No abstract

Six samples of red thyme (Thymus zygis) and two samples of winter thyme (Thymus hyemalis) essential oils (EOs) were obtained from plants cultivated in south-eastern Spain and extracted by steam distillation. Analysis by gas chromatography coupled with mass spectrometry detection provided the relative (%) and absolute (mM) concentrations. Thymol (30-54%), p-cymene (14-27%) and γ-terpinene (8-28%) were the most abundant components of T. zygis EO, while 1,8-Cineole (3-37%), p-cymene (1-29%), linalool (8-13%) and thymol (0-19%) were the most abundant components in the case of T. hyemalis EO. Enantioselective gas chromatography identified (-)-linalool, (-)-borneol and (+)-limonene as the main enantiomers. Several methods to evaluate antioxidant capacities were applied to the EOs, concluding that their activities were mainly due to thymol and linalool. The inhibition of lipoxygenase activity, mainly due to thymol, p-cymene and linalool, suggested their possible use as anti-inflammatories. The high antibacterial and antifungal activities determined for the EOs means that they can be used as natural preservatives. The results support the potential use of Thymus sp. EOs as natural food, cosmetic and pharmaceutical ingredients.

Compositions of true lavender (Lavandula angustifolia) and spike lavender (Lavandula latifolia) essential oils, cultivated and extracted in the Southeast of Spain, were determined by gas chromatography coupled with mass spectrometry detection, obtaining both relative (peak area) and absolute (using standard curves) concentrations. Linalool (37-54 %), linalyl acetate (21-36 %) and (E)-β-caryophyllene (1-3 %) were the most abundant components for L. angustifolia. Linalool (35-51 %), eucalyptol (26-32 %), camphor (10-18 %), α-pinene (1-2 %), α-terpineol (1-2 %) and α-bisabolene (1-2 %) were the most abundant components for L. latifolia. The characterization was completed with enantioselective gas chromatography, in which the determined main molecules were (-)-linalool, (-)-linalyl acetate and (+)-camphor. (S)-(-)-camphene, (R)-(+)-limonene, (1R, 9S)-(-)-(E)-β-caryophyllene and (1R, 4R, 6R, 10S)-(-)-caryophyllene oxide were found in this study as the predominant enantiomers in Spanish L. angustifolia. The characterised essential oils were tested for their antioxidant activity against free radicals ABTS, DPPH, ORAC, chelating, and reducing power. Inhibitory activity on lipoxygenase was observed indicating a possible anti-inflammatory activity, mainly due to linalool, camphor, p-cymene and limonene. These results can be the starting point for a future study of the potential use of L. angustifolia and L. latifolia essential oils as natural cosmetic and natural pharmaceutical ingredients for several skin diseases.

A flow-injection configuration for the determination of formaldehyde is proposed. The method is based on the enhancing effect of formaldehyde on the oxidation of acridine yellow by bromate in acidic medium. The proposed procedure is simple, inexpensive, sensitive and suitable for concentrations of formaldehyde between 1 and 56 microg mL(-1). A sampling-rate of 60 samples h(-1) was achieved. The effect of several organic and inorganic species was studied. The method was applied to the determination of formaldehyde in pharmaceuticals, milk and air in work environments. The accuracy of the method was confirmed by comparing the results with those obtained using the standard acetylacetone method.

The compositions of essential oils (EOs) from Spanish marjoram (Thymus mastichina L.) grown in several bioclimatic zones of Murcia (SE Spain) were studied to determine their absolute and relative concentrations using gas chromatography-mass spectrometry. 1,8-Cineole and linalool were the main components, followed by α-pinene, β-pinene and α-terpineol. (–)-Linalool, (+)-α-terpineol and (+)-α-pinene were the most abundant enantiomers. When the antioxidant capacities of T. mastichina EOs and their compounds were measured by five methods, EOs and linalool, linalyl acetate, α-terpinene and γ-terpinene, among others, showed antioxidant activities. All four T. mastichina EOs inhibited both lipoxygenase and acetylcholinesterase activities, and they might be useful for further research into inflammatory and Alzheimer diseases. Bornyl acetate and limonene showed the highest lipoxygenase inhibition and 1,8-cineole was the best acetylcholinesterase inhibitor. Moreover, these EOs inhibited the growth of Escherichia coli, Staphylococcus aureus and Candida albicans due to the contribution of their individual compounds. The results underline the potential use of these EOs in manufactured products, such as foodstuff, cosmetics and pharmaceuticals.