Publications by authors named "John Teye Azietaku"

Naoxintong capsule (NXT), a prescribed Chinese medicine, has been used clinically for more than 20 years and is widely received by patients. We determined five probe drugs, namely, omeprazole (CYP2C19), midazolam (CYP3A4), phenacetin (CYP1A2), tolbutamide (CYP2C9), and dextromethorphan (CYP2D6) to study the potential influences of NXT on the activities of CYP enzymes and assessed the pharmacokinetics effect of NXT on metoprolol tartrate in rat plasma. The study showed that AUC and AUC of midazolam (CYP3A4) in NXT coadministration group (283.

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An ultra-high-performance liquid chromatography-quadrupole/time of flight mass spectrometry is used to identify 33 compounds in rhizoma and radix, after which a single standard to determine multi-components method is established for the simultaneous determination of 19 compounds in rhizoma and radix using chlorogenic acid and notopterol as the internal standard. To screen the potential chemical markers among rhizoma and radix planted in its natural germination area and in others, the quantitative data of 19 compounds are analyzed via partial least-squares discriminant analysis (PLS-DA). Depending on the variable importance parameters (VIP) value of PLS-DA, six compounds are selected to be the potential chemical markers for the discrimination of rhizoma and radix planted in the different regions.

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Columbianadin and its metabolite columbianetin exhibited the anti-inflammatory, analgesic, calcium channel blocking and antitumor activities. To compare the differences between pharmacokinetics of columbianadin and its metabolite columbianetin after oral administration of pure columbianadin and (APR) extract, a simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established and validated to simultaneously determine columbianadin and columbianetin in rat plasma. Two analytes and an internal standard (warfarin) were well separated and determined after liquid-liquid extraction with ethyl acetate.

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Periplocin is a cardiac glycoside and has been used widely in the clinic for its cardiotonic, anti-inflammatory and anti-tumor effects. Although it is taken frequently by oral administration in the clinic, there have been no reports demonstrating that periplocin could be detected in vivo after an oral administration, so there is an urgen need to determine the characteristics of periplocin in vivo after oral administration. In this study, a sensitive and reliable liquid chromatography-tandem mass spectrometry method was developed and validated to identify and quantify periplocin and its two metabolites in rat tissue after a single dosage of perplocin at 50 mg/kg.

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is a well-known traditional Chinese medicinal herb used as a diuretic, for treating cough and for stopping uterine bleeding. A simple, sensitive, and reliable LC-MS/MS method was developed to determine six active compounds in rat plasma and this method was further applied to the pharmacokinetic study of these compounds after oral administration of extract. Acetonitrile was used to precipitate the protein in the plasma samples.

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Small molecules isolated from herbal medicines (HMs) were identified as the potential neuraminidase inhibitors which are effective in influenza prevention and treatment. Unfortunately, current available screen methods of small molecules isolated from HMs are inefficient and insensitive. Here a novel Ultra Performance Liquid Chromatography coupled with diode-array detectors and auto-fraction collector / time-of-flight mass spectrometry (UPLC-DAD-FC/Q-TOF-MS) screening method with high efficiency was developed and validated to separate, collect, enrich, identify and quantify potential neuraminidase inhibitors from Radix Scutellariae.

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Ethnopharmacological Relevance: Notopterygium incisum Ting ex H.T. Chang, known in Chinese as 'Qianghuo' is a traditional Chinese medicinal herb with the rhizome and roots associated with meridians of the kidney and urinary bladder.

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A specific, sensitive, and reliable high performance liquid chromatography with fluorescence detection (HPLC-FLD) was first optimized and then used in the simultaneous quantification of bergapten, imperatorin, notopterol, and isoimperatorin in rat plasma using osthole as the internal standard. Liquid-liquid extraction with ethyl acetate was employed in treating the rat plasma samples obtained. Separation was carried out with a Hedera™ ODS column (4.

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A sensitive, reliable and validated LC-MS/MS method was developed to determine the presence of eight flavonoids (catechin, typhaneoside, isorhamnetin-3-O-neohesperidoside, astragalin, isorhamnetin-3-O-β-d-glucoside, naringenin, kaempferol and isorhamnetin) in rat plasma. Puerarin was selected as the internal standard. Precipitation of the protein method with acetonitrile was used to extract these flavonoids from the rat plasma samples.

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A sensitive, specific, reproducible and optimized high performance liquid chromatography with fluorescence detection (HPLC-FLD) method for the determination of bergapten in rat plasma was established and applied to the pharmacokinetic and bioavailability study in rat after oral and intravenous administration of bergapten. The method was also successfully applied to the excretion study of bergapten after an oral administration of bergapten at a dose of 15 mg kg to rats. The sample preparation was achieved using liquid-liquid extraction.

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An in-capillary 2, 2-diphenyl-1-picrylhydrazyl (DPPH)-CE-the DAD (in-capillary DPPH-CE-DAD) combined with reversed-electrode polarity stacking mode has been developed to screen and quantify the active antioxidant components of Cuscuta chinensis Lam. The operation parameters were optimized with regard to the pH and concentration of buffer solution, SDS, β-CDs, organic modifier, as well as separation voltage and temperature. Six antioxidants including chlorogenic acid, p-coumaric acid, rutin, hyperin, isoquercitrin, and astragalin were screened and the total antioxidant activity of the complex matrix was successfully evaluated based on the decreased peak area of DPPH by the established DPPH-CE-DAD method.

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Traditional Chinese medicine (TCM) has been used for the treatment of many complex diseases. However, the bioactive components are always undefined. In this study, a bioactivity-based method was developed and validated to screen lipase inhibitors and evaluate the effects of processing on the lipase inhibitory activity of TCM by ultrahigh performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry and fraction collector (UHPLC/Q-TOF-MS-FC).

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A rapid, sensitive and selective high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous determination of four phenolic acids (neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid and ferulic acid) and seven alkaloids (berberine, epiberberine, coptisine, magnoflorine, berberubine, palmatine and jatrorrhizine) in rat plasma. After mixing with the internal standards tetrahydropalmatine (IS1) and rosmarinic acid (IS2), plasma samples were pretreated by protein precipitation using acetonitrile. The HPLC analysis was performed on an Agilent Eclipse plus C18 (4.

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A sensitive and reliable LC-MS/MS method was developed and validated for the simultaneous determination of periplocin and its two metabolites (periplocymarin and periplogenin) in rat plasma using psoralen as the internal standard (IS). After liquid-liquid extraction with ethyl acetate, chromatographic separation was performed on a C18 column with a 13 min gradient elution using 0.1% formic acid and acetonitrile as mobile phase at a flow rate of 0.

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