Rapid and sensitive determination of enzymatic degradation products of isomeric chondroitin sulfates by high-performance liquid chromatography

Author(s):  
George Jia-Long Lee ◽  
James E. Evans ◽  
Howard Tieckelmann
2006 ◽  
Vol 89 (6) ◽  
pp. 1552-1556
Author(s):  
ArmaĞan Önal ◽  
Olcay SaĞiri ◽  
S Müge Çetin ◽  
Sidika Toker

Abstract Reboxetine is used as a selective noradrenaline reuptake inhibitor for the treatment of major depressive disorders. It is effective in the treatment of severe depression and safer to use than traditional tricyclic antidepressants. In this study, a novel, simple, and rapid stability-indicating high-performance liquid chromatography (HPLC) method for reboxetine methansulfonate was successfully developed and validated for the assay of tablets. The method was used to quantify reboxetine in tablets; it employed a C18 column (150 4.6 mm id) with an isocratic mobile phase consisting of methanolphosphate buffer (pH 7, 0.02 M; 55 + 45, v/v) at a flow rate of 1.0 μmL/min. Reboxetine was detected by an ultraviolet detector at 277 nm. The retention time of reboxetine was about 4.5 min. The developed HPLC method was validated with respect to linearity, precision, sensitivity, accuracy, and selectivity. The method was linear over the concentration range 150 g/mL (r 0.9999). The limits of detection and the quantitation of reboxetine were 0.1 and 0.3 μg/mL, respectively. The relative standard deviation values for intraday and interday precision were 0.781.01 and 1.081.37%, respectively. Selectivity was validated by subjecting a stock solution of reboxetine to neutral, acid, and alkali hydrolysis, as well as oxidation, dry heat treatment, and photodegradation. The peaks of the degradation products did not interfere with the peak of reboxetine. The results indicated that the proposed method could be used in a stability assay. The proposed method was successfully applied to the determination of reboxetine in tablets. Excipients present in the tablets did not interfere with the analysis.


2020 ◽  
Vol 75 (3-4) ◽  
pp. 75-86
Author(s):  
Taiji Nomura ◽  
Yasuo Kato

AbstractTuliposides (Pos) are major defensive secondary metabolites in tulip (genus Tulipa), having 4-hydroxy-2-methylenebutanoyl and/or (3S)-3,4-dihydroxy-2-methylenebutanoyl groups at the C-1 and/or C-6 positions of d-glucose. The acyl group at the C-6 position is converted to antimicrobial lactones, tulipalins, by tuliposide-converting enzymes (TCEs). In the course of a survey of tulip tissue extracts to identify novel Pos, we found a minute high-performance liquid chromatography peak that disappeared following the action of a TCE, and whose retention time differed from those of known Pos. Spectroscopic analyses of the purified compound, as well as its enzymatic degradation products, revealed its structure as 5″-O-(6-O-(4′-hydroxy-2′-methylenebutanoyl))-β-d-glucopyranosyl-(2″R)-2″-hydroxymethyl-4″-butyrolactone, which is a novel glucoside ester-type Pos. We gave this compound the trivial name ‘tuliposide G’ (PosG). PosG accumulated in bulbs, at markedly lower levels than 6-PosA (the major Pos in bulbs), but was not found in any other tissues. Quantification of PosG in bulbs of 52 types of tulip, including 30 cultivars (Tulipa gesneriana) and 22 wild Tulipa spp., resulted in the detection of PosG in 28 cultivars, while PosG was present only in three wild species belonging to the subgenus Tulipa, the same subgenus to which tulip cultivars belong, suggesting the potential usefulness of PosG as a chemotaxonomic marker in tulip.


2014 ◽  
Vol 29 (3) ◽  
pp. 341-345 ◽  
Author(s):  
José Carlos Aguilar-Carrasco ◽  
Jessica Hernández-Pineda ◽  
Juan Miguel Jiménez-Andrade ◽  
Francisco Javier Flores-Murrieta ◽  
Miriam del Carmen Carrasco-Portugal ◽  
...  

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