Antioxidant Properties of Croton zehntneri Pax et Hoffm. Essential Oil and Its Inclusion Complex with β-Cyclodextrin Prepared by Spray Drying

Croton zehntneri Pax et Hoffm. is a plant from Northeastern Brazil, whose main component of its essential oil is estragole. Its thermal instability and low aqueous solubility prevent its technological application. This study aimed to prepare and characterize the Croton zehntneri essential oil (CZEO) complexed with beta-cyclodextrin (beta-CD), and to evaluate antioxidant activity of free and complexed-CZEO in vitro systems by the elimination of 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH center dot), 2,2' -azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS(center dot+)), hydroxyl and nitric oxide, as well as their ability to transfer electrons by the reducing potential. The infrared spectroscopy and thermal techniques demonstrated the formation of the inclusion complex (Est/beta-CD) obtained by spray drying method. The free CZEO and its Est/beta-CD at 0.9, 1.8, 3.6, 7.2, 14.4 and 28.8 mu g mL(-1) showed the ability to remove DPPH center dot (EC50 (half maximal effective concentration) 26.06 and 9.46 mu g mL(-1), respectively) and ABTS(center dot+) (EC50 22.73 and 4.47 mu g mL(-1), respectively), nitric oxide inhibition (EC50 17.65 and 2.68 mu g mL(-1), respectively), hydroxyl radical sequestration (EC50 23.42 and 2.34 mu g mL(-1), respectively) and reducing potential (EC50 46.48 and 12.47 mu g mL(-1), respectively). The formation of the inclusion complex significantly increases its antioxidant potential.