- A Cyclopeptide and a Tetrahydroisoquinoline Alkaloid from Ophiorrhiza nutans
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A new cyclopeptide, ophiorrhisine A (1), a new tetrahydroisoquinoline alkaloid, 7′,10-dide-O-methylcephaeline (2), two known β-carboline alkaloids, and four known tetrahydroisoquinoline alkaloids were isolated from Ophiorrhiza nutans (Rubiaceae). Compound 1 is a tetrapeptide possessing a 14-membered paracyclophane ring and a novel N,N,N-trimethyltyrosine residue in the side chain. The stereochemistry at the aryl-alkyl ether bond was different from that of other known 14-membered paracyclophanes. The structure of 2 was established by spectroscopic analysis and semisynthesis.
- Onozawa, Tadayoshi,Kitajima, Mariko,Kogure, Noriyuki,Peerakam, Nichakan,Santiarworn, Dammrong,Takayama, Hiromitsu
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p. 2156 - 2160
(2017/08/04)
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- Concise total synthesis of dihydrocorynanthenol, protoemetinol, protoemetine, 3-epi-protoemetinol and emetine
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A concise asymmetric assembly of secologanine tryptamine and dopamine alkaloids by means of a one-pot three-component cascade reaction methodology is disclosed. This is demonstrated by the expeditious total syntheses of (-)-dihydrocorynanthenol, (-)-protoemetinol, (-)-protoemetine, (-)-3-epi-protoemetinol, and emetine (3-6 steps). The biomimetic synthetic strategy involved the following key steps: (i) One-pot three-component highly enantioselective catalytic Michael/Pictet-Spengler/lactamization cascade reactions; (ii) One-pot tandem Swern oxidation/Wittig sequences; (iii) One-pot tandem hydrogenation sequences. Copyright
- Lin, Shuangzheng,Deiana, Luca,Tseggai, Abrehet,Cordova, Armando
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p. 398 - 408
(2012/02/16)
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- Molecular cloning of an O-methyltransferase from adventitious roots of carapichea ipecacuanha
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Carapichea ipecacuanha produces various emetinetype alkaloids, known as ipecac alkaloids, which have long been used as expectorants, emetics, and amebicides. In this study, we isolated an O-methyltransferase cDNA from this medicinal plant. The encoded protein (CiOMT1) showed 98% sequence identity to IpeOMT2, which catalyzes the 7′-O-methylation of 7′-O- demethylcephaeline to form cephaeline at the penultimate step of emetine biosynthesis (Nomura and Kutchan, J. Biol. Chem., 285, 7722-7738 (2010)). Recombinant CiOMT1 showed both 7′-O-methylation and 6′-O-methylation activities at the last two steps of emetine biosynthesis. This indicates that small differences in amino acid residues are responsible for distinct regional methylation specificities between IpeOMT2 and CiOMT1, and that CiOMT1 might contribute to two sequential O-methylation steps from 7′-O- demethylcephaeline to emetine.
- Cheong, Bo Eng,Takemura, Tomoya,Yoshimatsu, Kayo,Sato, Fumihiko
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experimental part
p. 107 - 113
(2011/09/30)
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- Compounds and compositions for treating infection
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Compounds from 14 Kenyan plants, including from the root of Dovyalis abyssinica and Clutia robusta have been characterized and isolated, and their uses are disclosed.
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- Formal total synthesis of (-)-emetine using catalytic asymmetric allylation of cyclic imines as a key step
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Catalytic asymmetric allylation of 3,4-dihydro-6,7-dimethoxyisoquinoline was carried out using allyltrimethoxysilane in the presence of Cu(I) and tol-BINAP. The allyl adduct thus obtained was transformed to a chiral synthetic intermediate for (-)-emetine in good yield. The procedure was applied to the total synthesis of ent-emetine.
- Itoh, Takashi,Miyazaki, Michiko,Fukuoka, Hiromi,Nagata, Kazuhiro,Ohsawa, Akio
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p. 1295 - 1297
(2007/10/03)
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- Ipecac alkaloids from Cephaelis acuminata
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From the dried roots of Cephaelis acuminata, five ipecac alkaloids, neocephaeline, 7'-O-demethylcephaeline, 10-O-demethylcephaeline, 2'-N-(1''- deoxy-1''-β-D-fructopyranosyl)cephaeline and 2'-N-(1''-deoxy-1''-β-D- fructopyranosyl)neocephaeline, were isolated, along with emetine, cephaeline, psychotrine, protoemetine, 9-demethylprotoemetinol and isocephaeline. Structures were determined by spectroscopic and chemical means.
- Itoh, Atsuko,Ikuta, Yuki,Baba, Yoshikazu,Tanahashi, Takao,Nagakura, Naotaka
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p. 1169 - 1176
(2007/10/03)
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- The Pent-4-enoyl Group: A Novel Amine-Protecting Group That Is Readily Cleaved under Mild Conditions
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Primary and secondary amines are readily protected as N-pent-4-enoyl derivatives, the resulting N-pent-4-enamides being usually highly crystalline.Deprotection is rapidly and efficiently effected under mild conditions by treatment with 3 equiv of iodine in aqueous THF solution.Although an oxidizing medium, these deprotection conditions do not affect oxidizable functionalities including p-methoxybenzyl ethers and alkyl sulfides.
- Madsen, Robert,Roberts, Carmichael,Fraser-Reid, Bert
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p. 7920 - 7926
(2007/10/03)
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