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71.
This is a report of extraction and identification of 1-O-alkyl glycerol present in the dried leaves of Bauhinia scandens. Fifty percent aqueous ethanolic extract of the plant at room temperature was fractionated over petroleum ether and diethyl ether. The diethyl ether soluble fraction showed positive bioactivity in Brine Shrimp bioassay. Isolation and purification of the active principle was subsequently done from diethyl ether fraction. The diethyl ether fraction was separated into acidic and neutral part. The acid free fraction was screened to be positive in Brine Shrimp bioassay. The NMR spectra (in CDCl3) indicated the probability of its lipoidal nature. The total lipid fraction was resolved into neutral, glyco, and phospho-lipids by column chromatography. Only the neutral fraction showed positive response to Brine Shrimp toxicity test, out of which again a Brine Shrimp positive fraction was separated by thin layer chromatography and identified as 1-O-alkyl glycerol. This fraction was acetylated and GLC analysis of the 1-O-alkyl-2,3-diacetyl glycerol was done. Our results demonstrate that the work may be cited as a nonhazardous and nonchemical management of therapeutic importance. 相似文献
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Oral administration of the ethanolic extract (200 and 400 mg/kg, p.o) and its fractions (200 mg/kg each) of the aerial parts of Cleome rutidosperma produced significant analgesic activity in acetic acid-induced writhing and tail immersion tests, anti-inflammatory effect against carrageenin induced inflammation and adjuvant induced polyarthritis and antipyretic activity against yeast-induced pyrexia. Fractionation of the ethanolic extract potentiated the activities. 相似文献
75.
Ghosh M Song X Mouneimne G Sidani M Lawrence DS Condeelis JS 《Science (New York, N.Y.)》2004,304(5671):743-746
A general caging method for proteins that are regulated by phosphorylation was used to study the in vivo biochemical action of cofilin and the subsequent cellular response. By acute and local activation of a chemically engineered, light-sensitive phosphocofilin mimic, we demonstrate that cofilin polymerizes actin, generates protrusions, and determines the direction of cell migration. We propose a role for cofilin that is distinct from its role as an actin-depolymerizing factor. 相似文献
76.
Neurofibromatosis type 1 (NF1) is one of the most prevalent dominantly inherited genetic diseases of the nervous system. NF1 encodes a tumor suppressor whose functional loss results in the development of benign neurofibromas that can progress to malignancy. Neurofibromas are complex tumors composed of axonal processes, Schwann cells, fibroblasts, perineurial cells, and mast cells. Through use of a conditional (cre/lox) allele, we show that loss of NF1 in the Schwann cell lineage is sufficient to generate tumors. In addition, complete NF1-mediated tumorigenicity requires both a loss of NF1 in cells destined to become neoplastic as well as heterozygosity in non-neoplastic cells. The requirement for a permissive haploinsufficient environment to allow tumorigenesis may have therapeutic implications for NF1 and other familial cancers. 相似文献
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McNamara C Zinkernagel AS Macheboeuf P Cunningham MW Nizet V Ghosh P 《Science (New York, N.Y.)》2008,319(5868):1405-1408
Antigenically variable M proteins are major virulence factors and immunogens of the human pathogen group A Streptococcus (GAS). Here, we report the approximately 3 angstrom resolution structure of a GAS M1 fragment containing the regions responsible for eliciting type-specific, protective immunity and for binding fibrinogen, which promotes M1 proinflammatory and antiphagocytic functions. The structure revealed substantial irregularities and instabilities throughout the coiled coil of the M1 fragment. Similar structural irregularities occur in myosin and tropomyosin, explaining the patterns of cross-reactivity seen in autoimmune sequelae of GAS infection. Sequence idealization of a large segment of the M1 coiled coil enhanced stability but diminished fibrinogen binding, proinflammatory effects, and antibody cross-reactivity, whereas it left protective immunogenicity undiminished. Idealized M proteins appear to have promise as vaccine immunogens. 相似文献
79.
Modification of the active site of alkaline phosphatase by site-directed mutagenesis 总被引:4,自引:0,他引:4
The catalytically essential amino acid in the active site of bacterial alkaline phosphatase (Ser-102) has been replaced with a cysteine by site-directed mutagenesis. The resulting thiol enzyme catalyzes the hydrolysis of a variety of phosphate monoesters. The rate-determining step of hydrolysis, however, is no longer the same for catalysis when the active protein nucleophile is changed from the hydroxyl of serine to the thiol of cysteine. Unlike the steady-state kinetics of native alkaline phosphatase, those of the mutant show sensitivity to the leaving group of the phosphate ester. 相似文献
80.
Development of an agricultural crops spectral library and classification of crops at cultivar level using hyperspectral data 总被引:1,自引:0,他引:1
In the context of a growing interest in remote sensing for precision agriculture applications, the utility of space-borne hyperspectral imaging for the development of a crop-specific spectral library and automatic identification and classification of three cultivars for each of rice (Oryza sativa L.), chilli (Capsicum annuum L.), sugarcane (Saccharum officinarum L.) and cotton (Gossipium hirsutum L.) crops have been investigated in this study. The classification of crops at cultivar level using two spectral libraries developed using hyperspectral reflectance data at canopy scale (in-situ hyperspectral measurements) and at pixel scale (Hyperion data) has shown promising results with 86.5 and 88.8% overall classification accuracy, respectively. This observation highlights the possible integration of in-situ hyperspectral measurements with space-borne hyperspectral remote sensing data for automatic identification and discrimination of various crop cultivars. However, considerable spectral similarity is observed between cultivars of rice and sugarcane crops which may pose problems in the accurate identification of various crop cultivars. 相似文献