Bay laurel contains antimutagenic kaempferyl coumarate acting against the dietary carcinogen 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2)

A novel antimutagen in bay laurel (Laurus nobilis L.) acts against the diet ary carcinogen 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). The antim utagen was purified chromatographically from ethyl acetate extract of bay l eaf and identified instrumentally to be 3-kaempferyl p-coumarate. The yield was 20 mg from 100 g of bay, and its IC50 value, the amount required for 5 0% inhibition of the mutagenicity of 20 ng of Trp-P-2, was 1.9 mu g. This v alue is close to those for strong antimutagens such as flavones and flavono ls. The antimutagenicity was due to a desmutagenic action that inhibited th e metabolic activation of Trp-P-2 to its ultimate carcinogenic form. The ka empferyl moiety contributed to the activity. Interestingly, this compound h ad weak bioantimutagenicity and could also suppress the mutagenicity of dir ect mutagens.