- Contalactone, a contaminant formed during chemical synthesis of the strigolactone reference GR24 is also a strigolactone mimic
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Strigolactone (SL) plant hormones control plant architecture and are key players in both symbiotic and parasitic interactions. GR24, a synthetic SL analog, is the worldwide reference compound used in all bioassays for investigating the role of SLs in plant development and in rhizospheric interactions. In 2012, the first characterization of the SL receptor reported the detection of an unknown compound after incubation of GR24 samples with the SL receptor. We reveal here the origin of this compound (P270), which comes from a by-product formed during GR24 chemical synthesis. We present the identification of this by-product, named contalactone. A proposed chemical pathway for its formation is provided as well as an evaluation of its bioactivity on pea, Arabidopsis, root parasitic plant seeds and AM fungi, characterizing it as a SL mimic. Quality of GR24 samples can be easily checked by carrying out microscale hydrolysis in a basic aqueous medium to easily detect P270 as indicator of the presence of the contalactone impurity. In all cases, before being used for bioassays, GR24 must be careful purified by preparative HPLC.
- de Saint Germain, Alexandre,Retailleau, Pascal,Norsikian, Stéphanie,Servajean, Vincent,Pelissier, Franck,Steinmetz, Vincent,Pillot, Jean-Paul,Rochange, Soizic,Pouvreau, Jean-Bernard,Boyer, Fran?ois-Didier
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- A new efficient synthesis of GR24 and dimethyl A-ring analogues, germinating agents for seeds of the parasitic weeds Striga and Orobanche spp.
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An efficient and high yielding preparation for the synthetic germination stimulant GR24 (5) and its A-ring dimethyl-substituted analogues 30-32 has been described. The first step involves a Stobbe condensation of benzaldehydes 9-11 with dimethyl succinate. Subsequent transposition of the ester and reduction of the double bond provides the building blocks 15-17 for an intramolecular Friedel-Crafts acylation. ABC-lactones 22-25 are prepared from γ-keto esters 18-21 by saponification, subsequent reduction with sodium borohydride followed by acid-catalyzed lactonization. Coupling of the lactones with the D-ring is accomplished by formylation and subsequent treatment with bromobutenolide 8 to give GR24 and its dimethyl analogues. Bioassays with Striga hermonthica seeds reveal that the dimethyl analogues are slightly less active than GR24 itself.
- Malik, Heetika,Rutjes, Floris P.J.T.,Zwanenburg, Binne
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experimental part
p. 7198 - 7203
(2010/10/02)
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