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Succinate dehydrogenase (SDH) has been demonstrated as a promising target for fungicide discovery. Crystal structure data have indicated that the carboxyl "core" of current SDH inhibitors contributed largely to their binding affinity. Thus, identifying novel carboxyl "core" SDH inhibitors would remarkably improve the biological potency of current SDHI fungicides. Herein, we report the discovery and optimization of novel carboxyl scaffold SDH inhibitor via the integration of in silico library design and a highly specific amide feature-based pharmacophore model. To our delight, a promising SDH inhibitor, A16c (IC = 1.07 μM), with a novel pyrazol-benzoic scaffold was identified, which displayed excellent activity against Rhizoctonia solani (EC = 11.0 μM) and improved potency against Sclerotinia sclerotiorum (EC = 5.5 μM) and Phyricularia grisea (EC = 12.0 μM) in comparison with the positive control thifluzamide, with EC values of 0.09, 33.2, and 33.4 μM, respectively. The results showed that our virtual screening strategy could serve as a powerful tool to accelerate the discovery of novel SDH inhibitors.

The role of Toll-like receptor 4 (TLR4) in immune cells is well characterized, but its biological properties in bladder epithelial cells (BECs), especially reciprocal crosstalk between mitogen-activated protein (MAP) kinase pathway and signal transducer and activator of transcription (STAT)3-mediated signal transduction elicited by TLR4 have not been demonstrated so far. The present studies were to demonstrate the signal transduction and inflammatory cytokine response elicited through activation of TLR4 in BECs with a special focus on the crosstalk between the MAPK-pathway and STAT3-mediated signals and its regulatory relevance for the inflammatory response towards lipopolysaccharide (LPS). We selected human bladder cancer T24 cell line in the present study and examined its expression of TLR4 by reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. The expression of p38, extracellular signal regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and STAT3 were performed by RT-PCR, quantitative PCR, and Western blotting. Signal transduction was analyzed by Western blotting. Interleukin-6 (IL-6) and interleukin-10 (IL-10) secretion in culture supernatants were tested by human enzyme-linked immunosorbent assay (ELISA) kit. BECs of rat infection in vivo model and patients with cystitis glandularis (CG) were analyzed as described above. Our study demonstrated that TLR4 was significantly upregulated following LPS treatment, with the maximum mRNA expression occurring at 4 h after stimulation. Activation of TLR4 signaling by LPS resulted in phosphorylation of MAPK and STAT pathways and upregulation of IL-10 in dose- and time-dependent manners in T24 cells. Pretreatment of cells with SB203580 (inhibitor of p38) and SP600125 (inhibitor of JNK) attenuated LPS-induced IL-10 expression, whereas it markedly inhibited the STAT3 expression. IL-10 mRNA expression was increased in inflamed lesions compared to noninflamed tissue in rats and patients with CG disease. Our results demonstrate that activation of TLR4 signaling in BECs induces IL-10 expression via activation of p38 and JNK, and the activation of STAT-3 was upregulated. Our data indicated that the reciprocal crosstalk between the MAPK pathway and STAT3-mediated signal transduction forms a critical axis successively activated by LPS in BECs.

A novel series of podophyllotoxin derivatives bearing 4β-disulfide/trisulfide were designed, synthesized and biologically evaluated for their cytotoxic activities against KB cells and KB/VCR cells.

No abstract

Hepatocellular carcinoma (HCC) is the most common malignancy of the liver. It is unfortunate that HCCs are highly refractory to conventional chemotherapy, radiation therapy, and even immunotherapy. Thus, novel therapeutic targets need to be sought for the successful treatment of HCCs. We now report that (Ϯ)-(3aRS,4SR)-2-(2-chloro-4-methylsulfonylphenyl)-4Ј-chloro-3␣,4-diethoxy-flavane[4,3-d]-D1,9b-1,2,3-thiadiazoline (MSFTZ), a synthesized flavanone derivative, induced growth arrest and apoptosis of HCCs both in vitro and in vivo. MSFTZ induced a time-and dose-dependent increase in HCC apoptosis through caspase-3 activation and poly(ADP-ribose) polymerase-1 cleavage. Activation of caspase-9 induced by MSFTZ suggested that MSFTZ-induced signaling was mediated through a mitochondrial death pathway. In addition, we observed an elevation of reactive oxygen species (ROS) and a consequent loss of mitochondrial membrane potential, further suggesting that MSFTZ-induced death signaling was mediated through a mitochondrial oxygen stress pathway. These events were associated with a decrease and increase in Bcl-2 and Bax expression, respectively, as well as phosphorylation of mitogen-activated protein kinase (MAPK) and activation of p53-MDM2 pathway. However, the antioxidant N-acetylcysteine opposed MSFTZ-mediated mitochondrial dysfunction, caspase activation, Bcl-2/Bax modulation, and apoptosis, supporting the role of ROS in the apoptotic process. We were surprised that we failed to observe the protective effect of N-acetylcysteine against MSFTZ-induced MAPK activation. Furthermore, MSFTZ had an antitumor effect in vivo by 34.8 to 78.7% reduction of tumor size in SMMC-7721-xenografted nude mice. We conclude that MSFTZ induces HCC cell apoptosis both in vivo and in vitro via caspase-and ROS-dependent mitochondrial pathway. In addition, MSFTZ has potential as a novel therapeutic agent for the treatment of HCC.Hepatocellular carcinoma (HCC) is currently the fifth most common solid tumor worldwide and the fourth leading cause of cancer-related death, and its incidence is rising in many countries (El-Serag, 2004;Thomas and Zhu, 2005). It is usually treated by surgical resection or liver transplantation, with curative options for the patients when the disease is diagnosed at an early stage. However, approximately 70% of patients are inoperable because of advanced tumor growth or liver cirrhosis, or, alternatively, the hepatoma belongs to the group of cancers that are resistant to systemic chemotherapies, radiation therapy, and even immunotherapy (Wirth et al., 2005). Thus, novel therapeutic strategies are needed to improve the efficacy in treating HCC.Natural products derived from plants have recently received much attention as potential chemopreventive and chemotherapeutic agents. Flavanones (Fig. 1A), a subclass of flavonoids, are plant polyphenols found in vegetables, fruit, and beverages of plant origin that is well known for their physiological antipyretic, analgesic, and anti-inflammatory activities. The antitumor ...

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By the strategy of equipping a fluorophore with two reaction triggers that are tailored to the specific chemistry of peroxynitrite, we have developed a highly selective probe for detecting peroxynitrite in live cells. Sequential response by the two triggers enabled the probe to reveal various degrees of nitrosative stress in live cells via a sensitive emission colour change.