Information regarding drug interactions is useful for avoiding adverse effects from medicinal drug administration, and similar information is obviously desirable for health food products and supplements. When examining findings related to drug-supplement interactions, it is vital to understand pharmacokinetics such as drug absorption, distribution, metabolism, and excretion. The interaction disposition of one particular drug is primarily related to inhibition and induction of the drug-metabolizing enzyme cytochrome P450 (CYP). Thus, experiments evaluating the expression level of CYP isoforms in human hepatic microsomes and their relative ratio in drugs metabolized by them would be useful. However, investigations of drug-supplement interactions such as inhibition tests using the cDNA-expressed human CYP and specific substrates in combination are scarce. It is essential to consider studies for averting such interactions and to disseminate information for improving safety.

Coix lacryma-jobi L. var. ma-yuen Stapf is a grass long been used in traditional medicine as a nourishing food and reported to possess pharmacological effects including anti-tumor, anti-obesity, anti-diabetic, etc. In order to evaluate the possible mutagenicity of the hot water extract of all parts (husks, pellicles, and astringent skin) of the food, we performed a reverse mutation test in bacteria, a mouse lymphoma assay and a mouse micronucleus test. The results of all tests were negative. It was concluded that the extract has no mutagenicity for living bodies.