| Title |
Netirpių rozmarino rūgšties ir chitozano kompleksų gavimas ir savybių įvertinimas / |
| Translation of Title |
Obtaining and properties of insoluble rosmarinic acid and chitosan complexes. |
| Authors |
Almonaitytė, Karolina |
| Full Text |
|
| Pages |
61 |
| Keywords [eng] |
rosmarinic acid ; chitosan ; adsorption |
| Abstract [eng] |
Water insoluble chitosan (Chz) and rosmarinic acid (RR) complexes (RR-Chz) of different composition were obtained by adsorbing RR from aqueous solutions on Chz powder. The adsorption of RR on Chz powder occurred in two stages. The pseudo-second kinetic model was fitted to the data of both adsorption steps. The mechanism of RA adsorption on the surface of Chz powder was elaborated. The RR-Chz with RR to Chz molar ratio of 0.11, 0.22, 0.39, 0.6 and 0.8 were obtained. FT-IR spectra confirmed the composition of RR-Chz complexes. Fluorescence spectroscopy investigation of RR-Chz aqueous dispersions showed that with an increase of RR amount in the complex the fluorescence emission spectrum maximum was shifted towards shorter wavelengths and that suggests stronger association of RR molecules on Chz powder surface. The thermal destruction of RR-Chz complexes occurred in two steps: release of physically retained water (first step) and decomposition of complex (second step) at temperature lower than that of CH alone. RR can be released from RR-Chz complexes into solution of 0.1 M HCl or phosphate buffer (pH=6.8). However, RR-Chz complexes are stable in distilled water ant ethanol. The antioxidant activity estimated by ABTS assay showed that RR-Chz complexes containing higher amount of adsorbed RA demonstrated prolonged antioxidant activity. |
| Dissertation Institution |
Kauno technologijos universitetas. |
| Type |
Master thesis |
| Language |
Lithuanian |
| Publication date |
2018 |
