Occurrence of various chemotypes in niaouli [Melaleuca quinquenervia (Cav.) S. T. Blake] essential oil from New Caledonia

The chemical composition of the leaf essential oil of Melaleuca quinquenervia (Cav.) S. T. Blake from New Caledonia has been investigated on 133 samples collected from seven harvesting locations on the island. Forty-two components were identified by GC–MS analysis and the major ones were 1,8-cineole (0.1–76%), viridiflorol (0–67%), p-cymene (0–40%), γ-terpinene (0–33%), α-pinene (0–30%), α-terpineol (0–24%), terpinolene (0–19%), limonene (0.1–16%) and ledol (0–21%). Viridiflorol and ledol, two sesquiterpene alcohols, were identified unambiguously by 1H- and 13C-NMR analyses. A sulphur compound, methylthiobenzoate, was characterized by gas chromatography–mass spectrometry (GC–MS). Niaouli essential oils from New Caledonia were classified into three chemotypes, using principal component analysis (PCA). Of these three chemotypes, found co-occurring in the harvesting locations across the island, chemotype 2, already characterized in Madagascar, is rich in 1,8-cineole (up to 80%) and is widespread (65.4% of the overall samples); chemotype 1 (24.8% of samples) is rich in terpinene derivatives; and chemotype 3 (9.8% of samples) is rich in α-pinene and viridiflorol. Copyright © 2006 John Wiley & Sons, Ltd.