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Objective:To establish the quality evaluation method of Astmgali Radix based on three-dimensional fluorescence spectroscopy. Methods:The three-dimensional fluorescence spectra of Astmgali Radix extract was measured by fluorescence spectrum analysis technology, and the characteristics of fluorescence components of three-dimensional fluorescence spectrum of Astmgali Radix were analyzed by parallel factor analysis. The three-dimensional fluorescence spectra of Astmgali Radix samples from 23 different places were measured for quality discriminant analysis. Results:After the optimization, the three-dimensional fluorescence spectrum of 80% ethanol extract of Astmgali Radix showed that three groups of characteristic excitation/emission (λex/λem) peak, which located at 305 nm/420 nm (Peak 1), 280 nm/315 nm (Peak 2) and 265 nm/475 nm (Peak 3), respectively. The results of parallel factor analysis showed that Peak 1 and Peak 3 both contained one isoflavones fluorescent component, and Peak 2 contained two amino acid fluorescent components. There were differences in the number of characteristic peaks and fluorescence intensity of three-dimensional fluorescence spectra of Astmgali Radix samples from different origins. Conclusion:The three-dimensional fluorescence spectrum could evaluate the consistency of Astmgali Radix from different places. The method is simple, fast, and efficient. This method is accurate, which could provide reference for the quality evaluation of Astmgali Radix.
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The study of interaction mechanism between chrysin and leptin was investigated by various spectroscopic techniques and atom force microscope. The ultraviolet spectrum presents a red shift in 200-220 nm after chrysin upon. And there is a structure alternative showed in 270 nm when the concentration ratio of chrysin and leptin in 10-15. From the fluorescence spectrum, it was found that chrysin could combine with leptin in physiological condition. The binding constant (Ka) values, at 298 K and 310 K, were (0.41±0.05)×10⁶ and (3.26±0.46)×10⁶ L·mol⁻¹, and the binding site number were 1.02±0.04 and 0.51±0.01, respectively. The atom force microscope results showed that the dimension of leptin molecules became more swollen after binding with chrysin because of the hydrophobicity. These results demonstrate that the mechanism of chrysin and leptin interaction could play a role in leptin adjust in human body, and it could provide a new aspect for the study of obesity treatment.
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Objective:To investigated the activity inhibition and inhibitory type of polyphenol oxidase (PPO) induced by galangin and the interaction mechanism of galangin with polyphenol oxidase was preliminarily indicated,and prove the related mechanism of galangin on proliferation of on human melanoma A375 cells.Methods: The activity inhibition and inhibitory type of PPO induced by galangin were investigated by spectrophotometric method,and interation mechanism of galangin with PPO was preliminarily indicated by fluorescence quenching and molecular docking,and chelating copper ions with the inhibitory mechanism of galangin on polyphenol oxidase was measured.Results: Galangin was a competitive inhibitor,the IC50 and Ki on PPO were obtained to be (47.86±3.33) and (24.83±1.45)μmol/L,respectively.Fluorescence spectrum indicated the fluorescence of PPO was quenched effectively by galangin and the binding constant Ka was obtained to be (4.67±0.43)×104 L/mol.Chelating copper ions and molecular simulation further showed that galangin was combined with active center of copper ions,and formed hydrogen bonds with catalytic site His259.Luteolin could induce the apoptosis of A375 cells significantly,and the tyrosinase activity and melanin synthesis were decreased.Conclusion: Galangin as a competitive polyphenol oxidase inhibitor and reduced the activity of polyphenol oxidase.which provides the theoretical basis for the clinical anti skin cancer.
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To unvestugate the evolutuon law and unfluenced factors of dussolved organuc matter for electron transfer capacuty durung unutual landfull stage, dussolved organuc matter ( DOM ) was extracted from landfull wastes at dufferent depth. Shewanella oneudensus MR-1 and cutrate uron ( FeCut ) were respectuvely used as electron donor and electron acceptor to measure electron donatung capacuty, electron acceptung capacuty and electron shuttlung capacuty. Afterwards, the unfluenced factors of electron transfer capacuty were studued by analyzung spectral unformatuon. The results showed that proteun-luke components and humuc-luke components were able to transfer electrons, and they also accepted electrons from mucroorganusms. Electron donatung capacuty and electron acceptung capacuty uncreased furstly and then decreased. However, the electron shuttlung capacuty uncreased persustently durung the landfull process. Proteun-luke components were the maun components of dussolved organuc matter durung the unutual landfull stage, and ut was maunly responsuble for the electron donorung capacuty and electron acceptung capacuty of DOM. Electron shuttlung capacuty resulted from humuc-luke components durung the cycluc redox process. Electron shuttlung capacuty persustently uncreased durung the landfull process based on humuc-luke components generated durung the stage.
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Objective To investigate the interaction of pullulan acetate nanoparticles (PANs) and bovine serum albumin (BSA),and to provide the basis for in vivo pharmacokinetic study of PANs.Methods Mixed solutions of different concentration of PANs and BSA solution was prepared,the interaction was studied by fluorescence quenching method and circular dichroism (CD) measurement.Apparent quenching constant (Kq) between the PANs and BSA was calculated,and the anti-stress effect induced by urea and heating of PANs-BSA solution was observed.Results The fluorescence spectrum of BSA was affected by PANs on density-related manner,and Kq calculated by the modified Stern-Volmer plot increased from 2.64×104 to 3.55 ×l05 with the concentration of PANs increased from 0.015 mg/ml to 0.25 mg/ml.With the denaturation of urea or heating,the CD spectrum of PANs-BSA and free BSA had the similar variation tendency.Conclusions The fluorescence spectrum display results show that interaction between PANs and BSA exists,but the interaction does not protect the BSA from degeneration by urea and heating.
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Objective To measure the fluorescence spectral information of UVRF in the facial skin of patients with acne vulgaris and seborrheic dermatitis and to comprehend the optical properties of UVRF.Methods The lesions were squeezed to extract the sebaceous secretions containing UVRF in the facial skin.Ocean Optics USB2000 +F02243 Spectrometer and the 308nm excimer laser were used as an excitation light source to measure the signal of the LIF spectrum of UVRF in 6 acne vulgaris and 4 seborrheic dermatitis patients' facial part,compared with protoporphyrin Ⅸ.Results 1-4 peaks were detected in 10 patients' UVRF specimen respectively.The fluorescence spectra's characteristic peak of UVRF in 10 patients was at 680 nm.Protoporphyrin Ⅸ was at 688 nm and more gentle and generous than UVRF's characteristic peak.Conclusions LIF system can be used to detect the fluorescence spectroscopy of UVRF.UVRF has similar spectral characteristics to protoporphyrin Ⅸ,but it is not the same species.
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The mechanism of complex unfolding process of Pseudomonas aeruginosa apoazurin is an arguing problem. Recent published results indicated that this problem could be resolved by hypothesizing two native conformations coexisting in solution.Urea-induced unfolding of apoazurin was investigated further using intrinsinc fluorescence and CD spectra. Equilibrium unfolding curves in urea could be depicted with an apparent two-state transition, but a biphase kinetic process. The fast unfolding process is finished within a few seconds as monitored by stopped-flow fluorescence intensity, whereas the slow process requires several hours for as well as the circular dichroism spectra just after manual mixing of protein and denaturant could be simulated by superposition of the spectra of the native and fully unfolded protein with the same coefficient of 0.37. This strongly suggests the three-state mechanism with a partially unfolded intermediate on its pathway is inadequate. The hypothesis of two native conformations coexistence is a reasonable selection.
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Objective To investigate the value of the high performance liquid chromatography (HPLC) with fluorescence detection of gastric juice in the diagnosis of gastric carcinoma. Methods After being super centrifuged, the supernatant of the gastric juice was chromatographed by reversed phase HPLC using C 18 column as the stationary phase and 20% methanol/H 2O as the mobile phase. The flow rate was set to 1 ml/min. The eluate was then detected with a fluorometer. Results 251 patients with different gastric diseases including 40 cases with gastric carcinoma were enrolled in our study. There were two characteristic peaks in the chromatograms, which appeared in both the benign and malignant lesions. The difference between benignancy and malignancy was the areas of the two peaks. The areas in the malignancy were much larger than those of the benignancy ( P
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Objective To explore the mechanism of the interaction between sulfur dioxide(SO2) and bovine serum albumin (BSA). Methods The spectrum characteristic of the interaction between SO2 and BSA was studied by fluorescence quenching spectrum and three dimensional fluorescence spectrum. Results The binding constants and thermodynamic parameters of SO2 with BSA were calculated at different temperatures. The quenching mechanism of BSA by SO2 was determined,the result showed that it did not belong to dynamic quenching but belonged to static quenching,which produced the complex. The hydrophobic interaction and electrostatic force played a main role in the binding of SO2 with BSA and only about one binding site occurred in the reaction. There was a certain influence to the conformation of BSA after adding SO2. Conclusion The quenching reaction of BSA by SO2 was weak. SO2 dissolved in body fluid easily and then SO32-and HSO3-are generated in vivo.