The essential oil of Phlomis lanata has been analyzed by GC/MS. 48 compounds (96.85%) of the oil were identified; a-pinene, limonene and trans-caryophyllene were found as main components. The essential oil showed a moderate activity against six Gram (+) bacteria and a stronger against the three tested pathogenic fungi.

Phlomis L. (Labiatae) comprises 12 taxa naturalized in Europe and its species are mentioned by Dioskorid as herbal drugs. P. lanata is a shrub, endemic of Crete.

Aerial parts of P. lanata were collected in Crete, Greece. A voucher specimen has been deposited in the Laboratory of Pharmacognosy, University of Athens.

Plant material was subjected to hydrodistillation using a modified Clevenger-type apparatus. Then, the oil was submitted to GC/MS. The GC-MS analyses were carried out using a Hewlett Packard 6890/5973 system, with a HP-5MS capillary column (30m x 0.25 mm; film thickness: 0.25 mm) GC oven initial temperature was 60°C and programmed to 280°C at a rate of 3°C/min. The identification of the chemical constituents was based on comparison of their retention Kovats indices, their retention times and mass spectra with those obtained from authentic samples and/or the NBS/NIST and the literature.

Antimicrobial activity

The bacteriostatic activity of the essential oil against the two Gram (+) bacteria: Staphylococcus aureus, S. epidermidis the four Gram (-) bacteria: E., Ent. cloacae, Kl. pneumoniae and Ps. aeruginosa and the antifungal activities against the pathogens fungi C. albicans, C. tropicalis and T. glabrata were determined, using the dilution technique, the MIC was measured for the oil, a-pinene and limonene (Table 2). Standard antibiotics (netilmicin, and amoxicillin with clavulanic acid) were used in order to control the sensitivity of the tested bacteria and 5-flucytocine, amphotericin B and intraconazole were used in order to control the tested fungi.

Results obtained in the qualitative and quantitative analysis are shown in Table 1. Fourty eight constituents were identified and quantified from the oil of P. lanata representing 98.85% (area percent) of the total oil. The major constituents were a-pinene (25.41%), limonene (15.67%), and trans-carryophyllene (8.76%).

The results on the bioassays showed that the oil appeared a moderate activity against the four of the six Gram (+) tested bacteria and a stronger one against the Gram (-) bacteria E. coli and P. aeruginosa (MIC values 3-6.5).

It is noteworthy that the oil exhibited a specific activity against all the three tested pathogenic fungi (MIC values 4.65-4.95mg/ml). In the screening standard of the pure monoterpene a-pinene as well as limonene, which were found to be the major compounds of the oil (25.4% and 15.67% respectively), were tested on the same cultures under identical conditions to compare their activity with that of the investigated oil. The results suggest that the activity of the oil can be attributed, to a considerable degree, to the existence of a-pinene which appears to possess a similar activity against all the tested microorganisms, as limonene appeared completely inactive.

1. De Filipps R.A. (1972): In: Flora Europaea, Tutin T.G, Heywood V.H, Burges N.A, Moore D.M, Valentine S.M, Webb D.A, editors, Cambridge University Press Vol.3., Cambridge, 145.

2. Gennadios P.G. (1997): Phytological Dictionary, Trohalia ed, Athens, 999.

3. Janssen A.M, Scheffer J.J.C., Baerheim Svendsen A.(1987): Antimicrobial Activity of Essential Oils: A 1976-1986 Literature Review. Aspects of the Test Methods, Planta Medica. 5, 395-397.