Natural sesquiterpenoids (1999)

Fraga, Braulio M.

doi:10.1039/a904424h

Cited by 37 publications

(17 citation statements)

References 285 publications

(311 reference statements)

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“…6,[10][11][12][13][14] These ubiquitous natural products have been identified from insects, microorganisms and plants of both terrestrial and marine origins. [15][16][17][18][19] Most terpenoids originate from plants and are known as precursors of many essential compounds like vitamins, hormones and medicines, apart from providing plants with their distinct fragrance and flavor properties. 20 Essentially all terpenoids are derived by the condensation of multiple units of IDP and its isomer DMADP ( Fig.…”

Section: Abith Vattekkattementioning

confidence: 99%

Enhanced structural diversity in terpenoid biosynthesis: enzymes, substrates and cofactors

et al. 2018

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The enormous diversity of terpenes found in nature is generated by enzymes known as terpene synthases, or cyclases. Some are also known for their ability to convert a single substrate into multiple products. This review comprises monoterpene and sesquiterpene synthases that are multiproduct in nature along with the regulation factors that can alter the product specificity of multiproduct terpene synthases without genetic mutations. Variations in specific assay conditions with focus on shifts in product specificity based on change in metal cofactors, assay pH and substrate geometry are described. Alterations in these simple cellular conditions provide the organism with enhanced chemodiversity without investing into new enzymatic architecture. This versatility to modulate product diversity grants organisms, especially immobile ones like plants with access to an enhanced defensive repertoire by simply altering cofactors, pH level and substrate geometry.

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Section: Abith Vattekkattementioning

confidence: 99%

Enhanced structural diversity in terpenoid biosynthesis: enzymes, substrates and cofactors

et al. 2018

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“…3 Eudesmane sesquiterpenes are common in nature, 4,5 and in the past decade, several biotransformations of these kinds of compounds have been carried out to acquire products difficult to achieve by chemical means. [6][7][8][9][10][11][12][13][14][15][16] Cryptomeridiol is a natural sesquiterpene diol 17 that exerts a potent antispasmodic effect on the isolated rabbit ileum, 18 and 4-epi-cryptomeridiol is also a natural compound.…”

mentioning

confidence: 99%

Chemical-Microbiological Synthesis of Cryptomeridiol Derivatives by Gliocladium roseum: Semisynthesis of 11-Hydroxyeudesmanolides

et al. 2002

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Biotransformations of 4R-and 4 -hydroxyeudesmane derivatives by the filamentous fungus Gliocladium roseum were achieved. Hydroxylation at C-11 was the main action of this microorganism, producing new cryptomeridiol (12 and 14) and 4-epi-cryptomeridiol derivatives (6 and 7), respectively, in good yields. The biotransformation activity of G. roseum toward 4 -hydroxyeudesmane was focused on the isopropyl moiety, but more scattered on the 4R-hydroxylated derivative, acting in both the "A" and "B" rings and the isopropyl group of the molecule. Semisyntheses of 11-hydroxyeudesmanolides from the isolated 11,12-dihydroxylated metabolites were also accomplished and used in assigning the stereochemistry of hydroxylation.Gliocladium roseum CECT 2733, the anamorphic form of Nectria ochroleuca IMI 40022, is a filamentous fungus that has been used previously to hydroxylate the sesquiterpene patchoulol, 1 to biotransform a derivative of the diterpene varodiol, to produce an ent-Ambrox derivative, 2 and to carry out the bioconversion of a 4 -hydroxyeudesmane derivative. 3 Eudesmane sesquiterpenes are common in nature, 4,5 and in the past decade, several biotransformations of these kinds of compounds have been carried out to acquire products difficult to achieve by chemical means. [6][7][8][9][10][11][12][13][14][15][16] Cryptomeridiol is a natural sesquiterpene diol 17 that exerts a potent antispasmodic effect on the isolated rabbit ileum, 18 and 4-epi-cryptomeridiol is also a natural compound. 19 Sesquiterpene lactones show a wide variety of remarkable biological activities, but many of them present strong cytotoxic properties, apparently due to the R, -unsaturated lactone group. 20-23 Some authors suspect that 11-hydroxysesquiterpenolides are the precursors of those compounds, and thus the unsaturated system could be released in small quantities, thereby attenuating the cytotoxic effect. 24 In previous papers 25,26 we reported the incubations of several 4 -hydroxyeudesmane compounds by the filamentous fungi Curvularia lunata ATCC 12017 and Rhizopus nigricans ATCC 10404. The action of these microorganisms was directed mainly toward the isopropyl moiety; specifically, C. lunata was active toward C-12 and R. nigricans to C-11. Some of the best results were achieved on the 6 -acetoxy-1-keto derivative. Also we have described the incubations of some 4R-hydroxylated derivatives, 25,26 but with poor transformation results. Therefore, in this study we have chosen 6 -acetoxy-1-keto derivatives that are 4 -or 4R-hydroxylated to carry out several biotransformations with the microorganism G. roseum. Results and Discussion6 -Acetoxy-4 -hydroxyeudesman-1-one (1) and its 4R-epimer compound (2) were obtained respectively, by Jones' oxidation at C-1, from the natural compounds 3 27 and 4. 28 Incubation of substrate 1 with G. roseum for 9 days yielded the metabolites 5 (3%), 6 (6%), 7 (58%), and 8 (4%).Metabolite 5 had a molecular formula of C 17 H 26 O 5 , which indicated the presence of an additional oxygen atom and the absence of two hydrog...

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“…The mechanism of the adduct formed between oxoammonium salt 1 and the alcohol in question can be proposed by a cyclic or acyclic concerted elimination ( [17b,18]. This sesquiterpene lactone was isolated from Melanoselinum decipiens on the archipelago of Madeira, Portugal [32] and belongs to the class of eudesmanolides [33]. 5), performed by Massanet and co-workers (Scheme 1) [31].…”

Section: A Brief History Of the Tempo As An Oxidant Reagentmentioning

confidence: 99%

TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl) an Important Reagent in Alcohol Oxidation and its Application in Synthesis of Natural Products

Souza

2006

MROC

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The oxidation of alcohols is a fundamental transformation in organic synthesis and a large number of reagents have been developed for this purpose. In spite of the different methodologies, the modern organic synthesis still requires more efficient oxidant reagents. In this context, TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl) has emerged as the chosen reagent. The aim of this review is to highlight the TEMPO oxidation as a very important procedure in the synthesis of natural products accomplished between 2000 and 2004.

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Natural sesquiterpenoids (1999)

Cited by 37 publications

References 285 publications

Enhanced structural diversity in terpenoid biosynthesis: enzymes, substrates and cofactors

Enhanced structural diversity in terpenoid biosynthesis: enzymes, substrates and cofactors

Chemical-Microbiological Synthesis of Cryptomeridiol Derivatives by Gliocladium roseum: Semisynthesis of 11-Hydroxyeudesmanolides

TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl) an Important Reagent in Alcohol Oxidation and its Application in Synthesis of Natural Products

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