Leaf essential oils of the genusLeptospermum (Myrtaceae) in eastern Australia, Part 6.Leptospermum polygalifolium and allies

Abstract

The leaf essential oils of Leptospermum polygalifolium and related species were isolated and examined. L. morrisonlii produced an essential oil in which the principal component was the β-triketone grandiflorone, while in L. oreophilum the principal component was (E,E)-farnesol. L. variabile gave oils with a spread of composition, the majority of samples being rich in geranyl acetate, β-caryophyllene and humulene, while another sample was rich in 1,8-cineole and a further sample contained comparable amounts of α-pinene, β-caryophyllene and α-, β- and γ-eudesmol. Leptospermum sp. (Mt Maroon, A.R. Bean 6665) appeared to be a chemically variable species; one specimen showed β-caryophyllene and humulene as principal components, while a second gave an oil rich in sesquiterpenes with β-caryophyllene, δ-cadinene, calamenene and an unidentified sesquiterpene hydrocarbon being the major contributors. Of the seven subspecies of L. polygalifolium, ssp. polygalifolium, montanum and howense contained oils which were rich in α-, β, and γ-eudesmol. These were the only subspecies to contain these compounds in more than trace amounts. Of the remaining four subspecies, ssp. cismontanum, transmontanum, tropicum and ‘wallum’, all contained significant amounts of 1,8-cineole. They usually contained larger quantities of spathulenol. All seven subspecies contained α-pinene in significant amounts, while all but spp. howense also contained β-pinene, usually in comparable amounts. Leptospermum madidum spp. sativum gave an oil rich in monoterpenes, with α-pinene, β-pinene, and γ-terpinene being the major components. α-, β-, and γ-eudesmol also made significant contributions to the oil. Copyright © 2000 John Wiley & Sons, Ltd.