No. 88 Property improvements of arctigenin from burdock (Arctium lappa L.) using cyclodextrins
Burdock seeds are called "goboshi" and have been used as a traditional Chinese medicine. The key active ingredient of burdock seeds is arctigenin (ARG, Fig. 1). It has been reported that ARG exhibits various physiological activities such as anti-inflammatory, anti-HIV, anti-cancer and hepatoprotective activities 1). ARG is included not only in burdock seeds but also sprouts taken as food. Therefore, burdock sprouts are also expected to be used as health food materials in the future. However, burdock sprouts have strong bitterness and ARG has poor water solubility and low bioavailability 2). For the reasons, it is necessary to improve such properties when used in the health food field.
Cyclodextrins (CDs) have various functions such as solubilization in water, improvement of absorbability, stabilization, and masking of bitterness and astringency, by inclusion-complexing fat-soluble components.
Here, by the use of CDs, we investigated to improve the water solubility of ARG in burdock sprouts and also evaluated to reduce the bitterness of burdock sprouts.
Burdock sprouts were grown from the seeds in the dark at room temperature for 9 days. The obtained burdock sprouts were harvested, added with an appropriate amount of water and crushed with a mixer. The resulting dispersion was divided into 4 test tubes? and α-CD, β-CD and γ-CD were respectively added to three test tubes. The water-soluble fractions (burdock sprouts extracts) were taken from 4 test tubes and each amount of ARG was analyzed by HPLC. The bitterness of each sample was also evaluated.
Results and discussion
As a result of measuring the amount of ARG in the burdock sprouts extracts, the amount of ARG from the γ-CD dispersion of burdock sprouts was higher than that from the dispersion without CD. On the other hand, the amount of ARG from α-CD and β-CD dispersions were not significantly different in comparison with that from the dispersion without CD. From those points of view, it can be expected that the water solubility of ARG in burdock sprouts can be enhanced by using γ-CD to improve the low absorbability of ARG (Fig. 2).
Next, the bitterness suppression of burdock sprouts by adding CDs was evaluated. The strong bitterness of burdock sprouts could not be suppressed when α-CD or β-CD was added to the dispersion of burdock sprouts. On the other hand, it was found that the bitterness was remarkably suppressed when γ-CD was added to the dispersion of burdock sprouts.
The combination of burdock sprouts and γ-CD can be used for the development of new health foods and beverages as a ARG-containing material that 1) suppress the bitterness of burdock sprouts and 2) can be expected to have high absorption efficiency of ARG.
1) N. Hata, et al., Agriculture and horticulture, 86 (1), 10-20 (2011)
2) Cai E. et al., Sci. Rep., 8, 3307 (2018).
3) C. C. Ratnasooriya et al., Food Chemistry, 134, 625-631 (2012).