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Composition of the surface waxes from bell pepper and eggplant 总被引:2,自引:0,他引:2
Stefan?Bauer Erhard?SchulteEmail author Hans-Peter?Thier 《European Food Research and Technology》2005,220(1):5-10
Surface waxes from the skins of bell pepper (Capsicum annuum) and eggplant (Solanum melongena) were rinsed with tert-butylmethyl ether (TBME). The wax components were separated into two fractions by elution from a small silica gel column with toluene/hexane (2+1) followed by methanol. They were identified by GC/MS and quantitatively determined by GC/FID. For 12 bell pepper cultivars, fraction 1 made up 39% of the total and contained mainly n-alkanes C20–C35 (with C31 dominating), iso-alkanes C25–C35, and some aldehydes. The 61% of fraction 2 consisted of 15 triterpenes, namely - and -amyrin, lupeol, glutinol, 3-friedelanol, friedelin, taraxerol, taraxasterol, -amyrin, germanicol, multiflorenol, -taraxasterol, isomultiflorenol, isobauerenol and bauerenol, as well as n-alkanoic acids C16–C32, 2-hydroxy-alkanoic acids C20–C26 and traces of n-alkanols and phytosterols (campesterol, stigmasterol and -sitosterol). For the three eggplant cultivars, 77% of fraction 1 was obtained with (in decreasing order) n-alkanes C23–C36, anteiso-alkanes C29–C36, iso-alkanes C27–C35, and some aldehydes. In the 23% of fraction 2, the n-alkanoic acids C16–C32 predominated compared with the 2-hydroxy-alkanoic acids C22–C26, the n-alkanols C24–C29, triterpenols (- and -amyrin, lupeol, germanicol) and sterols (stigmasterol and -sitosterol). 相似文献
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Claus RA Wüstholz A Müller S Bockmeyer CL Riedel NH Kinscherf R Deigner HP 《Chembiochem : a European journal of chemical biology》2005,6(4):726-737
The enantioselective synthesis of an analogue of scyphostatin, a potent inhibitor of the neutral sphingomyelinase, is described. The synthesis starts with cyclohexanone and a protected D-serine derivative. The key step is an asymmetric hydroxylation to access a hydroxycyclohexanone, which is transformed into a substituted hydroxycyclohexenone. This is converted into the scyphostatin analogue 14, a chemically and metabolically stabilised compound lacking the epoxy function of the natural congener and carrying a palmitic acid group instead of the native trienoyl residue. An evaluation of the biological activity of 14 revealed neutral sphingomyelinase inhibition in several in vivo test systems (monocytes, macrophages, hepatocytes) monitoring antiapoptotic effects and the inversion of phorbolester-induced translocation of green fluorescent protein labelled kinase (protein kinase C-alpha). 相似文献
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Summary The longitudinal acoustic modes (LAM) of several cycloalkanes ((CH2)14 to (CH2)96) measured by Raman spectroscopy are described. The frequency differences between the LAMs of the cycloalkanes and the corresponding n-alkanes are explained by a simple linear chain model. It is shown that the LAM-modes are practically not affected by the gauche conformations of the two folds in the cyclic molecule. 相似文献
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This paper presents the accelerated active power cycling test (APCT) results on SiC JFETs power module dedicated to operate at high temperature. This study partly focuses on the new chip joining technology (LTJT), which permit to use SiC JFETs transistors at higher temperatures. We present the different die attachments tested with high temperature lead solder and silver sintering joining technologies. Active power cycling results for high junction temperature Tjmax = 175 °C with ΔTj = 80 K to perform an evaluation of main damages during active test are carried out and a comparison between lead and silver chip joining technologies is presented. 相似文献