Regina Karousou

AUTUMN ESSENTIAL OILS OF GREEK OREGANO

The essential oils of Origanum vulgare subsp. hirtum plants collected in late autumn from six localities of three distinct geographic areas of Greece were analysed by means of GC and GC-mass spectrometry. A high quantitative variation was found in the amount of the four main components; γ-terpinene ranged from 0.6 to 3.6% of the total essential oil, p-cymeme from 17.3 to 51.3%, thymol from 0.2 to 42.8%, and carvacrol from 1.7% to 69.6%. Plants collected from the northern part of Greece were rich in thymol (30.3–42.8% of total oil), whereas those from the southern part of the country were rich in carvacrol (57.4–69.6% of total oil). Furthermore, comparison with the essential oils obtained from plants collected from the same localities in mid-summer shows noticeable differences in the total oil content and the concentration of the four main oil components.

Pattern of geographic variations of Origanum vulgare trichomes and essential oil content in Greece

Abstract The variation of the total plant pubescence and essential oil content of Origanum vulgare plants grown all over the species range in Greece has been studied. In respect to their glandular and non-glandular trichomes. o. vulgare plants are differentiated along a direction fromeastern and central Aegean islands, through Crete and Peloponnese, to the northern part of Greece. The same variation pattern is found when the essential oil content of O. vulgare plants is considered. Along this direction, a gradual change of the climate from the Real Mediterranean to the Continental Mediterranean type occurs. Plants grown in the Mediterranean climatic zones are characterized by numerous sessile glands and are essential oil-rich (ssp. hirtum), whereas those of the Continental type climate have few glands and are oil-poor (ssp. viridulum and ssp. vulgare).

Effects of enhanced UV-B radiation on Mentha spicata essential oils

Abstract In vitro propagated plantlets representing two distinct chemotypes of Mentha spicata, viz. plants producing essential oils rich in piperitone oxide and piperitenone oxide (chemotype I) and rich in carvone and dihydrocarvone (chemotype II), were grown in the field under ambient or ambient plus supplemental UV-B radiation, biologically equivalent to a 15% ozone depletion over Patras (38.3°N, 29.1°E), Greece. Enhanced UV-B radiation stimulated essential oil production in chemotype II substantially, while a similar, non-significant trend was observed in chemotype I. No effect was found on the qualitative composition of the essential oils, whereas the quantitative composition was slightly modified in chemotype I. This is the first investigation reporting an improved essential oil content under UV-B supplementation in aromatic plants under field conditions.

Essential Oil Composition of Greek (Origanum vulgare ssp. hirtum) and Turkish (O. onites) Oregano: a Tool for Their Distinction

Abstract Aiming to find out if any distinction between the Greek (Origanum vulgare ssp. hirtum) and Turkish oregano (O. onites) essential oils exists, the composition of six wild Greek populations of the former and four of the latter taxon were analyzed by means of GC and GC/MS. A PCA analysis showed that Turkish oregano oils had higher amounts of sabinene, myrcene, γ-terpinene, borneol and carvacrol, and Greek oregano oils had higher p-cymene content. The latter were further divided into two subgroups, distinguished respectively by their thymol and carvacrol content. A comparison of our results with the published information showed that p-cymene percentages>14% and/or thymol>6% is found only in Greek oregano, while borneol content>2% is found only in Turkish oregano oils.

Clinal Variation of Mentha pulegium Essential Oils Along the Climatic Gradient of Greece

Abstract The essential oil content and the C-3 oxygenated p-menthane compounds of Mentha pulegium collected from 38 populations scattered all over Greece are presented. The oil content ranged from 1.0–3.8 mL/100 g (d.w.) and the C-3 oxygenated p-menthane compounds constitute in all populations the bulk of the oil (78.6–99.7% of the total oil). The quantitative composition of the different oils varied greatly with most variable compounds being pulegone (ranging from < 0.1–90.7% of the total oil), piperitone (not detected-97.2%), menthone (0.2–53.4%), isomenthone (0.1—45.1%), piperitenone (< 0.1–39.8%) and isopiperitenone (not detected-23.5%). Discriminant analysis revealed that the oil variation forms a cline along Greece. In southern Greece, where the real Mediterranean climate dominates, the total oil content and the amounts of the more reduced products of the C-3 p-menthane biosynthetic pathway, menthone and/or isomenthone and their derivatives, were increased.

Variation of Pulegone Content in Pennyroyal (Mentha pulegium L.) Plants Growing Wild in Greece

Abstract The study of the essential oils obtained from 10 wild Mentha pulegium L. populations scattered all over Greece has shown that the content of pulegone varies greatly, ranging from <0.1–90.7% of tin total oil. Only two populations have oils rich in pulegone (42.9% and 90.7%), whereas the rest have a low pulegone content (up to 35.6%). The latter are rich either in menthone/isomenthone or in piperitone/piperitenone or in piperitone (up to 97.2% of the total oil).

Piperitone Oxide-Rich Essential Oils from Mentha longifolia subsp. petiolata and M. x villoso-nervata Grown Wild on the Island of Crete (S Greece)

The essential oils of Mentha longifolia subsp. petiolata and M. x villoso-nervata growing wild on scattered localities on the island of Crete (S Greece) are studied. The results of qualitative and quantitative analyses, by means of GC and GC/MS, have shown that all oils are characterized by the high contribution of C-3 p-menthane components, and in particular, by trans-piperitone oxide. Quantitative variation has been found in the total oil content and the percentages of the single components. The results are further discussed in comparison to data obtained from plants growing in Northern Greece.

Distribution and essential oils of Salvia pomifera subsp. pomifera (Labiatae) on the island of Crete (S Greece)

Abstract The distribution of Salvia pomifera subsp. pomifera (Cretan sage) on the island of Crete is presented. The essential oils of six populations scattered on the island are studied. The essential oil content varies from 2.1–4.2%, whereas the main oil components were in all cases α - and/or β -thujone (27.4–72.3% and 7.1–40.8%, respectively). The comparison of our results to literature data, suggest that S. pomifera can be distinguished from S. fruticosa (Greek sage), on the basis of its essential oil composition.

Essential Oils of Micromeria dalmatica Benth., a Balkan Endemic Species of Section Pseudomelissa

The essential oils of 13 Greek populations of Micromeria dalmatica, a Balkan endemic species and member of the section Pseudomelissa, were examined for the first time. Among the studied populations, two main oil types could be distinguished. Type I was found to be rich in β‐pinene, limonene, and germacrene D (accounting for 55.6–70.2% of the total oil), and Type II was characterized by the preponderance of p‐menthane compounds (accounting for 64.2–89.9% of the oil). The latter oil type could be further divided into two subtypes, one comprising oils with predominance of piperitenone and piperitenone oxide and another composed of oils containing high proportions of pulegone, menthone, and isomenthone. The abundance of p‐menthane compounds is a common feature of the oils of all members of the section Pseudomelissa studied to date. However, the existence of oils of Type I has not been previously reported for M. dalmatica, neither for other members of the section Pseudomelissa.

Distribution and clinal variation of Salvia fruticosa Mill. (Labiatae) on the island of Crete (Greece)

Abstract Karousou, R. & Kokkini, S.: Distribution and clinal variation of Salvia fruticosa Mill. (Labiatae) on the island of Crete (Greece). — Willdenowia 27: 113–120. 1997. — ISSN 0511-9618. The distribution of the aromatic species Salvia fruticosa on the island of Crete (S Greece) is presented in a grid map. Discriminant analyses of the variation in morphological features and essential oil content of 34 S. fruticosa populations from all over the distributional range on the island reveal that both the morphological and chemical variation form a W-E directed cline.