B1/cdk1 levels. Evidence supporting the induction of apoptosis by LA was based on the appearance of sub-G₁ peak in flow cytometry analysis and the cleavage of poly(ADP-ribose) polymerase (PARP) from its native 112-kDa form to the 89-kDa truncated product in immunoblot assays. Apoptosis elicited by LA was preceded by diminution in the expression of anti-apoptotic protein bcl-2 and increased expression of apoptogenic protein bax, and also the release and translocation of apoptosis inducing factor AIF and cytochrome c from the mitochondria to the nucleus, without altering the subcellular distribution of the caspases.

Conclusion

This study provides evidence that LA induces multiple cell cycle checkpoint arrest and caspase-independent cell death in HL-60 cells, in support of its efficacious potential as a chemopreventive agent.