BackgroundRoutine alcohol screening scores are increasingly available in electronic health records (EHRs). Changes in such scores could be useful for monitoring response to brief intervention or treatment of alcohol use disorder. However, it is unclear whether changes in clinically-documented AU...
SummaryThe present study focuses on the regulation of diatoxanthin (Dtx) epoxidation in the diadinoxanthin (Ddx) cycle containing algae Phaeodactylum tricornutum, Thalassiosira pseudonana, Cyclotella meneghiniana and Prymnesium parvum and its significance for the control of the photosystem II (P...
A cell-free system prepared from an axenic culture of the alga Amphidinium carterae converted [14C]zeaxanthin into neoxanthin and then into peridinin (62%) and diadinoxanthin (38%). Peridinin, therefore, is made by the excision of three carbon atoms from a C40 carotenoid and the acetylene group ...
Cd has pleiotropic effects on plant physiology and in particular on photosynthesis. It has not been established yet if Cd alters the functioning of the xanthophyll cycle. To answer this question, an exponentially growing culture of the marine diatom Phaeodactylum tricornutum was incubated with C...
The absolute configurations of heteroxanthin ((3S,5S,6S,3′R)- 7′,8′-didehydro-5,6-dihydro-β,β-carotene-3,5,3′,6′-tetrol) ex Euglena gracilis and of diadinoxanthin ((3S,5R,6S,3′R)-5,6-epoxy-7′,8′-didehydro-5,6-dihydro-β,β-carotene-3,3′-diol) from the same source have been established...
The principal crystallizable xanthophylls of Tribonema aequale are heteroxanthin, diatoxanthin, and diadinoxanthin. The latter pigment from Tribonema is identical with the diadinoxanthin from Euglena and the diatom Nitzschia. Description and identification of the pigments have been based upon co...
SummaryThe present study shows that thylakoid membranes of the diatom Cyclotella meneghiniana contain much higher amounts of negatively charged lipids than higher plant or green algal thylakoids. Based on these findings, we examined the influence of SQDG on the de-epoxidation reaction of the dia...
The lifetimes of the first excited singlet states (21Ag) of diadinoxanthin and diatoxanthin, carotenoids involved in the xanthophyll cycle in some genera of algae, have been measured by femtosecond time-resolved optical spectroscopy to be 22.8 ± 0.1 ps and 13.3 ± 0.1 ps, respectively. Using th...
SummaryBased on our recent findings that in the diatom Phaeodactylum tricornutum, chlororespiration in periods of prolonged darkness leads to the accumulation of diatoxanthin (DT), we have elaborated in detail the interdependence between the chlororespiratory proton gradient and the activation o...
The study investigated the influence of the xanthophyll cycle pigments diadinoxanthin (DD) and diatoxanthin (Dt) on the spectroscopic characteristics, structure and protein composition of isolated fucoxanthin chlorophyll protein (FCP) complexes of the pennate diatom Phaeodactylum tricornutum. 77...
Steady-state and femtosecond time-resolved transient absorption spectra of diadinoxanthin and diatoxanthin were measured in the visible and near-infrared (NIR) regions at 293 K. The difference in energy between the visible S0 → S2 transitions from the steady-state absorption measurements and th...
The isolation of taxol from Taxus x. media Hicksii includes four taxinines which co-elute and interfere with HPLC analyses of taxol. Their structures: 1,9α-dihydroxy-2α,10β-diacetoxy-5α-cinnamatetaxa-4(20),11-diene-13-one; 1,10β-dihydroxy-2α,9α-diacetoxy-5α-cinnamatetaxa-4(20),11-diene-1...
A simple chemical oxidation of 2-deacetoxytaxinine J derivative 3 using an excess of dimethyldioxirane (DMDO) results in a highly regio- and stereospecific hydroxylation of the C-1 position to afford the 1β-hydroxy α-4(20)-epoxide 6 and 1β-hydroxy β-4(20)-epoxide 7. A plausible mechanism of ...
A small library of 2-deacetoxytaxinine J (DAT-J) 1 derivatives was synthesised and tested in vitro for their reversal activity in human mammary carcinoma MDR cell line MCF7-R. One of the new taxoids showed to be active at 0.1 μM when tested in combination with paclitaxel.
The taxane diterpneoid 2-deacetoxytaxinine J (2-DAT-J) 1 has been isolated from the bark of Himalayan yew, Taxus baccata L. spp. wallichiana in a reasonably good yield (0.1%) and its anticancer activity against breast cancer cell lines (MCF-7 and MDA-MB-231) and normal human kidney epithelial ce...
Three novel taxinine analogues were prepared and tested for their activity as multidrug resistance (MDR) reversal agents in comparison with verapamil. In vitro testing demonstrated that compounds 8–10 possess MDR-reversal activity in the KB/V cell line. Half-hour after treatment with 5, 10, and...
Oxidation of 20-hydroxy-4,5-ene-7-oxotaxinine 4 derived from a natural taxoid taxinine B via four steps gave a corresponding aldehyde 5, which afforded a new dimeric taxoid 6 through regio- and stereospecific hetero Diels–Alder cycloaddition. Similar hetero Diels–Alder reaction of 4:5,6:7-dien...
Treatment of the 1,3-bis(trimethylsilyl)propene by Li2PdCl4 (1 equiv.) in methanol affords the bis[η3-(1-trimethylsilylallyl)chloropalladium] complex. Alkylation of this derivative with sodium malonates leads to (E)-vinylsilanes.
A series of simple and new C2-symmetric diphenylmethylidene malonate-type bis(oxazoline) ligands were synthesized and applied to the Friedel–Crafts reaction and allylic alkylation. The Cu(II) complex of ligand 4b bearing the benzyl group afforded good to excellent enantioselectivity for the F–...
The regioselective synthesis of alkenylcyclanones by the oxidative radical cyclisation of malonyl radicals onto both allenes and an allylsilane is reported, along with the diastereoselective formation of [3.3.0]-bicyclic γ-lactones from two of these alkenylcyclanones. Furthermore, the cyclisati...
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