Kátia Andressa Santos

Antioxidant activity and chemical composition of oleoresin from leaves and flowers of Brunfelsia uniflora

In this study, the temperature and pressure of supercritical CO2 extraction were evaluated to obtain oleoresin of Brunfelsia uniflora leaves and flowers. The oleoresin compounds were identified by gas chromatography-mass spectrometry. The antioxidant activity was evaluated by three different methods. The highest oleoresin yields were 3.32% at 40°C and 200 bar for the leaves, and 1.03% at 60°C and 200 bar for the flowers. The main extracted compounds from leaves were phytol varying from 11.95 to 36.42% and α-tocopherol from 15.53 to 43.10%, and from flowers were geranyl linalool from 11.05 to 21.42% and α-amyrin from 9.66 to 22.12%. Oleoresin obtained at 60°C and 150 bar from leaves presented high antioxidant activity by DPPH (IC50 1.90 mg/mL) and by FRAP (1.8 µmol Fe2+/mg). β-carotene/linoleic acid co-oxidation oleoresin from leaves at 0.25 mg/mL presented higher antioxidant activity than Trolox. The total phenolic content of the oleoresin from leaves ranged from 66.20 to 83.33 µg/mg and from flowers it was just up to 12.46 µg/mg. The extraction conditions affected yield, chemical composition, and antioxidant activity of oleoresin from leaves and flowers. This is the first report on the antioxidant activity of B. uniflora oleoresin from leaves and flowers and provides subsidies for potential applications in chemical, pharmaceutical, and food industries.

Study of Heterogenious Catalysts in Transesterification of Soybean Oil Aiming Biodiesel Production

Heterogeneous catalysts represent a solution to some difficulties found in the biodiesel production. This work aims to study the effects of temperature and catalyst weight ratio in the transesterification reaction between soybean oil and methanol/ethanol in a heterogeneous medium. Some catalysts were tested, and one of those was the magnesium oxide doped with potassium hydroxide, which showed the highest yield of methyl ester and, therefore it was used for the next step of planning. A factorial design was made at two levels to evaluate the effect of temperature and catalyst level for both methanol and ethanol. A conversion of about 90% to esters was obtained as a result of methanol tests and a strong dependence of the temperature factor, and approximately 30% for tests with ethanol, demonstrating the greater reactivity of methanol. The model cannot be conclusive for planning invol-