China
Africa
Explore chapters and articles related to this topic
Asparagus Sp.: Phytochemicals and Marketed Herbal Formulations
Published in Amit Baran Sharangi, K. V. Peter, Medicinal Plants, 2023
Vikas Bajpai, Pratibha Singh, Preeti Chandra, Brijesh Kumar
Complete separation of adjoining reference analytes is certainly not required in MS/MS detection. Normally, a suitable chromatographic column, mobile phase, and elution mode are critically important for good separation. To obtain better resolution, various compositions of solvents were tried to get a suitable mobile phase. Acetonitrile possesses stronger elution capability over methanol, which made it more suitable for the final selection in this method. Similarly, as compared to other tested columns, an Acquity UPLC BEH C18 (2.1 × 50 mm, 1.7 µm; Waters, Milford, MA) column was found more suitable for acidic mobile phase with smoother baseline. After testing various concentrations (0.1%, 0.2% and 0.3%) of formic acid, 0.1% formic acid concentration was finally selected. Formic acid was found more effective for ionization of compounds detected in positive and negative ESI mode. A gradient elution with 0.1% formic acid in water and acetonitrile at a flow rate of 0.4 mL/min with a column temperature of 30°C was resulted in separation of the 7 analytes in less than 5.5 min chromatographic run time. Figure 12.2 shows the typical MRM chromatograms of reference analytes under the above optimized conditions.
Qualitative and Quantitative Determination of Bioactive Phytochemicals in Selected Cassia Species Using HPLC-ESI-QTOF-MS and UPLC-ESI-QqQLIT-MS/MS
Published in Brijesh Kumar, Vikas Bajpai, Vikaskumar Gond, Subhashis Pal, Naibedya Chattopadhyay, Phytochemistry of Plants of Genus Cassia, 2021
Brijesh Kumar, Vikas Bajpai, Vikaskumar Gond, Subhashis Pal, Naibedya Chattopadhyay
Complete separation of proximate analytes is certainly not required for MS/MS detection. In this study, chrysophanic acid and emodin are having same product ion, while catechin and epicatechin are having same precursor and product ion. To obtain better resolution various compositions of solvents were tried to get a suitable mobile phase. Due to stronger elution ability of acetonitrile over methanol, it was selected for this method. Similarly, an Acquity UPLC BEH C18 (2.1 mm × 50 mm, 1.7µm; Waters, Milford, MA) column which was more suitable for acidic mobile phase with smoother baseline was selected as compared to other tested columns. Formic acid was found more effective for ionization of compounds detected in the negative ESI mode. After testing various concentrations (0.05%, 0.1%, 0.2% and 0.3%) of formic acid 0.1% formic acid concentration was finally selected. A gradient elution with 0.1% formic acid in water and acetonitrile at a flow rate of 0.4 mL/min with the column temperature of 30 °C resulted in separation of the 18 compounds in less than 8 min chromatographic run time.
Current Perspectives and Methods for the Characterization of Natural Medicines
Published in Rohit Dutt, Anil K. Sharma, Raj K. Keservani, Vandana Garg, Promising Drug Molecules of Natural Origin, 2020
Muthusamy Ramesh, Arunachalam Muthuraman, Nallapilai Paramakrishnan, Balasubramanyam I. Vishwanathan
UV spectroscopy is another type of spectroscopy. The basic principles of UV spectroscopy are absorption of light and make the changes of the incident after passing to samples. It lies between the wavelength of 200–400 nm and visible spectroscopy lie at the wavelength of 400–800 nm. The instrument used for obtaining the spectrum is UV-Vis spectrophotometer. Ethyl alcohol and hexane are the solvents widely used to prepare the sample for UV-Vis spectroscopy. UV-Vis spectrum assists to characterize the aromatic group of compounds and conjugated dienes in qualitative analysis. In quantitative analysis, UV-Vis spectroscopy also helps to determine the molar concentration of constituents present in a given sample. In addition, it is also used to detect impurities, isomers, and molecular weight (Perkampus, 2013). UV-Vis spectroscopy was employed to characterize diarylheptanoids in association with other spectral techniques (Alberti et al., 2018). Diarylheptanoids have a specific absorption range, i.e., 250–290 nm. Acetonitrile was used as a solvent to get the UV-Vis spectrum. Further, a wider absorption band observed for curcumin, i.e., 410–430 nm. Keto-enol tautomerism of curcumin was characterized from the intra- and intermolecular hydrogen bonding. UV-Vis spectroscopy method is also used for the quantification of the curcuminoid content of Curcuma Longa extract (Alberti et al., 2018). The UV-Visible spectroscopy-based characterized phytoconstituents and marine compounds are listed in Table 2.2.
Effects of ginkgo leaf tablet on the pharmacokinetics of rosiglitazone in rats and its potential mechanism
Published in Pharmaceutical Biology, 2022
Xueting Xing, Mengzhu Kong, Qiaoyu Hou, Jiaqi Li, Wen Qian, Xijing Chen, Hanhan Li, Changqing Yang
ROS (purity > 99%) was purchased from the Macklin Biochemical Co., Ltd. (Shanghai, China). GLT was provided by Yangtze River Pharmaceutical Group Co., Ltd. (Taizhou, Jiangsu, China). Diclofenac (purity > 98%) was purchased from the Tokyo Chemical Industry (Tokyo, Japan). Amodiaquine, quercetin, kaempferol, and isorhamnetin were supplied by Wuhan Yuan Cheng Technology Co., Ltd. (Wuhan, Hubei, China). The internal standard testosterone (purity > 98%) and carbamazepine (purity > 97%) were obtained from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China) and Beijing Bailingwei Technology Co., Ltd. (Beijing, China), respectively. Both RHCYP2C8 and RHCYP2C9 yeasts were purchased from Nanjing BRT-Biomed Co., Ltd. (Nanjing, Jiangsu, China). The NADPH regeneration system was purchased from iPhase Biosciences Co., Ltd. (Beijing, China). Lowry Protein Assay Kit was obtained from Beijing Solarbio Science & Technology Co., Ltd. (Beijing, China). Acetonitrile was obtained from Merck Drugs & Biotechnology (chromatographic grade; Woodbridge, NJ, USA). Ultrapure water was prepared by the Milli-Q water purification system (Millipore, Billerica, MA, USA). All other chemicals were of analytical grade or better.
Simple and high sample throughput LC/ESI-MS/MS method for bioequivalence study of prazosin, a drug with risk of orthostatic hypotension
Published in Drug Development and Industrial Pharmacy, 2022
Gabriel Onn Kit Loh, Emily Yii Ling Wong, Yvonne Tze Fung Tan, Hong Chin Wee, Ru Shing Ng, Haroon Khalid Syed, Kok Khiang Peh
Acetonitrile was used as a deproteinization agent in the study. Different ratios of acetonitrile to plasma at 1:1, 2:1, 3:1 and 4:1, were used. At ratios of 1:1 and 2:1, viscous and dirty samples were obtained, which were not suitable to be injected as they may damage the analytical column, clog the tubing and contaminate the system. When the acetonitrile and plasma ratios were increased to 3:1 and 4:1, clean supernatants were obtained after centrifugation. These two ratios were compared in terms of matrix effect and sensitivity at HQC level (22.5 ng/mL). Matrix factors of 0.92 and 0.93 w obtained for ratio of 3:1 and 4:1, respectively, which were close to each other. It was found that acetonitrile and plasma of ratio 3:1 gave a higher sensitivity than that obtained at a ratio of 4:1. LLOQ of 0.5 ng/mL at S/N ratio of above 5 was achieved. Therefore, acetonitrile and plasma at a ratio of 3:1 was selected for sample preparation. Based on the LLOQ of 0.5 ng/mL with 1 μL injection volume, the present analytical method is more sensitive than earlier published methods (Table 1) for the determination of prazosin in plasma samples.
Luliconazole vesicular based gel formulations for its enhanced topical delivery
Published in Journal of Liposome Research, 2020
Manjot Kaur, Kanwardeep Singh, Subheet Kumar Jain
Albino rats (180–200 g) were divided into four groups, with each group having six animals. The first group served as control which did not received any treatment and the second was treated with marketed formulation. Third and fourth group received optimized elastic lipogel and ethogel formulations, respectively. One unit dose i.e. 500 mg of the formulation was applied on 1 ± 0.2 cm2 area of rat’s dorsal surface. After 24 h, the blood samples were collected by retro orbital plexus using a capillary and centrifuged at 3000 rpm for 10 min at 16 °C to separate the plasma. To the clear plasma 1 ml of methanol was added for precipitation of plasma protein. Acetonitrile was added for deproteinization and plasma drug concentration was determined by HPLC assay (Masuda & Yamaguchi 2015). The amount of drug deposited into skin was measured by washing five times with 50% v/v ethanol using the same procedure described in the skin permeation and deposition study (Kaur et al. 2015).