ABSTRACT
Based on the universal regularity of the automatic action of supramolecular "imprinted template" previously proposed, this paper further analyzed and summarized the historical evolution and research status of the toxicity of Chinese materia medica, and deeply analyzed the production of toxicity of Chinese materia medica by using the theory of supramolecular chemistry. After entering the human body, the aggregation of supramolecular "imprinted template" of Chinese materia medica can interact with the similar "imprinted template" of the subject supramolecular of human in the human body. In other words, the group of toxic components of Chinese materia medica can be identified with the corresponding hole channels in the body, which is the supramolecular chemical mechanism of the toxicity of Chinese materia medica. The dose-effect problem and detoxification treatment of toxic Chinese materia medica is closely related to the equilibrium constant and concentration. When the concentration of the drug with the same (similar to) imprinted template is the same, the toxicity depends on the equilibrium constant of its interaction with the target. Based on this, research idea of equilibrium constant of toxicity of Chinese materia medica was proposed. The equilibrium constant of supramolecular imprinted behavior can explain the toxicity of Chinese materia medica. By studying the equilibrium constant, the supramolecular interaction of the toxic effect can be revealed and the supramolecular system of Chinese materia medica can be well studied.
ABSTRACT
Volatile oils are important active components in traditional Chinese medicine, but their components are complicated and unstable. It is common to use cyclodextrin inclusion technique to improve the stability of volatile oils and make them easier to be prepared. At present, β-cyclodextrin (β-CD) is the most common inclusion material. The evaluation indicators for inclusion technique usually contain the inclusion rate and the oil content in the inclusion compound. However, the articles about the study on selecting inclusion materials for volatile oils were few. In this paper, menthol, the main active ingredient of mint volatile oil, was used as model drug, while β-CD and hydroxypropyl-β-cyclodextrin (HP-β-CD) were used as the inclusion materials. Inclusion equilibrium constant (K), solubilization ratio were investigated, and the results were combined with IR, DSC and TG to verify the formation of inclusion complexes. It turned out that in the range of 0-15 mmol•L⁻¹, the solubility of menthol was increased linearly with the increase of HP-β-CD concentration, with AL-type phase solubility diagram, K=3 188.62 L•mol⁻¹; in the range of 0-12.5 mmol•L⁻¹, the solubility of menthol was increased linearly with the increase of β-CD concentration, K=818.73 L•mol⁻¹. When the concentration was over 12.5 mmol•L⁻¹, the solubility of menthol appeared to be a negative deviation with the increase of β-CD concentration, with AN-type solubility diagram. The above results showed that the inclusion behavior was different between β-CD and HP-β-CD, laying a foundation for further study on inclusion complexes of volatile oil.
ABSTRACT
OBJECTIVE:To establish a method for determination of ionization equilibrium constant of sildenafil using ultraviolet spectrophotometry.METHODS:Methanol solutions of sildenafil with pH values of 2.26,8.56,9.31,9.83 and 12.38 were respectively scanned at the wavelength within the range of 200nm～400nm.The absorbability and pKa value of sildenafil were determined at the selected wavelength of 280,287,290,295 and 297nm respectively.RESULTS:The pKa value of sildenafil was 9.35?0.02.CONCLUSION:The present method is convenient and practicable.
ABSTRACT
Ribosomal proteins S7, S9 and S 19 from Escherichia coli have been studied by the sedimentation equilibrium technique for possible intermolecular interaction between pairs of proteins as well as in a mixture of 3 proteins. The proteins were isolated to a purity greater than 95% and were characterized in the reconstitution buffer. It was observed that none of the proteins has a tendency to self-associate in the concentration range studied in the temperature range 3–6°C. Protein S9 behaves differently in the presence of other proteins. Analysis of the sedimentation equilibrium data for S7–S9, S9– S19 and S7–S9–S19 complexes revealed the need for considering the presence of a component of higher molecular weight in the system along with the monomers and their complexes to provide a meaningful curve-fitting of the data. Proteins S7 and S19 were found to interact with an equilibrium constant of association of 3 ± 2 × 104 M–1 at 3°C with a Gibbs free energy of interaction ΔG° of -5·7 kcal/mol. These data are useful for the consideration of the stabilization of the 30S subunit through protein-protein interactions and also help in building a topographical model of the proteins of the small subunit from an energetics point of view.