Composition and chemical variability of myrtus communis leaf oil from northwestern Algeria

Abstract

Myrtus communis L. is a shrub growing wild in most countries all around the Mediterranean Sea and myrtle leaf oil is useful in the perfumery and pharmaceutical industries. Nowadays, “chemotyped” essential oils are more and more appreciated. Myrtle oil from eastern and central-north Algeria belong to the “α-pinene-cineole” chemotype. In contrast, Moroccan myrtle oil displayed appreciable content of myrtenyl acetate. Therefore, it appeared crucial to investigate the composition of myrtle leaf oil from northwestern Algeria in order to ensure the homogeneity of the composition of Algerian myrtle leaf oil. The chemical composition of 42 oil samples of M. communis isolated from leaves collected in five locations from Tlemcen Province was investigated by gas chromatography (GC) in combination with retention indices, GC-mass spectroscopy, and 13C nuclear magnetic resonance spectroscopy. Yields ranged between 0.13% and 1.04% (w/w). The chemical composition of the oils was largely dominated by monoterpene hydrocarbons, with α-pinene (24.3-59.0%) and 1,8-cineole (13.2-49.5%) being the major compounds followed by limonene (3.2-19.8%). The 42 compositions were submitted to statistical analyses. The combination of hierarchical cluster analysis and principal component analysis allowed the distinction of two groups, the second group being subdivided into two subgroups. Groups and subgroups were differentiated with respect to their contents of α-pinene and 1,8-cineole and, to a lesser extent, of limonene. This study ensures that Algerian myrtle leaf oil belongs to the “α-pinene-cineole” chemotype which displays various biological activities. The observed homogeneity could be a positive point to join the international market of essential oils.