PREPARATION OF COMPOSITE BASED ON CAFFEIC ACID AND FUMED SILICA AND EVALUATION OF ITS ANTIOXIDANT AND ANTIMICROBIAL PROPERTIES br

The aim of this work was the preparation of a composite comprising caffeic acid (CA) and fumed silica (A300), and comparison of antioxidant and antimicrobial properties of CA in solution and in composite. The CA+A300 composite with CA content of about 25 mg/g was obtained using the sorptive modification of silica with CA solution under fluidized bed conditions. Antioxidant properties of the CA solution and the CA+A300 composite were studied using DPPH center dot and Folin-Ciocalteu assays, in addition OH center dot and NO center dot scavenging activity and antimicrobial properties against Staphylococcus aureus209 strain were estimated. The results have shown that CA is very effective in the reaction with DPPH center dot radicals and that the inclusion of CA in the composite results in the slowing down of this reaction. The CA solution and the CA+A300 composite had a similar activity as NO center dot radicals' scavengers and as antimicrobial agents, whereas the CA solution was moreeffective in inhibition of OH center dot radicals. It has been assumed that the difference in activity between the CA+A300 composite and the CA solution may be due to the gradual release of CA from the composite into reaction mixtures and by the increase in this release as CA is consumed in the reactions