TiO2/SiO2 Core–Shell Composite-Based Sample Preparation Method for Selective Extraction of Phospholipids from Shrimp Waste Followed by Hydrophilic Interaction Chromatography Coupled with Quadrupole Time-of-Flight/Mass Spectrometry Analysis

2014 ◽  
Vol 62 (36) ◽  
pp. 8944-8951 ◽  
Author(s):  
Qing Shen ◽  
Hon-Yeung Cheung
Keyword(s):  
Preparation Method ◽  
Selective Extraction ◽  
Mass Spectrometry Analysis ◽  
Core Shell ◽  
Shrimp Waste ◽  
Hydrophilic Interaction ◽  
Sample Preparation Method ◽  
Spectrometry Analysis ◽  
Flight Mass Spectrometry ◽  
Shell Composite

A new ursane-type triterpene oxoglucopyranoside from Crossopteryx febrifuga

2019 ◽  
Vol 74 (11-12) ◽  
pp. 289-293
Author(s):  
Modjinan Kayangar ◽  
Raymond Ngansop Nono ◽  
Jonas Kühlborn ◽  
Roland Tchuenguem ◽  
Beaudelaire K. Ponou ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Antibacterial Properties ◽  
2D Nmr ◽  
Stem Bark ◽  
Mass Spectrometry Analysis ◽  
Moderate Activity ◽  
Dioic Acid ◽  
Spectrometry Analysis ◽  
Flight Mass Spectrometry ◽  
Mic Value

Abstract A new saponin, 3-O-β-d-3-oxo-glucopyranosyl-ursa-12,20(30)-diene-27,28-dioic acid (1), was isolated from the methanol extract of stem bark of Crossopteryx febrifuga together with the known 3β-d-glucopyranosyl-ursa-12,20(30)-diene-27,28-dioic acid (2), shanzhiside methyl ester (3), shanzhiside (4), β-sitosterol (5), β-sitosterol-3-O-β-d-glucopyranoside (6), ursa-12,20(30)-diene-27,28-dioic acid (7), hederagenin (8), and oleanolic acid (9). The structures were established by comprehensive interpretation of their spectral data 1D- (1H and 13C), 2D-NMR (1H-1H COSY, HMQC, HMBC), spectroscopic, and electrospray ionisation time-of-flight mass spectrometry analysis. The isolated compounds and extracts were screened for their antibacterial properties. Although the EtOAc and n-BuOH extracts exhibited considerable antibacterial activity against Pseudomonas aeruginosa with minimum inhibitory concentration (MIC) value of 32 μg/mL, compounds 2 and 8 showed moderate activity against Enterococcus faecalis with MIC values of 256 and 128 μg/mL, respectively. The new compound (1) exhibited a moderate antibacterial activity against Staphylococcus aureus with an MIC value of 512 μg/mL.

scholarly journals Involvement of Two Cytosolic Enzymes and a Novel Intermediate, 5′-Oxoaverantin, in the Pathway from 5′-Hydroxyaverantin to Averufin in Aflatoxin Biosynthesis

2003 ◽  
Vol 69 (11) ◽  
pp. 6418-6426 ◽  
Author(s):  
Emi Sakuno ◽  
Kimiko Yabe ◽  
Hiromitsu Nakajima
Keyword(s):  
Aspergillus Parasiticus ◽  
Laser Desorption ◽  
Mass Spectrometry Analysis ◽  
Laser Desorption Ionization ◽  
Aflatoxin Biosynthesis ◽  
Cytosol Fraction ◽  
Ionization Time ◽  
Spectrometry Analysis ◽  
Flight Mass Spectrometry ◽  
Physicochemical Methods

ABSTRACT During aflatoxin biosynthesis, 5′-hydroxyaverantin (HAVN) is converted to averufin (AVR). Although we had previously suggested that this occurs in one enzymatic step, we demonstrate here that this conversion is composed of two enzymatic steps by showing that the two enzyme activities in the cytosol fraction of Aspergillus parasiticus were clearly separated by Mono Q column chromatography. An enzyme, HAVN dehydrogenase, catalyzes the first reaction from HAVN to a novel intermediate, another new enzyme catalyzes the next reaction from the intermediate to AVR, and the intermediate is a novel substance, 5′-oxoaverantin (OAVN), which was determined by physicochemical methods. We also purified both of the enzymes, HAVN dehydrogenase and OAVN cyclase, from the cytosol fraction of A. parasiticus by using ammonium sulfate fractionation and successive chromatographic steps. The HAVN dehydrogenase is a homodimer composed of 28-kDa subunits, and it requires NAD, but not NADP, as a cofactor for its activity. Matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis of tryptic peptides of the purified HAVN dehydrogenase revealed that this enzyme coincides with a protein deduced from the adhA gene in the aflatoxin gene cluster of A. parasiticus. Also, the OAVN cyclase enzyme is a homodimer composed of 79-kDa subunits which does not require any cofactor for its activity. Further characterizations of both enzymes were performed.

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