Investigation Of Inclusion Complexation, Chemical Modification And Microemulsion Formulation Of Curcumin For Enhanced Antibacterial Property

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Date
2015-04
Authors
KHALID, SYED HAROON
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Abstract
The aim of this study was to investigate the effect of solubility enhancement, chemical modification and microemulsion formulation on antibacterial property of curcumin. Prior to the study, a stability indicating, simple and sensitive HPLC-UV method was developed to quantify curcumin concentration in Curcuma longa extract. For solubility enhancement, β-cyclodextrin (βCD) and its derivative hydroxypropyl- β-cyclodextrin (HPβCD) were used to prepare curcumin inclusion complex using kneading method. The inclusion complexes were examined using Fourier transformed infrared (FTIR), differential scanning calorimetry (DSC), powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Based on DSC and XRD results, Nuclear magnetic resonance (NMR) study was performed to investigate the inclusion complex formation. For chemical modification method, curcumin-Ag(I) complex was synthesized by replacing the phenolic protons of curcumin with sodium followed by silver ions as well as coordination of carbonyl groups to the silver metal center. The metal complex was characterized using FT-IR and FT-NMR spectroscopy. For microemulsion formulation, solubility studies of curcumin in different oils, surfactants, co-surfactants and surfactant-cosurfactant mixture, were performed. Pseudoternary phase diagram was constructed to identify the microemulsion region. The microemulsion formulations were evaluated for pH, viscosity, conductivity, particle size, polydispersity index, zeta potential, curcumin content and in-vitro release. The final ME formulation was used for stability (at 26 ± 2 ºC/ 55 % RH and 40°C/75% RH for 6 months) studies. The inclusion complex (Cur-HPβCD), metal complex (curcumin-Ag(I)) and microemulsion formulation (curcumin loaded) were evaluated for the antibacterial properties. The HPLC-UV method showed good recovery, accuracy and precision with short run time of less than 7 min. The inclusion complexation increased the solubility, dissolution and antibacterial activity of Cur- HPβCD. HPβCD produced higher curcumin solubility and dissolution than that of βCD. DSC thermograms of Cur-HPβCD showed a decrease in the intensity of endothermic peak of curcumin more than Cur-βCD. XRD results indicated that curcumin shifted to amorphous state when complexed with HPβCD but retained its crystalline nature with βCD. NMR study showed the inclusion complex formation. FTIR and 13C spectra of curcumin-Ag(I) indicated the significant changes in support of formation of the proposed complex. NMR studies confirmed the Ag attachment to the curcumin structure. Isopropyl myristate (IPM), Tween 80, PEG 400 were chosen to prepare microemulsion formulations. The microemulsion region was identified with the aid of ternary phase diagram. Seven formulations were selected from the microemulsion area. The final selected microemulsion formulation loaded with curcumin was stable after storage for six months. Cur-HPβCD inclusion complex was more active against both S. aureus and E. coli, when compared with curcumin, indicating that higher water solubility and dissolution of Cur-HPβCD led to increased antibacterial activity of curcumin. Curcumin-Ag(I) complex did not demonstrate antibacterial activity against bacteria tested. Microemulsion formulation was found to enhance curcumin antibacterial activity against the growth of S. aureus and E.coli. In conclusion, inclusion complexation and microemulsion formulation could be used to enhance activity of curcumin, via an increase in the solubility of curcumin.
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Investigation Of Inclusion Complexation, Chemical Modification And Microemulsion Formulation , Of Curcumin For Enhanced Antibacterial Property
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