A. Cristina Figueiredo

Antimicrobial and antioxidant properties of some commercial essential oils

The essential oil composition of Cananga odorata, Boswellia thurifera, Cymbopogon citratus, Marjorana hortensis, Ocimum basilicum, Rosmarinus officinalis, Cinnamomum zeylanicum and Citrus limon was analysed by GC and GC–MS, and their antimicrobial and antioxidant activity tested. Twenty-five different genera of bacteria and one fungal species were used in this study as test organisms. These included animal and plant pathogens, food poisoning and spoilage bacteria and the spoilage fungus Aspergillus niger. The volatile oils exhibited considerable inhibitory effect against all the tested organisms. The oils also demonstrated antioxidant capacities, comparable with α-tocopherol and butylated hydroxytoluene (BHT). The method adopted in this study was the modified thiobarbituric acid reactive species (TBARS) assay. The antioxidant activity was carried out under different conditions by using egg yolk and rat liver in the absence and presence of the radical inducer 2,2′-azobis (2-amidinopropane) dihydrochloride (ABAP).

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.

Variability of essential oils of Thymus caespititius from portugal

Abstract The composition and variability of the essential oils of several populations of Thymus caespititius from Portugal were investigated by GC, GC-mass spectrometry and 13 C NMR. All samples from NW Portugal were characterized by their high α-terpineol content, while the main components in the oil sample from Pico island (Azores archipelago) were carvacrol and thymol. The analytical data of individual samples from NW Portugal showed no chemical polymorphism in this area. The different areas of distribution (NW Portugal and Azores) that show great climatic and soil variation conditions may be the origin of the α-terpineol-type oil from NW Portugal and the carvacrol/thymol-type oil from the Azores. 13 C NMR spectra of the essential oil, previously fractionated by column chromatography, led to the identification of trans -dihydroagarofuran, a new oxygenated sesquiterpene for the genus Thymus and a characteristic compound of T.caespitiuius .

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.

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.

Antioxidant Capacity of the Essential Oils From Lavandula luisieri, L. stoechas subsp. lusitanica, L. stoechas subsp. lusitanica x L. luisieri and L. viridis Grown in Algarve (Portugal)

Abstract The antioxidant capacity of the essential oils isolated from the aerial parts of Lavandula luisieri, L. stoechas subsp. lusitanica, the hybrid L. stoechas subsp. lusitanica x L. luisieri, and L. viridis collected in different regions of Algarve (Portugal), as well as that of butylated hydroxytoluene (BHT), was evaluated using three different methods: free radical scavenging activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) method, thiobarbituric acid reactive substances assay (TBARS) and reductive potential. The chemical composition of the essential oils was analyzed by GC and GC/MS. The oils of L. luisieri were mainly constituted by 1,8-cineole (26–34%) and trans-α-necrodyl acetate (11–18%), only present in this lavender species. The oils of Lavandula stoechas subsp. lusitanica and the hybrid L. stoechas subsp. lusitanica x L. luisieri were dominated by fenchone (42–44%) and camphor (35–36%). Despite of the morphological resemblances of the L. stoechas subsp. lusitanica x L. luisieri with L. luisieri, no necrodane derivatives were detected in the hybrid, showing instead a major chemical similarity with L. stoechas oil. Lavandula viridis oil mainly comprised 1,8-cineole (33%) and camphor (20%). The oils of L. luisieri were the most effective as antioxidants, independent of the evaluation method used, although showing always lower antioxidant ability than BHT.

Bioactivity against Bursaphelenchus xylophilus: Nematotoxics from essential oils, essential oils fractions and decoction waters.

The Portuguese pine forest has become dangerously threatened by pine wilt disease (PWD), caused by the pinewood nematode (PWN), Bursaphelenchus xylophilus. Synthetic chemicals are the most common pesticides used against phytoparasitic nematodes but its use has negative ecological impacts. Phytochemicals may prove to be environmentally friendly alternatives. Essential oils (EOs) and decoction waters, isolated from 84 plant samples, were tested against B. xylophilus, in direct contact assays. Some successful EOs were fractionated and the fractions containing hydrocarbons or oxygen-containing molecules tested separately. Twenty EOs showed corrected mortalities ⩾96% at 2 μL/mL. These were further tested at lower concentrations. Ruta graveolens, Satureja montana and Thymbra capitata EOs showed lethal concentrations (LC100)<0.4μL/mL. Oxygen-containing molecules fractions showing corrected mortality ⩾96% did not always show LC100 values similar to the corresponding EOs, suggesting additive and/or synergistic relationships among fractions. Nine decoction waters (remaining hydrodistillation waters) revealed 100% mortality at a minimum concentration of 12.5μL/mL. R. graveolens, S. montana and T. capitata EOs are potential environmentally friendly alternatives for B. xylophilus control given their high nematotoxic properties. Nematotoxic activity of an EO should be taken in its entirety, as its different components may contribute, in distinct ways, to the overall EO activity.

Essential Oil Composition and Glandular Trichomes of Marrubium vulgare L. Growing Wild in Algeria

Abstract A scanning electron microscopic (SEM) study of the aerial parts of Marrubium vulgare L. grown wild in Algeria showed a dense woolly indumentum of stellate, nonglandular, point-shaped trichomes that completely hide both the adaxial and abaxial leaf epidermes, as well as the stem and flower surfaces bearing the glandular trichomes. Peltate and two types of capitate trichomes constitute the morphological distinct glandular trichomes that are spread over the vegetative and reproductive organs. The essential oils of M. vulgare were obtained by hydrodistillation and distillation-extraction from the aerial parts collected during the flowering (F) and vegetative phases (V), and analyzed by GC and GC/MS. The essential oils were obtained in a yield of ≤ 0.05% (v/w). Eugenol was the main component in the F oil (50%) but comprised only 16% in the V oil. β-Bisabolene was the dominant component of the V oil (29%) and the second main component in the F oil (11%).