André Michet

QUALITATIVE AND QUANTITATIVE VARIATION IN MONOTERPENE CO-OCCURRENCE AND COMPOSITION IN THE ESSENTIAL OIL OF THYMUS VULGARIS CHEMOTYPES

Thymus vulgaris has a chemical polymorphism with six different chemotypes that show marked spatial segregation in nature. Although some populations have a single chemotype in majority, many have two or three chemotypes. In this study we analyze the quantitative variation among T. vulgaris populations in the percentage of oil composed of the dominant monoterpene(s) for each chemotype. In general, phenolic chemotypes (thymol and carvacrol), which occur at the end of the biosynthetic chain, have a significantly lower proportion of their oil composed of their dominant monoterpene than nonphenolic chemotypes (geraniol, α-terpineol, and linalool). This is due to the presence of high amounts of precursors (γ-terpinene and paracymene) in the oil of phenolic chemotypes. The essential oil of the nonphenolic thuyanol chemotype has four characteristic monoterpenes that together make up a lower proportion of the oil than the single dominant monoterpene of the other nonphenolic chemotypes. For all chemotypes, the percentage composition of the dominant monoterpene decreased significantly at sites where the chemotype is not the majority type. This decrease is correlated with a significant increase in either the proportion of the two precursors for the thymol chemotype or the monoterpenes characteristic of the other chemotypes at the site. The latter result suggests that a plant with dominant genes is responsible for the production of different monoterpenes can produce several molecules.

Study of clones of Salvia officinalis L. Yields and chemical composition of essential oil

The essential oil of Salvia officinalis L. in five selected clones of different origins (France, Hungary, Portugal, Romania, Czech Republic) was studied. Yields of oils from dried leaves were excellent (2–3%), and higher than those previously reported. The α:β-thujone ratio varied according to origin. Overall, some of the oils were of high quality in terms of their α- and β-thujone and camphor contents.

Essential Oils of Rosemary (Rosmarinus officinalis L.). The Chemical Composition of Oils of Various Origins (Morocco, Spain, France)

ABSTRACT The chemical composition of the essential oil of rosemary (Rosmarinus officinalis L.) from various geographical origins (Morocco, Spain and France) was determined by GC/MS. Although 48 constituents were identified, the oils of different origins could be differentiated based both on their physicochemical characteristics and their major components. The Spanish oils were found to be rich in α-pinene (19.4–24.7%), 1,8-cineole (19.0–21.8%) and camphor (16.3–18.9%), while the French oils possessed α-pinene (19.9–35.1%), 1,8-cineole (5.3–24.8%) and bornyl acetate (1.2–14.3%). Moroccan oils were typically rich in 1,8-cineole (43.5–57.7%).

Essential Oils of Myrtle (Myrtus communis L.) of the Mediterranean Littoral

Abstract The chemical compositions of 15 commercial samples of essential oils of leaves of Myrtus communis L. from five different Mediterranean locations (Corsica, Morocco, Tunisia, Lebanon, and former Yugoslavia) were studied. Forty-seven compounds were identified by GC/MS. They could be divided into two groups on the basis of their percentages of α-pinene; over 50% (Corsica and Tunisia), and under 35% (the others). The percentages of limonene, 1,8-cineole and myrtenyl acetate were consistent with this classification. The chemical compositions of these oils can be compared to those of Spanish oils.

Variation of the Chemical Composition of Essential Oil of Mentha piperita L. during the Growing Time

Abstract This study was conducted over a period of three years. A marked inversion of the menthol/menthone ratio was observed according to harvesting time. The late blooming period gave oils rich in menthol. A second harvest gave a high-quality oil and increased overall yield. Pre-drying did not affect the chemical composition of the oil obtained but allowed larger amounts of plant material to be distilled.

Chemical Composition of Natural and Empyreumatic Oils and Extracts from Juniperus oxycedrus and Juniperus phoenicea Wood

ABSTRACT Ten oils (essential and empyreumatic) and extracts from the woods of Juniperus oxycedrus L. and Juniperus phoenicea L. were obtained by different methods (steam distillation, solvent extraction, wood pyrolysis, column chromatography, molecular distillation, rectification and extraction of precedent oils and extracts). The different oils and fractions were analyzed by coupled GC/MS; their chemical specificities are compared and discussed for subsequent dermatological applications.

Essential oil components in sawdust of Cedrus atlantica from Morocco

ABSTRACT The essential oil, which was obtained by steam distillation from the sawdust of Cedrus atlantica Man. from Morocco, was analyzed by GC and GC/MS. Fifty-three components were identified among which the three α-, β- and γ-isomers of himachalene (70%) were predominant. Smaller amounts of the (E) and (Z) isomers of α-, β- and γ-atlantone were also present.

Chemotypes in the Volatiles of Wild Thyme (Thymus pulegioides L.)

Abstract Two subspecies of Thymus pulegioides L. (subsp. effusus and subsp. similialpestris) were studied. Pentane extracts were analyzed by GC and GC/MS. Twenty-nine compounds were identified. The samples were collected in Massif Central (France) in Monts Dore and Puy de Sancy, altitude 1700 m. The main volatiles of Thymus pulegioides subsp. similialpestris were found to be α-terpinyl acetate (0–76.0%), γ-terpinene (0–24.5%), carvacrol (0–55.3%) and thymol (0–39.3%), thus revealing chemotypic differences. The main hybrid volatiles were α-terpinyl acetate (0–88.0%) and thymol (0–59.6%). In contrast, the main volatiles of Thymus pulegioides subsp. effusus were found to be α-terpineol (4.7–20.2%) and α-terpinyl acetate (65.4–81.4%). Preliminary examination of the data reveals the existence of an α-terpinyl acetate chemotype, carvacrol chemotype and a thymol chemotype of Thymus pulegioides subsp. similialpestris and an α-terpinyl acetate chemotype and a thymol chemotype of the Thymus pulegioides subsp. similialpestris x Thymus pulegioides subsp. effusus hybrid.

Bioconversion of Terpinolene and Its 4,8-Epoxide

ABSTRACT The action of Beauveria sulfurescens on terpinolene mainly gives products resulting from attack on the 4,8 double bond. Bioconversion of 4,8-epoxy p-menth-1-ene mainly gives p-menth-1-en 4,8-diol (Penicillium digitatum and Beauveria sulfurescens). The ratio of the two diastereoisomers is determined.