Derivative of cinnamic acid inhibits T3SS of Xanthomonas oryzae pv. oryzae through the HrpG-HrpX regulatory cascade.

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) has a significant impact on rice yield and quality worldwide. Traditionally, bactericide application has been commonly used to control this devastating disease. However, the overuse of fungicides has led to a number of problems such as the development of resistance and environmental pollution. Therefore, the development of new methods and approaches for disease control are still urgent. In this paper, a series of cinnamic acid derivatives were designed and synthesized, and three novel T3SS inhibitors A10, A12 and A20 were discovered. Novel T3SS inhibitors A10, A12 and A20 significantly inhibited the hpa1 promoter activity without affecting Xoo growth. Further studies revealed that the title compounds A10, A12 and A20 significantly impaired hypersensitivity in non-host plant tobacco leaves, while applications on rice significantly reduced symptoms of bacterial leaf blight. RT-PCR showed that compound A20 inhibited the expression of T3SS-related genes. In summary, this work exemplifies the potential of the title compound as an inhibitor of T3SS and its efficacy in the control of bacterial leaf blight.

Study on the Antiviral Activities and Hemagglutinin-Based Molecular Mechanism of Novel Chlorogenin 3-O-ß-Chacotrioside Derivatives Against H5N1 Subtype Viruses.

The objective of this study was to investigate the inhibitory effect of chlorogenin 3-O-ß-chacotrioside derivatives against H5N1 subtype of the highly pathogenic avian influenza (HPAI) viruses and its molecular mechanism. A series of novel small molecule pentacyclic triterpene derivatives were designed and synthesized and their antiviral activities on HPAI H5N1 viruses were detected. The results displayed that the derivatives UA-Nu-ph-5, XC-27-1 and XC-27-2 strongly inhibited wild-type A/Duck/Guangdong/212/2004 H5N1 viruses with the IC50 values of 15.59 ± 2.4 µM, 16.83 ± 1.45 µM, and 12.45 ± 2.27 µM, respectively, and had the selectivity index (SI) > 3, which was consistent with the efficacy against A/Thailand/kan353/2004 pseudo-typed viruses. Four dealt patterns were compared via PRNT. The prevention dealt pattern showed the strongest inhibitory effects than other patterns, suggesting that these derivatives act on the entry process at the early stages of H5N1 viral infection, providing protection for cells against infection. Further studies through hemagglutinin inhibition (HI) and neuraminidase inhibitory (NAI) assay confirmed that these derivatives inhibited H5N1 virus replication by interfering with the viral hemagglutinin function. The derivatives could recognize specifically HA protein with binding affinity constant KD values of 2.57 × 10-4 M and 3.67 × 10-4 M. In addition, through site-directed mutagenesis combined with a pseudovirion system, we identified that the high-affinity docking sites underlying interaction were closely associated with amino acid residues I391 and T395 of HA. However, the potential binding sites of the derivatives with HA did not locate at HA1 sialic acids receptor binding domain (RBD). Taken together, these study data manifested that chlorogenin 3-O-ß-chacotrioside derivatives generated antiviral effect against HPAI H5N1 viruses by targeting the hemagglutinin fusion machinery.

Synthesis and bioactivity of 3,5-dimethylpyrazole derivatives as potential PDE4 inhibitors.

A series of 3,5-dimethylpyrazole derivatives containing 5-phenyl-2-furan moiety were designed and synthesized as phosphodiesterase type 4 (PDE4) inhibitors. Bioassay results showed that the title compounds exhibited considerable inhibitory activity against PDE4B and blockade of LPS-induced TNFα release. Among the designed compounds, compound If showed the best inhibitory activity against PDE4B with the IC50 value of 1.7 µM, which also showed good in vivo activity in animal models of asthma/COPD and sepsis induced by LPS. The primary structure-activity relationship (SAR) study and docking results suggested that introduction of the substituent groups to the phenyl ring at the para-position, especially methoxy group, was helpful to enhance inhibitory activity against PDE4B.

Tetrahydroquinoline and tetrahydroisoquinoline derivatives as potential selective PDE4B inhibitors.

Tetrahydroquinoline and tetrahydroisoquinoline derivatives containing 2-phenyl-5-furan moiety were designed and synthesized as phosphodiesterase type 4 (PDE4) inhibitors. The bioassay results showed that title compounds showed good inhibitory activity against PDE4B and blockade of LPS (lipopolysaccharide) induced TNF-α release, which also exhibited considerable in vivo activity in animal models of asthma/COPD (chronic obstructive pulmonary disease) and sepsis induced by LPS. The bioactivity of compounds containing tetrahydroquinoline (series 4) was higher than that of tetrahydroisoquinoline derivatives (series 3). Compound 4 m with 4-methoxybenzene moiety exhibited the best potential selective activity against PDE4B. The primary structure-activity relationship study and docking results showed that the tetrahydroquinoline moiety of compound 4 m played a key role to form hydrogen bonds and π-π stacking interaction with PDE4B protein while the rest part of the molecule extended into the catalytic domain to block the access of cAMP and formed the foundation for inhibition of PDE4B. Based on LPS induced sepsis model for the measurement of TNF-α inhibition in Swiss Albino mice and neutrophilia inhibition for asthma and COPD in Sprague Dawley rats with the potential molecules, compound 4 m would be great promise as a hit inhibitor in the future study.

Synthesis and biological evaluation of 2,5-disubstituted furan derivatives as P-glycoprotein inhibitors for Doxorubicin resistance in MCF-7/ADR cell.

Multidrug resistance (MDR) is a tendency in which cells become resistant to structurally and mechanistically unrelated drugs, which is mediated by P-glycoprotein (P-gp). It is one of the noteworthy problems in cancer therapy. As one of the most important drugs in cancer therapy, doxorubicin has not good effectiveness if used independently. So targeting the P-gp protein is one of the key points to solve the MDR. Three series of furan derivatives containing tetrahydroquinoline or tetrahydroisoquinoline were designed and synthesized as P-gp inhibitors in this paper. Compound 5m containing 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline possessed good potency against P-gp (EC50 = 0.89 ±â€¯0.11 µM). The preliminary structure-activity relationship and docking studies demonstrated that compound 5m would be great promise as a lead compound for further study. Most worthy of mention is drug combination of doxorubicin and 5m displayed antiproliferative effect of about 97.8%. This study provides highlighted P-gp inhibitor for withstanding malignant tumor cell with multidrug resistance especially doxorubicin resistance setting the basis for further studies.

Design, synthesis and biological evaluation of 2,4-disubstituted oxazole derivatives as potential PDE4 inhibitors.

In this study, a series of pyrazole derivatives containing 4-phenyl-2-oxazole moiety were designed and synthesized in a concise way, some of which exhibited considerable inhibitory activity against PDE4B and blockade of LPS-induced TNF-α release. Compound 4c displayed the strongest inhibition activity (IC50=1.6±0.4µM) and good selectivity against PDE4B. Meanwhile, compound 4c showed good in vivo activity in animal models of asthma/COPD and sepsis induced by LPS. The primary structure-activity relationship study showed the 3,5-dimethylpyrazole residue was essential for the bioactivity, and the substituted group R1 at the benzene ring also affected the activity. Docking results showed that compound 4c played a key role to form integral hydrogen bonds and a π-π stacking interaction, using hydrazide scaffold (CONN) and pyrazole ring respectively, with PDE4B protein. While the rest part of the molecule extended into the catalytic domain to block the access of cAMP and formed the foundation for inhibition of PDE4B. Compound 4c would be great promise as a lead compound for further study based on the preliminary structure-activity relationship and molecular modeling studies.

Synthesis and bioactivity of pyrazole and triazole derivatives as potential PDE4 inhibitors.

A series of pyrazole and triazole derivatives containing 5-phenyl-2-furan functionality were designed and synthesized as phosphodiesterase type 4 (PDE4) inhibitors. The bioassay results showed that title compounds exhibited considerable inhibitory activity against PDE4B and blockade of LPS-induced TNFα release. Meanwhile, the activity of compounds containing 1,2,4-triazole (series II) was higher than that of pyrazole-attached derivatives (series I). The primary structure-activity relationship study and docking results showed that the 1,2,4-triazole moiety of compound IIk played a key role to form integral hydrogen bonds and π-π stacking interaction with PDE4B protein while the rest part of the molecule extended into the catalytic domain to block the access of cAMP and formed the foundation for inhibition of PDE4. Compound IIk would be great promise as a hit compound for further study based on the preliminary structure-activity relationship and molecular modeling studies.

Synthesis and Larvicidal Activity of Novel Thenoylhydrazide Derivatives.

A pair of chemical isomeric structures of novel N-tert-butylphenyl thenoylhydrazide compounds I and II were designed and synthesized. Their structures were characterized by MS, IR, (1)H NMR, elemental analysis and X-ray single crystal diffraction. The regioselectivity of the Meerwein arylation reaction and the electrophilic substitution reaction of N-tert-butyl hydrazine were studied by density functional theory (DFT) quantum chemical method. The larvicidal tests revealed that some compounds I had excellent larvicidal activity against Culex pipiens pallens. As the candidates of insect growth regulators (IGRs), the larval growth inhibition and regulation against Culex pipiens pallens were examined for some compounds, especially I1 and I7. Compounds I1 and I7 were further indicated as an ecdysteroid agonist by reporter gene assay on the Spodoptera frugiperda cell line (Sf9 cells). Finally, a molecular docking study of compound I7 was conducted, which was not only beneficial to understand the structure-activity relationship, but also useful for development of new IGRs for the control of mosquitos.

Antitumor Effects and Mechanism of Novel Emodin Rhamnoside Derivatives against Human Cancer Cells In Vitro.

A series of novel anthracene L-rhamnopyranosides compounds were designed and synthesized and their anti-proliferative activities on cancer cell lines were investigated. We found that one derivative S-8 (EM-d-Rha) strongly inhibited cell proliferation of a panel of different human cancer cell lines including A549, HepG2, OVCAR-3, HeLa and K562 and SGC-790 cell lines, and displayed IC50 values in low micro-molar ranges, which are ten folds more effective than emodin. In addition, we found EM-d-Rha (3-(2",3"-Di-O-acetyl-α-L-rhamnopyranosyl-(1→4)-2',3'-di-O-acetyl-α-L-rhamnopyranosyl)-emodin) substantially induced cellular apoptosis of HepG2 and OVCAR-3 cells in the early growth stage. Furthermore, EM-d-Rha led to the decrease of mitochondrial transmembrane potential, and up-regulated the express of cells apoptosis factors in a concentration- and time-dependent manner. The results indicated the EM-d-Rha may inhibit the growth and proliferation of HepG2 cells through the pathway of apoptosis induction, and the possible molecular mechanism may due to the activation of intrinsic apoptotic signal pathway.

Synthesis of a series of monosaccharide-fipronil conjugates and their phloem mobility.

To test the effect of adding different monosaccharide groups to a non-phloem-mobile insecticide on the phloem mobility of the insecticide, a series of conjugates of different monosaccharides and fipronil were synthesized using the trichloroacetimidate method. Phloem mobility tests in castor bean ( Ricinus communis L.) seedlings indicated that the phloem mobility of these conjugates varied markedly. L-Rhamnose-fipronil and D-fucose-fipronil displayed the highest phloem mobility among all of the tested conjugates. Conjugating hexose, pentose, or deoxysugar to fipronil through an O-glycosidic linkage can confer phloem mobility to fipronil in R. communis L. effectively, while the -OH orientation of the monosaccharide substantially affected the phloem mobility of the conjugates.