3036-18-8Relevant articles and documents
Enantioselective and Diastereodivergent Synthesis of Spiroindolenines via Chiral Phosphoric Acid-Catalyzed Cycloaddition
Gandon, Vincent,Masson, Géraldine,Mati?i?, Mateja,Neuville, Luc,Van Elslande, Elsa,Varlet, Thomas
supporting information, p. 11611 - 11619 (2021/08/16)
A diastereodivergent and enantioselective synthesis of chiral spirocyclohexyl-indolenines with four contiguous stereogenic centers is achieved by a chiral phosphoric acid-catalyzed cycloaddition of 2-susbtituted 3-indolylmethanols with 1,3-dienecarbamates. Modular access to two different diastereoisomers with high enantioselectivities was obtained by careful choice of reaction conditions. Their functional group manipulation provides an efficient access to enantioenriched spirocyclohexyl-indolines and -oxindoles. The origins of this stereocontrol have been identified using DFT calculations, which reveal an unexpected mechanism compared to our previous work dealing with enecarbamates.
Reconstitution of a Type II Polyketide Synthase that Catalyzes Polyene Formation
Du, Danyao,Katsuyama, Yohei,Shin-ya, Kazuo,Ohnishi, Yasuo
supporting information, p. 1954 - 1957 (2018/02/10)
While type II polyketide synthases (PKSs) are known for producing aromatic compounds, a phylogenetically new subfamily of type II PKSs have been recently proposed to synthesize polyene structures. Here we report in vitro analysis of such a type II PKS, IgaPKS for ishigamide biosynthesis. The ketoreductase (Iga13) and dehydratase (Iga16) were shown to catalyze the reduction of a β-keto group and dehydration of a β-hydroxy group, respectively, to form a trans double bond. Incubation of the acyl carrier protein (Iga10), the ketosynthase/chain length factor complex (Iga11–Iga12), Iga13 and Iga16 with malonyl and hexanoyl-CoAs and NADPH followed by KOH hydrolysis resulted in the formation of four unsaturated carboxylic acids (C8, C10, C12, and C14), indicating that IgaPKS catalyzes tetraene formation by repeating the cycle of condensation, keto-reduction and dehydration with strict stereo-specificity. We propose “highly reducing type II PKS subfamily” for the polyene-producing type II PKSs.
Teratogenic effects of diatom metabolites on sea urchin Paracentrotus lividus embryos
Romano, Giovanna,Miralto, Antonio,Ianora, Adrianna
experimental part, p. 950 - 967 (2010/12/18)
The diatom-derived polyunsaturated aldehydes (PUAs), 2-trans,4-trans- decadienal, 2-trans,4-trans-octadienal, 2-trans,4-trans,7-octatrienal, 2-trans,4-trans-heptadienal, as well as tridecanal were tested on early and later larval development in the sea urchin Paracentrotus lividus. We also tested the effect of some of the more abundant diatom polyunsaturated fatty acids (PUFAs) on development, in particular 5,8,11,14,17-eicosapentaenoic acid (EPA), one of the main precursors of diatom PUAs, as well as 4,7,10,13,16,19- docosahexaenoic acid (DHA), 6,9,12,15-octadecatetraenoic acid (stearidonic acid), 6,9,12-octadecatrienoic acid (γ-linolenic acid) and 9,12-octadecadienoic acid (linoleic acid). PUAs blocked sea urchin cell cleavage in a dose dependent manner and with increasing chain length from C7 to C10 PUAs, with arrest occurring at 27.27 μM with heptadienal, 16.13 μM with octadienal, 11.47 μM with octatrienal and 5.26 μM with decadienal. Of the PUFAs tested, only EPA and stearidonic acid blocked cleavage, but at much higher concentrations compared to PUAs (331 μM for EPA and 181 μM for stearidonic acid). Sub-lethal concentrations of decadienal (1.32-5.26 μM) delayed development of embryos and larvae which showed various degrees of malformations depending on the concentrations tested. Sub-lethal concentrations also increased the proportion of TUNEL-positive cells indicating imminent death in embryos and larvae. Using decadienal as a model PUA, we show that this aldehyde can be detected spectrophotometrically for up to 14 days in f/2 medium.
