Chemical Composition of the Leaf Oil of Mentha rotundifolia (L.) from Algeria

Journal of Essential Oil Research: JEOR, Nov/Dec 2006 by Brada, M, Bezzina, M, Marlier, M, Lognay, G C

Abstract

Two Algerian origin oils of Mentha rotundifolia (L.) Hud. were analyzed by means of GC and GC/MS. Piperitenone oxide (23.5-38.6%) and cis-piperitone oxide (28.1-30.5%) were the two main constituents of the oils analyzed.

Key Word Index

Mentha rotundifolia, Lamiaceae, essential oil composition, piperitenone oxide, cis-piperitone oxide.

Introduction

Mentha rotundifolia (L.) Huds., Lamiaceae is a wild-growing, perennial, herbaceous, aromatic plant species, widespread in the nature. In Algeria and northern Africa, this endemic plant is well known such as "timarssat." In Algerian traditional medicine, it is popular and appreciated.

Mentha rotundifolia (L.) Huds. is a hybrid between M. longifolia (L.) and M. suaveolens Ehrh.(1-2). Some authors have considered M. rotundifolia (L.) Huds. as a synonym of M. suaveolens Ehrh. (3). Several studies dealing with the composition of M. rotundifolia oil from different parts of the world (1-11) have been reported and related chemotypes have been defined. One of them is particularly rich in piperitenone oxide, an oxygenated monoterpene whose biological effects (cardiovascular effects, CNS activity, antibacterial and antifungal properties, toxic, repellent and reproduction retardant toward malarial vector Anopheles stephensi) have been investigated (12-17). Moreover, this molecule is an interesting building-block for the chemical synthesis of heterocyclic compounds (18). The present article deals on the original GC/MS and GC characterization of the oils isolated from M. rotundifolia growing wild in two sites in Algeria.

Materials and Methods

Plant material and isolation of volatile constituents: Mentha rotundifolia leaves were collected in the second week of November 2004 in two localities of Algeria (Rouina: altitude 250 m, Miliana: altitude 780 in) within the region of Ain-Defla located in northern Algeria. Voucher specimens were deposited in the Herbarium of the Agronomic Institute of the Hassiba Ben Bouali University of Chief.

Air-dried leaves (10 g) of the two M. rotundifolia samples were finely ground and separately subjected to hydrodistillation for 1 h using a Likens-Nickerson apparatus. The solvent used was diethyl ether.

Gas chromatographic analysis: The analysis of the oil was carried out by HP GC 6890A with FID, using a capillary column coated with 5% phenyl methyl siloxane (30 m x 0.25 mm x 0.25 �m film thickness); column temperature, 40�C (1 min) to 200�C at 6�C/min, 200�-280�C at 30�C/min, 280�C (2 min). Injector temperature 280�C; detector temperature 300�C, injection mode, split; volume injected, 1 �L of the oil. Carrier gas was He, 1 mL/min.

Gas chroma to graphy/mass spectrometry: GC/MS was conducted using an Agilent 5973 GC/MS coupled to an Agilent 6890 gas chromatograph fitted with a split-splitless injector at 250�C (splitless mode). Analytical conditions have been fixed as follows: Agilent HP-5MS capillary column (30 m x 0.25 mm, 0.25 �m film thickness), temperature program: from 40�-250�C at 6�C/min, mobile phase: He at 1 mL/min. The mass spectra have been recorded in EI mode (70 eV), scanned mass range: 35 to 500 amu. Source and quadrupole temperatures were fixed at 230�C and 150�C, respectively. The identification of the components was performed on the basis of chromatographic retention indices and by comparison of the recorded spectra with computed data libraries (Wiley 275.L, Adams 2001). For sesquiterpene hydrocarbons, further confirmations were obtained by comparing the mass spectra with data from the literature (19,20).

Results and Discussion

Table I lists the compounds identified in the oils (yield: 0.2%), obtained by hydrodistillation, of wild M. rotundifolia. Thirty-nine compounds were identified in leaf oil of sample 1, the main one being cis-piperitone oxide. Piperitone oxide has been previously reported as the main constituent of the essential oils of M. rotundifolia (1,6,24).

Thirty-nine compounds were identified in leaf oil of sample 2. The main one being piperitenone oxide. This oxygenated monoterpene has been reported to characterize the oils of some chemotypes of Mentha spicata (8), M. longifolia (21, 22), M. villosa (23) and M. rotundifolia (2,5,24-26). Previous studies on the oil of M. rotundifolia revealed the existence of chemotypes with different major components, as menthyl acetate (1), dihydrocarvone (3), p-mentha-2,4(8),6-triene (8) and pulegone (10).

The present original study demonstrated that the oils composition of M. rotundifolia from Algeria is similar to those quoted in the literature.

References

1. S. Kokkini and V.P. Papageorgiou, Constituents of Essential Oils from Mentha x rotundifolia Growing Wild in Greece. Planta Med., 38, 166-167 (1988).

2. D. Lorenzo, D. Paz, E. Dellacassa, P. Davies, R. Vila and S. Canigueral, Essential Oils of Mentha puleglum and Mentha rotundifolia from Uruguay. Bras. Arch. Biol. Technol., 45, 519-524 (2002).

3. H. Hendriks and F.H.L. Van Os, Essential oils of two chemotypes of M. suaveolens during ontogenesis. Phytochemistry, 15, 1127-1130 (1976).