Abstract

Houttuynia cordata Thunb. is an aromatic and medicinal wild herb. However, little information is available about the monoterpene composition of the flowers and bracts. Gas chromatography-mass spectroscopy (GC-MS) analyses led to the identification of 15 monoterpenes in the essential oils of H. cordata accessions w01-39 [chemotype decanal (D)], w01-94 [chemotype myrcene (M)] and w01-100 (chemotype M). 13 to 14 monoterpenes were detected in the flowers of the three H. cordata accessions, respectively. 10 and 11 monoterpenes were found in the bracts of w01-94 and w01-100, respectively, while only 7 monoterpenes were observed in the bracts of w01-39. The contents of total monoterpenes in the flowers and bracts of chemotype D and M were all high (33.60 to 56.15%), while it only showed little variations (52.39 to 56.15%) in the flowers either within chemotype M or between chemotype D and M. Interestingly, although the leaves of w01-39 produced very low levels of monoterpenes, the flowers and bracts were rich in monoterpenes. Like leaves, both the flowers and bracts were dominated by monoterpene hydrocarbons represented mainly by β-myrcene and β-phellandrene. It therefore concluded that both the flowers and bracts could prove to be a useful source of monoterpenes.

Key words: Bracts, flowers, essential oil, Houttuynia cordata, monoterpenes.