Abstract:
Our previous study reported that the fruit of Gordonia axillaris, an edible wild fruit, possessed
strong antioxidant activity. In this study, a microwave-assisted extraction (MAE) method was established
to extract antioxidants from the fruit of Gordonia axillaris. The influence of five parameters, including
ethanol concentration, solvent/material ratio, extraction time, extraction temperature and microwave
power, was investigated by single-factor experiments. Three factors, namely ethanol concentration,
solvent/material ratio, extraction time, were found to exert a major influence on extraction efficacy,
and were further studied by response surface methodology to investigate their interactions. Ethanol
concentration of 36.89%, solvent/material ratio of 29.56 mL/g, extraction time of 71.04 min, temperature
of 40 ◦C, and microwave power of 400 W were found to be the optimal condition. The TEAC value
was 198.16 ± 5.47 µmol Trolox/g DW under the optimal conditions, which was in conformity to
the predicted value (200.28 µmol Trolox/g DW). In addition, the MAE method was compared with
two conventional methods (Soxhlet extraction and maceration extraction). Results showed that the
antioxidant capacity of the extract obtained by MAE method was stronger than that obtained by
maceration (168.67 ± 3.88 µmol Trolox/g DW) or Soxhlet extraction (114.09 ± 2.01 µmol Trolox/g DW).
Finally, several phenolic compounds in the extract were identified and quantified by UPLC-MS/MS,
which were rutin, gallic acid, protocatechuic acid, epicatechin, epicatechin gallate, 2-hydrocinnamic acid,
p-coumaric acid, quercetin, chlorogenic acid and ferulic acid
