Optimization of microwave-assisted extraction, antioxidant capacity, and characterization of total flavonoids from the leaves of Alpinia oxyphylla Miq.

Abstract

To optimize the extraction of total flavonoids (TFL) from the leaves of Alpinia oxyphylla Miq. using microwave-assisted method, a orthogonal test was used. The optimal extraction conditions for TFL were determined as follows: ethanol concentration of 50%, solid–liquid ratio of 1:20, temperature of 70 °C, and cycle index of 3. Under these conditions, the extraction yield of TFL was 28.24%. The scavenging rate of TFL against a,a-diphenyl-b-picrylhydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzoth- iazoline-6-sulphonica cid) (ABTS), and superoxide anion radical (O₂^－·) was screened. The results showed that the bioactivity of extracts appeared to be TFL dose-dependent, while it also presented stronger ferric reducing antioxidant power (FRAP). The contents of chrysin and tectochrysin in TFL were quantitatively analyzed by HPLC.

Keywords:

• Antioxidant activity
• chrysin and tectochrysin
• microwave-assisted extraction
• total flavonoids

Acknowledgments

The authors acknowledge the technical assistance of Analytical and Testing Center of Hainan University.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is supported by the National Science and Technology Support Program of China [2011BAD14B01], the Provincial Science and Technology Program on Modernization of Traditional Chinese Medicine of Hainan [ZY201327], the Innovation Fund Project for Technology Based Firm [13C26244604892], and the Provincial Industry, University and Research Cooperation Project of Hainan [CXY20150034], Research and Development Project of Applied Technology in Haikou City [2017044].