Reduction of safrole and methyleugenol in Asari radix and rhizoma by decoction

Asari r adix and rhizom a (Xixin, Manchurian Wildginger, Asarum spp) is a herbal drug commonly used as an ingredient in Traditional Chinese Medicine (TCM). Many species of Asarum contain safrole and methyleugenol as the main components of their volatile oils [1,2,3]. However, toxicological studies have shown that safrole may be a hepatocarcinogen and genotoxic leading to concerns regarding the habitual consumption of this herbal drug [4,5]. An HPLC method was established to assess the levels of safrole and methyleugenol in five batches of Asari r adix and rhizom a and two TCM formulae containing this herbal drug as an ingredient. Analysis showed that the content of safrole in the dried herbal drugs tested ranged from 0.14-2.78 mg/g whilst the content of methyleugenol ranged from 1.94-16.04mg/g.

The present study demonstrated that following a 1 hour decoction, the amount of safrole was decreased by more than 92% resulting in the equivalent of no more than 0.20 mg/g safrole remaining in the aqueous extract. Such a reduction in the content of safrole is regarded as acceptable for therapeutic use. Similarly, the content of methyleugenol was decreased to the equivalent of 0.30-2.70mg/g. Furthermore, both TCM formulae, after decoction, showed negligible amounts of safrole (maximum, the equivalent of 0.06mg/g), and only 1.38-2.71mg/g of methyleugenol. Therefore, the present study shows that a decoction procedure, traditionally used for Chinese herbal preparations, is able to reduce the amount of safrole and methyleugenol effectively.

Acknowledgments: We thank Lian ChinaHerb, Switzerland , and Mr Stöger, Austria, for the supply of herbal drug material as well as SWISSMEDIC, Swiss Agency for Therapeutic Products, Pharmacopoeia division, for the financial support.

References: [1] The State Pharmacopoeia Commission of China (2005) Pharmacopoeia of the People's Republic of China, Vol. 1. Chemical Industry Press. Beijing.

[2] Xiao, P.G. et al. (2002) Modern Chinese Materia Medica, Vol. 3. Chemical Industry Press. Beijing.

[3] Cai, S.Q. et al. (2008) Fitoterapia 79:293–297.

[4] Scientific Committee on Food, European Commission (2001) Opinion of the Scientific Committee on Food on the safety of the presence of safrole (1-allyl-3,4-methylene dioxy benzene) in flavourings and other food ingredients with flavouring properties. http://ec.europa.eu/food/fs/sc/scf/out116_en.pdf.

[5] Scientific Committee on Food, European Commission (2001) Opinion of the Scientific Committee on Food on Methyleugenol (4-Allyl-1,2-dimethoxybenzene). http://ec.europa.eu/food/fs/sc/scf/out102_en.pdf.