4501-31-9Relevant articles and documents
Nielsen,Jensen
, p. 1049 (1976)
Photo-isomerization upshifts the pka of the photoactive yellow protein chromophore to contribute to photocycle propagation
Naseem, Sadia,Laurent, Adele D.,Carroll, Elizabeth C.,Vengris, Mikas,Kumauchi, Masato,Hoff, Wouter D.,Krylov, Anna I.,Larsen, Delmar S.
, p. 43 - 52 (2013)
The influence of chromophore structure on the protonation constant of the Photoactive Yellow Protein chromophore is explored with isolated para-coumaric acid (pCA) and thiomethyl-para-coumaric acid model chromophores in solution. pH titration coupled with visible absorption spectra of the trans and photogenerated cis conformer of isolated pCA demonstrates that the isomerization of the chromophore increases the pKa of the phenolate group by 0.6 units (to 10.1 ± 0.22). Formation of the pCA thioester reduces the pKa of the phenolic group by 0.3 units (from 9.5 ± 0.15 to 9.2 ± 0.16). Unfortunately, a macroscopic cis-TMpCA population was not achieved via photoexcitation. Both trends were explained with electronic structure calculations including a Natural Bond Orbital analysis that resolves that the pKa upshift for the cis configuration is attributed to increased Columbic repulsion between the coumaryl tail and the phenolate moieties. This structurally induced pKa upshift after isomerization is argued to aid in the protonation of the chromophore within the PYP protein environment and the subsequent propagation of the photocycle response and in vivo photo-activity.
Photo-induced phase transition from multilamellar vesicles to wormlike micelles
Wang, Dong,Dong, Renhao,Long, Pangfeng,Hao, Jingcheng
, p. 10713 - 10719 (2011)
A novel complex fluid system of tetradecyldimethylamine oxide (C 14DMAO) mixed with para-coumaric acid (PCA) in water was investigated. The phase behavior was determined in detail; one observed sequentially the L1-phase (micelles), two-phase L1/L α, Lα-phase (vesicles), and L α/precipitates with increasing PCA concentration at constant concentration of C14DMAO. The samples in the regions of micelles and vesicles were characterized by rheological measurements and cryo-TEM observations. Fascinatingly, we found a phase transition from vesicles to wormlike micelles performed via UV-light irradiation. The properties and structures after UV-light irradiation were determined by rheological measurements and cryo-TEM observations to demonstrate the phase transition. To the best of our knowledge, this transition is rarely reported, which could provide a better understanding of the phase transition via light irradiation and find potential applications in drug delivery, biochemistry, and the oilfield industry.
Understanding the role played by protic ionic liquids (PILs) and the substituent effect for enhancing the generation of: Z-cinnamic acid derivatives
Rodríguez, Roció B.,Rodríguez, Roció B.,Zapata, Ramiro L.,Salum, Mariá L.,Salum, Mariá L.,Erra-Balsells, Rosa,Erra-Balsells, Rosa
, p. 819 - 830 (2020/07/03)
Photoisomerization of a series of substituted E-cinnamic acids in MeCN in their acid forms and as their corresponding protic ionic liquids (PILs) with light of 300 nm is studied. The nature, strength, number, and position effects of substituents on the photochemical behavior of E-cinnamic derivatives are investigated. The photosensitization of the reaction in the presence of Michler's ketone is also studied at 366 nm and it demonstrates that the triplet-excited state is involved in the reaction. As the presence of n-butylamine needed to form the PILs significantly increases the photoproduct yields in all cases, the role of the PILs is also discussed. Thus, understanding of these fundamental aspects has allowed us to establish an excellent and practical synthetic protocol for successfully synthesizing Z-cinnamic acids. This journal is
Flavonoid glycosides from Sedum bulbiferum
Warashina, Tsutomu,Miyase, Toshio
, p. 1199 - 1204 (2017/12/26)
The MeOH extract from dried whole Sedum bulbiferum MAKINO (Crassulaceae) plants yielded 34 compounds, including six new flavonoid glycosides and 28 known compounds. The structures of new compounds were established using NMR, Mass spectroscopic analysis an
Phenolic glycosides from the twigs of Salix glandulosa
Kim, Chung Sub,Kwon, Oh Wook,Kim, Sun Yeou,Choi, Sang Un,Kim, Jae Yoon,Han, Ji Young,Choi, Soo Im,Choi, Jong Gil,Kim, Ki Hyun,Lee, Kang Ro
, p. 1955 - 1961 (2014/10/16)
As a part of an ongoing search for bioactive constituents from Korean medicinal plants, the phytochemical investigations of the twigs of Salix glandulosa afforded 12 new phenolic glycosides (1-12) and a known analogue (13). The structures of 1-13 were characterized by a combination of NMR methods (1H and 13C NMR, 1H-1H COSY, HMQC, and HMBC), chemical hydrolysis, and GC/MS. The absolute configuration of 13 [(1R,2S)-2-hydroxycyclohexyl-2′-O-trans-p-coumaroyl-β-d- glucopyranoside] was determined for the first time. Compounds 1-3, 6, and 7 exhibited inhibitory effects on nitric oxide production in lipopolysaccharide- activated murine microglial cells (IC50 values in the range 6.6-20.5 μM).
