Biologically active composite based on fumed silica and Anoectochilus formosanus Hayata extract.

Biologically active extract was obtained from the leaves of Anoectochilus formosanus Hayata plants grown in vitro, and the composite was prepared by adsorption/precipitation of this extract components on the fumed silica surface under fluidized bed conditions. The composite was characterized by means of ultraviolet–visible and Fourier transform infrared spectroscopy, thermogravimetric analysis–derivative thermogravimetric analysis, scanning electron microscopy, and nitrogen adsorption method. Antioxidant properties of the extract and the composite were studied using Folin–Ciocalteu method and 2,2-diphenyl-1-picrylhydrazyl (DPPH) test; nitric oxide radical and hydroxyl radical scavenging activities of the extract and the composite were also evaluated. It was shown that adsorption/precipitation of phytochemicals does not significantly affect the texture of silica powder, while the presence of silica does not reduce the antioxidant ability of the extract components. At the same time, inclusion in the composite was found to provide bioactive substances with elongated effect and enhanced storage stability; caking resistance of silica particles was improved, as well. [ABSTRACT FROM AUTHOR]