Daphnetin ameliorated GM-induced renal injury through the suppression of oxidative stress and apoptosis in mice.

Gentamicin (GM), an aminoglycoside antibiotic, is one of the most effective drugs used in the treatment of various types of bacterial infections, but the major adverse effect and drug-induced nephrotoxicity of GM limit its clinical applications. Daphnetin (Daph) is a natural coumarin derivative that is clinically used to treat rheumatoid arthritis and coagulopathy and exhibits antioxidant effects. However, the effect of Daph on GM-induced nephrotoxicity has not yet been elucidated. This study investigated Daph-mediated protection against GM-induced nephrotoxicity in mice and explored the underlying mechanisms of GM-induced renal dysfunction in mice. We found that Daph treatment significantly reduced GM-induced nephrotoxicity mainly by ameliorating renal injury in mice and attenuating cell damage in vitro. Mechanistically, we found that Daph upregulated the expression level of Nrf2 and its regulated antioxidant enzymes HO-1, NQO1, GCLC and GCLM in vivo and in vitro. GM upregulated the expression levels of NOX4, cleaved Caspase-3 and p53 and the BAX/BCL2 ratio in vivo to stimulate oxidative stress and apoptosis. However, Daph treatment significantly improved the oxidative stress and apoptosis caused by GM, thereby exerting antioxidative and antiapoptotic effects. Our study was the first to suggest that the natural product Daph protects against GM-induced nephrotoxicity through the activation of Nrf2 which regulates oxidative stress and apoptosis. The pharmacological activation of Nrf2 may be useful as a novel therapy to prevent renal injury.

Effects of umbelliferone isolated from the Ferulago pauciradiata Boiss. & Heldr. Plant on cecal ligation and puncture-induced sepsis model in rats.

Sepsis is a pathophysiological event involving systemic inflammatory response syndrome, multiple organ failure syndromes, and tissue damage. Overproduction of free radicals as a result of tissue damage during sepsis contributes to cellular toxicity, organ failure, and even mortality. Antioxidants, which scavenge free radicals, play a protective role against various diseases. Previous studies have shown that umbelliferone (UF) has antioxidant and anti-inflammatory effects. Since oxidative stress is naturally associated with sepsis-induced organ dysfunction, the application of antioxidant compounds could potentially illuminate the pathophysiology of sepsis, which does not yet have an effective treatment. The sepsis model induced by cecal ligation and puncture (CLP) was applied to rats. Different doses of UF (10░mg/kg, 20░mg/kg, and 40░mg/kg) on oxidant-antioxidant in septic rats, mRNA of inflammatory mediators such as tumor necrosis factor- α (TNF-α) and interleukin (IL)-1 its effects on expression levels were evaluated in lung, kidney, and liver tissues. When the lung, kidney, and liver tissues of septic rats were compared with those of the control group, it was found that UF administration increased dose-dependent superoxide dismutase activity and glutathione levels and significantly decreased malondialdehyde levels. The effects of UF administration on oxidative parameters were dose-dependent. The 40░mg/kg UF dose showed greater anti-oxidative properties than the 20░mg/kg and 10░mg/kg doses for all the evaluated parameters. Further, the TNF- α mRNA expression of the CLP +40░mg/kg group was reduced to a level comparable to that of the control group. UF has been found to be an effective molecule in reducing oxidative stress by supporting endogenous antioxidants and enhancing the scavenging effects of free radicals. The potent antioxidant property of UF may also be related to the suppression of the cytokine cascade during sepsis. The results suggest that UF administration may represent a new treatment for the prevention of lung, kidney and liver damage caused by septic conditions.

Effect of umbelliferone on adjuvant-induced arthritis in rats by MAPK/NF-κB pathway.

PURPOSE: Umbelliferone (Umb), a member of coumarin family, is found in many plants and is a promising molecule with potential anti-inflammatory, anti-oxidative, and anti-tumor activities. However, the effect of Umb on arthritis remains unclear. METHODS: A rat model with Freund's complete adjuvant (FCA)-induced arthritis was developed and used to test the efficacy of Umb on arthritis rats. Rats were given an intragastric injection of Umb (20 and 40 mg/kg) once daily from days 21 to 28 after the administration of FCA. Hind paw volume was assessed using a volume meter. The pro-inflammatory cytokine levels and prostaglandin E2 (PEG2) level in serum and synovial fluid were detected by ELISA. HE staining was used to determine representative histological changes in joint tissues, and Western blot analysis was employed to study the effects of Umb on MAPK/NF-κB signaling pathway. RESULTS: Our results showed that Umb suppressed the release of IL-6, IL-1ß, tumor necrosis factor-alpha, and PEG2. In addition, Umb could also dramatically ameliorate the pathological changes observed in rat joints. Based on the results of Western blot, we also observed that Umb could strikingly suppress the expression of MAPK/NF-κB pathway molecules. CONCLUSION: These results proved that treatment with Umb is very effective for arthritis and inhibiting the MAPK/NF-κB signaling pathway may be a potential therapeutic target for treatment of arthritis.

Development of a daphnetin transdermal patch using chemical enhancer strategy: insights of the enhancement effect of Transcutol P and the assessment of pharmacodynamics.

OBJECTIVE: The aim of this study was to develop a drug-in-adhesive patch for transdermal delivery of daphnetin (DA), which is a coumarin derivative in Girald Daphne, and to investigate the role of Transcutol P (TP) in the release and percutaneous permeation processes of DA. METHODS: Backing films, permeation enhancers and enhancer content in the transdermal patch were investigated through in vitro experiments using rat skin. Anti-inflammatory and analgesic effects of the optimized formulation were evaluated using the adjuvant arthritis model and the pain model induced by acetic acid, respectively. In addition, the enhancement effect of TP was investigated using differential scanning calorimetry (DSC), FTIR, and molecular dynamic simulation. RESULTS: The optimal formulation, composed of DURO-TAK® 87-2852, CoTranTM 9680, 1% DA, and 10% TP showed anti-inflammatory and analgesic effects. It was found that TP only promoted the release process of DA from its transdermal patch. Furthermore, the decrease of interaction between drug and pressure sensitive adhesive (PSA) as well as the improvement of PSA mobility due to TP addition were the main factors that enhanced the release of DA from patch. CONCLUSIONS: This study successfully used TP to develop a DA patch with good anti-inflammatory and analgesic effects, proving that TP promotes the release of DA by reducing the interaction between DA and PSA and increasing the mobility of PSA.

Umbelliprenin shows antitumor, antiangiogenesis, antimetastatic, anti-inflammatory, and immunostimulatory activities in 4T1 tumor-bearing Balb/c mice.

Umbelliprenin (UMB) has shown various pharmacological properties in vitro. We investigated the antineoplastic and immunostimulatory effects of UMB in 4T1 mammary-tumor-bearing mice. Two-hundred microliter of UMB (12.5 mg/ml) was intraperitoneally administrated to healthy and tumor-bearing female Balb/c mice for a period of 18 days. Data was analyzed using GraphPad Prism 5 software for Windows (version 5, La Jolla, CA). UMB caused a significant decrease in tumor size (P < 0.01). Serum interferon gamma (IFNγ) was augmented in both healthy and tumor-bearing animals (P < 0.01), and IL-4 declined in healthy animals (P < 0.01) treated with UMB. Expressions of Ki-67, VEGF, CD31, MMP2, MMP9, VCAM1, and NF-κB were significantly decreased in tumors from UMB-treated animals (P < 0.001), whereas E-Cadherin and TNFR1 expressions were markedly increased (P < 0.001). The rates of liver and lung metastases in UMB-administrated animals were smaller compared to the control. UMB can potently inhibit tumor growth, angiogenesis, metastasis, and inflammation and potentiate an antitumor immune response in vivo. However, further investigations are required to evaluate the UMB mechanisms of action in cancerous cells.

Effect of esculetin on bone metabolism in ovariectomized rats.

OBJECTIVE: To determine the effect of an esculetin formulation (at 97.4% purity) on osteoporosis, and to investigate the potential underlying molecular mechanism(s). METHODS: Sixty specific pathogen free-grade female Wistar rats were randomly assigned to three groups: blank control (n = 12), sham (n = 12), and model (n = 36). The model group were bilaterally ovariectomized. The sham group had the tissue surrounding the ovaries removed, while the ovaries were retained. After 3 months, the model group was randomly divided into three subgroups: OVX (n = 12), positive control (n = 12), and esculetin (n = 12). The positive control group and the esculetin group were intragastrically administered diethylstilbestrol (0.046 mg?kg-1?d-1) or esculetin (384 mg?kg-1?d-1), respectively, once per day for 6 consecutive days; medication administration was then stopped for 1 d, before being administered for another 6 consecutive days. All rats were treated for 3 months. Samples were collected at the end of the treatment period. An Osteocore3 Digital 2D bone densitometer was used to test the bone mineral density, and histomorphometric analysis was performed to measure bone mass, bone formation, and bone resorption. Enzyme-linked immunosorbent assay analysis was used to measure the serum concentrations of interleukin-6 (IL-6), osteoprotegerin (OPG), and receptor activator of nuclear factor-kappa B ligand (RANKL). Immunohistochemistry and in situ hybridization were performed to detect the protein and mRNA expressions of OPG and RANKL in osteoblasts and bone marrow stromal cells. RESULTS: Compared with the OVX group, the esculetin group had significantly greater femoral bone mineral density and tibial trabecular bone volume, and significantly smaller trabecular resorption surface. The percentage of trabecular formation surface, average osteoid width, trabecular bone mineralization rate, and cortical bone mineralization rate did not significantly differ between groups. Compared with the sham group, the esculetin group had significantly decreased serum levels of IL-6 and RANKL, and significant downregulation of RANKL protein and mRNA expression levels in osteoblasts and bone marrow stromal cells; however, there was no significant difference between groups in OPG. CONCLUSION: Esculetin can increase bone mass by upregulating RANKL expression in osteoblasts and bone marrow stromal cells, and decreasing serum IL-6 concentration. This indicates that the therapeutic effect of esculetin on osteoporosis occurs via decreased bone resorption.

Fabrication, optimization, and characterization of umbelliferone ß-D-galactopyranoside-loaded PLGA nanoparticles in treatment of hepatocellular carcinoma: in vitro and in vivo studies.

Umbelliferone ß-D-galactopyranoside (UFG), isolated from plants, exhibits promising inhibitory action on numerous diseases. The present research was initiated to develop a suitable delivery system for UFG with an intention to enhance its therapeutic efficacy against diethyl nitrosamine (DEN)-induced hepatocellular carcinoma (HCC) in Wistar rats. UFG-loaded polymeric nanoparticles prepared by sonication were scrutinized for average size, drug loading capacity, zeta potential, and drug release potency in animals. HCC cell lines HuH-7 and Hep G2 were used for in vitro cytotoxic investigation. Several hepatic, nonhepatic, antioxidant, and anti-inflammatory biochemical parameters were estimated to establish the anticancer potential of UFG nanoformulation. Microscopical and histopathological investigations were also undertaken to substantiate the results of our work. Umbelliferone ß-D-galactopyranoside-loaded poly(d,l-lactide-co-glycolide) nanoparticles (UFG-PLGA-NP) with particle size of 187.1 nm and polydispersity index 0.16 were uniform in nature with 82.5% release of the total amount of drug after 48 h. Our study successfully established the development and characterization of UFG-PLGA-NP with noticeable effect against both in vivo and in vitro models. The anticancer potential of UFG-PLGA-NP was brought about by the management of DEN-induced reactive oxygen species generation, mitochondrial dysfunction, proinflammatory cytokines alteration, and induction of apoptosis. Positive zeta potential on the surface of UFG-PLGA-NP would have possibly offered higher hepatic accumulation of UFG, particularly in the electron-dense mitochondria organelles, and this was the take-home message from this study. Our results demonstrated that such polymer-loaded delivery systems of UFG can be a better option and can be further explored to improve the clinical outcomes against hepatic cancer.

Umbelliferon-α-d-glucopyranosyl-(2I→1II)-α-Dglucopyranoside ameliorates Diethylnitrosamine induced precancerous lesion development in liver via regulation of inflammation, hyperproliferation and antioxidant at pre-clinical stage.

It is well documented that anomalous production of inflammatory proteins linked with most of the toxic expression and genesis of diverse chronic disease including cancer. Diethylnitrosamine (DEN) a well-known hepatotoxin and hepatocarcinogen, can induce oxidative stress and inflammatory reaction in it. Umbelliferone, secondary metabolites, is present in different plants and widely consumed by humans as medicine and food supplements. The aim of the current study was to scrutinize the chemoprotective potential of umbelliferon-α-d-glucopyranosyl-(2I→1II)-α-d-glucopyranoside (UFD) against DEN-induced hepatocellular carcinoma (HCC) in experimental rats. Single intraperitoneal injection of DEN (200mg/kg) was used for induction of HCC in rats and rats were grouped and orally treated with UFD (5, 10 and 20mg/kg) dose for 22 weeks. Parameters under investigation included hepatic, non-hepatic enzymes, oxidative stress, pro-inflammatory cytokines, COX-2 and NF-κB level along with histopathological examination in HCC rats. UFD exerted protective effect via reduction of oxidative stress, liver and non-liver parameters in a dose-dependent manner. It also reduced the expression of TNF-α, IL-1ß, IL-6 and COX-2 in diseased rats. Our result revealed the essential repression of the inflammation cascade through modulation of nuclear factor-kappa B (NF-κB) signaling pathway.

Esculetin Neutralises Cytotoxicity of t-BHP but Not of H2O2 on Human Leukaemia NB4 Cells.

The coumarin esculetin shows antioxidant action on some cell types, both by scavenging ROS and by decreasing ROS production. We have previously demonstrated the induction of apoptosis by esculetin on NB4 human leukaemia cells by an ill-defined mechanism related to ROS levels. In this work, we analyze the effect of the simultaneous treatment with esculetin and two oxidants to observe the early events in the mechanism of esculetin-induced apoptosis. Our results show that, from the early time of 15 min, esculetin acts synergistically with H2O2 to decrease cell viability and metabolic activity and to increase apoptosis in NB4 cells. In contrast, the early oxidative effects of t-BHP are neutralised by esculetin, protecting human leukaemia NB4 cells from apoptosis. Esculetin seems to restrict the increase in peroxides caused by H2O2 or t-BHP in the time interval analyzed. These results contribute to a better understanding of the cytotoxic effect caused by esculetin on NB4 cells. At the same time, the early neutralisation of exogenous oxidants could be of interest to prevent diseases related to oxidative stress imbalance.

Daphnetin-mediated Nrf2 antioxidant signaling pathways ameliorate tert-butyl hydroperoxide (t-BHP)-induced mitochondrial dysfunction and cell death.

Daphnetin (Daph), a natural coumarin derivative isolated from plants of the Genus Daphne, possesses abundant biological activities, such as anti-inflammatory, antioxidant and anticancer properties. In the present study, we focused on investigating the protective effect of Daph against tert-butyl hydroperoxide (t-BHP)-induced oxidative damage, mitochondrial dysfunction and the involvement of underlying molecular mechanisms. Our findings indicated that Daph effectively inhibited t-BHP-stimulated cytotoxicity, cell apoptosis, and mitochondrial dysfunction, which are associated with suppressed reactive oxygen species (ROS) generation, decreased malondialdehyde (MDA) formation, increased superoxide dismutase (SOD) levels and glutathione (GSH)/GSSG (oxidized GSH) ratio. Further investigation indicated that Daph significantly suppressed cytochrome c release and NLRP3 inflammasome activation and modulated apoptosis-related protein Bcl-2, Bax, and caspase-3 expression. Moreover, Daph dramatically induced the expression of the glutamate-cysteine ligase modifier (GCLM) subunit and the glutamate-cysteine ligase catalytic (GCLC) subunit, heme oxygenase-1 (HO-1), and NAD (P) H: quinone oxidoreductase (NQO1), which is largely dependent on upregulating the nuclear factor-erythroid 2-related factor 2 (Nrf2) nuclear translocation, reducing the Keap1 protein expression, and strengthening the antioxidant response element (ARE) promoter activity. Additionally, Daph remarkably activated a c-Jun NH2-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) phosphorylation, but ERK and JNK inhibitor pretreatment exhibited an evident decrease of the level of Daph-enhanced Nrf2 nuclear translocation. Furthermore, Daph exposure suppressed t-BHP-induced cytotoxicity and ROS overproduction, which are mostly blocked in Nrf2 knockout RAW 264.7 cells and peritoneal macrophages. Accordingly, Daph exhibited protective roles against t-BHP-triggered oxidative damage and mitochondrial dysfunction by the upregulation of Nrf2 antioxidant signaling pathways, which may be involved in the activation of JNK and ERK.

Daphnetin inhibits invasion and migration of LM8 murine osteosarcoma cells by decreasing RhoA and Cdc42 expression.

Daphnetin, 7,8-dihydroxycoumarin, present in main constituents of Daphne odora var. marginatai, has multiple pharmacological activities including anti-proliferative effects in cancer cells. In this study, using a Transwell system, we showed that daphnetin inhibited invasion and migration of highly metastatic murine osteosarcoma LM8 cells in a dose-dependent manner. Following treatment by daphnetin, cells that penetrated the Transwell membrane were rounder than non-treated cells. Immunofluorescence analysis revealed that daphnetin decreased the numbers of intracellular stress fibers and filopodia. Moreover, daphnetin treatment dramatically decreased the expression levels of RhoA and Cdc42. In summary, the dihydroxycoumarin derivative daphnetin inhibits the invasion and migration of LM8 cells, and therefore represents a promising agent for use against metastatic cancer.

Anti-inflammatory and proapoptotic effects of umbelliferone in colon carcinogenesis.

Colorectal cancer (CRC) is a serious health problem throughout the world. 5-Flurouracil, the first-line chemotherapy of colorectal cancer often produces more toxicity to neighboring cells; however, it is still used for CRC treatment. To overcome this, umbelliferone (UMB), a less toxic bioflavonoid has been used to test its anticancer effects on animal model. The objective of the present study is to evaluate the anticancer activity of UMB on 1,2-dimethylhydrazine (DMH)-induced rat colon tumorigenesis to determine the development of aberrant crypt foci (ACF), agyrophylic nucleolar organizer regions (AgNORs), mast cell recruitment, pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1ß and also study the expressions of inducible nitric oxide synthase, cyclooxygenase (COX)-2, and apoptotic markers. DMH-induced rats showed increased ACF number (incidence), multiplicity and its distribution, counts of AgNORs, mast cells, inflammatory markers and apoptotic proteins. Interestingly, UMB supplementation to DMH-induced rats (group 4) significantly (p < 0.05) suppressed ACF development, AgNORs, mast cells, and inflammatory markers and increased the apoptotic markers as compared to DMH-induced rats (group 2). We concluded that UMB is a potential anticancer agent that can be used for the prevention and treatment of CRC.

Anti-inflammatory and protective properties of daphnetin in endotoxin-induced lung injury.

Uncontrolled inflammatory responses cause tissue injury and severe immunopathology. Pharmacological interference of intracellular pro-inflammatory signaling may confer a therapeutic benefit under these conditions. Daphnetin, a natural coumarin derivative, has been used to treat inflammatory diseases including bronchitis. However, the protective effect of daphnetin in inflammatory airway disorders has yet to be determined, and the molecular basis for its anti-inflammatory properties is unknown. This paper shows that daphnetin treatment conferred substantial protection from endotoxin-induced acute lung injury (ALI), in parallel with reductions in the production of inflammatory mediators, symptoms of airway response, and infiltration of inflammatory cells. Further studies indicate that activation of macrophage and human alveolar epithelial cells in response to lipopolysaccharide (LPS) was remarkably suppressed by daphnetin, which was related to the down-regulation of NF-κB-dependent signaling events. Importantly, this study demonstrates that TNF-α-induced protein 3 (TNFAIP3), also known as A20, was significantly induced by daphnetin, which appeared to be largely responsible for the down-regulation of NF-κB activity through modulation of nondegradative TRAF6 ubiquitination. Accordingly, the deletion of TNFAIP3 in primary macrophages reversed daphnetin-elicited inhibition of immune response, and the beneficial effect of daphnetin in the pathogenesis of ALI was, partially at least, abrogated by TNFAIP3 knockdown. These findings demonstrate the anti-inflammatory and protective functions of daphnetin in endotoxin-induced lung inflammation and injury and also reveal the key mechanism underlying its action in vitro as well as in vivo.

Neuroprotective effects of daphnetin against NMDA receptor-mediated excitotoxicity.

The accumulation of glutamate can excessively activate the N-methyl-d-aspartate (NMDA) receptors and cause excitotoxicity. Daphnetin (Dap), a coumarin derivative, is a protein kinase inhibitor that exhibits antioxidant and neuroprotective properties. However, little is known about the neuroprotective effects of Dap on glutamate-induced excitotoxicity. We evaluated the neuroprotective activities in the primary cultured cortical neurons against NMDA-induced excitotoxicity. Pretreatment with Dap significantly prevented NMDA-induced neuronal cell loss. Dap significantly inhibited the neuronal apoptosis by regulating balance of Bcl-2 and Bax expression. Furthermore, pretreatment of Dap reversed the up-regulation of NR2B-containing NMDA receptors and inhibited the intracellular Ca2+ overload induced by NMDA exposure. In addition, Dap prevented cerebral ischemic injury in mice induced via a 2 h middle cerebral artery occlusion and a 24 h reperfusion in vivo. The findings suggest that Dap prevents the excitotoxicity through inhibiting the NR2B-containing NMDA receptors and the subsequent calcium overload in cultured cortical neurons.

The in vivo effect of esculetin ointment and esculetin-mixed Zyderm for Zyderm.

BACKGROUND: Injectable collagen is often used for treatment of wrinkles or scars in cosmetic surgery. However, it is degraded within a short period after subcutaneous injection. The authors aimed to achieve a long-lasting effect of the filler with a new collagenase inhibitor, esculetin (6,7-dihydroxy-2H-chromen-2-one). METHOD: Nude mice were divided into two study groups and a control group (35 mg cattle collagen): (1) those implanted with Zyderm 0.3 g subcutaneously into the dorsal region followed by daily topical application of 5% esculetin ointment (0.5 g/day) to the skin of the implanted area (the 5% esculetin ointment group), and (2) those implanted with a mixture of Zyderm 0.3 g and esculetin (1 to 4 mM) (the esculetin-mixed Zyderm groups). In each group, Zyderm was removed at different time points to measure the wet weight and hydroxyproline level. Furthermore, each removed Zyderm specimen was sectioned for histologic examination with Azan staining and immunostaining. RESULTS: In the esculetin ointment group and the 2 mM esculetin-mixed Zyderm group, the hydroxyproline levels at 30, 60, and 90 days were significantly higher than those in the control group, suggesting that esculetin suppresses the biodegradation of Zyderm. There was no significant difference in hydroxyproline level between the esculetin ointment group and the 2 mM esculetin-mixed Zyderm group; biodegradation occurred to a similar extent with either method of application. CONCLUSIONS: An atelocollagen implant is used as a safe and effective scaffold material for tissue regeneration. Future applications of the present study are expected.

Protective effects of daphnetin on sodium taurocholate­induced severe acute pancreatitis in rats.

Severe acute pancreatitis (SAP) is the sudden onset of pancreatic inflammation, which is characterized by edema, acinar cell necrosis, hemorrhage and severe inflammation of the pancreas and is associated with a high mortality rate. Daphnetin has been shown to alleviate organ injury in a variety of preclinical animal models of coagulation disorders. The aim of the present study was to investigate the protective effects of daphnetin on severe acute pancreatitis in a rat model. Severe acute pancreatitis in the rat model was induced by retrograde infusion of 5% sodium taurocholate (1 ml/kg) into the bile-pancreatic duct. Daphnetin (4 mg/kg) was administered intraperitoneally at 30 min prior to the infusion of sodium taurocholate. The severity of pancreatitis was evaluated by various analyses of serum amylase and lipase, tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) levels, myeloperoxidase (MPO) activity and malondialdehyde (MDA) content, as well as by histological grading. The levels of TNF-α and IL-1ß in the serum were measured by ELISA. The results revealed that the daphnetin-treated SAP rat group (SAP-D) exhibited a lower pathological score of the pancreas compared with the SAP group (SAP). Further analyses demonstrated that the SAP-D group had lower levels of serum amylase, lipase and pro-inflammatory cytokines, including TNF-α and IL-1ß, and a decreased MPO activity and MDA content 3, 6 and 12 h subsequent to the infusion of sodium taurocholate compared with the SAP group (SAP). These findings indicated that daphnetin exerted a protective function in the SAP rat model. Therefore, daphnetin may be considered as a potential compound for the therapy and prevention of acute pancreatitis.

Enhancement of cisplatin cytotoxicity in combination with herniarin in vitro.

Combinatorial chemotherapy is a valuable route, which can be conducted by different approaches. Use of cisplatin has been approved by the U.S. Food and Drug Administration for different kinds of cancers including bladder cancer. Herniarin is a member of simple coumarins, which are a group of common secondary metabolites in plants. In this study, the enhancing effects of herniarin on cisplatin cytotoxicity were investigated. Cytotoxicity of herniarin on transitional cell carcinoma (TCC) cells was first investigated in comparison with umbelliferone, the parent compound for a large number of coumarins including herniarin, by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. In order to test the effects of herniarin on cisplatin cytotoxicity, TCC cells were also treated with various combining concentrations of herniarin and cisplatin. In these experiments same amounts of dimethyl sulfoxide were used as controls. After 24, 48 and 72 h of treatments, the effects of herniarin on cisplatin cytotoxicity were evaluated by MTT assay. The level of chromatin condensation which represents the apoptotic morphology was also investigated by 4',6-diamidino-2-phenylindole (DAPI) staining. Results indicated that unlike umbelliferone, its methoxy analog, herniarin, had no significant cytotoxicity on TCC cells. On the other hand, the combination of 80 µg/mL herniarin with 5 µg/mL cisplatin, significantly enhanced the cytotoxicity of cisplatin. Furtheremore, DAPI staining revealed that combining concentrations of herniarin and cisplatin resulted in increased chromatin condensation in comparison with controls. This study is another confirmation for bioactivity of herniarin and shows that it might be a good candidate for further experiments investigating its mechanism of action.

Phagocytosis and killing of Salmonella by 7-hydroxycoumarin activated macrophages.

Coumarin and its derivatives have potent immunomodulatory activities. Here we describe the parameters of the protective effect of 7-hydroxycoumarin (7-OHC) in experimental Salmonella enterica Serovar Typhimurium infection in mice. The protective effect depended on the duration of treatment reaching its maximum after 10 days of pretreatment and lasted for at least 15 days after its end. Electron microscopy studies revealed that 7-OHC induced ultrastructural changes in macrophages consistent with their activation as well as faster destruction of ingested salmonellae. Superoxide and hydrogen peroxide secretion by macrophages was decreased in both healthy and Salmonella-infected 7-OHC treated animals, which is in line with the current view that some coumarins possess antioxidant and radical scavenging activity. Thus, 7-OHC pretreatment also appears beneficial to the host by limiting the harmful tissue damaging and immunosuppressive effects of the oxidative stress during a Salmonella infection but still activates the microbicidal capacity of exposed phagocytes.

Esculetin-induced protection of human hepatoma HepG2 cells against hydrogen peroxide is associated with the Nrf2-dependent induction of the NAD(P)H: Quinone oxidoreductase 1 gene.

Esculetin (6,7-dihydroxy coumarin), is a potent antioxidant that is present in several plant species. The aim of this study was to investigate the mechanism of protection of esculetin in human hepatoma HepG2 cells against reactive oxygen species (ROS) induced by hydrogen peroxide. Cell viability, cell integrity, intracellular glutathione levels, generation of reactive oxygen species and expression of antioxidant enzymes were used as markers to measure cellular oxidative stress and response to ROS. The protective effect of esculetin was compared to a well-characterized chemoprotective compound quercetin. Pre-treatment of HepG2 cells with sub-lethal (10-25 µM) esculetin for 8h prevented cell death and maintained cell integrity following exposure to 0.9 mM hydrogen peroxide. An increase in the generation of ROS following hydrogen peroxide treatment was significantly attenuated by 8h pre-treatment with esculetin. In addition, esculetin ameliorated the decrease in intracellular glutathione caused by hydrogen peroxide exposure. Moreover, treatment with 25 µM esculetin for 8h increased the expression of NAD(P)H: quinone oxidoreductase (NQO1) at both protein and mRNA levels significantly, by 12-fold and 15-fold, respectively. Esculetin treatment also increased nuclear accumulation of Nrf2 by 8-fold indicating that increased NQO1 expression is Nrf2-mediated. These results indicate that esculetin protects human hepatoma HepG2 cells from hydrogen peroxide induced oxidative injury and that this protection is provided through the induction of protective enzymes as part of an adaptive response mediated by Nrf2 nuclear accumulation.

Modulation of cytokine production by 7-hydroxycoumarin in vitro and its efficacy against influenza infection in mice.

We previously demonstrated that 7-hydroxycoumarin (7HC) was effective in reducing proinflammatory cytokine production in lipopolysaccharide-exposed macrophage-like P388D1 cells and fever production by suppressing the increase in interleukin (IL)-1alpha production in an influenza virus-intranasal infection model in mice. In this study, we assessed the effects of modulation of cytokine production by 7HC on influenza virus infection in relation to its efficacy in influenza virus-infected mice. 7HC was confirmed to suppress proinflammatory cytokine levels in P388D1 cells due to influenza virus infection. In the murine infection model, oral administration of 7HC (30 mg/kg) was significantly effective in reducing the weight loss of infected mice and virus titers in the bronchoalveolar lavage fluid (BALF) of lungs and in prolonging survival times without toxicity. The rise of proinflammatory and Th1 cytokine (IL-12 and interferon-gamma) production in the BALF from infected mice was significantly suppressed by 7HC at two and four days post-infection, respectively. This suppression correlated with the reduction of virus titers and diminution of lung consolidation. Because 7HC did not exhibit direct anti-influenza virus activity in vitro, 7HC was suggested to suppress pneumonia in influenza virus-infected mice through suppression of the cytokine production induced by infection.