Composition of the Leaf Oils of the Australian Species of Euodia and Melicope (Rutaceae)

Abstract

The leaf oils of the 14 Australian species of the genera Euodia and Melicope have been analyzed by GC and GC/MS. Euodia hylandii produced a leaf oil that was dominated by sesquiterpenes, with spathulenol (12–20%) as the major component. Euodia pubifolia gave a primarily sesquiterpenic oil with the major component being spathulenol (18.3%). Melicope affinis produced a sesquiterpenic oil in which the major components were the hydrocarbons bicyclogermacrene (7–18%) and (β-bisabolene (t-9%). Melicope bonwickii gave an oil in which sesquiterpenes predominated; zierone (0.3–3%) and three further suspected isomers (A, B each 5–10% and C 13–20%) were the principal components. The leaf oil of M. broadbentiana was, in most cases, dominated by monoterpenes. The major components detected were α-pinene (21–76%) and limonene (0.6–28%). Melicope elleryana gave a leaf oil which was dominated by zierone (26–42%) and the chromenes, allo-evodione (4–10%) and evodione (10–22%). Melicope fellii produced a sesquiterpenic oil with the principal components being (β-caryophyllene (9.9%), α-humulene (8.4%) and caryophyllene oxide (7.4%). Melicope hayesii produced an oil which was sesquiterpenic in nature. The principal components were bicyclogermacrene (22.8%), germacrene D (13.9%), (E,E)-α-farnesene (9.2%) and globulol (10.6%). Melicope jonesii also produced a complex sesquiterpenic oil with no one compound predominating. The leaf oil produced by M. micrococca was variable, with the major components being α-pinene (1–46%), (E)-(β-ocimene (t-10%), (β-caryophyllene (0.4–15%), bicyclogermacrene (t-11%), caryophyllene oxide (0.3–23%) and spathulenol (1–12%). The leaf oil of M. peninsularis was dominated by sesquiterpenes, with the principal components being (β-caryophyllene (30–49%) and α-humulene (26–35%). Melicope rubra gave a leaf oil containing significant amounts of both mono- and sesquiterpenes. Sabinene (31.1%), γ-terpinene and germacrene D (22.6%) were the principal components. The principal monoterpenes were sabinene (0.1–54%, the majority > 25%) and limonene (1–47%, the majority<2%). These were also the principal components of M. vitiflora. The leaf oil of M. xanthoxyloides contained major amounts of sesquiterpenes, though monoterpenes could contribute up to 20% of the oil. The principal components were (β-caryophyllene (13–47%), spathulenol (1–18%) and α-pinene (t-15%).