- Stable isotopic labelling of β-sitosteryl ferulate for use as analytical tool
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Rice is one of the major staple foods consumed worldwide and due to the presence of γ-oryzanol (γ-OZ) it is well-recognized as functional food. For this reason, the most appropriate varieties' identification in term of content of γ-OZ has become essential
- Baron, Giovanna,Fumagalli, Laura,Mazzotta, Sarah
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- Synthesis of deuterium-labeled cinnamic acids: Understanding the volatile benzenoid pathway in the flowers of the Japanese loquat Eriobotrya japonica
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Cinnamic acids are widely distributed in plants, including crops for human use, and exhibit a variety of activities that are beneficial to human health. They also occupy a pivotal position in the biosynthesis of phenylpropanoids such as lignins, anthocyanins, flavonoids, and coumarins. In this context, deuterium-labeled cinnamic acids have been used as tracers and internal standards in food and medicinal chemistry as well as plant biochemistry. Therefore, a concise synthesis of deuterium-labeled cinnamic acids would be highly desirable. In this study, we synthesized deuterium-labeled cinnamic acids using readily available deuterium sources. We also investigated a hydrogen–deuterium exchange reaction in an ethanol-d1/Et3N system. This method can introduce deuterium atoms at the ortho and para positions of the phenolic hydroxy groups as well as at the C-2 position of alkyl cinnamates and is applicable to various phenolic compounds. Using the synthesized labeled compounds, we demonstrated that the benzenoid volatiles, such as 4-methoxybenzaldehyde, in the scent of the flowers of the Japanese loquat Eriobotrya japonica are biosynthesized from phenylalanine via cinnamic and 4-coumaric acids. This study provides easy access to a variety of deuterium-labeled (poly)phenols, as well as to useful tools for studies of the metabolism of cinnamic acids in living systems.
- Koeduka, Takao,Nishitani, Shiori,Watanabe, Bunta
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p. 403 - 416
(2021/08/09)
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- Biosynthesis of Benzylic Derivatives in the Fermentation Broth of the Edible Mushroom, Ischnoderma resinosum
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Employing isotope incubation studies, the biosynthetic pathway leading to a series of benzylic derivatives was elucidated in the fermentation broth of the edible mushroom Ischnoderma resinosum (P. Karst). Twenty-six hydroxy- and methoxy- benzylic derivatives were screened by gas chromatography-mass spectrometry (GC-MS) of which 13 were detected in the culture media. Results from the isotope incubation studies showed the transformation of both benzyl alcohol and benzoic acid into benzaldehyde. Benzaldehyde was then converted into 4-methoxybenzaldehyde via hydroxylation and subsequent methylation of the 4-C position. The resulting 4-methoxybenzaldehyde was then hydroxylated in the 3-C position followed by methylation into 3,4-dimethoxybenzaldehyde. Based on these findings, a novel metabolic scheme for the biosynthesis of benzylic derivatives in I. resinosum was proposed. The knowledge of the biosynthetic pathway was utilized to produce 4-hydroxy-3-methoxybenzaldehyde (vanillin) from 4-hydroxy-3-methoxybenzoic acid (vanillic acid). This is the first report to elucidate the biosynthetic pathway of benzyl derivatives and production of vanillin from I. resinosum.
- Wickramasinghe, Purni C. K.,Munafo, John P.
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p. 2485 - 2492
(2020/02/27)
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- Facile synthesis of deuterated and [14C]labeled analogs of vanillin and curcumin for use as mechanistic and analytical tools
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Curcumin is a dietary diphenol with antioxidant, antinflammatory, and antitumor activity. We describe facile procedures for the synthesis of [ 14C2]curcumin (4 mCi/mmol), [d6]curcumin, [d3]curcumin, [13C5]curcumin, and [d 6]bicyclopentadione, the major oxidative metabolite of curcumin. We also describe synthesis of the labeled building blocks [14C]vanillin, [d3]vanillin, and [13C5]acetylacetone. The overall molar yields of the labeled products were 52 ([14C]) and 47% ([d3]) for vanillin and 25 ([14C2]) and 27% ([d6]) for curcumin. The compounds can be used as radiotracers in biotransformation studies and as isotopic standards for mass spectrometry-based quantification in pharmacokinetic analyses. Copyright 2013 John Wiley & Sons, Ltd. Curcumin is readily synthesized by fusing two vanillin moieties with acetylacetone. [14C] and [2H]isotopic labels are introduced by modification of the methoxy group of vanillin, which is accessible by selective methylation of the meta position of 3,4-dihydroxybenzaldehyde in basic conditions. A [13C5]analog is synthesized using [13C5]acetylacetone, which is prepared from [ 13C3]acetone and [13C4]acetic anhydride. Copyright
- Gordon, Odaine N.,Graham, Leigh A.,Schneider, Claus
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p. 696 - 699
(2014/01/06)
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- Biosynthesis of yatein in Anthriscus sylvestris.
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Little is known about the biosynthesis of yatein, in spite of its importance as a typical heartwood lignan and a key biosynthetic intermediate of the antitumor lignan podophyllotoxin. The present study, based on individual administration of [13C]phenylalanine and deuterium labelled lignans and simultaneous administration of two distinct lignans labelled with deuterium atoms to Anthriscus sylvestris, established the two independent branch pathways from matairesinol, one to afford yatein via thujaplicatin, 5-methylthujaplicatin, and 4,5-dimethylthujaplicatin and the other to bursehernin via pluviatolide. The latter pathway did not lead to yatein, eliminating the presence of a metabolic grid from matairesinol to yatein.
- Sakakibara, Norikazu,Suzuki, Shiro,Umezawa, Toshiaki,Shimada, Mikio
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p. 2474 - 2485
(2007/10/03)
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- Preparation of synthetic lignins with superior NMR characteristics via isotopically labeled monolignols
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Synthetic lignins are particularly valuable for studying aspects of lignification, plant cell wall cross-linking, and lignin structure. If they are not too highly polymeric, they are soluble in normal lignin solvents and amenable to solution-state NMR studies. However, in the application of inverse-detected correlation experiments, particularly the popular HMQC and HMBC experiments, the spectra have annoying T1-noise ridges. These artifacts make it difficult to locate correlation peaks that are near the methoxy signal in the proton dimension. One solution is to use gradient-enhanced NMR but that requires additional hardware that is not yet ubiquitous. An alternative is to produce monolignols in which the atoms of the methoxy group are NMR-invisible. We have accomplished this by preparing coniferyl and sinapyl alcohols using 13C-depleted deuterated methyl iodide (12C2H3I). The methods, which incorporate steps simpler than have been used previously for labeled monolignols, are sufficiently low cost and straight-forward that these monomers can be utilized for any synthetic lignins destined for NMR studies. The NMR spectra of lignins derived from these 'methoxy-less' monomers are markedly superior to their normal-monomer counterparts. Several popular NMR experiments are illustrated for synthetic lignins derived from normal vs. isotopically labeled coniferyl alcohol, along with some useful experiments that have not been seen in lignin-related publications to date.
- Ralph, John,Zhang, Yingsheng,Ede, Richard M.
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p. 2609 - 2613
(2007/10/03)
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