Solubility of Core Materials in Aqueous Polymeric Solution Effect on Microencapsulation of Curcumin

Abstract

Curcumin, the main active constituent of turmeric herb (Curcuma longa L.) have been reported to possess many medicinal values. The application of curcumin in dermatological preparations is limited by their intense yellow color property, which stains the fabric and skin. The objectives of this study were to reduce the color staining effect and enhance the stability of curcumin via microencapsulation using gelatin simple coacervation method. As for curcumin, ethanol and acetone were used as coacervating solvents. Curcumin was dispersed in ethanol while dissolved in acetone. Irrespective of the types of coacervating solvents used, microencapsulation resolved the color-staining problem and enhanced the flow properties and photo-stability of curcumin. Nevertheless, it was found that more spherical curcumin microcapsules with higher yield, higher curcumin loading, and higher entrapment efficiency were obtained with acetone than ethanol. The in vitro release of curcumin after microencapsulation was slightly prolonged. Further evaluation of the effects of solubility of core materials in coacervating solvent or polymeric aqueous solution using six different drug compounds, namely, ketoconazole, ketoprofen, magnesium stearate, pseudoephedrine HCl, diclofenac sodium, and paracetamol, suggested that the solubility of core materials in aqueous polymeric solution determined the successful formation of microcapsules. Microcapsules could only be formed if the core materials were not dissolved in the aqueous polymeric solution while the core materials could either be dissolved or dispersed in the coacervating solvent. In summary, microencapsulation not only circumvents the color-staining problem but also improved the stability and flowability of curcumin. The solubility of core material in aqueous polymeric solution plays a pivotal role in determining the successful formation of microcapsules.

Solubility of Drugs in Aqueous Polymeric Solution: Effect of Ovalbumin on Microencapsulation Process

“…The coacervated layer determined was similar to that previously described (19,20). The ratio of drug to gelatin was set at 1:1.…”

“…When examined under microscope, only curcuminoidgelatin particles appeared as discrete particles and were spherical in shape (19). In contrast, the water-soluble drugs, PE, VP, PP, and PC, existed in agglomeration and were not encapsulated.…”

“…Dehydrated molecules of polymer tend to aggregate with surrounding molecules to form the coacervate. In previous studies (19,20), gelatin was unable to encapsulate water-soluble drugs, pseudoephedrine HCl (PE), diclofenac sodium, and paracetamol (PC), in coacervation-phase separation method. During phase separation process, the drugs were separated from gelatin phase and partitioned into the aqueous phase when coacervated with ethanol.…”

“…The percentage of yield, drug loading, and entrapment efficiency (EE) of the drug-loaded particles were calculated using the following equations (19,34 In addition, the percentage of compositions of CU1, CU2, and CU3 in CU powder and encapsulated CU particles were compared. The percentages of PC and PE entrapped in drug-gelatin and drug-ovalbumin-gelatin particles were determined and compared.…”

“…The CU content (CU1, CU2, and CU3) was analyzed using HPLC method (19,20). Briefly, the HPLC system was comprised of a pump (Model 307, Gilson), 6-valve injection port (Rheodyne, Cotati, CA, USA), a UV detector (Model 115, Gilson, France) and an integrator (D-2500 Chromato-Integrator, Hitachi, Japan).…”