[Aromatic and polyphenolic composition of infused peppermint, Mentha x piperita L].

The qualitative and quantitative composition of the main aromatic and polyphenolic constituents of Mitcham type peppermint (Mentha x piperita L.) tisane, were examined and compared with those of leaves before and after infusion. The original peppermint leaves contained 2.4% essential oil of which menthol was 0.99%, total polyphenolic compounds 19% and total flavonoid compounds 12% comprising eriocitrin 7%, luteolin-7-rutinoside 1.5%, hesperidoside 0.6% and total hydroxycinnamic compounds 7% (rosmarinic acid 1.4%). The tisane contained 21% of the original essential oil corresponding to 25 mg/l, with increased alcohol and ketone contents and lower contents of hydrophobic terpenecarbons, oxides and esters. It contained also a high proportion of the polyphenolic compounds (about 750 mg/l) corresponding to an extraction yield of 75%. In consequence the monograph "Peppermint leaf" of the Pharmacopoeia should be amended.