Search results for "Molecular Structure"
showing 10 items of 1246 documents
Chionaeosides A–D, Triterpene Saponins from Paronychia chionaea
2007
Four new triterpenoid saponins, chionaeosides A-D (1-4) were isolated from the roots of Paronychia chionaea. On the basis of their spectroscopic data, the structures of the new saponins were established as 3-O-alpha-L-arabinopyranosylgypsogenic acid 28-O-beta-D-glucopyranosyl-(1--3)-beta-D-glucopyranosyl-(1--6)-beta-D-glucopyranoside (1), 3-O-alpha-L-arabinopyranosylgypsogenic acid 28-O-beta-D-glucopyranosyl-(1--6)-beta-D-glucopyranoside (2), 3-O-alpha-L-arabinopyranosylgypsogenic acid 28-O-beta-D-glucopyranoside (3), and 3-O-alpha-L-arabinopyranosylgypsogenic acid (4).
Triterpene Glycosides from the Roots of Astragalus flavescens
2007
Six new triterpene saponins, 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-xylopyranosyl-(1-->2)-beta-D-glucuronopyranosyl-21-epi-kudzusapogenol A (1), 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->2)-beta-D-glucuronopyranosyl-21-epi-kudzusapogenol A (2), 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-xylopyranosyl-(1-->2)-beta-D-glucuronopyranosyl-22-O-beta-D-glucopyranosyl-21-epi-kudzusapogenol A (3), 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->2)-beta-D-glucuronopyranosyl-22-O-beta-D-glucopyranosyl-21-epi-kudzusapogenol A (4), 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-xylopyranosyl-(1-->2)-beta-D-glucuronopyranosyl-22-O-alpha-L-arabinopyranosyl-21-epi-kudzus…
Indirect oxidation of the antitumor agent procarbazine by tyrosinase—Possible application in designing anti-melanoma prodrugs
2008
The interaction of tyrosinase with the anticancer drug procarbazine has been investigated. In the presence of the enzyme alone no oxidation of this dialkylhydrazine above the background level was observed. However, when phenolic substrates (4-tert-butylcatechol or N-acetyl-l-tyrosine) were included in the reaction mixture, procarbazine was rapidly degraded. Oxygen consumption measurements showed that in a mixture both the phenolic substrate and the drug were oxidized. The major product of procarbazine degradation was isolated and identified as azoprocarbazine, the first active metabolite of this drug detected in previous in vivo and in vitro studies. This indirect oxidation of the hydrazine…
Conserved alternative splicing in the 5'-untranslated region of the muscle-specific enolase gene. Primary structure of mRNAs, expression and influenc…
1995
We report here the isolation and characterization of cDNAs covering the 5'-end region of mouse and rat mRNAs that encode the beta or muscle-specific isoform of the glycolytic enzyme enolase. As previously determined for humans, two classes of beta-enolase transcripts with distinct sequences in their 5'-untranslated regions are present in both mouse and rat muscles. A mechanism of alternative splicing, conserved from mouse to man, generates the two forms of mRNA. Secondary-structure predictions indicated that, in all cases, a more stable secondary structure could exist in the 5' end of the message with the longer leader. In vitro transcripts containing defined human or mouse 5'-untranslated …
Identifying and validating the presence of guanine-quadruplexes (G4) within the blood fluke parasite schistosoma mansoni
2021
Schistosomiasis is a neglected tropical disease that currently affects over 250 million individuals worldwide. In the absence of an immunoprophylactic vaccine and the recognition that mono-chemotherapeutic control of schistosomiasis by praziquantel has limitations, new strategies for managing disease burden are urgently needed. A better understanding of schistosome biology could identify previously undocumented areas suitable for the development of novel interventions. Here, for the first time, we detail the presence of G-quadruplexes (G4) and putative quadruplex forming sequences (PQS) within the Schistosoma mansoni genome. We find that G4 are present in both intragenic and intergenic regi…
High yielding one-pot enzyme-catalyzed synthesis of UDP-glucose in gram scales
2001
Abstract Uridine diphosphoglucose is an important cofactor of glucosylating enzymes. A simple and high yielding one-pot enzymatic synthesis of UDPG on a gram scale from glucose via hexokinase, phosphoglucomutase and UDPG pyrophosphorylase (UGPase) is described. Repetitive addition of substrate was used to avoid inhibition of UGPase. The approach allows recovery of active enzymes and their re-use. The synthesis of UDP-[4-13C]-glucose on a 0.5 g scale resulted in a final yield of 70% and a purity of >95% after chromatographic purification.
Metal-Free and User-Friendly Regioselective Hydroxyfluorination of Olefins
2018
A simple, user-friendly, metal-free protocol for the regioselective anti-Markovnikov hydrofluorination of olefins using readily available and inexpensive reagents has been developed. This new approach displays a broader scope than previously reported methodologies and has been applied to the late-stage fluorination of a complex molecule, giving rise to a fluorosteroid derivative. The stereochemistry of the process has also been studied in some detail.
Exploring the anticancer potential of pyrazolo[1,2-a]benzo[1,2,3,4] tetrazin-3-one derivatives: The effect on apoptosis induction, cell cycle and pro…
2013
In order to investigate their anticancer potential, four new pyrazolo[1,2-a]benzo[1,2,3,4]-tetrazinone derivatives, designed through the chemometric protocol VLAK, and three of the most active compounds of the previous series have been evaluated on some cellular events including proliferation, apoptosis induction, and cell cycle. The NCI one dose (10 mu M) screening revealed that the 8,9-di-methyl derivative showed activity against Leukemia (CCRF-CEM) and Colon cancer cell line (COLO 205), reaching 81% and 45% of growth inhibition (GI), respectively. Replacement of the two methyl groups with two chlorine atoms maintained the activity toward Leukemia cell (CCRF-CEM, GI 77%) and selectively e…
Synthetic vaccines of tumor-associated glycopeptide antigens by immune-compatible thioether linkage to bovine serum albumin.
2007
Solvent-Enhanced Diastereo- and Regioselectivity in the PdII-Catalyzed Synthesis of Six- and Eight-Membered Heterocycles viacis-Aminopalladation
2009
The Pd(II)-catalyzed intramolecular oxidative cyclization of tosyl-protected cis- and trans-N-allyl-2-aminocyclohexanecarboxamides was examined, and efficient syntheses of cyclohexane-fused pyrimidin-4-ones and 1,5-diazocin-6-ones were developed. In the course of the research, a marked solvent effect was observed on both the regio- and diastereoselectivity. Additionally, a novel Pd(II)-mediated domino oxidation, oxidative amination reaction was discovered. Our experimental and theoretical findings suggest that the reactions proceed via a cis-aminopalladation mechanism.