Mutagenicity testing of a herbal tea containing spiny restharrow (Ononis spinosa) root: results of an Ames-Test

The genus Ononis belongs to the family of Leguminosae. The dried root of Ononis spinosa is used for the irrigation of the urinary tract, especially in cases of inflammation and renal gravel and as an adjunctive treatment of bacterial urinary tract infections [1]. A publication of Joksic et al. [2] revealed increased micronuclei formation in human blood lymphocytes after treatment with an ethanolic Ononis root extract pointing to a possible clastogenic effect. Based on this finding the German health authority BfArM required further genotoxicity testing from the marketing authorisation holders. An in vitro bacterial reverse mutation assay was performed with an aqueous restharrow root extract (Bad Heilbrunner Nieren- und Blasentee) according to OECD-Guideline 471 [3]. Five concentrations ranging from 100–5000mg/plate where employed in independent experiments each carried out without and with metabolic activation. No sings of cytotoxicity where observed in both experiments each carried out without and with metabolic activation in all test strains. Furthermore, no mutagenic effect was observed for the tested extract up to a concentration of 5000mg/plate in any of the five test strains in two independent experiments without and with metabolic activation.

In conclusion, under the present test conditions the tested aqueous extract from restharrow root caused no mutagenic effect in the Salmonella typhimurium strains TA98, TA100, TA102, TA1535 and TA1537 neither in the plate incorperation test nor in the preincubation test each carried out without and with metabolic activation.

[1] ESCOP: Ononidis radix Monograph. Stuttgart, New York: Thieme; 2003: 351–353.

[2] Joksic G et al.: Antibacterial medicinal plants Equiseti herba and Ononidis radix modulate micronucleus formation in human lymphocytes in vitro. J Environ Pathol Toxicol Oncol. 2003; 22 (1): 41–48.

[3] OECD Guideline for testing chemicals: Bacterial Reverse Mutation Test, adopted 21st July 1997 (No. 471), pp. 1–11.