Acid–base equilibrium of puerarin in CTAB micelles

Xi, Juqun; Guo, Rong

doi:10.1016/j.jpba.2006.06.028

Cited by 31 publications

(10 citation statements)

References 26 publications

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“…And the pK a values of puerarin have been reported to be pK a1 ¼ 6.91 and pK a2 ¼ 9.93. [27] Therefore, the mole fractions (f) present as the PuH 2 , PuH À and Pu 2À are shown as functions of pH in Figure 3 and the pH dependence of k 2 may be represented as the sum of the contributions for three species.…”

Section: Results and Discussion Ph Dependence Of Dpph-radical-scavengmentioning

confidence: 99%

Effects of pH and Micelle on the Radical Scavenging Ability of Puerarin

Guo

2009

Journal of Dispersion Science and Technology

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The radical scavenging properties of puerarin are investigated in buffered hydroalcoholic media and Triton X-100 micellar solutions using the free-radical diphenylpicrylhydrazyl (DPPH.) method. The reactions, which follow the mixed second-order rate law, are investigated under pseudo-first-order condition by use of a large excess of puerarin. The rate constants (k 2 ) observed for puerarin show notable pH dependence. These differences in reactivity of puerarin toward the oxidants at different acidity of the solution have been assumed to arise from the acid-base equilibrium of puerarin. The influence of acid-base equilibrium on bond dissociation energy for puerarin has also been investigated by means of DFT calculations. It has been concluded on the basis of these calculations that monoanionic form of puerarin is more powerful radical scavenger than the neutral molecule. When the reactions take place in Triton X-100 micelles, the radical scavenging properties of puerarin are enhanced. The results may be due to the special location of puerarin in Triton X-100 micelles.

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Section: Results and Discussion Ph Dependence Of Dpph-radical-scavengmentioning

confidence: 99%

Effects of pH and Micelle on the Radical Scavenging Ability of Puerarin

Guo

2009

Journal of Dispersion Science and Technology

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“…Figure 2 shows the morphological character of lecithin liposomes and the mean liposome diameters ranges from 50 to 100 nm. Puerarin possesses a hydrophobic character and is a weak acid, having two ionizable moieties and the pK 1 and pK 2 values are 6.91 and 9.93 respectively in aqueous solutions [19] . At physiological pH (pH = 7.4), about 75% of puerarin molecules are negatively charged.…”

Section: Measurements Of Membrane Permeabilitymentioning

confidence: 99%

“…In liposomal solutions, the acid and base forms of puerarin exhibit different trends in their absorption spectra. The absorbance of acid form at 306 nm decreases, giving increase to the absorbance of base form at 345 nm [19] . The result shows that the puerarin molecule undergoes the deprotonation reaction in PC liposome system.…”

Section: Measurements Of Membrane Permeabilitymentioning

confidence: 99%

“…The optimization of the puerarin molecule by ab initio quantum chemical calculations can give the information about the localization part of puerarin in liposomes. The results show that the stable structures of puerarins with different charges are not planar (Figure 4), but with the B-ring connected to the C-ring by a single C-C bond around which rotation can occur, and the B-ring deviates with 36.83° [ 19] , 33.44° and 35.86° from the planarity for neutral, monoanionic and dianionic forms, respectively. In addition, the presence of a sugar moiety renders puerarin less hydrophobic and more bulky.…”

Section: Special Topicsmentioning

confidence: 99%

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Studies on molecular interactions between puerarin and PC liposomes

Guo

2007

CHINESE SCI BULL

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Fluorescence emission spectra, FTIR spectra, zeta potential measurements, and ab initio quantum calculation are used to study the interaction between puerarin and membranes composed of egg phosphatidylcholine (PC) liposome. The hydrophobic interactions cause the puerarin molecule to partition into lipid bilayers with its B-ring, and favor the displacement of acid-base equilibrium of puerarin towards the base form. Due to the hydrogen bond formation between the puerarin hydroxyl groups and polar groups of PC molecules on the water/membrane interface, puerarin can easily intercalate into the organized structure of phospholipids and modulate the membrane function. Our results reveal that the liposome membrane integrity is significantly higher compared with that of empty liposome.puerarin, phosphatidylcholine, liposome, drug encapsulation

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“…As a weak acid, puerarin dissociates in aqueous solution [11]. The present work describes the application of a new double solvent extraction by changing pH for the recovery of puerarin from the extract.…”

Section: Introductionmentioning

confidence: 99%

Separation and purification of puerarin with solvent extraction

2007

Separation and Purification Technology

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Acid–base equilibrium of puerarin in CTAB micelles

Cited by 31 publications

References 26 publications

Effects of pH and Micelle on the Radical Scavenging Ability of Puerarin

Effects of pH and Micelle on the Radical Scavenging Ability of Puerarin

Studies on molecular interactions between puerarin and PC liposomes

Separation and purification of puerarin with solvent extraction

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