Objective: Curcumin and piperine exibit poor aqueous solubility and dissolution. Solid dispersion technology is a promising way to improve dissolution of lipophilic compounds. Therefore, to investigate the dissolution behavior, an accurate determination of curcumin and piperine concentrations in a sample containing 0.5 wt-% SLS in sodium phosphate buffer as the dissolution medium was required. The goal of research was to investigate whether UV-Vis spectroscopy can be used to accurately determine curcumin and piperine concentrations in aqueous solutions. Method: Stock solutions (1 mg/mL) of curcumin and piperine were prepared in methanol. A series of solutions for calibration were prepared by mixing the stock solutions in various ratios after which they were diluted with dissolution medium (0.5%-wt sodium lauryl sulfate in 20 mM phosphate buffer; pH 6.0). Solutions of curcumin (2μg/mL) and piperine (1 μg/mL were subjected to overlay scan in a UV-VIS spectrophotometer in each λmax of 430 and 335.5 nm for curcumin and piperine, respectively. The method was validated according ICH requirements, such as specificity, linearity, accuracy, precision, limit of detection and limit of quantification. Results: At a concentration range of 0.1 to 5μg/mL, calibration curves of curcumin and piperine showed linearity with R2 = 0.9980 and 0.9982, respectively. Precision and accuracy was confirmed by AOAC. Furthermore, LOD of both compounds was 0.23 μg/mL and LOQ of curcumin and piperine was 0.72 and 0.69μg/mL, respectively. Conclusion: UV-Vis spectroscopy can be used to accurately determine curcumin and piperine concentrations in dissolution samples obtained during screening the dissolution behavior of solid dispersions containing these compounds.
Key words: Curcumin, Piperine, Dissolution, UV-Vis spectroscopy.