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Optimization of Aqueous Two-Phase Extraction of Total Flavonoids from Farfugium japonicum (L. f.) Kitam by Response Surface Methodology and Antibacterial Activity

CHEN Jianzhong1,2, GE Shuilian1, ZAN Lifeng1, XING Haochun1, FU Jing1, WANG Gengxian1   

  1. 1. College of Life Science and Engineering, Handan College, Handan 056005, China;
    2. Wild Resources Plant Research Center of South Hebei Mt. Taihang, Handan 056005, China
  • Online:2015-12-25 Published:2015-12-24

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Abstract:

Objective: To optimize the aqueous phase extraction system for total flavonoids (TFF) from the aboveground
parts of Farfugium japonicum and to study the antibacterial activity of the extract. Methods: Ultrasonic was used to assist
C2H5OH-(NH4)2SO4 aqueous two-phase extraction of TFF, and the multivariate quadratic regression model using TFF yield
as the response variable was established based on a Box-Behnken experimental design involving three factors at three levels
each and subjected to analysis of variance (ANOVA) and response surface analysis. The Kirby-Bauer disk diffusion method
was used to determine the diameters of inhibition zone of six tested strains and the minimum inhibitory concentration (MIC)
and minimum bactericidal concentration (MBC) values were compared to study their antibacterial activities. Results: The
24% C2H5OH-18% (NH4)2SO4 aqueous two-phase extraction system was found to be optimal to extract TFF. The results
of ANOVA showed that mass fraction of TFF in crude ethanolic extracts significantly affected the extraction rate of TFF
(P = 0.023 9 < 0.05), but the effects of pH and NaCl concentration in the aqueous two-phase system were not significant.
The optimal extraction conditions were determined as follows: crude extract concentration, 20%; pH, 7.64; and NaCl
concentration, 2.68%. Under these conditions, the maximum extraction rate of 96.366 7% (P = 0.994) was obtained. The
inhibitory effect of TFF on Bacillus subtilis was the strongest with a percentage inhibition of 98.67% at high dose and an
MIC of 1.56 mg/mL, followed by Salmonella, Staphylococcus aureus and Escherichia coli, and the inhibitory effects on
Penicillium and Aspergillus niger were the weakest. Conclusions: The flavonoid concentration of crude extracts had greater
influence on the extraction rate of TFF than pH and NaCl. TFF showed obvious antibacterial activity against the six tested
strains. The percentage inhibition was positively correlated to TFF concentration. The antibacterial activity of TFF was
relatively stronger against bacteria than fungi.

Key words: response surface methodology, aqueous two-phase extraction, total flavonoids, F. japonicurn (L. f.) Kitam, antimicrobial activity

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