Current Perspectives and Methods for the Characterization of Natural Medicines
Rohit Dutt, Anil K. Sharma, Raj K. Keservani, Vandana Garg in Promising Drug Molecules of Natural Origin, 2020
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.
Using iodine for analysis
Tatsuo Kaiho in Iodine Made Simple, 2017
If properly done, the Raman spectrum analysis can make a quantitative assessment from the spectral intensity. Raman spectrum analysis is extremely effective as a method to analyze iodine compounds. Graph (1) shows an example of the quantitative assessment of iodine in acetonitrile. From the Raman spectrum of acetonitrile solutions with different iodine concentrations, an iodine peak of around 200 cm−1 is detected, theoretically indicating the existence of iodine in the I2 state in the solution. Furthermore, as indicated in the diagram, from the iodine concentration in the acetonitrile and the peak area ratio (iodine/acetonitrile), iodine concentration can be seen to have a good linear relationship. From the above, within the concentration shown above, a quantitative assessment of iodine (I2) in acetonitrile can be made.
Asparagus Sp.: Phytochemicals and Marketed Herbal Formulations
Amit Baran Sharangi, K. V. Peter in Medicinal Plants, 2023
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.
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.
In vitro phase I metabolism of vinclozolin by human liver microsomes
Published in Xenobiotica, 2019
Marycarmen Cruz-Hurtado, Ma de Lourdes López-González, Victor Mondragón, Adolfo Sierra-Santoyo
The in vitro metabolism assays of Vin by HLM were carried out as previously described by Sierra-Santoyo et al. (2012), with some modifications. Briefly, Vin (50 μM) and HLM were incubated in a final volume of 1 mL of 100 mM KH2PO4 and 5 mM MgCl2 buffer at pH 7.4 in a shaking water bath at 37°C. The linear conditions for Vin metabolism by HLM to determine the enzyme kinetic parameters were experimentally established at 1 mg/mL of microsomal protein, 1 mM NADPH and an incubation time of 30 min (data not shown). Reactions were started by NADPH addition. After the incubation time, the reactions were finalized by the addition of 5 mL cold acetonitrile to 100 μL of incubation media, then vortexed and centrifuged (1650 x g) at 4°C for 10 min. The supernatants were dried using sodium sulfate and evaporated under a stream of N2 at 45 °C. Samples were stored at 4 °C and reconstituted in 100 μL of acetonitrile just before the chromatographic analysis. Blanks at zero time, of CO-bubbled HLM, and without NADPH were carried out using the same enzyme assay conditions and processed for the analysis of metabolites. All samples were prepared in triplicate and repeated three times.
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.
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