A Pharmacological Appraisal of Antimalarial Plant Species
Namrita Lall in Medicinal Plants for Cosmetics, Health and Diseases, 2022
The leaf water extract of Maytenus arbutifolia (L.) displayed a significantly high parasite selectivity (SI = 3838) for P. falciparum (D6) strain. It showed an IC50 value of 0.95 µg/mL and a cytotoxicity value of 3645.7 µg/mL when tested on Vero E6 cells (Muthaura et al., 2007b). Warburgia ugandensis from the Canellaceae family was reported by Muthaura et al. (2011) to have significant antiplasmodial activity. Its MeOH stem bark extract displayed an IC50 value of 1.4 µg/mL on the KI strain of P. falciparum, with a cytotoxicity value of 0.34 µg/mL on L6 cells. Warburgia ugandensis showed a very low parasite selectivity (SI = 0.24), which does not fall within the acceptable range of potential drug hits (Muthaura et al., 2011). However, there are many different derivatization procedures, techniques and approaches that can be applied to chemically manipulate the plant extract to be clinically safe and more selective.
Drug Targeting to the Lung: Chemical and Biochemical Considerations
Anthony J. Hickey, Sandro R.P. da Rocha in Pharmaceutical Inhalation Aerosol Technology, 2019
As mentioned previously, a significant reduction in antibody reactivity is often observed after multiple sites of conjugation of drug with antibody. This has led to the development of carriers that, when covalently linked to antibody, are able in turn to covalently bind many drug molecules to appropriate carrier functionalities. Examples of carrier molecules that have been used include dextran (Pimm et al. 1982, Hurwitz et al. 1979, Tsukada et al. 1987), human serum albumin (Garnett et al. 1983), and poly-L-glutamate (Tsukada et al. 1984). Obviously, such a gross molecular modification of the parent antibody may well affect its overall properties, and this often leads to significant differences in biodistribution of an antibody-carrier-drug complex relative to the parent antibody. In addition, for reasons stated previously, such a structural derivatization may also result in lower tissue specificity and increased toxicity. Factors affecting the pharmacology of antibody-drug conjugates (ADCs) and the interaction between ADC carriers and biological systems has recently been reviewed (Lucas et al. 2018).
Fumonisins
Dongyou Liu in Handbook of Foodborne Diseases, 2018
For the determination of fumonisins in food and feed, methods based on high-performance liquid chromatography (HPLC) or ultrahigh performance liquid chromatography (UPLC) are the most commonly described. Fumonisins have no strongly ultraviolet absorbing or fluorescing functionality.72 Consequently, different derivatization reagents have been reported to enhance fluorescence, namely, o-phthaldialdehyde the most used73 and naphthalene-2,3-dicarboxaldehyde,74 allowing for detection by HPLC with fluorescence detection. Each reaction system for derivatization offers different degrees of success, but all of them have limitations including lack of sensitivity, instability, long testing time, or analytical interferences with certain cereal matrices.
Advances and challenges in the measurement of 1,25-dihydroxyvitamin D: a comprehensive review
Published in Critical Reviews in Clinical Laboratory Sciences, 2023
Zhicheng Jin, Roger L. Bertholf, Xin Yi
As previously discussed, vitamin D and its metabolites lack easily charged groups and have low ionization efficiency in a mass spectrometer. Another approach to increase the sensitivity of MS-based assays is chemical derivatization, which can boost the ionization efficiency of analytes measured by MS using ESI or atmospheric chemical ionization ion source [60]. The presence of conjugated diene groups in vitamin D metabolites makes them ideal targets for Diels-Alder derivatization, and several highly reactive 4-substituted 1,2,4-triazoline-3,5-diones (Cookson-type reagents) have been reported as derivatization agents for vitamin D metabolites [75–78]. Derivatization introduces polar groups to the analyte and increases sensitivity compared to non-derivatized compounds. Additionally, derivatization increases mass-to-charge ratio of precursor ions of 1,25(OH)2D and separates them from other steroid hormone ions that could potentially interfere. In 2001, Higashi et al. reported the derivatization of 25(OH)D3 using a Cookson-type reagent, DMEQTAD (4-[2-(6,7-dimethoxy-4-methyl-3-oxo-3,4-dihydroquinoxalyl)ethyl]-1,2,4-triazoline-3,5-dione) to form a Diels-Alder adduct [75]. Later, the same group reported using another agent, 4-(4-nitrophenyl)-1,2,4-triazoline-3,5-dione (NPTAD, Figure 2), to derivatize 25(OH)D3 [76].
Integrative multiomics analysis reveals host-microbe-metabolite interplays associated with the aging process in Singaporeans
Published in Gut Microbes, 2022
Liwei Chen, Tingting Zheng, Yifan Yang, Prem Prashant Chaudhary, Jean Pui Yi Teh, Bobby K. Cheon, Daniela Moses, Stephan C. Schuster, Joergen Schlundt, Jun Li, Patricia L. Conway
Fecal samples were prepared for metabolomics analysis as previous described GC-MS method91,92 with modification. Methanol was added to 250 mg of fecal sample to a final concentration of 200 mg/ml, ribitol (10 ug/ml) was added as an internal standard. Solutions were completely homogenized and then centrifuged at 2530 × g at 10°C for 15 min. A 50 ul aliquot of each extract was dried in an Eppendorf rotary vacuum concentrator and stored at −80°C until derivatization. Derivatization was conducted as follows: methoximation was achieved by adding 40 ul of methoxyamine–HCl (20 mg/ml in pyridine), followed by incubation for 90 min at 30°C with shaking at 1200 rpm. Trimethylsilyl derivatization was carried out by adding 40 ul N-trimethylsilyl-N-methyl trifluoroacetamide (MSTFA) and incubation at 60°C for 45 min. The sample is centrifuged at 12000 rpm for 60 min, and the supernatant was transferred to a glass vial for GC-MS analysis.
Noninvasive amino acid turnover predicts human embryo aneuploidy
Published in Gynecological Endocrinology, 2022
I. Orcun Olcay, Berkay Akcay, Mustafa Bahceci, Aydin Arici, Kubra Boynukalin, Cengiz Yakicier, Aysel Ozpinar, Murat Basar
The amino acids were analyzed by reverse-phase LC-MS/MS as previously described [41], but using a Kontron 500 series automated HPLC system fitted with a Jasco F920 fluorescence detector and a 4.5×250mm Hypersil ODS-16 column (Jones Chromatography, Hengoed, Mid Glamorgan, UK). Derivatization was achieved by the automated reaction of a 25µl sample with an equal volume of reagent [10µl 2-mercaptoethanol and 5ml ophthaldialdehyde (OPA) reagent]. The elution gradient operated at a flow rate of 1.3ml/min. Solvent A consisted of 18ml tetrahydrofuran (Fisher Scientific, Loughborough, Leics, UK), 200ml methanol, and 800ml sodium acetate (83mmol/l, pH 5.9). Solvent B consisted of 800ml methanol and 200ml sodium acetate (83mmol/l, pH 5.9). Using this method, it was not possible to detect isoleucine. Results were expressed as amino acid depletion/appearance in pmol/embryo/h ± SEM. The term ‘turnover’ has been used to describe the sum in pmol/embryo/h of amino acid depletion from, and appearance in, the culture medium.
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