Qualitative and quantitative analysis of endogenous jasmonoids in potato plant (Solanum tuberosum L.).
(65/2057)
Qualitative and quantitative analyses of endogenous jasmonoids were done by liquid chromatography/ selected ion monitoring (LC-SIM) using deuterium-labeled compounds as internal standards. To prove the practicality of this way of analyzing the contents of endogenous jasmonoids in plants, the method was used for estimating jasmonoids in potato plants. (+info)
Transient accumulation of jasmonic acid during the synchronized hypersensitive cell death in Tobacco mosaic virus-infected tobacco leaves.
(66/2057)
Jasmonic acid (JA) transiently accumulated during temperature-dependent synchronous necrotic lesion formation in Tobacco mosaic virus-infected tobacco leaves. The accumulation of JA was preceded by activation of a tobacco mitogen-activated protein kinase, WIPK, which functions upstream of JA in wound signal transduction pathways. (+info)
Synthesis and potato cell expansion-inducing activity of the stereochemically restricted bicyclic analogue of 7-epi-jasmonic acid.
(67/2057)
The stereochemically restricted bicyclic analogue of 7-epi-jasmonic acid was synthesized from a known bicyclo[3.3.0]octane derivative. The enol triflate derived from the bicyclic compound was subjected to palladium-catalyzed coupling with allyltributyltin to give the desired carbon skeleton. Selective catalytic hydrogenation and subsequent acidic hydrolysis gave a new bicyclic analogue of 7-epi-jasmonic acid. The ACC conjugate of the bicyclic analogue was also synthesized. This ACC conjugate exhibited only slightly weaker potato cell expansion-inducing activity than that of the JA standard. (+info)
Potency of Michael reaction acceptors as inducers of enzymes that protect against carcinogenesis depends on their reactivity with sulfhydryl groups.
(68/2057)
Induction of phase 2 enzymes and elevations of glutathione are major and sufficient strategies for protecting mammals and their cells against the toxic and carcinogenic effects of electrophiles and reactive forms of oxygen. Inducers belong to nine chemical classes and have few common properties except for their ability to modify sulfhydryl groups by oxidation, reduction, or alkylation. Much evidence suggests that the cellular "sensor" molecule that recognizes the inducers and signals the enhanced transcription of phase 2 genes does so by virtue of unique and highly reactive sulfhydryl functions that recognize and covalently react with the inducers. Benzylidene-alkanones and -cycloalkanones are Michael reaction acceptors whose inducer potency is profoundly increased by the presence of ortho- (but not other) hydroxyl substituent(s) on the aromatic ring(s). This enhancement correlates with more rapid reactivity of the ortho-hydroxylated derivatives with model sulfhydryl compounds. Proton NMR spectroscopy provides no evidence for increased electrophilicity of the beta-vinyl carbons (the presumed site of nucleophilic attack) on the hydroxylated inducers. Surprisingly, these ortho-hydroxyl groups display a propensity for extensive intermolecular hydrogen bond formation, which may raise the reactivity and facilitate addition of mercaptans, thereby raising inducer potencies. (+info)
Comparison of the anti-influenza virus activity of RWJ-270201 with those of oseltamivir and zanamivir.
(69/2057)
We have recently reported an influenza virus neuraminidase inhibitor, RWJ-270201 (BCX-1812), a novel cyclopentane derivative discovered through structure-based drug design. In this paper, we compare the potency of three compounds, RWJ-270201, oseltamivir, and zanamivir, against neuraminidase enzymes from various subtypes of influenza. RWJ-270201 effectively inhibited all tested influenza A and influenza B neuraminidases in vitro, with 50% inhibitory concentrations of 0.09 to 1.4 nM for influenza A neuraminidases and 0.6 to 11 nM for influenza B neuraminidases. These values were comparable to or lower than those for oseltamivir carboxylate (GS4071) and zanamivir (GG167). RWJ-270201 demonstrated excellent selectivity (>10,000-fold) for influenza virus neuraminidase over mammalian, bacterial, or other viral neuraminidases. Oral administration of a dosage of 1 mg/kg of body weight/day of RWJ-270201 for 5 days (beginning 4 h preinfection) showed efficacy in the murine model of influenza virus infection as determined by lethality and weight loss protection. RWJ-270201 administered intranasally at 0.01 mg/kg/day in the murine influenza model demonstrated complete protection against lethality, whereas oseltamivir carboxylate and zanamivir at the same dose demonstrated only partial protection. In the delayed-treatment murine influenza model, oral administration of a 10-mg/kg/day dose of RWJ-270201 or oseltamivir (GS4104, a prodrug of GS4071) at 24 h postinfection showed significant protection against lethality (P < 0.001 versus control). However, when the treatment was delayed for 48 h, no significant protection was observed in either drug group. No drug-related toxicity was observed in mice receiving 100 mg/kg/day of RWJ-270201 for 5 days. These efficacy and safety profiles justify further consideration of RWJ-270201 for the treatment and prevention of human influenza. (+info)
Protective effects of bilobalide on amyloid beta-peptide 25-35-induced PC12 cell cytotoxicity.
(70/2057)
AIM: To study the effect of bilobalide, a terpene extracted from the leaves of Ginkgo biloba, on beta-amyloid peptide fragment 25-35 (A beta 25-35)-induced PC12 cell cytotoxicity. METHODS: 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assay were used to measure the viability of PC12 cells. Thiobarbituric acid-reactive substances were measured to determine lipid peroxidation of cells. Antioxidant enzymes in PC12 cells were detected. RESULTS: Treatment of PC12 cells with A beta 25-35 (100 mumol.L-1) for 24 h caused a great decrease in cell viability (P < 0.01 compared with control). Bilobalide 25-100 mumol.L-1 dose-dependently attenuated the cytotoxic effect of A beta 25-35. Bilobalide also inhibited A beta 25-35 (100 mumol.L-1)-induced elevation of lipid peroxidation and decline of antioxidant enzyme activities. CONCLUSION: Bilobalide protected PC12 cells from A beta 25-35-induced cytotoxicity. (+info)
Bilobalide promotes expression of glial cell line-derived neurotrophic factor and vascular endothelial growth factor in rat astrocytes.
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AIM: To study the effects of bilobalide on the expression of glial cell line-derived neurotrophic factor (GDNF) and vascular endothelial growth factor (VEGF) in rat astrocytes in vitro. METHODS: Semiquantification polymerase chain reaction (SQ-PCR) was used to investigate GDNF and VEGF mRNA expression in the astrocytes after bilobalide (5, 15, 50, 100 mumol.L-1) treatment. Immunohistochemistry method was used to detect GDNF and VEGF protein expression in cells treated with bilobalide 50 mumol.L-1 for 24 h. RESULTS: GDNF and VEGF mRNA increased markedly after astrocytes were treated with bilobalide 50 mumol.L-1 for 12 h. GDNF and VEGF protein were detected in the cytoplasm of astrocytes after the cells were treated with bilobalide 50 mumol.L-1 for 24 h. CONCLUSION: Bilobalide induced GDNF and VEGF expression in the cultured astrocytes. (+info)
A hot pepper cDNA encoding a pathogenesis-related protein 4 is induced during the resistance response to tobacco mosaic virus.
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Hot pepper (Capsicum annuum) plants exhibit a hypersensitive response (HR) against infection by many tobamoviruses. A clone (CaPR-4) encoding a putative pathogenesis-related protein 4 was isolated by differential screening of a cDNA library prepared from resistant pepper plant leaves inoculated with tobacco mosaic virus (TMV) pathotype P0. The predicted amino acid sequence of CaPR-4 is very similar to those of other plant PR-4s. Southern blot analysis showed that small gene families of PR-4-related sequences were present in the pepper genome. Hot pepper cultivar Bugang, resistant to TMV-P0 and susceptible to TMV-P1.2, induced CaPR-4 expression by pathotype P0 inoculation in inoculated and systemic leaves, but not by pathotype P1.2. Effects of exogenously applied abiotic elicitors upon the CaPR-4 expression were also examined. The expression of the CaPR-4 gene was stimulated by methyl jasmonate (MeJA), ethephon and wounding treatment. However, application of salicylic acid (SA) did not trigger the expression. Evidence is emerging that jasmonic acid and ethylene play key roles in the SA-independent pathways of plant-pathogen interaction. Taken together, these results suggest that the CaPR-4 gene is one of the defense-related genes conferring resistance on pepper plants by the SA-independent pathway and the cross-talk between signaling compounds, jasmonic acid and ethylene could have a great regulatory potential in a plant's defense against TMV. (+info)