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Seaweed Fucoidans and Their Marine Invertebrate Animal Counterparts
Published in Se-Kwon Kim, Marine Biochemistry, 2023
Mauro Sérgio Gonçalves Pavão, Fernanda de Souza Cardoso
Similarly, the purification methods are diverse and depend on the degree of purity of the desired fucoidan extract. Deproteination might be carried out by protein precipitation (Zou et al. 2020; C. H. Wang and Chen 2016). The application of anion exchange or dye affinity chromatography using a salt gradient is usually followed by a chromatographic gel permeation (Zou et al. 2020) or a dialysis step against water using small molecular weight cut-off (MWCO) membranes (Zou et al. 2020; Sichert et al. 2021; Jayawardena et al. 2019) to remove salts, but this combination usually increases the production costs (Zayed and Ulber 2020). Dialysis might also be applied with different MWCO membranes to separate fucoidans according to their molecular weight, making it possible to separate the low-molecular-weight fucoidans (LMWF) from the high-molecular-weight fucoidans (HMWF) (Zayed and Ulber 2020). Another option is the application of ultrafiltration, which also allows the separation of different fucoidan sizes and the removal of low-molecular-weight impurities, such as laminarin (Zhang et al. 2021).
Towards the Importance of Fenugreek Proteins
Published in Dilip Ghosh, Prasad Thakurdesai, Fenugreek, 2022
Salt extraction (micellization) is another frequent approach in protein extraction from legumes. The procedure lies in the salting-in and salting-out phenomena of food proteins. Accordingly, proteins solubility increases at appropriate ionic strength (salting in). This is usually followed by protein precipitation through centrifugation or filtration. Similar to other extraction methods, the procedure could be accomplished by employment of a drying method. El-Nasri and El-Tinay (2007) used the micellization method for extraction of Sudanese fenugreek seed with 28.4% protein using 1 M NaCl and flour to solvent ratio of 1:10 for 30 min. The extraction was accomplished by further precipitation of protein at pI (4.5) and drying in open air. Final protein concentrate contained 73.9% protein. Abdel-Aal et al. (1986) applied a similar procedure, using 0.5 M NaCl and stirring for 1 h, for protein extraction from Egyptian fenugreek seeds, and produced protein isolate with 94.7% protein. The influential role of salt on protein extraction from legumes like fenugreek is possibly attributed to their high amount of globulins, salt soluble proteins. Globulins are the second major fraction of fenugreek and the most dominant one in others including soybean, peas, etc. (Feyzi et al., 2015).
Separation Of The Bound And Unbound Forms Of The Radioactivity
Published in Erwin Regoeczi, Iodine-Labeled Plasma Proteins, 2019
As may be concluded from the previous sections, none of the techniques available for the separation of protein-bound and unbound radioactivities is guaranteed against pitfalls, and therefore the long-standing practice has been to ascertain the covalent nature of the protein-radioactivity association by direct testing. A simple way of doing this is protein precipitation. It is based on the premise that only covalently bound radioactivity will ac- company the protein in the precipitate. Many agents, including alkaline ZnS0441 and organic solvents,42 can be used for protein precipitation, but the most widely used techniques involve the use of an acid, trichloroacetic acid, or phosphotungstic acid in particular. The present discussion will be limited to these two agents.
Development and validation of a highly sensitive and selective LC-MS/MS method for the determination of 15-hydroxylubiprostone in human plasma: application to a pharmacokinetic study in healthy Chinese volunteers
Published in Xenobiotica, 2022
Xianjing Li, Haitao Yu, Wenjing Guo, Minlu Cheng, Qinxin Song, Li Ding
Due to the high requirement of detection sensitivity, an aliquot of 300 μL plasma was used and the plasma sample should be concentrated in sample preparation procedures. Therefore, typical sample preparation methods including protein precipitation and LLE were first considered. First of all, the protein precipitation was investigated, with methanol used as the precipitant. The supernatant after centrifugation was evaporated with a steam of nitrogen and reconstituted with the initial mobile phase. However, at the retention time of 15-hydroxylubiprostone, obvious interference was observed. Hence, the LLE method was investigated, and three commonly used extraction solvents were selected, including methyl tert-butyl ether (MTBE), cyclohexane as well as ethyl acetate. Ethyl acetate was the most polar solvent, followed by MTBE and cyclohexane. The results indicated that the recovery of 15-hydroxylubiprostone was highest with ethyl acetate used as the extraction solvent, and endogenous interference could be effectively eliminated as well.
Development of LC-MS/MS method and application to bioequivalence study of a light sensitive drug montelukast
Published in Drug Development and Industrial Pharmacy, 2021
Emily Yii Ling Wong, Gabriel Onn Kit Loh, Yvonne Tze Fung Tan, Kok Khiang Peh
Montelukast sodium is an oral selective leukotriene receptor antagonist that inhibits the cysteinyl leukotriene cysLT1. It is used in the treatment of chronic asthma in adult and children [1,2]. The reported bioanalytical methods for the quantification of montelukast in biological matrixes, which include HPLC [3–12] and LC-MS/MS methods [13–27], are presented in Table 1. The limitations of HPLC methods were low sensitivity, utilization of large volume of samples, large injection volume and relatively long sample run time [3–12]. Some of these methods used liquid-liquid extraction [9,13,18,19,26] or solid phase extraction [15,21,24], which were tedious and time consuming. These methods may not be feasible for high throughput sample analysis. Protein precipitation is widely used in studies that involve analysis of large number of samples such as bioequivalence study, due to its simplicity, high throughput analysis and cost effectiveness. However, protein precipitation technique is more susceptible to matrix effects, compared to LLE and SPE, which could be attributed to insufficient sample clean up [28].
A novel redox/pH dual-responsive and hyaluronic acid-decorated multifunctional magnetic complex micelle for targeted gambogic acid delivery for the treatment of triple negative breast cancer
Published in Drug Delivery, 2018
Mang Mang Sang, Fu Lei Liu, Yang Wang, Ren Jie Luo, Xiao Xian Huan, Ling Fei Han, Zhong Tao Zhang, Feng Feng, Wei Qu, Wenyuan Liu, Feng Zheng
The analytical method was validated in our laboratory. The peak area ratio of olmesartan to diazepam (internal standard) in rat plasma was linear with respect to the analyte concentration over the range 0.1–100 μg/mL. For samples preparation protein precipitation method was used. 100 μL plasma (contain 50% 0.5 M HCl) was taken in an Eppendorf tube and spiked with 50 mL of mixed standard solution (200 ng/mL diazepam, different concentration of GA) which dissolved in acetonitrile and a volume of 100 mL of chilled acetonitrile was added as a protein precipitating agent, vortexed for 1 min and then centrifuged at 14,000 rpm for 10 min. The supernatant layer was filtered through 0.45 μm syringe filters and 20 mL of the sample solution was injected for HPLC-MS analysis.