The aim of this paper was to prepare the solid-state inclusion complexes of trans-resveratrol with β-cyclodextrin and (2-hydroxypropyl)-β-cyclodextrin from ethanol-water mediums in order to improve its physico-chemical properties. The structure characterization was performed using FTIR, XRD and NMR methods. It was confirmed that the complexed trans-resveratrol has higher photostability than free trans-resveratrol. The results of DPPH assay suggested that the complexes have enhanced the antioxidant activity compared with trans-resveratrol. The inclusion complex with (2-hydroxypropyl)-β-cyclodextrin showed a better antioxidant activity than the complex based on β-cyclodextrin. The prepared inclusion complexes represent potential pharmaceutical active substances for a new products design.

New, simple, cost effective, accurate and reproducible RP-HPLC method was developed and validated for the quantification of trans-resveratrol in the extracts of grape exocarp and seeds. The method has proved to be simpler and faster than available methods. Methanol was used as a mobile phase with a flow rate of 1.0 cm3 min-1, while the quantification was effected at 306 nm. The separation was performed at 35?C using a C18 column. The results showed that the peak area response was linear in the concentration range of 1-40 ?g cm-3. The values of LOD and LOQ were found to be 0.125 and 0.413 ?g cm-3, respectively. The antioxidant activity of the extracts was determined using DPPH assay. The ability of DPPH radicals inhibition decreases in the following order: the extract of grape exocarp > trans-resveratrol standard > the extract of grape seeds. [Projekat Ministarstva nauke Republike Srbije, br. TRp-34012]

Pot marigold (Calendula officinalis L.) contains various bioactive compounds such as flavonoids, tannins, saponosides, carotenoids, triterpene alcohols, polysaccharides, amino acids, and essential oil. The extract of pot marigold flower has a benefit to the skin due to the presence of flavonoids that possess the anti-inflammatory, astringent, antifungal, and antiseptic effects. The aim of this study was to apply the ultrasound-assisted extraction as an advanced extraction technique and to investigate the impact of extraction time (5-35 min), ethanol concentration (20-80%, v/v), and extraction temperature (30-70 °C) on the total flavonoid content of pot marigold flower at the liquid-to-solid ratio of 20 cm 3 g -1 . The total flavonoids content of the extracts was determined spectrophotometrically with aluminium (III) chloride. The modeling of ultrasound-assisted extraction was carried out using a Box-Behnken design. Thus found optimal extraction conditions were the extraction time of 29 min, 39.6% (v/v) ethanol, and extraction temperature of 64.2 °C. The experimental value (220.2 mg 100 g -1 d.w.) of the total flavonoid content under optimal conditions was in a good agreement with the predicted value (221.5 mg 100 g -1 d.w.). According to the results of statistical analysis, the proposed second-order polynomial equation can be used to describe the extraction of flavonoids and to predict the total flavonoid content. The extraction procedure can be accepted from the point of the pharmaceutical application due to the use of ethanol as a representative of green solvents. The extraction time was shorter compared with other conventional extraction techniques.

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