ESSENTIAL OILS FROM NEW-ZEALAND MANUKA AND KANUKA - CHEMOTAXONOMY OF LEPTOSPERMUM

Standardized steam distillation and GC analytical methods for oils fro m manuka, Leptospermum scoparium, are described. These methods were us ed to analyse two oils from each of 15 L. scoparium populations derive d from all around New Zealand, seven Australian Leptospermum populatio ns and one population of Kunzea sinclairii. These populations were all grown from seed at a single site. Principal component analyses of the levels of 50 GC peaks in these 46 oils revealed compositional pattern s. Kunzea sinclairii oils were distinguished from Leptospermum oils by higher alpha-pinene levels (mean 76%). Australian Leptospermum oils h ad significantly higher 1,8-cineole (mean 20%) and total monoterpene l evels (mean 51%) than New Zealand L. scoparium oils (1,8-cineole mean 0.9%, total monoterpene mean 14%). This indicates the need for further taxonomic study of plants currently included in L. scoparium in Austr alia and New Zealand. There is evidence for three chemotypes of L. sco parium in New Zealand, conforming in part to morphological types: a hi gh-pinene chemotype in the far north, a high-triketone (especially lep tospermone) chemotype on the East Cape, and a type containing a comple x of sesquiterpenes found over the rest of the country. An oil from th e East Cape chemotype showed the strongest antimicrobial activity. Cop yright (C) 1997 Elsevier Science Ltd.