Preparation and Study of nticancer Activity of Curcuminoid-Rich Curcuma longa Extracts (CRE) and CRE-Cyclodextrin Inclusion Complexes

Abstract

Curcuma longa extracts contain three major curcuminoids, namely curcumin, demethoxycurcumin, and bisdemthoxycurcumin, which possess various pharmacological activities, such as antioxidative, anti-inflammatory and anticancer activities. It has been reported that acetone and ethyl acetate were the most suitable solvents for extraction of curcuminoids. However, these solvents are dangerous and expensive. The present study therefore focused on preparation of curcuminoid-rich C. longa extracts (CRE) using a microwave-assisted extraction (MAE) and bio-solvents that have been approved as a green extraction. The optimal conditions of MAE were: employing ethanol as solvent, microwave power of 900 W, with three irradiation cycles (one cycle was 3 min power-on, and 30 sec power-off), at 75°C. The curcuminoid extract was subsequently fractionated on a macroporous resins (Diaion HP-20) column eluted with 55% and 60% v/v ethanol, respectively, to obtain the extracts enriched in curcuminoids, which contain total curcuminoids of not less than 88% w/w. CRE exhibited stronger anticancer activity against A-549, MCF-7, HT-29 and HeLa cell lines with the IC50 values 5.18, 3.46, 2.73 and 7.66 μg/mL, respectively than that of the crude ethanol extract, and almost equal to that of the pure curcuminoids. Therefore, for industrial applications, a large-scale one-step preparation of CRE has more advantages than the use of pure curcuminoids in terms of convenience, a low-cost production and environmental-friendly process. Water solubility of curcuminoids in CRE was enhanced by a formulation of binary (CRE/HP-B-CD) and ternary inclusion complexes (CRE/HP-ẞ-CD/PVP K30) with hydroxypropyl-ẞ-cyclodextrin (HP-ẞ-CD) and polyvinylpyrrolidone K30 (PVP K30) using the solvent evaporation method. The physicochemical characteristic of inclusion complexes were investigated by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), powder X-ray diffractometry (PXRD), scanning electron microscopy (SEM) compared with their physical mixture. Dissolution, anticancer activity and stability of the inclusion complexes were also investigated. The optimal conditions for formulation of binary inclusion complex were: employing 1:1 mole ratio between CRE and HP-B-CD and 9% w/w PVP K30, respectively. All the characteristic information demonstrated that the formation of binary and ternary inclusion complexes exhibited specific spectroscopic features and properties. The binary and ternary inclusion complexes improved water solubility of curcuminoids up to 50 and 70 μg/mL, respectively. The CRE inclusion complexes were stable for 4 months when kept in a well- closed container protected from light when stored at 4-25°C and accelerated conditions at 45°C, 75% humidity. Both inclusion complexes exhibited stronger cytotoxic activity against the cancer cells than CRE. The inclusion complexes of curcuminoids are therefore potentially applied as pharmaceutical and dietary supplement products.