Identification of 10-desoxyiridal as an intermediate in the biosynthesis of iridals

Ritzdorf, Ingrid; Bartels, Melanie; Kerp, Bianca; Kasel, Torsten; Klonowski, Sabine; Marner, Franz‐Josef

doi:10.1016/s0031-9422(98)00639-6

Cited by 10 publications

(6 citation statements)

References 7 publications

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“…2D NMR showed the hydroxylation to be at the Z allylic methyl (C23). 1 H NMR data reported 28 for 12b were consistent with our NMR results but insufficient for unambiguous structure identification due to the modest chemical-shift precision (±0.01 ppm) and lack of 13 C NMR data. Very minor unidentified side-chain oxygenated marnerol derivatives, possibly CYP71A16 metabolites, were observed in GC−MS and HSQC spectra (Figures S10,S11).…”

Section: ■ Introductionsupporting

confidence: 76%

“…We detected only traces (<0.1%) of 23-aldehyde species, such as the marnerol derivative, for which NMR data have been reported. 28 Thus, CYP71A16 hydroxylates marnerol/marneral in high accuracy specifically at C23. HSQC Gives a Comprehensive Profile of Substances in Crude Extracts.…”

Section: ■ Introductionmentioning

confidence: 98%

“…However, GC–MS gave only partial chemical structures of the novel products, a result underscoring the reliance of MS-based methods on databases and authentic standards. Even with standards for the few known oxygenated derivatives of these unusual triterpene skeletons, − GC–MS would be challenged to identify the regio- and stereochemistry of oxidation unambiguously.…”

Section: Introductionmentioning

confidence: 99%

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An Effective Strategy for Exploring Unknown Metabolic Pathways by Genome Mining

2013

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Plants allocate an estimated 15-25% of their proteome to specialized metabolic pathways that remain largely uncharacterized. Here, we describe a genome mining strategy for exploring such unknown pathways and demonstrate this approach for triterpenoids by functionally characterizing three cytochrome P450s from Arabidopsis thaliana . Building on proven methods for characterizing oxidosqualene cyclases, we heterologously expressed in yeast known cyclases with candidate P450s chosen from gene clustering and microarray coexpression patterns. The yeast cultures produced mg/L amounts of plant metabolites in vivo without the complex phytochemical background of plant extracts. Despite this simplification, the product multiplicity and novelty overwhelmed analytical efforts by MS methods. HSQC analysis overcame this problem. Side-by-side HSQC comparisons of crude P450 extracts against a control resolved even minor P450 products among ~100 other yeast metabolites spanning a dynamic range of >10,000:1. HSQC and GC-MS then jointly guided purification and structure determination by classical NMR methods. Including our present results for P450 oxidation of thalianol, arabidiol, and marneral, the metabolic fate for most of the major triterpene synthase products in Arabidopsis is now at least partially known.

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Section: ■ Introductionsupporting

confidence: 76%

Section: ■ Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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An Effective Strategy for Exploring Unknown Metabolic Pathways by Genome Mining

2013

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“…However, little attention has been paid to the secondary metabolites of in vitro tissue from cultivated species of this genus. It has been demonstrated that Iris cell cultures contain terpenoids [3,4]. Earlier we studied the qualitative pigment composition of I. ensata Thunb.…”

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confidence: 99%

Flavones from Callus Tissue of Iris ensata

Boltenkov

Rybin²,

Зарембо

2005

Chem Nat Compd

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Flavonoids uncharacteristic of intact plants were isolated from callus tissue of Iris ensata and were identified as 5-hydroxy-4′-methoxyflavone, 5-hydroxy-3′-methoxyflavone, and 5-hydroxy-2′-methoxyflavone using PMR and mass spectrometry. It was proposed that the lack of growth of callus tissue after changing cultivation conditions was related to the inhibiting effect of these flavones on cell proliferation.Key words: Iris ensata, Iridaceae, callus tissue, 5-hydroxy-4′-methoxyflavone, 5-hydroxy-3′-methoxyflavone, 5-hydroxy-2′-methoxyflavone.Flavonoids are the most studied group of secondary plant metabolites from the Iridaceae family [1]. Information on the contents of these compounds is used in chemotaxonomic studies of representatives of this family. The flavonoid composition is known for almost 60% of Iris species [2]. However, little attention has been paid to the secondary metabolites of in vitro tissue from cultivated species of this genus. It has been demonstrated that Iris cell cultures contain terpenoids [3,4]. Earlier we studied the qualitative pigment composition of I. ensata Thunb. heterotrophic callus culture [5]. A determination of the nature of pigments from callus tissue of this plant indicated an acculumation of flavonoids. The goal of the present work was to isolate and identify red pigments from callus tissue of I. ensata.Extract of I. ensata callus tissue contained three isomers of 5-hydroxy-monomethoxyflavone. The isolated compounds were identified as 5-hydroxy-2-(4-methoxyphenyl)-chromen-4-one (5-hydroxy-4′-methoxyflavone) (1), 5-hydroxy-2-(3-methoxyphenyl)-chromen-4-one (5-hydroxy-3′-methoxyflavone) (2), and 5-hydroxy-2-(2-methoxyphenyl)-chromen-4-one (5-hydroxy-2′-methoxyflavone) (3).Compound 3 and other lipophilic flavones unsubstituted at the 7-position were observed in secretory emissions of aerial organs of plants from the genus Primula [6,7]. It has been found that flavones found in leaves of P. veris are synthesized in in vitro cultivated tissues of this plant [8].The results suggest that the spectrum of synthesized secondary-exchange compounds changed in callus culture of I. ensata when compared with the intact plants. According to the literature, intact plants of this species contain flavonoid pigments of the anthocyan [9, 10], flavone, and xanthone [11] types. However, the dominant pigments in callus tissue were lipophilic flavones 1-3 uncharacteristic of this plant.Our results for the pigment composition of I. ensata callus tissue showed that flavone formation in tissue was suppressed in the subcultivation medium [5]. However, the change of cultivation conditions (reduced content of phytohormones, increased concentration of saccharose, change of pH) favored flavonoid accumulation and inhibited callus growth.It was noted that the synthesis of secondary compounds in isolated instances was related to a slowing or cessation of cell proliferation [12,13]. Apparently the flavonoids identified by us and compounds similar to them in biogenetic origin were responsible for the suppression ...

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“…In conclusion, we have demonstrated a novel and concise total synthesis of dysidiolide that is characterized by a high level of intramolecular stereoinduction. Furthermore, the synthetic potential of enone 3 for the synthesis of the iridals and that of enone 5 for the synthesis of the cacospongionolides is apparent.…”

mentioning

confidence: 99%