Key points are not available for this paper at this time.
The microwave-assisted extraction (MAE) presents some advantages compared to the conventional method like lower extraction time and solvent consumption, besides being more selective. This study aimed to combine important parameters for MAE by using Humiria balsamifera leaves, from Restinga Jurubatiba, in comparison to the maceration method in terms of its flavonoid contents, the antioxidant activity and the crude yield. For microwave extraction (MO), a 23 factorial design was performed, combining three factors: solvent proportion (ethanol: water 1:1)/mass, temperature and stirring in 30 min. Concomitantly, a maceration extraction was also done during 7 days with the same solvent. The solutions were concentrated, the yields calculated and then analyzed by HPLC-DAD for the total flavonoids dosage. The antioxidant activity was performed by the DPPH method (2,2-diphenyl-1-picryl-hidrazil), in which the standardized EGb 761® extract of Ginkgo biloba was used as standard. The best yield (18.83%) was observed under the following conditions: higher proportion (1:20), higher rotation (1000 rpm) and higher temperature (55 °C), being significantly greater when compared to the maceration (5.13%). The calibration curve allowed the quantification of flavonoids with the UV spectra equivalent to rutine (λmáx 202, 255, 354nm). To the antioxidant activity, the results were expressed as EC50 values, where the sample in the same conditions showed the lowest EC50 (33.06 ± 0.73), which is also in accordance with the result obtained for total flavonoids (7.94 EqR%). All samples, including that prepared by the conventional method exhibited best antioxidant activity compared to the standard (EC50= 45.07 ± 0.15), already recognized for showing outstanding antioxidant activity. MAE was more efficient, showing higher yields in lower time in comparison to the maceration, thus achieving favorable conditions. The model was satisfactorily explained by the experimental design.
Dutra et al. (Wed,) studied this question.