Ultrasonics Sonochemistry 8 (2001) 299±301

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The extraction of rutin from ¯ower buds of Sophora japonica
L. Paniwnyk *, E. Beaufoy, J.P. Lorimer, T.J. Mason
School of Natural and Environmental Sciences, Coventry University, Coventry CV1 5FB, UK

Abstract
The eciency of extraction of rutin from Sophora japonica is improved by ultrasound but is dependent on the solvent employed.
Rutin is a compound with antioxidant activity and aqueous solvents appear to be unsuitable for ultrasonic extractions due to the
formation of free radicals from the insonation of the solvent. The application of ultrasound to methanolic extraction gave a signi®cant reduction in extraction time and an increase in maximum yield. Ó 2001 Elsevier Science B.V. All rights reserved.
Keywords: Rutin; Extraction; Ultrasound; Antioxidant

1. Introduction
Renewed interest in plant derived drugs has led to an
increased need for ecient extraction methods. The aim
of this study was to compare conventional and ultrasonic methods for the extraction of the ¯avonoid, rutin
(Fig. 1) from the dried ¯ower buds of the Chinese
Scholar Tree (Sophora japonica) [5].
Flavonoids are products of secondary metabolism in
plants and are of interest to the pharmaceutical and
food industries because of their reported antioxidant
activity [1]. Such compounds can interact with free
radicals and so prevent the damage which radicals might
otherwise cause to cell membranes and biological molecules such as DNA.
Ultrasound has been shown to aid extraction in a
number of plant materials by signi®cantly reducing extraction times and increasing maximum extraction
yields. An example is the extraction of helicid, a Chinese
medicine used in the treatment of fatigue and listlessness, from the dried seeds of Helicid erraticum using
aqueous ethanol [2]. Conventional extraction is usually

2. Results and discussion
Conventional extraction methods using dilute aqueous alkali and methanol as solvents were compared with
ultrasonic extractions in the same solvents. In aqueous
extractions ultrasonic methods were found to give reduced yields when compared with conventional methods
as shown in Fig. 2.

1350-4177/01/$ - see front matter Ó 2001 Elsevier Science B.V. All rights reserved.
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L. Paniwnyk et al. / Ultrasonics Sonochemistry 8 (2001) 299±301

Fig. 1. Structure of rutin.

Fig. 3. E€ect of ultrasound on the extraction of rutin from Sophora
japonica using methanol.

during sonication of methanol the extracted rutin is not
degraded.

3. Experimental methods
The conventional and ultrasonic methods employed
are summarised as follows:
3.1. Aqueous extractions
Fig. 2. E€ect of ultrasound on the extraction of rutin from Sophora
japonica using water.

The observed reduction in extraction yield is believed

6±8 and the solution was boiled for 30 min. It was ®ltered under vacuum and the ®ltrate was acidi®ed and
left to stand overnight. The resulting precipitate was
collected by vacuum ®ltration and dried in an oven at
70°C.
3.2. Alcoholic extractions
Ten grams of dried ¯ower buds were crushed using a
pestle and mortar and mixed with methanol (100 cm3 ).
The mixture was either re¯uxed (for conventional extraction) or subjected to ultrasound (for ultrasonic extraction) using a 20 kHz ultrasonic probe at 23°C for
varying lengths of time. The mixture was ®ltered and the
solvent removed using a rotary evaporator. The residue,


L. Paniwnyk et al. / Ultrasonics Sonochemistry 8 (2001) 299±301

containing rutin alcoholate, was dissolved in water to
convert it into the hydrated form which precipitated
from solution. The mixture was extracted with diethyl
ether to remove chlorophyll and the precipitate in the
aqueous phase was collected by vacuum ®ltration and
dried in an oven at 70°C.

301

Acknowledgements
The authors thank the EC for ®nancial support
(COPERNICUS research program ERB-CIPA-CT940227-1995).
References

4. Conclusions
In any extraction process consideration must be given