Isolation and structure of lettucenin A, a novel guaianolide phytoalexin from Lactuca sativa var. capitata(Compositae)

Takasugi, Mitsuo; Okinaka, Shigetomo; Katsui, Nobukatsu; Masamune, Tadashi; Shirata, Akira; Ohuchi, Muneki

doi:10.1039/c39850000621

Cited by 36 publications

(34 citation statements)

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“…2 (+)-Germacrene A (1) is considered to be the biogenetic precursor of (+)-costunolide (3) in chicory,3 the simplest member of the large group of naturally occurring germacranolides, 4 and an important natural product itself owing to its role as a common precursor of all gemacranolide-derived lactones (ie., guaianolides and eudesmanolides). 5 In addition, germacrene A has often been postulated as an intermediate in the biosynthesis of phytoalexins6 including capsidiol,7 debneyol,7a,b,c costunolide,3a 8 vetispiradienes (lubimin and rishitin), 9 solavetivone10 and lettucenin A.8 11…”

Section: Introductionmentioning

confidence: 99%

Conformational analysis of (+)-germacrene A by variable-temperature NMR and NOE spectroscopy

Faraldos

Chappell

et al. 2007

Tetrahedron

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Abstract(+)-Germacrene A, an important intermediate in sesquiterpene biosynthesis, was isolated in pure form from a genetically engineered yeast and was characterized by chromatographic properties (TLC, GC), MS, optical rotation, UV, IR, 1 H NMR and 13 C NMR data. Variable-temperature 500 MHz 1 H NMR spectra in CDCl 3 showed that this flexible cyclodecadiene ring exists as three NMR-distinguishable conformational isomers in a ratio of about 5:3:2 at or below ordinary probe temperature (25° C). The conformer structures were assigned by 1 H NMR data comparisons, NOE experiments, and vicinal couplings as follows: 1a (52%, UU), 1b (29% UD), and 1c (19%, DU).

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Section: Introductionmentioning

confidence: 99%

Conformational analysis of (+)-germacrene A by variable-temperature NMR and NOE spectroscopy

Faraldos

Chappell

et al. 2007

Tetrahedron

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“…The sesquiterpene lactones, niveusin B (27), ethoxyniveusin B and, leptocarpin described from the different species of Helianthus, are among the most active fungicidal compounds (Spring et al, 1982). In addition, costunolide (28) and cichoralexin (29) have been also recognized as phytoalexins in lettuce (Takasugi et al, 1985) and chicory (Grayer and Harborne, 1994), respectively.…”

Section: Terpenoids Act As Phytoalexinsmentioning

confidence: 99%

Induced plant secondary metabolites for phytopatogenic fungi control: a review

Ribera

Zúñiga

2012

J. Soil Sci. Plant Nutr.

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Pathogenic fungi constitute one of the main infectious agents in plants, causing alterations during developmental stages including post-harvest. Phytopathogenic fungi are controlled by synthetic fungicides; however, the use of these is progressively restricted due to both, the harmful effects of pesticides on the environment and human health and the appearance of highly resistant fungal strains. Therefore, there is a great demand for novel natural fungicides. Higher plants are rich source of bioactive secondary metabolites of wide variety such as tannins, terpenoids, saponins, alkaloids, flavonoids, and other compounds, reported to have in vitro antifungal properties. Thus, secondary metabolites with antifungal activity represent an alternative for achieving a sustainable control of phytopathogenic fungi and to reduce the heavy reliance of synthetic pesticides used to control them. Plant antifungal metabolites may be preformed inhibitors that are present constitutively in healthy plants (phytoanticipins), or they may be synthesized de novo in response to pathogen attack or another stress conditions (phytoalexins). These molecules may be used directly or considered as a precursor for developing better fungicidal molecules. This review presents a selection of antifungal agents induced in plants during fungal attack that can be potentially used for phytopathogenic fungi control in crops.

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“…This result suggested that natural HaG8H variants in other Asteraceae plants might catalyze related reactions from GAA. Lettuce and closely-related chicory showed evidence of costunolide biosynthesis (23,26). Hence, we examined the HaG8H homologs from lettuce (Lactuca sativa).…”

Section: The [M-h]mentioning

confidence: 99%

“…Costunolide was first isolated from costus roots (Saussurea lappa) (24) and is now found in several plant species, including Magnolia spp. and lettuce (25,26). It is known that costunolide is not only the precursor of STLs but also displays several bioactivities.…”

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confidence: 99%

Lettuce Costunolide Synthase (CYP71BL2) and Its Homolog (CYP71BL1) from Sunflower Catalyze Distinct Regio- and Stereoselective Hydroxylations in Sesquiterpene Lactone Metabolism

Ikezawa

Göpfert

Nguyen

et al. 2011

Journal of Biological Chemistry

110

153

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Sesquiterpene lactones (STLs) are terpenoid natural products possessing the ␥-lactone, well known for their diverse biological and medicinal activities. The occurrence of STLs is sporadic in nature, but most STLs have been isolated from plants in the Asteraceae family. Despite the implication of the ␥-lactone group in many reported bioactivities of STLs, the biosynthetic origins of the ␥-lactone ring remains elusive. Germacrene A acid (GAA) has been suggested as a central precursor of diverse STLs. The regioselective (C6 or C8) and stereoselective (␣ or ␤) hydroxylation on a carbon of GAA adjacent to its carboxylic acid at C12 is responsible for the ␥-lactone formation. Here, we report two cytochrome P450 monooxygenases (P450s) capable of catalyzing 6␣-and 8␤-hydroxylation of GAA from lettuce and sunflower, respectively. To identify these P450s, sunflower trichomes were isolated to generate a trichome-specific transcript library, from which 10 P450 clones were retrieved. Expression of these clones in a yeast strain metabolically engineered to synthesize substrate GAA identified a P450 catalyzing 8␤-hydroxylation of GAA, but the STL was not formed by spontaneous lactonization. Subsequently, we identified the closest homolog of the GAA 8␤-hydroxylase from lettuce and discovered 6␣-hydroxylation of GAA by the recombinant enzyme. The resulting 6␣-hydroxy-GAA spontaneously undergoes a lactonization to yield the simplest form of STL, costunolide. Furthermore, we demonstrate the milligram per liter scale de novo synthesis of costunolide using the lettuce P450 in an engineered yeast strain, an important advance that will enable exploitation of STLs. Evolution and homology models of these two P450s are discussed.

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Isolation and structure of lettucenin A, a novel guaianolide phytoalexin from Lactuca sativa var. capitata(Compositae)

Cited by 36 publications

References 0 publications

Conformational analysis of (+)-germacrene A by variable-temperature NMR and NOE spectroscopy

Conformational analysis of (+)-germacrene A by variable-temperature NMR and NOE spectroscopy

Induced plant secondary metabolites for phytopatogenic fungi control: a review

Lettuce Costunolide Synthase (CYP71BL2) and Its Homolog (CYP71BL1) from Sunflower Catalyze Distinct Regio- and Stereoselective Hydroxylations in Sesquiterpene Lactone Metabolism

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