Antioxidant activity of the inclusion complex of bixa orellana seeds extract in β-cyclodextrin obtained by supercritical CO2

Abstract

Background: Bixa orellana extracts are used to food coloring and it is important in pharmaceutical industry as a potential source of antioxidant activity. The application may be limited because it is unstable, but the process of inclusion in β-cyclodextrin (β-CD) by supercritical fluid CO2 (FSC-CO2) is an alternative to mediate this disadvantage. Objectives: we compared different conditions of temperature and pressure of FSC-CO2 extraction, to obtain a Bixa orellana extract with excellent antioxidant activity, and we evaluated the effect of inclusion in β-CD in the antioxidant capacity. Methods: extracts were obtained by FSC-CO2 with different conditions of pressure and temperature: (I) 3583 psi, 35°C, (II) 1413 psi, 35°C, (III) 2184 psi, 45°C, (IV) 5076 psi, 45°C, and (V) 2300 psi, 40°C. The antioxidant activity by DPPH assay was determined and the IC50 was evaluated. We performed the inclusion complex in β-CD with the highest antioxidant activity extract. The extract/β-CD complex was characterized by IR, DSC and NMR. This complexation was verified by comparative analysis of the spectra of the β-CD, free extract and β-CD/extract complex. The antioxidant capacity of this inclusion complex was evaluated. Results: the extract with highest antioxidant activity was obtained under the extraction condition IV, with an IC50 of 23.55 μg/mL, followed extract II (28.76 μg/mL), extract III (37.23 μg/mL), extract V (81.09 μg/mL) and extract I (193.82 μg/mL). Analysis showed significant differences (P<0.01) between these extracts. The spectra obtained by IR, DSC and NMR evidence the encapsulation process. The IC50 value of the extract/β-CD complex (104.84 μg/mL) was significantly higher than the value obtained for the pure extract (23.55 µg/mL). Conclusions: the highest antioxidant activity of Bixa orellana extracts was obtained by supercritical fluid pressure at 5076 psi and temperature of 45°C. Variations in IR, DSC and NMR spectra showed the inclusion of the β-CD/extract, and the IC50 values indicated the protective effect of β-CD to the reaction with DPPH radical.