Abstract
Purpose: To identify the main flavonoid in Adinandra nitida leaf, employ response surface methodology to optimize its ultrasonic-assisted extraction, and determine the antioxidant activity of the obtained extract. Methods: The main flavonoid in Adinandra nitida leaf was obtained by traditional solvent extraction and recrystallization methods, and identified by ultraviolet-visible spectroscopy (UV), Fourier transform infrared spectroscopy (FT-IR), electrospray ionization-mass spectrometry (ESI-MS), nuclear magnetic resonance spectroscopy (NMR). By using response surface methodology, the effects of extraction time, ethanol concentration and ultrasonic frequency on flavonoid yield were investigated and optimal conditions determined. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and reducing power of the obtained extract was also examined. Results: The main flavonoid in Adinandra nitida leaf was identified as camellianin A. Optimal extraction conditions were as follows: extraction time, 30.25 min; ethanol concentration, 63.84 %; and ultrasonic frequency, 45 KHz. The mean experimental flavonoid yield under optimum conditions was 84.52 ±1.65 %, which agreed with the predicted value of 83.02 %. The obtained flavonoid extract was an effective scavenger of DPPH radicals with IC50 of 0.02 mg/mL. A linear correlation between concentration of the flavonoid extract and reducing power was observed with a coefficient of r 2 = 0.9867. Conclusion: By using ultrasonic-assisted extraction, the main flavonoid in Adinandra nitida leaf can be obtained at a high yield. The flavonoid displays a strong DPPH radical scavenging activity and reducing power, which makes it potentially useful in the food and pharmaceuticals industries.
Highlights
Adinandra nitida, a particular wild plant in South China, is a kind of flavonoid-rich plant source
It has been reported that the flavonoid content of its leaves could be > 20 % [1,2,3]
The objective of this study was to identify the main flavonoid in Adinandra nitida leaves, employ response surface methodology to optimize its ultrasonicassisted extraction, and determine the antioxidant activity of the obtained spectrophotometer (Bruker, Germany) and the data were recorded and processed by OPUS 4.0 software
Summary
A particular wild plant in South China, is a kind of flavonoid-rich plant source. It has been reported that the flavonoid content of its leaves could be > 20 % [1,2,3]. The classical techniques for the solvent extraction of materials from plants are based upon the correct choice of solvent coupled with the use of heat and/or agitation. The extraction of organic compounds contained within the body of plants and seeds by a solvent is significantly improved by the use of power ultrasound. The mechanical effects of ultrasound provide a greater penetration of solvent into cellular materials and improves mass transfer. There is an additional benefit for the use of power ultrasound in extractive processes which results from the disruption of biological cell walls to facilitate the release of contents [4]
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