The acid constants of mangiferin (a natural xanthonoid) in aqueous solution were determined through an UV/vis spectroscopic study employing the SQUAD program as a computational tool. A NMR study complements the pK(a) values assignment and evidences a H-bridge presence on 1-C. The chemical model used was consistent with the experimental data obtained. The pK(a) values determined with this procedure were as follows: H(4)(MGF)=H(3)(MGF)(-)+H(+), pKa1 (6-H)=6.52+/-0.06; H(3)(MGF)(-)=H(2)(MGF)(2-)+H(+), pKa2 (3-H)=7.97+/-0.06; H(2)(MGF)(2-)=H(MGF)(3-)+H(+), pKa3 (7-H)=9.44+/-0.04; H(MGF)(3-)=(MGF)(4-)+H(+), pKa4 (1-H)=12.10+/-0.01; where it has been considered mangiferin C(19)H(18)O(11) as H(4)(MGF). Mangiferin UV/vis spectral behavior, stability study in aqueous solution as well as NMR spectroscopy studies: one-dimensional (1)H,(13)C, 2D correlated (1)H/(13)C performed by (g)-HSQC and (g)-HMBC methods; are also presented. pK(a) values determination of H(4)(MGF) in aqueous solution is a necessary contribution to subsequent pharmacokinetic study, and a step towards the understanding of its biological effects.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.saa.2005.09.009 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Comparative photocatalytic degradation of cationic rhodamine B and anionic bromocresol green using reduced ZnO: A detailed kinetic modeling approach.
Chemosphere
January 2025
Center for Green Chemistry and Environmental Biotechnology, Ghent University Global Campus, 119-5 Songdomunhwa-Ro, Yeonsu-Gu, Incheon, 406-840 South Korea; Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, 653 Coupure Links, Ghent, B-9000, Belgium. Electronic address:
The photocatalytic degradation of rhodamine B (RhB), a cationic dye, and bromocresol green (BCG), an anionic dye, was investigated using oxygen vacancy-enriched ZnO as the catalyst. These dyes were selected due to their differing charges and molecular structures, allowing for a deeper exploration of how these characteristics impact the degradation process. The catalyst was prepared by reducing ZnO with 10% H/Ar gas at 500°C, and the introduction of oxygen vacancies was confirmed using various characterization techniques.
View Article and Find Full Text PDFAqueous Solubility of Sodium and Chloride Salts of Glycine─"Uncommon" Common-Ion Effects of Self-Titrating Solids.
Mol Pharm
January 2025
Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, New York 11439, United States.
Although glycine is the simplest of the amino acids, its solution and solid-state properties are far from straightforward. The aqueous solubility of glycine plays an important role in various applications, including nutrition, food products, biodegradable plastics, and drug development. There is evidence that glycine in subsaturated pH 3-8 solutions forms a dimer, as suggested by several techniques.
View Article and Find Full Text PDFCyclocurcumin potently inhibits human aromatase as a potential therapeutic agent.
J Steroid Biochem Mol Biol
December 2024
Department of Obstetrics and Gynecology, the Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027, China. Electronic address:
Curcuminoids, including curcumin and its derivatives, show potent inhibition of aromatase (CYP19A1), crucial for estradiol synthesis and breast cancer metastasis. Our study evaluated the efficacy and mechanism of 10 curcuminoids and their metabolites against human and rat CYP19A1 using placental microsomes, revealing species-specific IC values. Cyclocurcumin (IC, 4.
View Article and Find Full Text PDFNutraceuticals silybin B, resveratrol, and epigallocatechin-3 gallate-bind to cardiac muscle troponin to restore the loss of lusitropy caused by cardiomyopathy mutations , , and .
Front Physiol
December 2024
National Heart and Lung Institute, Imperial College London, London, United Kingdom.
Introduction: Adrenergic activation of protein kinase A (PKA) in cardiac muscle targets the sarcolemma, sarcoplasmic reticulum, and contractile apparatus to increase contractile force and heart rate. In the thin filaments of the contractile apparatus, cardiac troponin I (cTnI) Ser22 and Ser23 in the cardiac-specific N-terminal peptide (NcTnI: residues 1 to 32) are the targets for PKA phosphorylation. Phosphorylation causes a 2-3 fold decrease of affinity of cTn for Ca associated with a higher rate of Ca dissociation from cTnC leading to a faster relaxation rate of the cardiac muscle (lusitropy).
View Article and Find Full Text PDFThe Protein Engineering of Zearalenone Hydrolase Results in a Shift in the pH Optimum of the Relative Activity of the Enzyme.
Toxins (Basel)
December 2024
All-Russian Research Institute of Phytopathology of RAS, Bolshie Vyazemy, 143050 Moscow, Russia.
An acidic shift in the pH profile of zearalenone hydrolase (ZHD), the most effective and well-studied zearalenone-specific lactone hydrolase, is required to extend the range of applications for the enzyme as a decontamination agent in the feed and food production industries. Amino acid substitutions were engineered in the active center of the enzyme to decrease the pKa values of the catalytic residues E126 and H242. The T216K substitution provided a shift in the pH optimum by one unit to the acidic region, accompanied by a notable expansion in the pH profile under acidic conditions.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!