Luis G. Pedro

Antimicrobial activity of essential oils isolated from Portuguese endemic species of Thymus

Aims: Thymus species are wild species mostly found in the arid lands of Portugal. Possible antimicrobial properties of Thymus essential oils have been investigated. The chemical composition of the essential oils and the antimicrobial activity of Thymus mastichina (L) L. subsp. mastichina, T. camphoratus and T. lotocephalus from different regions of Portugal were analysed.

Portuguese Thymbra and Thymus Species Volatiles: Chemical Composition and Biological Activities

Thymbra capitata and Thymus species are commonly known in Portugal as thyme and they are currently used as culinary herbs, as well as for ornamental, aromatizing and traditional medicinal purposes. The present work reports on the state of the art on the information available on the taxonomy, ethnobotany, cell and molecular biology of the Portuguese representatives of these genera and on the chemotaxonomy and antibacterial, antifungal and antioxidant activities of their essential oils and other volatile-containing extracts.

Essential oils from hairy root cultures and from fruits and roots of Pimpinella anisum

Abstract Hairy root cultures of Pimpinella anisum were established following inoculation of aseptically grown plantlets with an A 4 pRiA 4 70 GUS strain of Agrobacterium rhizogenes . The essential oils from the hairy roots, maintained in four different media, and from the fruits and roots of the parent plant were analysed and their compositions compared by GC and GC-mass spectrometry. The major components of the essential oils from the hairy root cultures were trans -epoxypseudoisoeugenyl 2-methylbutyrate, geijerene, pregeijerene, zingiberene and β-bisabolene, in varying amounts depending on the light or dark growth conditions and on the culture media tested. trans -Epoxypseudoisoeugenyl 2-methylbutyrate, β-bisabolene and pregeijerene were the major components of the essential oil from the roots of the parent plant, whereas the main component of the fruit oil was trans -anethole. Geijerenes were not detected in the fruit oil. The essential oil yield of the transformed roots grown in one of the media was comparable with that obtained for the roots of the parent plant and, calculated on a dry weight basis, the oil yield of these hairy roots was comparable with that of the fruits.

Plectranthus madagascariensis: Morphology of the Glandular Trichomes, Essential Oil Composition, and Its Biological Activity

Glandular and nonglandular trichomes are spread over the vegetative and reproductive organs of Plectranthus madagascariensis. Two morphologically distinct types of glandular trichomes (capitate and peltate) are described. Capitate trichomes have an ovoid unicellular head and a short stalk cell or an elongated two- to three-celled stalk slightly enlarged at the base. Peltate trichomes, which show in vivo a characteristic orange-to-reddish color, are large, flattened-to-depressed in the center, and often appear as a ring of minute gems. They are composed of a large head with eight glandular cells arranged in a single layer. An unusual kind of capitate trichomes, reported for the first time in Lamiaceae, occurs typically restricted to the calyx. These trichomes possess a two- or three-celled stalk and a long, unicellular conical, glandular head. The several types of trichomes differ in the secretion process The essential oils of P. madagascariensis, isolated by hydrodistillation and by distillation-extraction separately from flowers and from leaves collected during the flowering and the vegetative phases of the plant were analyzed by gas chromatography and gas chromatography-mass spectrometry (GC and GC-MS). The main component of the oils was a diterpene, 6,7-dehydroroyleanone, isolated as orange-to-reddish crystals, which represented 28%, 87%, and 41% of the oils from the flowers and from the leaves collected during the flowering and vegetative phases, respectively. The essential oils of P. madagascariensis showed bactericidal activity against Bacillus subtilis, Micrococcus sp., Staphylococcus aureus, and Yersinia enterocolitica, and revealed a modest antioxidant activity.

Essential oils from Azorean Laurus azorica.

The essential oils isolated from leaves of ten and from unripe berries of eight populations of Laurus azorica (Seub.) Franco, collected on five islands of the Azorean archipelago, were analysed by GC and GC-MS. All oil samples were dominated by their monoterpene fraction (60-94%), alpha-pinene (15-37%) and 1,8-cineole (12-31%) being the main components of the leaf oils, while trans-beta-ocimene (27-45%) and alpha-pinene (12-22%) were the main components of the oils from the berries. The sesquiterpene fractions of the oils ranged from 3 to 17% and the main components were beta-caryophyllene (traces-8%) and beta-elemene (traces-3%) both in the leaf and berry oils. Some phenylpropanoid components were also present, in total amounting to 17%, trans-cinnamyl acetate (215% of the leaf oils) being the main component of this fraction. Cluster analysis of the enantiomeric composition of alpha- and beta-pinene in the oils from the leaves clearly showed two groups, one constituted by the two populations growing on the island S. Jorge, and the other constituted by the remaining populations.

Composition of the essential oil of Hypericum foliosum Aiton from five Azorean islands

Eight collective samples of terminal cymose inflorescences of Hypericum foliosum Aiton were collected on five islands of the Azores (S. Jorge. S. Miguel, Pico, Terceira and Faial). The essential oils isolated by hydrodistillation to estimate the oil yields, and by distillation-extraction to determine the percentage composition of the oils, were analysed by GC and GC-MS. The oil yield varied between 0.10% and 0.25% and the main components (> 5%) were n-nonane (29-73%), limonene (7-46%), terpinolene (1-19%), β-caryophyllene (1-7%) and β-pinene (0.3-6%). With the exception of one oil sample from S. Jorge, cluster analysis showed a high degree of similarity between the populations studied.

Chemical polymorphism of the essential oils from populations of Thymus caespititius grown on the island S. Jorge (Azores)

The compositions of the essential oils obtained from ten populations of Thymus caespititius grown on S. Jorge (Azores) were studied by GC and GC-MS. All the oils analysed were dominated by their monoterpene fraction (69-9%). The sesquiterpene fraction was rather small (4-17%) and consisted mainly of oxygen-containing compounds (3-13%). Enantiomeric ratio of sabinene and alpha-terpineol was investigated in the oils from some populations. (+)-Sabinene was detected with high enatiomeric purity (96 99%). Although ( +)-alpha terpineol was the predominant enantiomer, its purity varied considerably (66-97%). Cluster analysis of all identified components grouped the oils into four main clusters that corresponded with their major components: alpha-terpineol (43-68%), carvacrol (32-52%), thymol (44-58%) and sabinene (41%). The essential oil from Th. caespititius showed a clear chemical polymorphism, that was particularly evident among four populations growing along a 200 m distance at Pico Verde.

Essential oils from hairy root cultures and from plant roots of Achillea millefolium

Abstract The essential oils isolated from roots of two Achillea millefolium populations (BGL and CGA) and from two hairy root cultures (A4 and LBA) derived from one of these were analysed by GC and GC–mass spectrometry. The essential oils from the plant roots were obtained in a yield of 0.10% (BGL) and 0.05% (CGA) (v/w), whereas that of both hairy root cultures attained 0.05% (v/w). Compared on a dry weight basis, the yield from the hairy root cultures was similar to or higher than that from the plant roots. The oxygen-containing sesquiterpene fraction of the root oils from both plant populations was the most characteristic one, epi-cubenol being the main component of these oils (18% for BGL and 26% for CGA). Oxygen-containing monoterpenes constituted the most important fraction of the essential oils from both hairy root cultures, neryl isovalerate being the main component (27% and 43% for A4 and LBA, respectively). No major differences were detected in the root essential oil profiles of the two A. millefolium plant populations, but qualitative and quantitative differences were found between the essential oils from the plant roots and those from the hairy roots, and also between the oils from the two hairy root cultures.

HAIRY ROOT CULTURES OF ANETHUM GRAVEOLENS (DILL): ESTABLISHMENT, GROWTH, TIME-COURSE STUDY OF THEIR ESSENTIAL OIL AND ITS COMPARISON WITH PARENT PLANT OILS

Transformed root cultures of Anethum graveolens were induced by inoculation of aseptically grown seedlings with Agrobacterium rhizogenes carrying plasmid pRi 1855. The main component of the essential oils from the fruits and from the roots of the parent plant was carvone, whereas α-phellandrene and apiole were dominant in the oil from, respectively, the aerial parts and the hairy roots. The essential oils from the fruits, aerial parts and roots of the parent plant were at 2%, 0.3% and 0.06% (v/w), respectively, but only 0.02% (v/w) in the hairy root cultures. Growth of the hairy root cultures reached 600 mg dry wt/50 ml medium after 50 days. The essential oil composition did not change significantly during their growth.

Salvia officinalis L. essential oils: effect of hydrodistillation time on the chemical composition, antioxidant and antimicrobial activities

Salvia officinalis L. oils were isolated from the plants commercial dried aerial parts, by hydrodistillation, with different distillation times. The essential oils were analysed by gas chromatography and gas chromatography–mass spectrometry. The antioxidant ability was measured using a free radical scavenging activity assay using 2,2-diphenyl-1-picrylhydrazyl (DPPH), a thiobarbituric acid reactive substances (TBARS) assay, a deoxyribose assay for the scavenging of hydroxyl radical, an assay for site-specific actions and a 5-lipoxygenase assay. Antibacterial activity was determined by the agar diffusion method. 1,8-Cineole, α-pinene and camphor were the dominant components of all the essential oils. The different hydrodistillation times did not affect the oil yield nor the relative amount of the oil components. The time of hydrodistillation influenced the antioxidant activity. With the DPPH method, the oils isolated for 2 and 3 h were stronger free radical scavengers, while with the TBARS method, the highest antioxidant values were obtained in the oils isolated for 30 min, 2 and 3 h. Hydroxyl radical scavenging and lipoxygenase activity assays showed the best results with oils isolated for 1 and 3 h. With the deoxyribose method, sage oils at concentrations <1000 mg L−1 showed better activity than mannitol. The essential oil of S. officinalis showed very weak antimicrobial activity.