A detailed analysis of Rosmarinus officinalis L. essential oil from Sardinia and Corsica (˛-pinene/verbenone/bornyl acetate chemotype) was carried out using GC-RI, GC-MS and 13 C-NMR, on the bulk sample or after repeated chromatography. Fifty-eight compounds were identified. The antimicrobial activity of two Sardinian samples was investigated and both exhibited a moderate antibacterial activity. Gram-positive bacteria were more sensitive (MIC 2.5-4 mg/ml) than Gram-negative bacteria. Killing time experiments demonstrated that prolonged times (60 min) are needed to completely inactivate the bacterial inoculum.

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A commercial sample of the essential oil of Chenopodium ambrosioides L. from Madagascar was analysed by GC, GC-MS and 13C-NMR. By GC analysis, the major constituents were found to be ascaridole (1) (41.8%), isoascaridole (2) (18.1%), p-cymene (16.2%), alpha-terpinene (9.7%) and limonene (3.8%). However, ascaridole undergoes a partial thermal isomerisation to 2 and hence the amount of 1 is under-estimated by GC analysis. The actual contents of 1 and 2 (55.3 and 4.6%, respectively) were obtained following combined analysis of the sample by GC and 13C-NMR. Several hydroxy- and polyhydroxy-menthanes were identified by 13C-NMR.

Tome e Prõ ncipe were investigated for the ®rst time. They were analysed by GC, GC-mass spectrometry and 13 g NMR. Monoterpene hydrocarbons were the main group of constituents in three of the samples (P. capense, P. nigrum and P. umbellatum), whereas for the other species (P. guineense) phenylpropanoid derivatives were the most important ones. b-Pinene (32.5%) and b-caryophyllene (12.6%) were the major compounds in the volatile oil of P. capense. Dillapiole (44.8%), followed by myristicin (9.8%), were the main constituents of P. guineense. The most important constituents in the essential oil of P. nigrum were limonene (18.8%), b-caryophyllene (15.4%), sabinene (16.5%) and b-pinene (10.7%). The essential oil of P. umbellatum was characterised by its high b-pinene (26.8%), a-pinene (17.6%) and (E)-nerolidol (12.4%) content.

The essential oil composition of three Zingiberaceae widely used as medicinal aromatic plants from S. Tomé and Príncipe: Aframomum danielli (Hook. f.) K. Schum., Curcuma longa L. and Zingiber officinale Rosc. was studied. Two samples of the essential oils from fruit of A. danielli and from rhizomes of the other two species, were obtained by hydrodistillation and analyzed by GC, GC-MS, and (13)C-NMR. The essential oil from fruits of A. danielli has been studied for the first time and was characterised by its high content of monoterpenes, with 1,8-cineole (25.5 - 34.4 %) the major constituent, followed by beta-pinene (14.1 - 15.2 %) and alpha-terpineol (9.9 - 12.1 %). Essential oils from the rhizomes of C. longa contained a lower content of ar-turmerone (4.0 - 12.8 %) than those reported in the literature for C. longa from other origins (24.7 - 31.4 %), whereas the results for Z. officinale essential oils were in accordance with the literature data. The essential oils of A. danielli and Z. officinale showed antimicrobial activity against all Gram-positive and Gram-negative bacteria tested, as well as against yeasts and filamentous fungi, using the agar diffusion method.

Peel and leaf oils of 30 sour orange cultivars, belonging to four different species (C. aurantium L., C. myrtifolia Raf., C. natsudaidai Hay. and C. neo‐aurantium Tan.) were obtained from fruits and leaves collected on sour orange trees submitted to the same pedoclimatic and horticultural conditions. Their chemical composition was investigated by capillary GC, GC–MS and 13C‐NMR. Two chemotypes, limonene and limonene/β‐pinene, were distinguished for peel oils, while four chemotypes, linalool/linalyl acetate, sabinene/(E)‐β‐ocimene, limonene/β‐pinene and β‐pinene/linalool, were observed for leaf oils. Copyright © 2001 John Wiley & Sons, Ltd.

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