24259-59-4Relevant articles and documents
A new oleanane-type triterpenoidal saponin from Pulsatilla chinensis
Shu, Zhan,Chen, Zhong,Liu, Yan-Li,Zhu, Wei-Feng,Feng, Yu-Lin,Xu, Qiong-Ming,Li, Xiao-Ran,Yang, Shi-Lin
, p. 2196 - 2201 (2013)
A new oleanane-type triterpenoidal saponin, 3-O-β-d-glucopyranosyl- hederagenin 23-O-α-d-ribofuranoside (1), was isolated from the roots of Pulsatilla chinensis, and its structure was established on the basis of the spectral data. Compounds 2, 7 and 8 showed moderate cytotoxic activity by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazoliumbromide assay. 2013
NAD(P)H oxidase v from Lactobacillus plantarum (NoxV) displays enhanced operational stability even in absence of reducing agents
Park, Jonathan T.,Hirano, Jun-Ichiro,Thangavel, Vaijayanthi,Riebel, Bettina R.,Bommarius, Andreas S.
, p. 159 - 165 (2011)
Active pharmaceutical ingredients (APIs) such as l-sugars and keto acids are favorably accessed through selective oxidation of sugar alcohols and amino acids, respectively, catalyzed by NAD(P)-dependent dehydrogenases. Cofactor regeneration from NAD(P)H conveniently is achieved via water-forming NAD(P)H oxidases (nox2), which only need molecular oxygen as co-substrate. Turnover-dependent overoxidation of the conserved cysteine residue in the active site of water-forming NADH oxidases is the presumed cause of the limited nox2 stability. We present a novel NAD(P)H oxidase, NoxV from Lactobacillus plantarum, with specific activity of 167 U/mg and apparent kinetic constants at air saturation and 25 °C of kcat,app = 212 s-1 and KM,app = 50.2 μM in the broad pH optimum from 5.5 to 8.0. The enzyme features a higher stability than other NAD(P)H oxidases against overoxidation, as is evidenced by a higher total turnover number, in the presence (168,000) and, most importantly, also in the absence (128,000) of exogenously added reducing agents. While the native enzyme shows exclusively activity on NADH, we engineered the substrate binding pocket to generate variants, G178K,R and L179K,R,H that accommodate and oxidize both NADH and NADPH as substrates.
A heterogeneous Pd-Bi/C catalyst in the synthesis of l-lyxose and l-ribose from naturally occurring d-sugars
Fan, Ao,Jaenicke, Stephan,Chuah, Gaik-Khuan
supporting information; experimental part, p. 7720 - 7726 (2011/12/04)
A critical step in the synthesis of the rare sugars, l-lyxose and l-ribose, from the corresponding d-sugars is the oxidation to the lactone. Instead of conventional oxidizing agents like bromine or pyridinium dichromate, it was found that a heterogeneous catalyst, Pd-Bi/C, could be used for the direct oxidation with molecular oxygen. The composition of the catalyst was optimized and the best results were obtained with 5:1 atomic ratio of Pd:Bi. The overall yields of the five-step procedure to l-ribose and l-lyxose were 47% and 50%, respectively. The synthetic procedure is advantageous from the viewpoint of overall yield, reduced number of steps, and mild reaction conditions. Furthermore, the heterogeneous oxidation catalyst can be easily separated from the reaction mixture and reused with no loss of activity.
