- Chloptosin, an apoptosis-inducing dimeric cyclohexapeptide produced by Streptomyces
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In the course of screening for apoptosis-inducing agents, chloptosin (1) was isolated from the culture broth of Streptomyces. The dumbbell-type structure of the dimeric cyclohexapeptide consisting of D-valine, (3S)- and (3R)-piperazic acids, O-methyl-L-serine, D-threonine, and (2S,3aR,8aR)-6- chloro-3a-hydroxy-2,3,3a,8a-hexahydropyrrolo[2,3-b]indole-2-carboxylic acid was elucidated by spectroscopic and chemical degradation studies. The amino acid components in each cyclohexapeptide domain were presented in alternating R and S configurations. Chloptosin (1) was found to induce apoptotic activity in apoptosis-resistant human pancreatic adenocarcinoma cell line AsPC-1 and showed a strong antimicrobial activity against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus.
- Umezawa, Kazuo,Ikeda, Yoko,Uchihata, Yuki,Naganawa, Hiroshi,Kondo, Shinichi
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- Synthesis of cyclic α-hydrazino acids
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Synthesis of five-, six-, seven-, eight-, and nine-membered cyclic α-hydrazino acids from a common starting material 'diethylmalonate' with 26, 16, 34, 13.5, and 13.33% overall yields is described. Sequential allylation or homoallylation and electrophilic amination followed by cyclization gave the desired rings. The methyl esters of eight- and nine-membered rings were synthesized by RCM and the corresponding free acids were generated after hydrolysis in the presence of 1 M BBr3 solution in DCM.
- Duttagupta, Indranil,Goswami, Koushik,Sinha, Surajit
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experimental part
p. 8347 - 8357
(2012/09/21)
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- An alternative convenient synthesis of piperidazine-3-carboxylic acid derivatives
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The short-step synthesis of the unsubstituted, 5-hydroxy- and 5-chloropiperidazine-3-carboxylic acids using an aza Diels-Alder reaction between the 1,3-diene and azodicarboxylate was described. This synthetic methodology could be used for the preparation
- Kaname, Mamoru,Yamada, Masae,Yoshifuji, Shigeyuki,Sashida, Haruki
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experimental part
p. 49 - 54
(2009/07/25)
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