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Leaf essential oils of the genus Leptospermum (Myrtaceae) in eastern Australia. Part 7. Leptospermum petersonii, L. liversidgei and allies
Author(s) -
Brophy Joseph J,
Goldsack Robert J,
Punruckvong Acharaporn,
Bean Anthony R,
Forster Paul I,
Lepschi Brendan J,
Doran John C,
Rozefelds Andrew C
Publication year - 2000
Publication title -
flavour and fragrance journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.393
H-Index - 70
eISSN - 1099-1026
pISSN - 0882-5734
DOI - 10.1002/1099-1026(200009/10)15:5<342::aid-ffj924>3.0.co;2-v
Subject(s) - citronellal , chemotype , geranyl acetate , chemistry , citral , essential oil , botany , myrtaceae , geraniol , sesquiterpene , monoterpene , terpene , organic chemistry , food science , biology
Leptospermum amboinense was shown to exist in two chemical varieties, the oil of one chemotype being entirely sesquiterpenoid and that of the second predominantly monoterpenoid, while L. ?amboinense gave an oil which was monoterpenoid in character and contained geranial (13%) and sabinene (13%) as major components. The principal components of the oil of L. emarginatum were α‐eudesmol (7 – 17%), β‐eudesmol (17 – 26%) and γ‐eudesmol (9 – 18%). L. grandiflorum gave an oil which from a coastal location contained up to 50% of α‐, β‐ and γ‐eudesmol and from inland locations ca. 5% α‐, β‐ and γ‐eudesmol. There is a range of oil compositions within L. liversidgei , varying from oils that are high in citronellal (ca. 44%) and contain virtually no neral/geranial (the more common variety), to oils that contain very little citronellal and high amounts of neral (20%) and geranial (35%). The oil of L. petersonii was found to occur in chemical varieties, with much variation in most of them. Variety 1 contained aldehydes, ranging from high citronellal and low neral/geranial to low citronellal and high neral/geranial. Two oil chemotypes, comprising mainly hydrocarbons, were identified. One chemotype, corresponding to Penfold's ‘variety A’, contained mainly monoterpenes, while a newly discovered chemotype contained mainly sesquiterpenes, with either β‐caryophyllene or globulol/viridiflorol/spathulenol as major components. The existence of a further chemotype, corresponding to Penfold's ‘variety B’, containing geranyl acetate (21 – 38%) and geraniol (21 – 29%), was also confirmed. A study of the cotyledon and seedling leaf volatiles of a form of L. petersonii , the parent of which was rich in citronellal and neral/geranial, showed that both cotyledons and seedling leaf volatiles consisted of only sesquiterpene hydrocarbons, being δ‐elemene, bicycloelemene, β‐elemene, germacrene‐D and bicyclogermacrene. It was not until the seedling had 15 nodes (ca. 170 mm tall) that citronellal and neral/geranial were found in the leaves above the fifth node. Leptospermum rotundifolium produced an oil in which the principal components were α‐pinene (16 – 25%) and 1,8‐cineole (21 – 28%). The oil from L. wooroonooran contained comparable amounts of mono‐ and sesquiterpenes, the main monoterpenes being α‐pinene (4 – 11%), β‐pinene (4 – 9%), sabinene (9 – 19%), β‐caryophyllene (5 – 7%) and humulene (11 – 20%). Copyright © 2000 John Wiley & Sons, Ltd.