scholarly journals Oenothein B, a dimeric hydrolyzable tannin of cyclic structure.

1989 ◽  
Vol 37 (8) ◽  
pp. 2269-2271 ◽  
Author(s):  
Tsutomu HATANO ◽  
Taeko YASUHARA ◽  
Muneto MATSUDA ◽  
Kazufumi YAZAKI ◽  
Takashi YOSHIDA ◽  
...  
Keyword(s):  
Cyclic Structure ◽  
Hydrolyzable Tannin ◽  
Oenothein B

scholarly journals Identification of a Hydrolyzable Tannin, Oenothein B, as an Aluminum-Detoxifying Ligand in a Highly Aluminum-Resistant Tree, Eucalyptus camaldulensis

2013 ◽  
Vol 164 (2) ◽  
pp. 683-693 ◽  
Author(s):  
Ko Tahara ◽  
Koh Hashida ◽  
Yuichiro Otsuka ◽  
Seiji Ohara ◽  
Katsumi Kojima ◽  
...  
Keyword(s):  
Eucalyptus Camaldulensis ◽  
Hydrolyzable Tannin ◽  
Resistant Tree ◽  
Oenothein B

scholarly journals Dehydroquinate dehydratase/shikimate dehydrogenases involved in gallate biosynthesis of the aluminum-tolerant tree species Eucalyptus camaldulensis

Planta ◽  
2020 ◽  
Vol 253 (1) ◽  
Author(s):  
Ko Tahara ◽  
Mitsuru Nishiguchi ◽  
Evelyn Funke ◽  
Shin-Ichi Miyazawa ◽  
Takafumi Miyama ◽  
...  
Keyword(s):  
Tree Species ◽  
Toxic Metal ◽  
Shikimate Pathway ◽  
Eucalyptus Camaldulensis ◽  
In Vitro Assays ◽  
Shikimate Dehydrogenase ◽  
Hydrolyzable Tannin ◽  
Oenothein B ◽  
Phenolic Constituent

Abstract Main conclusion Eucalyptus camaldulensis EcDQD/SDH2 and 3 combine gallate formation, dehydroquinate dehydratase, and shikimate dehydrogenase activities. They are candidates for providing the essential gallate for the biosynthesis of the aluminum-detoxifying metabolite oenothein B. Abstract The tree species Eucalyptus camaldulensis shows exceptionally high tolerance against aluminum, a widespread toxic metal in acidic soils. In the roots of E. camaldulensis, aluminum is detoxified via the complexation with oenothein B, a hydrolyzable tannin. In our approach to elucidate the biosynthesis of oenothein B, we here report on the identification of E. camaldulensis enzymes that catalyze the formation of gallate, which is the phenolic constituent of hydrolyzable tannins. By systematical screening of E. camaldulensis dehydroquinate dehydratase/shikimate dehydrogenases (EcDQD/SDHs), we found two enzymes, EcDQD/SDH2 and 3, catalyzing the NADP+-dependent oxidation of 3-dehydroshikimate to produce gallate. Based on extensive in vitro assays using recombinant EcDQD/SDH2 and 3 enzymes, we present for the first time a detailed characterization of the enzymatic gallate formation activity, including the cofactor preferences, pH optima, and kinetic constants. Sequence analyses and structure modeling suggest the gallate formation activity of EcDQD/SDHs is based on the reorientation of 3-dehydroshikimate in the catalytic center, which facilitates the proton abstraction from the C5 position. Additionally, EcDQD/SDH2 and 3 maintain DQD and SDH activities, resulting in a 3-dehydroshikimate supply for gallate formation. In E. camaldulensis, EcDQD/SDH2 and 3 are co-expressed with UGT84A25a/b and UGT84A26a/b involved in hydrolyzable tannin biosynthesis. We further identified EcDQD/SDH1 as a “classical” bifunctional plant shikimate pathway enzyme and EcDQD/SDH4a/b as functional quinate dehydrogenases of the NAD+/NADH-dependent clade. Our data indicate that in E. camaldulensis the enzymes EcDQD/SDH2 and 3 provide the essential gallate for the biosynthesis of the aluminum-detoxifying metabolite oenothein B.

scholarly journals Electronic Structure of n-Cycloparaphenylenes Directly Observed by Photoemission Spectroscopy

2021 ◽  
Author(s):  
Kaname Kanai ◽  
Takuya Inoue ◽  
Takaya Furuichi ◽  
Kaito Shinoda ◽  
Takashi Iwahashi ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Electronic Structures ◽  
Photoemission Spectroscopy ◽  
Cyclic Structure ◽  
Visible Absorption ◽  
X Ray ◽  
Inverse Photoemission

A series of n-cycloparaphenylenes ([n]CPP) were studied by ultraviolet photoemission, inverse photoemission, ultraviolet-visible absorption, and X-ray photoemission spectroscopy to detect their unique electronic structures. [n]CPP has a cyclic structure in...

scholarly journals Phytochemical variability during vegetation of Chamerion angustifolium (L.) Holub genotypes derived from in vitro cultures

2021 ◽  
Author(s):  
Mariola Dreger ◽  
Katarzyna Seidler-Łożykowska ◽  
Milena Szalata ◽  
Artur Adamczak ◽  
Karolina Wielgus
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Array Detector ◽  
Reproduction Rate ◽  
Full Spectrum ◽  
Breeding Programs ◽  
Chamerion Angustifolium ◽  
Oenothein B

AbstractThe purpose of the study was to evaluate Chamerion angustifolium (L.) Holub genotypes for preliminary selection and further breeding programs aimed at obtaining a suitable industrial form for the pharmaceutical applications. Clonally propagated plants representing 10 genotypes of Ch. angustifolium were regenerated under in vitro conditions, hardened and planted in the field. Studies included an evaluation of shoot proliferation, phytochemical assessment of in vitro and ex vitro plants as well as investigations of intraspecies variability regarding four phenological stages: vegetative, beginning of blooming, full blooming, and green fruit phases. Quantitative and qualitative analyses of bioactive compounds were performed using high-performance liquid chromatography coupled with diode array detector and tandem mass spectrometer (HPLC–DAD–MS/MS) and high-performance liquid chromatography (HPLC) methods. The efficiency of shoot multiplication varied between genotypes from 8.12 to 21.48 shoots per explant. A high reproduction rate (> 20 shoots per explant) was recorded for four lines (PL_45, PL_44, PL_58, DE_2). Plants grown in vitro synthesized oenothein B (11.2–22.3 mg g−1 DW) and caffeic acid derivatives. Plants harvested from field contained the full spectrum of polyphenols characteristic for this species, and oenothein B and quercetin 3-O-glucuronide were the most abundant. The maximal content of oenothein B was determined in the vegetative phase of fireweed, while some flavonoids were found in the highest amount in full blooming phase. The results of analysis of variance indicated significant differences among genotypes in oenothein B, 3-O-caffeoylquinic acid and flavonoids accumulation in four phenological phases. PL_44 plants were characterized by high content of oenothein B and quercetin 3-O-glucuronide as well as a relatively high level of other flavonoids. Based on our phytochemical and micropropagation studies, PL_44 genotype was the best candidate for early selection and further breeding programs.

Cyclic Structure of Adenovirus DNA

Science ◽  
1965 ◽  
Vol 148 (3666) ◽  
pp. 100-102 ◽  
Author(s):  
K. O. Smith
Keyword(s):  
Cyclic Structure

Kinetics and Mechanism of the Aminolysis of S-Aryl O-Ethyl Dithiocarbonates in Acetonitrile

2004 ◽  
Vol 69 (12) ◽  
pp. 2174-2182 ◽  
Author(s):  
Hyuck Keun Oh ◽  
Ji Young Oh ◽  
Dae Dong Sung ◽  
Ikchoon Lee
Keyword(s):  
Transition State ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Interaction Constant ◽  
Kinetics And Mechanism ◽  
Cyclic Structure ◽  
Concerted Mechanism ◽  
Tetrahedral Intermediate ◽  
Kinetic Isotope ◽  
Hydrogen Bonded

The aminolysis of S-aryl O-ethyl dithiocarbonates with benzylamines are studied in acetonitrile at -25.0 °C. The βX (βnuc) values are in the range 0.67-0.77 with a negative cross-interaction constant, ρXZ = -0.24, which are interpreted to indicate a concerted mechanism. The kinetic isotope effects involving deuterated benzylamine nucleophiles (XC6H4CH2ND2) are large, kH/kD = 1.41-1.97, suggesting that the N-H(D) bond is partially broken in the transition state by forming a hydrogen-bonded four-center cyclic structure. The concerted mechanism is enforced by the strong push provided by the EtO group which enhances the nucleofugalities of both benzylamine and arenethiolate from the putative zwitterionic tetrahedral intermediate.

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