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81.
82.
The root bark of Zanthoxylum dipetalum contained the alkaloids canthin-6-one, chelerythrine, nitidine and tembetarine, the pyranocoumarins avicennol and xanthoxyletin, the triterpene lupeol and the flavanoid hesperidin. The MS fragmentation pattern for avicennol is discussed and a tentative structure is proposed for a third coumarin, designated ZD/1. The root wood of the type species and the stem bark of the γ variety contained most of the above compounds plus sitosterol and, in the root wood only, magnoflorine. The chemotaxonomic implications of these findings are briefly discussed. 相似文献
83.
The long-chain saturated and mono-unsaturated hydrocarbon content of the juice sacs of five mandarin cultivars (Mediterranean, Honey, Wilking, Kinnow, King) were examined. Normal homologues accounted for more than 47% of the saturated and more than 75% of the monoene hydrocarbons. In the saturated fraction the major hydrocarbon was n-C25 but in the monoene fraction n-C25 predominated in Kinnow and King while C29 predominated in Mediterranean, Honey and Wilking. All five cultivars could be differentiated from each other and from other citrus species by their hydrocarbon patterns. The noticeably high normal/iso ratios of saturated C23 and C25 hydrocarbons previously shown to be characteristic of mandarin species, Citrus unshiu and C. reticulata, were also found in C. nobilis and C. deliciosa. 相似文献
84.
A new flavone and two diterpenes have been isolated from the extracts of Pamburus missionis. The flavone was identified as an isopentylated apigenin derivative on the basis of spectroscopic studies on it and its diacetate. One of the diterpenes has been identified as daniellic acid and the second as a closely related butenolide. 相似文献
85.
86.
A cell-free system obtained from Citrus paradisii flavedo transformed mevalonic acid into mono- and sesquiterpenoids of E- and Z-conformation. The enzyme system required bivalent metal ions and the presence of sulfhydryl groups. IPP isomerase activity (EC 5.3.3.2) was independent of metal ions and almost insensitive to sulfhydryl group reagents, while prenyltransferase (EC 2.5.1.1) was inactivated by DTNB and required bivalent metals for activity. The nature of the metal ion defined the stereochemistry of the products formed by prenyltransferase. The ratio of E–Z farnesylpyrophosphates was 3:1. This Citrus species could, therefore, be a good starting material for the study of the stereochemistry of the enzymes forming E and Z sesquiterpenoids. 相似文献
87.
88.
Zanthoxylum williamsii (Rutaceae) was found to contain (+)-asaranin, (+)-sesamin, esculetin dimethyl ether, nitidine, chelerythrine, magnoflorine, laurifoline, skimmianine and edulinine. The quaternary alkaloid fraction of Z. monophyllum contained berberine, magnoflorine, chelerythrine and a 1,2,9,10-substituted dihydroxydimethoxy-N,N-dimethylaporphinium salt. Leaves of Z. fagara were found to contain synephrine. Leaves of each species were examined for the presence of bishordeninyl terpene alkaloids, but none was found. Some chemotaxonomic relationships among Zanthoxylum species are discussed. 相似文献
89.
Separation of the ethanolic extract of the fruit of Murraya omphalocarpa afforded a new flavonol, murrayanol, which was characterized as 5,4′-dihydroxy-3,6,7,3′,5′-pentamethoxyflavone, together with the known substances coumurrayin, mexoticin, 3,5,6,7,3′,4′,5′-heptamethoxyflavone, 5,7-dimethoxy-8-(3′-methyl-2′-oxobutyl) coumarin and sitosterol. 相似文献
90.
Cell-free extracts of calamondin orange (Citrus mitis) catalysed the O-methylation of almost all hydroxyls of a number of flavonoids, indicating the existence in citrus tissues of ortho, meta, para and 3-O-methyltransferases. The latter, hitherto unreported enzyme, catalysed the formation of 3-O-methyl ethers of galangin and quercetin. The stepwise O-methylation of a number of compounds, especially quercetin and quercetagetin, tends to suggest a coordinated sequence of O-methylations on the surface of a multienzyme complex. The methyl acceptor abilities of the flavonoid substrates used are discussed in relation to their hydroxyl substitution patterns and their negative electron density distribution. 相似文献