Essential oil characterization of Ocimum basilicum and Syzygium aromaticum free and complexed with β-cyclodextrin. Determination of its antioxidant, antimicrobial, and antitumoral activities

This research evaluated the chemical composition of Ocimum basilicum and Syzygium aromaticum and to characterize their complex with beta-cyclodextrin (beta-CD) using physical mixing, kneading, and co-precipitation methods. Gas chromatography coupled to a mass spectrometer showed that methyl-chavicol and eugenol were, respectively, the major compounds from O. basilicum and S. aromaticum. By the use different vibrational spectroscopic methods (ATR-FTIR and FT-Raman) and thermal analysis (DSC and TGA), it was possible to strongly suggest the formation of EO-beta-CD complex. The antioxidant activity was evident in S. aromaticum EO due to the presence of the eugenol compound in the complexes. The antioxidant stability was evaluated at different temperatures, in which OE had its antioxidant activity reduced drastically while the complexes had a reduction of 6-13% of its activity. The antimicrobial activity was observed for EO and its complexes of S. aromaticum against yeasts of the genus Candida, in which there was a reduction of the concentration of the MIC and CFM for the complexes formed by the co-precipitation methodology. The antitumor activity against HT-29 and HeLa cells was observed in both EOs, in contrast, the cytotoxicity of EOs was also increased. The complex formed from OE S. aromaticum showed the best antitumor activity against HT-29 cells (IC 50 = 12.5 mu g/mL) with a better selectivity index (IS = 12.32). It is concluded that the techniques used were suitable for the confirmation of the complexes with beta-CD, and that the complexation contributed with the stability and action of the essential oils evaluated, allowing their use in the various industrial sectors, such as pharmaceutical and food industry. Graphic abstract