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991.
Khan KM Mughal UR Khan MT Zia-Ullah Perveen S Choudhary MI 《Bioorganic & medicinal chemistry》2006,14(17):6027-6033
The tyrosinase inhibitory potential of seventeen synthesized oxazolone derivatives has been evaluated and their structure-activity relationships developed in the present work. All the synthesized derivatives, 3-19, demonstrated excellent in vitro tyrosinase inhibitory properties having IC50 values in the range of 1.23+/-0.37-17.73+/-2.69 microM, whereas standard inhibitors l-mimosine and kojic acid have IC50 values 3.68+/-0.02 and 16.67+/-0.52 microM,, respectively. Compounds 4-8 having IC50 values 3.11+/-0.95, 3.51+/-0.25, 3.23+/-0.66, 1.23 +/- 0.37, and 2.15+/-0.75, respectively, were found to be very active members of the series, even better than both the standard inhibitors. However, compounds 3, 9-11, 13, 14, 16, 17, and 19 were found to be better than kojic acid but not l-mimosine. (2-Methyl-4-[E,2Z)-3-phenyl-2-propenyliden]-1,3-oxazol-5(4H)-one (7) bearing a cinnamyol residue at C-4 of oxazolone moiety and an IC50 = 1.23+/-0.37 microM was found to be the most active one among all tested compounds. These studies reveal that the substitution of functional group (s) at C-4 and C-2 positions plays a vital role in the activity of this series of compounds. It is concluded that compound 7 may act as a potential lead molecule to develop new drugs for the treatment of tyrosinase based disorders. 相似文献
992.
Kaschani F Shabab M Bozkurt T Shindo T Schornack S Gu C Ilyas M Win J Kamoun S van der Hoorn RA 《Plant physiology》2010,154(4):1794-1804
Since the leaf apoplast is a primary habitat for many plant pathogens, apoplastic proteins are potent, ancient targets for apoplastic effectors secreted by plant pathogens. So far, however, only a few apoplastic effector targets have been identified and characterized. Here, we discovered that the papain-like cysteine protease C14 is a new common target of EPIC1 and EPIC2B, two apoplastic, cystatin-like proteins secreted by the potato (Solanum tuberosum) late blight pathogen Phytophthora infestans. C14 is a secreted protease of tomato (Solanum lycopersicum) and potato typified by a carboxyl-terminal granulin domain. The EPIC-C14 interaction occurs at a wide pH range and is stronger than the previously described interactions of EPICs with tomato defense proteases PIP1 and RCR3. The selectivity of the EPICs is also different when compared with the AVR2 effector of the fungal tomato pathogen Cladosporium fulvum, which targets PIP1 and RCR3, and only at apoplastic pH. Importantly, silencing of C14 increased susceptibility to P. infestans, demonstrating that this protease plays a role in pathogen defense. Although C14 is under conservative selection in tomato, it is under diversifying selection in wild potato species (Solanum demissum, Solanum verrucosum, and Solanum stoliniferum) that are the natural hosts of P. infestans. These data reveal a novel effector target in the apoplast that contributes to immunity and is under diversifying selection, but only in the natural host of the pathogen. 相似文献
993.
Muhammad Asim Helmi Hussien Luis Poveda John Thor Arnason Tony Durst 《Phytochemistry》2010,71(11-12):1418-1422
Five spirocaracolitone triterpenoids were isolated from the dichloromethane-soluble fraction of the bark of Ruptiliocarpon caracolito, and their structures were determined mainly by application of 1D and 2D NMR spectroscopy. Two known CD-spirotriterpenoids were also isolated from the same source. This brings the total number of known CD-spirotriterpenoids from this source to 17. The discovery of such a large number of closely-related compounds in a single species represents an excellent example of phytochemical redundancy as a defense mechanism. 相似文献
994.
Salinity is one of the most important stresses that hamper agricultural productivity in nearly every part of the world. Enhanced biosynthesis of ethylene in plants under salinity stress is well established. Higher ethylene concentration inhibits root growth and ultimately affects the overall plant growth. Overcoming this ethylene-induced root inhibition is a prerequisite for successful crop production. Recent studies have shown that ethylene level in plants is regulated by a key enzyme 1-aminocyclopropane-1-carboxylicacid (ACC)-deaminase. This enzyme is present in plant growth-promoting bacteria (PGPR) and lowers the ethylene level by metabolizing its precursor ACC into α-ketobutyrate and ammonia (NH3). Inoculation of plants under salinity stress with PGPR having ACC-deaminase activity mitigates the inhibitory effects of salinity on root growth by lowering the ethylene concentration in the plant. This in turn results in prolific root growth, which is beneficial for the uptake of nutrients and maintenance of growth under stressful environment. The present review critically discusses the effects of salinity stress on plant growth with special reference to ethylene production and the effects of rhizobacteria containing ACC-deaminase on crop improvement under salinity stress. It also discusses how much progress has been made in producing transgenic lines of different crops over-expressing the gene encoding ACC-deaminase and how far such transformed lines can tolerate salinity stress. 相似文献
995.
Md. Maksudul Alam Sazia Sharmin Zinnatun Nabi Shakhinur Islam Mondal Md. Shahidul Islam Sarmah Bin Nayeem Muhammad Shoyaib Haseena Khan 《Plant Molecular Biology Reporter》2010,28(3):394-402
A putative leucine-rich repeat receptor-like protein kinase (LRR-RLK) gene together with its 5′ and 3′ untranslated regions
of jute (Corchorus olitorius L.) has been identified and sequenced. The gene is 3,371 bp long containing two exons and one intron. The coding sequence
of the gene is 2,879 bp long encoding a peptide of 957 amino acids. The predicted protein contains several domains and motifs
characteristic of a transmembrane protein kinase. It is complete with domains for an N-terminal leucine-rich repeat and a
protein kinase core, an active site for serine/threonine protein kinase, an ATP binding conserved site and a transmembrane
region. Expression of the gene is induced by low temperature, high salt concentration, dehydration, abscisic acid treatment,
and fungal infection, suggesting the involvement of the gene in multiple stress response pathways in jute (C. olitorius L.). A possible mechanism of the role of the gene in signal transduction and environmental stress response is discussed.
To date, LRR-RLK is the only jute gene which has been completely sequenced and characterized. 相似文献
996.
Bo Yang Muhammad H. Rahman Yue Liang Saleh Shah Nat N. V. Kav 《Plant Molecular Biology Reporter》2010,28(2):253-263
Canola (Brassica napus L.) is an agriculturally and economically important crop in Canada, and its growth and yield are frequently influenced by
fungal pathogens. Sclerotinia sclerotiorum is among those fungal pathogens and causes stem rot disease in B. napus whereas it has been reported that Brassica carinata is moderately tolerant to S. sclerotiorum. Jasmonic acid/ethylene (JA/ET) and salicylic acid (SA) are phytohormones that are known to be involved in plant disease
responses. To investigate the defense signaling cascades involved in the interaction of B. napus and B. carinata with S. sclerotiorum, we examined the expression of five orthologs of B. napus genes involved in JA/ET or SA signaling pathways using quantitative RT-PCR. Our results indicated that there are differences
in the timing of JA/ET and SA signaling pathways between B. napus and B. carinata. Our results in these two Brassica species also support previous observations that necrotrophic pathogens trigger JA/ET signaling in response to infection.
Finally, we observed that transgenic canola expressing 1-aminocyclopropane-1-carboxylate-deaminase producing low levels of
ET was relatively more susceptible to S. sclerotiorum than its wild-type counterpart, suggesting that ET inhibits S. sclerotiorum-induced symptom development. 相似文献
997.
Mohammad Iqbal Muhammad Dawood Shah Chau Ann Lie Chin Kim San 《Molecular and cellular biochemistry》2010,341(1-2):271-277
This study was aimed to evaluate the effect of Strobilanthes crispus extract for possible protection against lipid peroxidation and DNA damage induced by iron nitrilotriacetate (Fe-NTA) and hydrogen peroxide (H2O2). Fe-NTA is a potent nephrotoxic agent and induces acute and subacute renal proximal tubular necrosis by catalyzing the decomposition of H2O2-derived production of hydroxyl radicals, which are known to cause lipid peroxidation and DNA damage. Incubation of postmitochondrial supernatant and/or calf thymus DNA with H2O2 (40 mM) in the presence of Fe-NTA (0.1 mM) induces lipid peroxidation and DNA damage to about 2.3-fold and 2.9-fold, respectively, as compared to control (P < 0.05). In lipid peroxidation protection studies, S. crispus treatment showed a dose-dependent inhibition (45–53% inhibition, P < 0.05) of Fe-NTA and H2O2 induced lipid peroxidation. Similarly, in DNA damage protection studies, S. crispus treatment also showed a dose-dependent inhibition (18–30% inhibition, P < 0.05) of DNA damage. In addition, the protection was closely related to the content of phenolic compounds as evident by S. crispus extract showing the value of 124.48 mg/g total phenolics expressed as gallic acid equivalent (GAE, mg/g of extract). From these studies, it is concluded that S. crispus inhibits peroxidation of membrane lipids and DNA damage induced by Fe-NTA and H2O2 and possesses the potential to be used to treat or prevent degenerative diseases where oxidative stress is implicated. 相似文献
998.
Sumra Afzal Mahjabeen Saleem Riffat Yasmin Mamoona Naz Muhammad Imran 《Molecular biology reports》2010,37(4):1717-1723
Consistent with its precloning characterization from the cellulolytic Bacillus sp., β-1,4-endoglucanase purified from the recombinant E. coli exhibited maximum activity at 60°C and pH 7.0. It was highly specific for CMC hydrolysis, with stability up to 70°C and over
a pH range of 6.0–8.0. The K
m and V
max values for CMCase activity of the enzyme were 4.1 mg/ml and 25 μmole/ml min−1, respectively. The purified enzyme was a monomer of 65 kDa, as determined by SDS-PAGE. The presence of sucrose and IPTG in
fermentation media increased the endoglucanase activity of the recombinant enzyme to 5.2-folds as compared with that of the
actual one. 相似文献
999.
Feng Sun Zheng Cai Muhammad Ishtiaq Chaudhary Peigen Xiao Yiyu Cheng 《Biochemical Systematics and Ecology》2010
Selected species of the genus Clematis (Ranunculaceae) have been screened for occurrence of triterpenoid saponins by qualitative HPLC-MSn analysis of root and rhizome materials from 18 Clematis samples as well as the whole plant materials of Clematis puberula var. ganpiniana and Clematis terniflora. The HPLC-MSn analysis allowing the detection of 17 oleanolic acid or hederagenin saponins was carried out in the negative selected ion monitoring (SIM) mode. Triterpenoid saponin profiles of these taxa were used for phylogenetic studies, and results are presented as a dendrogram. Huzhangoside B could be unambiguously identified in all analyzed Clematis taxa, as well as in the investigated Ranunculus taxa. The distribution and chemotaxonomic importance of the triterpenoid saponin profile within this genus are discussed. 相似文献