2,6-Epoxy-2H-naphthaceno[1,2-b]oxocin-14-carboxylicacid, 11-[(6-deoxy-3-C-methyl-2,3,4-tri-O-methyl-a-L-mannopyranosyl)oxy]-4-(dimethylamino)-3,4,5,6,9,11,12,13,14,16-decahydro-3,5,8,10,13-pentahydroxy-6,13-dimethyl-9,16-dioxo-,methyl ester, (2R,3S,4R,5R,6R,11S,13S,14R)-

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CAS: 1404-15-5
MF: C39H49NO16
MW: 787.80346
Synonyms: 2,6-Epoxy-2H-naphthaceno[1,2-b]oxocin-14-carboxylicacid, 11-[(6-deoxy-3-C-methyl-2,3,4-tri-O-methyl-a-L-mannopyranosyl)oxy]-4-(dimethylamino)-3,4,5,6,9,11,12,13,14,16-decahydro-3,5,8,10,13-pentahydroxy-6,13-dimethyl-9,16-dioxo-,methyl ester, (2R,3S,4R,5R,6R,11S,13S,14R)-

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Xiang-Min ZHANG

Fudan University
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Co-reporter: Chunhui Deng;Ji Qian;Weimin Zhu;Xiaofeng Yang;Xiangmin Zhang
pp: 1137-1142
Publication Date(Web):14 JUL 2005
DOI: 10.1002/jssc.200401891

Many plants infested by herbivores or viruses can rapidly produce and accumulate a plant-signaling compound, methyl salicylate (MeSA), in their leaves to activate disease resistance. In the present work, a simple, rapid, and sensitive method was developed for the determination of MeSA in tomato leaves by direct sample introduction and thermal desorption followed by GC-MS. Results show that the proposed method has a low detection limit (0.08 ng mg–1) and good precision (RSD = 8.9%). The present method was applied to the investigation of tomato plant defense response to tobacco mosaic virus (TMV) by rapid analysis of volatile compounds in plant leaves. It was found that tomato plants can produce large amounts of MeSA as a defense response to TMV. This indicates that MeSA may be a plant-signaling compound in tomato plant defense response to TMV.

A. Richard Chamberlin

University of California, Irvine
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Philip DeShong

University of Maryland
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Dabney W. Dixon

Georgia State University
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Mark S. Searle

University Park
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Gideon J. Davies

University of York
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Mikko Metsa-Ketela

University of Turku
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Co-reporter: Vilja Siitonen;Magnus Claesson;Pekka Patrikainen;Maria Aromaa; emer. Pekka Mäntsälä; Gunter Schneider;Dr. Mikko Metsä-Ketelä
pp: 120-128
Publication Date(Web):
DOI: 10.1002/cbic.201100637

Abstract

Nogalamycin is an anthracycline antibiotic that has been shown to exhibit significant cytotoxicity. Its biological activity requires two deoxysugar moieties: nogalose and nogalamine, which are attached at C7 and C1, respectively, of the aromatic polyketide aglycone. Curiously, the aminosugar nogalamine is also connected through a C[BOND]C bond between C2 and C5′′. Despite extensive molecular genetic characterization of early biosynthetic steps, nogalamycin glycosylation has not been investigated in detail. Here we show that expression of the majority of the gene cluster in Streptomyces albus led to accumulation of three new anthracyclines, which unexpectedly included nogalamycin derivatives in which nogalamine was replaced either by rhodosamine with the C[BOND]C bond intact (nogalamycin R) or by 2-deoxyfucose without the C[BOND]C bond (nogalamycin F). In addition, a monoglycosylated intermediate—3′,4′-demethoxynogalose-1-hydroxynogalamycinone—was isolated. Importantly, when the remaining biosynthetic genes were introduced into the heterologous host by using a two-plasmid system, nogalamycin could be isolated from the cultures, thus indicating that the whole gene cluster had been identified. We further show that one of the three glycosyltransferases (GTs) residing in the cluster—snogZ—appears to be redundant, whereas gene inactivation experiments revealed that snogE and snogD act as nogalose and nogalamine transferases, respectively. The substrate specificity of the nogalamine transferase SnogD was demonstrated in vitro: the enzyme was able to remove 2deoxyfucose from nogalamycin F. All of the new compounds were found to inhibit human topoisomerase I in activity measurements, whereas only nogalamycin R showed minor activity against topoisomerase II.