Physico-chemical study of flavonoids from different matureness corn silk material

Anotace: There was tested a simple extraction procedure of flavonoids separation from the original corn silk (CS) material. It was found, that the total flavonoids content differs with the extraction time and extraction temperature. There were found different flavonoids contents in extracts prepared from different maturity stages of the original corn silk material (silking stage (CS-S), milky stage (CS-M)). Extracted flavonoids content was quantified by the lutin standardization method by means of colorimetry at 510 nm wavelength. Obsreved flavonoids concentration was ranging from 2×10-3 mg.mL-1 to 7 ×10-3 mg.mL-1 dependent on the extraction time period and extraction temperature. The highest flavonoids concentration of 7.5×10-3 mg.mL-1 was found for CS-M after 20 minutes extraction time and 80 °C extraction temperature. There was confirmed the presence of flavonoids by fluorescence mapping experiments. There was found a typical multistep decomposition process for both CS-S and CS-M materials by TG analysis. There was found a melting temperature of flavonoids of 54.3 °C for corn silk silking stage material exhibiting 58.9 J.g-1 heat of fusion and 60.2 °C for corn silk milky stage material with 112.9 J.g-1 heat of fusion. The optimal conditions of corn silk flavonoids extraction were 40 ℃, 50 minutes for CS-S, the optimal flavonoids extraction content was (6.8 ±2.1)×10-3 mg.mL-1, 80℃, 20 minutes for CS-M and the optimal extraction content was (7.2 ±0.3)×10-3 mg.mL-1.