- 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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- Alternative Pathway to the Formation of trans-Cinnamic Acid Derived from l -Phenylalanine in Tea (Camellia sinensis) Plants and Other Plants
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trans-Cinnamic acid (CA) is a precursor of many phenylpropanoid compounds, including catechins and aroma compounds, in tea (Camellia sinensis) leaves and is derived from l-phenylalanine (l-Phe) deamination. We have discovered an alternative CA formation pathway from l-Phe via phenylpyruvic acid (PPA) and phenyllactic acid (PAA) in tea leaves through stable isotope-labeled precursor tracing and enzyme reaction evidence. Both PPA reductase genes (CsPPARs) involved in the PPA-to-PAA pathway were isolated from tea leaves and functionally characterized in vitro and in vivo. CsPPAR1 and CsPPAR2 transformed PPA into PAA and were both localized in the leaf cell cytoplasm. Rosa hybrida flowers (economic crop flower), Lycopersicon esculentum Mill. fruits (economic crop fruit), and Arabidopsis thaliana leaves (leaf model plant) also contained this alternative CA formation pathway, suggesting that it occurred in most plants, regardless of different tissues and species. These results improve our understanding of CA biosynthesis in tea plants and other plants.
- Dong, Fang,Kang, Ming,Liao, Yinyin,Tan, Haibo,Wang, Xiaoqin,Xu, Ping,Yang, Ziyin,Zeng, Lanting
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p. 3415 - 3424
(2020/04/08)
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- Stereochemistry and mechanism of a microbial phenylalanine aminomutase
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The stereochemistry of a phenylalanine aminomutase (PAM) on the andrimid biosynthetic pathway in Pantoea agglomerans (Pa) is reported. PaPAM is a member of the 4-methylidene-1H-imidazol-5(4H)-one (MIO)-dependent family of catalysts and isomerizes (2S)-α-phenylalanine to (3S)-β-phenylalanine, which is the enantiomer of the product made by the mechanistically similar aminomutase TcPAM from Taxus plants. The NH2 and pro-(3S) hydrogen groups at Cα and Cβ, respectively, of the substrate are removed and interchanged completely intramolecularly with inversion of configuration at the migration centers to form β-phenylalanine. This is a contrast to the retention of configuration mechanism followed by TcPAM.
- Ratnayake, Nishanka Dilini,Wanninayake, Udayanga,Geiger, James H.,Walker, Kevin D.
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supporting information; experimental part
p. 8531 - 8533
(2011/07/29)
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- Isotope labeled 'HEA Moiety' in the synthesis of labeled HIV-protease inhibitors - Part 1
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[(S)-1′-((N-tert-Butyloxycarbonyl)amino)-2S-[2H 5]phenyl-ethyl]oxirane 11, made from [2H 5]-bromobenzene, was transformed into the HIV-protease inhibitors [2H5J-DPH 153893 and [2H5]-DPH 140
- Ekhato, I. Victor,Liao, Yuan,Plesescu, Mihaela
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p. 821 - 835
(2007/10/03)
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- Mechanism leading to the observed product of intramolecular aryl Diels-Alder reaction
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A mechanistic investigation into the recently reported intramolecular aryl Diels-Alder reaction was carried out using deuterium labeling. These studies led to the conclusion that the initial Diels-Alder adduct is isomerized to a highly conjugated tetra-ene intermediate which undergoes a stereospecific suprafacial 1,5-dienyl hydrogen shift to give the observed product.
- Chackalamannil, Samuel,Doller, Darío,Eagen, Keith
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p. 5101 - 5103
(2007/10/03)
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- A plant-like biosynthesis of benzoyl-CoA in the marine bacterium 'Streptomyces maritimus'
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The first plant-like biosynthesis of benzoic acid in a prokaryote, the marine actinomycete 'Streptomyces maritimus', has been characterized. Feeding experiments with 2H- and 13C-labeled intermediates revealed that phenylalanine is metabolized to benzoyl-coenzyme A (CoA) by means of a phenylalanine ammonia lyase and subsequent β-oxidation of cinnamoyl-CoA. Benzoyl-CoA serves as the rare starter unit of a type II polyketide synthase producing the structurally novel bacteriostatic polyketides enterocin and the wailupemycins. The results from the feeding study are consistent with the proposed biosynthetic model deduced from the cloned enterocin biosynthesis gene cluster. (C) 2000 Elsevier Science Ltd.
- Hertweck, Christian,Moore, Bradley S
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p. 9115 - 9120
(2007/10/03)
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