Activation of the JNK pathway promotes phosphorylation and degradation of BimEL--a novel mechanism of chemoresistance in T-cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemias (T-ALLs) are highly malignant tumors with 20% of patients continues to fail therapy, in part due to chemoresistance of T-ALL cells via largely unknown mechanisms. Here, we showed that lack of Bcl-2-interacting mediator of cell death (Bim)(EL) protein expression, a BH3-only member of the Bcl-2 family proteins, conferred resistance of a T-ALL cell line, Sup-T1, to etoposide-induced apoptosis. Overexpression of Bim(EL) significantly restored its sensitivity to etoposide-induced caspase activation and poly(ADP-ribose) polymerase cleavage. Surprisingly, we found that constitutive activation of the c-Jun N-terminal kinase (JNK) pathway in Sup-T1 cells promoted phosphorylation and degradation of Bim(EL) via the proteosome. Blocking with a proteosome inhibitor yielded an elevated level of Bim(EL) and accumulation of Bim(EL) species phosphorylated at Ser(69). Pretreatment of Sup-T1 cells with a specific JNK inhibitor, SP600125, also increased the Bim(EL) level and resensitized the cells to etoposide-induced apoptosis. Together, our findings suggest that the JNK activation status may correlate with the Bim(EL) level and in turn can control the sensitivity of T-ALL cells to chemotherapeutic agents.

Chemical properties, mode of action, and in vivo anti-herpes activities of a lignin-carbohydrate complex from Prunella vulgaris.

The chemical nature, the mode of action, and the in vitro and in vivo anti-HSV activities of the polysaccharide from Prunella vulgaris were characterized. The polysaccharide was isolated by ethanol precipitation, dialysis, CTAB precipitation, and gel exclusion chromatography. The isolated compound (PPS-2b) was a lignin-carbohydrate complex with a molecular weight of 8500. The carbohydrate moiety was composed of glucose, galactose, mannose, galacturonic acid, rhamnose, xylose, and arabinose with glucose as the major sugar. In plaque reduction assay, PPS-2b showed activities against HSV-1 and HSV-2. The anti-HSV activity could be abolished by periodate oxidation. Mechanism studies showed that PPS-2b inactivated HSV-1 directly, blocked HSV-1 binding to Vero cells, and inhibited HSV-1 penetration into Vero cells. A similar inhibition was observed with a gC-deficient strain of HSV-1. The in vivo activities of a Prunella cream formulated with a semi-purified fraction was assessed in a HSV-1 skin lesion model in guinea pigs and a HSV-2 genital infection model in BALB/c mice. Guinea pigs that received the Prunella cream treatment showed a significant reduction (P<0.01) in skin lesions. Mice that received the Prunella cream treatment showed a significant reduction (P<0.01) in mortality. In conclusion, the anti-HSV compound from P. vulgaris is a lignin-polysaccharide complex with potent activity against HSV-1 and HSV-2. Its mode of action appears to be inhibiting viral binding and penetration into host cells.

Antiviral effect of Phyllanthus nanus ethanolic extract against hepatitis B virus (HBV) by expression microarray analysis.

Ethanolic extract of Phyllanthus nanus (P. nanus) treatment exhibited potent antiviral activity against Hepatitis B virus (HBV). The effects of these extracts on HBV in the HBV genome integrated cell lines--Alexander cells and HepG2 2.2.15 cells were examined. Experimental results showed that the ethanolic extract of P. nanus produced suppressive effect on HBsAg secretion and HBsAg mRNA expression. The extract also inhibited HBV replication as measured by HBV DNA level in vitro. In addition, using a duck HBV (DHBV) primary culture model, the P. nanus ethanolic extract suppressed viral replication of DHBV in DHBV infected primary duck hepatocytes. The gene expression pattern in Alexander cells that had been treated with the ethanolic extract of P. nanus was also revealed by microarray techniques. The microarray results indicated that there was up-regulation of expression of several genes, including annexin A7 (Axn7). The subcellular localization of Axn7 and anti-HBV effect of Axn7 over-expression in Alexander cells were also investigated. Results showed that expression of Axn7-GFP fusion protein are localized around the secretory vesicles and could cause a decrease in HBsAg secretion in Alexander cells. Axn7 protein might play an important role in the medicinal effect of the active principle(s) of P. nanus.

A polysaccharide fraction from medicinal herb Prunella vulgaris downregulates the expression of herpes simplex virus antigen in Vero cells.

Herpes simplex viruses (HSV) are pathogenic. With the emergence of drug-resistant strains of HSV, new antiviral agents, especially those with different modes of action, are urgently needed. Prunella vulgaris L. (Labiatae), a perennial plant commonly found in China and Europe, has long been used as a folk medicine to cure ailments. In this study, a polysaccharide fraction was prepared from Prunella vulgaris (PPV), and its effects on the expressions of HSV-1 and HSV-2 antigens in their host Vero cells were investigated with flow cytometry. The HSV antigen increased time-dependently in the infected cells, and PPV reduced its expression. The effective concentrations of PPV with 50% reductions of the HSV-1 and HSV-2 antigens were 20.6 and 20.1 microg/ml, respectively. The novelty of PPV is that it also reduces the antigen expression of acyclovir-resistant strain of HSV-1. After incubations with 25-100 microg/ml of PPV the HSV antigen-positive cells were reduced by 24.8-92.6%, respectively, showing that this polysaccharide fraction has a different mode of anti-HSV action from acyclovir. Results from this study show that PPV is effective against both the HSV-1 and HSV-2 infections, and flow cytometry offers a quantitative and highly reproducible anti-HSV drug-susceptibility assay.

Effects of dimethyl sulphoxide against liver injury caused by carbon tetrachloride in rats.

A single oral dose of 1.25 ml kg(-1) of carbon tetrachloride (CCl(4)) was sufficient to induce significantly elevated levels of serum glutamic pyruvic transaminase (SGPT) and serum glutamic oxaloacetic transaminase (SGOT) together with signs of acute centrilobular necrosis and fatty accumulation in liver tissue. Dimethyl sulfoxide (DMSO) in different dosages (2750 mg kg(-1), 5500 mg kg(-1) and 8250 mg kg(-1); dissolved in saline) were screened for their potential activity against CCl(4)-induced liver injury in Sprague-Dawley rats. The results showed that post-administration of high dosages (5500 mg kg(-1) and 8250 mg kg(-1)) of DMSO-saline solution significantly reduced CCl(4)-induced acute elevation in the levels of SGPT and SGOT. The same result was observed in histopathological study of liver tissue. DMSO, in high doses, probably prevented CCl(4)-induced liver injury through its antioxidant, anti-inflammatory or microsomal enzyme arresting properties.

Molecular structures and antiviral activities of naturally occurring and modified cassane furanoditerpenoids and friedelane triterpenoids from Caesalpinia minax.

Further investigation of the active components of the chloroform fraction of the seeds of Caesalpinia minax led to the isolation of a new cassane furanoditerpenoid, caesalmin H (1), together with two known furanoditerpenoid lactones, caesalmin B (2) and bonducellpin D (3). Reduction of the naturally abundant caesalmin D (9), E (10) and F (11) resulted in three new furanoditerpenoid derivatives 4-6. Phytochemical study of the stem of the same plant and subsequent reduction afforded two friedelane triterpenoids (7-8), which were identified by spectroscopic methods. Compounds 1-2 and 4-8 were corroborated by single crystal X-ray analysis. The factors governing the reduction of cassane furanoditerpenoids and friedelane triterpenoids were investigated by correlating the crystallographic results with density functional theory. The inhibitory activities of 2-8 on the Para3 virus were evaluated by cytopathogenic effects (CPE) reduction assay.

Antiviral Chinese medicinal herbs against respiratory syncytial virus.

Forty-four medicinal herbs were tested for antiviral activities against respiratory syncytial virus (RSV) by means of the cytopathologic effect (CPE) assay. Twenty-seven of the 44 medicinal herbs showed potent or moderate antiviral activities against RSV with 50% inhibition concentration (IC(50)) ranging from 6.3 to 52.1 microg/ml, and with selectivity index (SI) ranging from 2.0 to 32.1. Further purification of the active extracts from Sophora flavescens Ait. and Scutellaria baicalensis Georgi led to the identification of anagyrine (2), oxymatrine (7), sophoranol (10), wogonin (12), and oroxylin A (13) as the potent anti-RSV components.