Pyrrolizidine Alkaloid-Induced Hepatotoxicity Associated with the Formation of Reactive Metabolite-Derived Pyrrole-Protein Adducts.

Pyrrolizidine alkaloids (PAs) with 1,2-unsaturated necine base are hepatotoxic phytotoxins. Acute PA intoxication is initiated by the formation of adducts between PA-derived reactive pyrrolic metabolites with cellular proteins. The present study aimed to investigate the correlation between the formation of hepatic pyrrole-protein adducts and occurrence of PA-induced liver injury (PA-ILI), and to further explore the use of such adducts for rapidly screening the hepatotoxic potency of natural products which contain PAs. Aqueous extracts of Crotalaria sessiliflora (containing one PA: monocrotaline) and Gynura japonica (containing two PAs: senecionine and seneciphylline) were orally administered to rats at different doses for 24 h to investigate PA-ILI. Serum alanine aminotransferase (ALT) activity, hepatic glutathione (GSH) level, and liver histological changes of the treated rats were evaluated to assess the severity of PA-ILI. The levels of pyrrole-protein adducts formed in the rats' livers were determined by a well-established spectrophotometric method. The biological and histological results showed a dose-dependent hepatotoxicity with significantly different toxic severity among groups of rats treated with herbal extracts containing different PAs. Both serum ALT activity and the amount of hepatic pyrrole-protein adducts increased in a dose-dependent manner. Moreover, the elevation of ALT activity correlated well with the formation of hepatic pyrrole-protein adducts, regardless of the structures of different PAs. The findings revealed that the formation of hepatic pyrrole-protein adducts-which directly correlated with the elevation of serum ALT activity-was a common insult leading to PA-ILI, suggesting a potential for using pyrrole-protein adducts to screen hepatotoxicity and rank PA-containing natural products, which generally contain multiple PAs with different structures.

Efficacy and action mechanisms of a Chinese herbal formula on experimental models of atopic dermatitis.

ETHNOPHARMACOLOGICAL RELEVANCE: Atopic dermatitis (AD) is a skin inflammatory disease characterized by erythema, eruption, lichenification and pruritus. Shi Zhen Formula (SZF), an empirical Chinese herbal preparation, has clinical efficacy in relieving the symptoms of AD patients. However, the underlying molecular mechanisms of SZF remained unclear. AIM OF THE STUDY: We aimed to investigate the anti-AD effects of SZF and elucidate its underlying molecular mechanisms using in vitro and in vivo models of AD. MATERIALS AND METHODS: High-performance liquid chromatography analysis was performed for quality control of SZF extract. The anti-inflammatory effect of SZF was investigated through evaluating the levels of nitric oxide (NO), chemokines and pro-inflammatory cytokines in the lipopolysaccharide (LPS) stimulated RAW264.7 cells. AD-like skin lesions in female BALB/c mice were induced by 2,4-dinitrochlorobenzene (DNCB). SZF (3.15, 6.30 and 9.45 g/kg) and dexamethasone (5 mg/kg) were administered by gavage daily for 15 consecutive days. The body weight, skin thickness, skin dermatitis severity and scratching behaviors were recorded throughout the study. Histological analysis, reverse transcription-quantitative polymerase chain reaction (RT-PCR), western blot (WB) and ELISA analysis were used to illuminate the molecular targets associated with the anti-AD effects of SZF. RESULTS: SZF markedly decreased the epidermal thickening and infiltration of mast cells in the ears and dorsal skin of the 2,4-dinitrochlorobenzene (DNCB)-treated mice. SZF not only suppressed the levels of immunoglobulin E (IgE), histamine, thymic stromal lymphopoietin (TSLP) and IL-4 in the serum but also suppressed the over-production of IL-4 and IL-6 and gene expressions of IL-4, IL-13, IL-31 and TSLP in the dorsal skin. Moreover, SZF improved epidermal barrier by increasing the protein expressions of filaggrin, involucrin and loricrin and inhibited the activation of NF-κB p65 pathway in the dorsal skin of the DNCB-treated mice. CONCLUSION: SZF alleviates DNCB induced AD-like skin lesions in mice through regulating Th1/Th2 balance, improving epidermal barrier and inhibiting skin inflammation. Our research findings provide scientific footing on the use of this Chinese herbal formula for the treatment of AD.

Anti-atopic dermatitis effects of dictamni cortex: Studies on in vitro and in vivo experimental models.

BACKGROUND: Dictamni Cortex (DC), a Chinese herbal medicine with wind dispelling and itchiness relieving effects, is the most popular single herb prescribed for the treatment of atopic dermatitis (AD), as it is used in up to 12.68% of all herbal prescriptions for AD. PURPOSE: The present study aimed to evaluate the anti-AD effect of Dictamni Cortex extract (DCE) and elucidate the underlying molecular mechanisms of its action using the 1-chloro-2,4-dinitrobenzene (DNCB)-induced AD-like mouse model and a relevant in vitro experimental model. METHODS: Female Balb/c mice were sensitized with 200 µl 0.5% DNCB for three days. After sensitization, mice were challenged with 200 µl 1% DNCB on the same dorsal skin and also 20 µl 1% DNCB on each ear every 3 days, and orally administrated by gavage with DCE (0.6, 1.2 and 2.4 g/kg) daily from day 14 to day 29 for 16 consecutive days. At the end of experiment, the clinical scores for AD on the mice were calculated to evaluate the therapeutic effect of DCE; and serum, ears and dorsal skin of the mice were collected for mechanistic study. The anti-allergic activity of DCE was also evaluated using antigen-induced RBL-2H3 cell line. The release of selected cytokines, chemokines and ß-hexosaminidase was measured to determine the anti-allergic activity of DCE. In addition, intracellular Ca2+ level, MAPKs and Lyn phosphorylations were further investigated to reveal its anti-allergic molecular mechanisms. RESULTS: Our results demonstrated that DCE could markedly improve the AD-like symptoms in AD-like mice by inhibiting the mast cell infiltration, suppressing the production of Th2-associated cytokine (IL-4) and pro-inflammatory cytokines (TNF-α), and enhancing the protein expression of filaggrin through inhibition of the MAPKs and NF-κB pathways. Moreover, DCE suppressed mast cell degranulation through decreasing the intracellular Ca2+ level and inactivation of Lyn, Syk and PLCγs, suggesting DCE could regulate mast-cell-mediated allergic response. CONCLUSION: Our experimental results unambiguously indicate that DCE possesses potent anti-allergic effect, and help place the application of DC for the treatment of AD on a scientific footing.

Huang-Lian-Jie-Du extract ameliorates atopic dermatitis-like skin lesions induced by 2,4-dinitrobenzene in mice via suppression of MAPKs and NF-κB pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: Huang-Lian-Jie-Du Decoction (HLJDD), is a well-known traditional Chinese herbal formula first written in the Tang dynasty. In Chinese medicine practice, HLJDD is commonly prescribed to treat various inflammatory skin diseases, such as atopic dermatitis (AD) and psoriasis. AIM OF THE STUDY: The present study aimed at investigating the therapeutic effect of HLJDD extract (HLJDE) and to elucidate the underlying molecular mechanisms of action in the 1-chloro-2,4-dinitrobenzene (DNCB)-induced AD-like mice. MATERIALS AND METHODS: Female Balb/c mice were sensitized with DNCB for three days. After sensitization, mice were challenged with DNCB every three days and orally administrated with HLJDE (150, 300 and 600 mg/kg) daily from day 14 to day 29 for consecutive 16 days. At the end of experiment, the clinical AD scores of the mice were calculated to evaluate the therapeutic effect of HLJDE, and serum, ears and dorsal skin of the mice were collected for unravelling molecular mechanisms. RESULTS: HLJDE significantly reduced the clinical symptoms in the AD-like mice by inhibiting eosinophil and mast cell infiltration, suppressing the production of Th2-associated cytokine (IL-4) and pro-inflammatory cytokines (TNF-α). In addition, HLJDE significantly suppressed the NF-κB and MAPKs pathways. Moreover, HLJDE was able to accentuate filaggrin expression in the skin lesion when compared to the sensitized mouse without treatment. CONCLUSION: HLJDE significantly improved the AD-like symptoms on the DNCB-sensitized mice through mitigating the production of inflammatory mediators via suppressing MAPKs and NF-κB pathways. Additionally, the elevated expression of filaggrin in the skin lesion by HLJDE contributes to the recovery of dysfunctional skin barrier on the DNCB-sensitized mice.

Anti-inflammatory and anti-allergic effects and underlying mechanisms of Huang-Lian-Jie-Du extract: Implication for atopic dermatitis treatment.

ETHNOPHARMACOLOGICAL RELEVANCE: Huang-Lian-Jie-Du Decoction (HLJDD), a well-known Chinese herbal formula recorded in the Tang dynasty, is composed of Coptidis rhizoma (Huang-Lian), Scutellariae radix (Huang-Qin), Phellodendri Chinensis cortex (Huang-Bai) and Gardenia fructus (Zhi-Zi). It has clinical efficacy of purging fire for removing toxin and is commonly used for the treatment of disease including Alzheimer's disease, stroke and gastrointestinal disorders. HLJDD is also frequently applied for the treatment of various skin diseases, such as atopic dermatitis (AD) and various types of eczema. The aim of this study is to investigate the anti-inflammatory and anti-allergic actions of Huang-Lian-Jie-Du ethanolic extract (HLJDE) and to elucidate underlying molecular mechanisms of action using relevant in vitro experimental models. MATERIALS AND METHODS: The anti-inflammatory effects of HLJDE were investigated through evaluating the change of nitric oxide (NO) and the production of several cytokines and chemokines in lipopolysaccharide (LPS)-stimulated RAW264.7 cell line. Expression of mitogen-activated protein kinases (MAPKs), NF-κB p65 phosphorylation, inhibitor-κBα (IκBα) degradation were further investigated to elucidate its anti-inflammatory molecular mechanisms. Meanwhile, the anti-allergic activities of HLJDE was also evaluated using antigen-induced RBL-2H3 cell line. ß-hexosaminidase and histamine release and selected cytokines and chemokines were measured to evaluate the anti-allergic activities of HLJDE. In addition, intracellular Ca(2+)level, MAPKs and Lyn phosphorylation were further investigated to reveal its anti-allergic molecular mechanisms. RESULTS: HLJDE could significantly suppress the secretion of NO, IL-1ß, IL-4, MCP-1 and GM-CSF in RAW264.7 cells in a dose-dependent manner. In addition, HLJDE also markedly reduced the phosphorylation of MAPKs, and inhibited the transcriptional activity of NF-κB and IκBα degradation. Furthermore, HLJDE exerted marked anti-allergic activity through inhibiting the release of ß-hexosaminidase and histamine. The release of cytokines and chemokines (IL-4, TNF-α, MCP-1) from activated RBL-2H3 cells were also attenuated by pretreatment with HLJDE. The inhibitory effects on intracellular Ca(2+)level, and reduced phosphorylation of MAPKs and Lyn are believed to be the anti-allergic mechanisms. CONCLUSIONS: HLJDE exerted significant anti-inflammatory and anti-allergic effects through suppressing the production of allergic and inflammatory mediators via the NF-κB and MAPKs inactivation and IκBα degradation in the LPS-stimulated RAW24.7 cells, inactivation of MAPKs and Lyn pathway in antigen-induced RBL-2H3 cells. The present study provides in vitro experimental evidence to support the use of HLJDE for the clinical treatment of AD.

Protective effects of a Rhodiola crenulata extract and salidroside on hippocampal neurogenesis against streptozotocin-induced neural injury in the rat.

Previously we have demonstrated that a Rhodiola crenulata extract (RCE), containing a potent antioxidant salidroside, promotes neurogenesis in the hippocampus of depressive rats. The current study was designed to further investigate the protective effect of the RCE on neurogenesis in a rat model of Alzheimer's disease (AD) induced by an intracerebroventricular injection of streptozotocin (STZ), and to determine whether this neuroprotective effect is induced by the antioxidative activity of salidroside. Our results showed that pretreatment with the RCE significantly improved the impaired neurogenesis and simultaneously reduced the oxidative stress in the hippocampus of AD rats. In vitro studies revealed that (1) exposure of neural stem cells (NSCs) from the hippocampus to STZ strikingly increased intracellular reactive oxygen species (ROS) levels, induced cell death and perturbed cell proliferation and differentiation, (2) hydrogen peroxide induced similar cellular activities as STZ, (3) pre-incubation of STZ-treated NSCs with catalase, an antioxidant, suppressed all these cellular activities induced by STZ, and (4) likewise, pre-incubation of STZ-treated NSCs with salidroside, also an antioxidant, suppressed all these activities as catalase: reduction of ROS levels and NSC death with simultaneous increases in proliferation and differentiation. Our findings indicated that the RCE improved the impaired hippocampal neurogenesis in the rat model of AD through protecting NSCs by its main ingredient salidroside which scavenged intracellular ROS.

Bufalin induces autophagy-mediated cell death in human colon cancer cells through reactive oxygen species generation and JNK activation.

Colorectal cancer is the second most common cause of cancer death in the world and about half of the patients with colorectal cancer require adjuvant therapy after surgical resection. Therefore, the eradication of cancer cells via chemotherapy constitutes a viable approach to treating patients with colorectal cancer. In this study, the effects of bufalin isolated from a traditional Chinese medicine were evaluated and characterized in HT-29 and Caco-2 human colon cancer cells. Contrary to its well-documented apoptosis-promoting activity in other cancer cells, bufalin did not cause caspase-dependent cell death in colon cancer cells, as indicated by the absence of significant early apoptosis as well as poly(ADP-ribose) polymerase and caspase-3 cleavage. Instead, bufalin activated an autophagy pathway, as characterized by the accumulation of LC3-II and the stimulation of autophagic flux. The induction of autophagy by bufalin was linked to the generation of reactive oxygen species (ROS). ROS activated autophagy via the c-Jun NH(2)-terminal kinase (JNK). JNK activation increased expression of ATG5 and Beclin-1. ROS antioxidants (N-acetylcysteine and vitamin C), the JNK-specific inhibitor SP600125, and JNK2 siRNA attenuated bufalin-induced autophagy. Our findings unveil a novel mechanism of drug action by bufalin in colon cancer cells and open up the possibility of treating colorectal cancer through a ROS-dependent autophagy pathway.

Qianliguang (Senecio scandens) safety dilemma: dose is the key?

Qianliguang ( SENECIO SCANDENS) is a common Chinese medicinal herb. Qianliguang-containing herbal proprietary products are registered as over-the-counter remedies in China and exported to Western countries. The safety of using Qianliguang and its products has raised general concerns because of a potential risk of the presence of hepatotoxic pyrrolizidine alkaloids (PAs). A systematic toxicological study is thus required to verify this public concern. In the present article, we report, for the first time, that S. SCANDENS contains nine hepatotoxic PAs with a content of 6.95-7.19 microg/g. At a dose equivalent to the daily intake recommended by the Pharmacopoeia of China, the total content of toxic PAs in Qianliguang was determined to be 3.48 microg/kg/day, which is far below the lowest dose to cause hepatotoxicity (15 microg/kg/day) suggested by the International Program on Chemical Safety. No significant hepatotoxic effects were observed in rats fed with the extract at this human-equivalent dose for 14 consecutive days. However, a single overdose of the herbal water extract (6 g/kg), which was about 8-fold higher than the recommended dose, produced typical PA-induced hepatotoxicity in rats. Therefore, appropriate dosage guidelines should be implemented for the herbal industry, for export/import retailers, and for herbal medicine practitioners to ensure the safe and beneficial use of these herbal medicines.

Thrombopoietin protects against in vitro and in vivo cardiotoxicity induced by doxorubicin.

BACKGROUND: Doxorubicin (DOX) is an important antineoplastic agent. However, the associated cardiotoxicity, possibly mediated by the production of reactive oxygen species, has remained a significant and dose-limiting clinical problem. Our hypothesis is that the hematopoietic/megakaryocytopoietic growth factor thrombopoietin (TPO) protects against DOX-induced cardiotoxicity and might involve antiapoptotic mechanism exerted on cardiomyocytes. METHODS AND RESULTS: In vitro investigations on H9C2 cell line and spontaneously beating cells of primary, neonatal rat ventricle, as well as an in vivo study in a mouse model of DOX-induced acute cardiomyopathy, were performed. Our results showed that pretreatment with TPO significantly increased viability of DOX-injured H9C2 cells and beating rates of neonatal myocytes, with effects similar to those of dexrazoxane, a clinically approved cardiac protective agent. TPO ameliorated DOX-induced apoptosis of H9C2 cells as demonstrated by assays of annexin V, active caspase-3, and mitochondrial membrane potential. In the mouse model, administration of TPO (12.5 microg/kg IP for 3 alternate days) significantly reduced DOX-induced (20 mg/kg) cardiotoxicity, including low blood cell count, cardiomyocyte lesions (apoptosis, vacuolization, and myofibrillar loss), and animal mortality. Using Doppler echocardiography, we observed increased heart rate, fractional shortening, and cardiac output in animals pretreated with TPO compared with those receiving DOX alone. CONCLUSIONS: These data have provided the first evidence that TPO is a protective agent against DOX-induced cardiac injury. We propose to further explore an integrated program, incorporating TPO with other protocols, for treatment of DOX-induced cardiotoxicity and other forms of cardiomyopathy.

Immunohistological evidences of Ginkgo biloba extract altering Bax to Bcl-2 expression ratio in the hippocampus and motor cortex of senescence accelerated mice.

Ginkgo biloba extract 761 appears to display neuroprotective effect in many nervous diseases and aging. Deterioration of mental functions during aging is always accompanied by loss of neurons, presumably through apoptosis. Here, we studied the effect of G. biloba extract in the expression of Bax/Bcl-2 ratio, an important apoptotic index, in the hippocampus and motor cortex of the aging brain. Bax and Bcl-2 expressions were examined with immunohistochemical methods. Senescence Accelerated Mice Prone Strain 8 was used because the aging process was accelerated with neuropathological alterations similar to those found in the aging human brain. The mice were fed with either G. biloba extract or sucrose from the age of 3 weeks until sacrifice at 3 or 9 months old. In the hippocampus of G. biloba fed 9-month-old mice, the ratio of Bax positive cell to Bcl-2 positive cell (Bax/Bcl-2 expression ratio) was 11.43 +/- 3.11 (mean +/- SD); significantly lower (P < 0.05) than the Bax/Bcl-2 expression ratio of 20.99 +/- 5.34 in the sucrose fed mice. The Bax/Bcl-2 expression cell ratios, however, in the motor cortex were not significantly different between the two groups (2.22 +/- 1.35 versus 2.27 +/- 2.02 for the G. biloba and the sucrose fed mice, respectively). The decrease in the Bax/Bcl-2 expression cell ratio following G. biloba treatment might hence be able to protect the aging hippocampus from moving further down the apoptotic pathway. Western blotting confirmed the decrease of Bax in the brain even after a short term and high dose Ginkgo treatment. It is speculated that the G. biloba extract may be a potential neuroprotective agent against apoptosis through the differential expressions of the Bax and Bcl-2 in the hippocampus.

Expression patterns of PSA-NCAM in the human ganglionic eminence and its vicinity: role of PSA-NCAM in neuronal migration and axonal growth?

The ganglionic eminence (GE) is a transient but conspicuous structure of the developing forebrain which not only gives rise to a large number of precursor neurons and glial cells for various structures of the forebrain, but in addition serves as an intermediate target for growing axons to the cerebral cortex. To investigate the roles of the highly polysialylated isoform of the neural cell adhesion molecule (PSA-NCAM) in cell migration and axonal growth within the GE and its neighbouring structures, the spatio-temporal expression pattern of PSA-NCAM was examined in human fetal forebrains between 14 and 36 weeks of gestation with a specific immunohistochemical method. Scattered PSA-NCAM-positive cells were found in the centre but more frequently in the marginal zone of the GE. Intensely labelled cells were also identified in the gangliothalamic body, basolateral nuclei of the amygdala and the subventricular and intermediate zone adjacent to the GE. This cellular immunoreactivity started to appear in various structures during the period from 14 to 19 weeks and gradually diminished after 25-28 weeks. Strong immunoreactivity was also detected in fibres running from the intermediate zone of the neocortex to the internal capsule from 16 weeks onwards, and after 24 weeks, the immunoreactivity was gradually decreased. In the vicinity of the GE, between 16 and 22 weeks, short fibre bundles were observed to leave the longitudinally oriented axons of the internal capsule to reach the marginal zone of the GE. Our results suggest a close relationship between PSA-NCAM expression and neuronal migration (over short distances) and transitory axonal projections (target recognition and axonal fasciculation) in the region of the GE.

Pien Tze Huang protects the liver against carbon tetrachloride-induced damage.

Pien Tze Huang, a traditional Chinese medicine, has been extensively used as a therapeutic drug in the treatment of liver diseases. In this study, we have examined its ability to protect the liver from carbon tetrachloride (CCl4)-induced damage in the mouse. Histological observations revealed that CCl4 treatment induced extensive degenerative changes in the hepatocytes surrounding the central veins of the liver. However, these changes were much reduced by more than 28% in mice fed with 0.5 mg of Pien Tze Huang/g body weight/dose (3 doses over 36 hr) prior to CCl4 treatment. The effects of Pien Tze Huang were then further investigated in a hepatoma cell line. Flow analysis showed that it had no significant effects on cell proliferation. When the ability of Pien Tze Huang to influence various response elements of important signal transduction pathways was examined in the hepatoma cell line, it was found that Pien Tze Huang stimulated an increase in the response of AP1, CRE and NFkappaB responsive elements. The transcriptional factors of these responsive elements are known to play important roles in regulating cell death and survival. We thus postulate that the ability of Pien Tze Huang to protect the liver from damage is attained through its ability to modulate the activity of these important signal transduction pathways.