Chemical polymorphism of the essential oils from populations of Thymus caespititius grown on the islands Pico, Faial and Graciosa (Azores).

The compositions of the essential oils isolated from the aerial parts of 11 populations of Thymus caespititius collected during the flowering phase on Pico, Faial and Graciosa (Azores) were studied by GC and GC-MS. The monoterpene fraction was dominant in all the oils analysed (55-90%) and consisted mainly of oxygen-containing compounds (44-79%). Sesquiterpenes represented an important fraction of the oils from the populations grown on Graciosa (13-28%). In contrast, this fraction was rather small in the oils from the populations grown on Pico and Faial (6-11%). Despite this, oxygen-containing compounds (4-18%) were always dominant. Cluster analysis of all identified oil components grouped the oils into three main clusters that corresponded with their main components. The oils from the 11 populations studied showed a clear chemical polymorphism that, in some cases, was more evident among populations growing on the same island than among those from different islands.

Anti-bacterial activity of Galega officinalis L. (Goat's Rue).

Alcoholic extracts of Goat's Rue (Galega officinalis L.; Papilionaceae) were tested on Gram +ve and Gram -ve bacteria as the plant was claimed to hasten skin healing after surgery. Ethanolic (60%) extract exhibited significant inhibition on growth of both Gram +ve and Gram -ve bacteria.

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.

Pharmacological and antimicrobial studies on different tea-tree oils (Melaleuca alternifolia, Leptospermum scoparium or Manuka and Kunzea ericoides or Kanuka), originating in Australia and New Zealand.

Three different species of Myrtaceae growing in Australia and New Zealand are known as 'Tea-tree': the Australian Tea tree (Melaleuca alternifolia), the New Zealand Manuka (Leptospermum scoparium) and Kanuka (Kunzea ericoides). All three essential oils are used by aromatherapists, although only Melaleuca has been tested for toxicity, and its antimicrobial effects studied. The pharmacology and antimicrobial activity of the three 'tea-tree' oils was determined using guinea-pig ileum, skeletal muscle (chick biventer muscle and the rat phrenic nerve diaphragm) and also rat uterus in vitro. Differences were shown between the three essential oils in their action on smooth muscle: Manuka had a spasmolytic action, while Kanuka and Melaleuca had an initial spasmogenic action. Using the diaphragm, Manuka and Melaleuca decreased the tension and caused a delayed contracture; Kanuka had no activity at the same concentration. The action on chick biventer muscle was, however, similar for all three oils, as was the action on the uterus, where they caused a decrease in the force of the spontaneous contractions. The latter action suggests caution in the use of these essential oils during childbirth, as cessation of contractions could put the baby, and mother, at risk. The comparative antimicrobial activity showed greater differences between different samples of Manuka and Kanuka than Melaleuca samples. The antifungal activity of Kanuka was inversely proportional to its strong antibacterial activity, whilst Manuka displayed a stronger antifungal effect, though not as potent as Melaleuca. The antioxidant activity of Manuka samples was more consistent than that of Kanuka, while Melaleuca showed no activity. The variability in the Manuka and Kanuka essential oils suggests caution in their usage, as does the fact that the oils have not been tested for toxicity.

Antimicrobial agents from plants: antibacterial activity of plant volatile oils.

The volatile oils of black pepper [Piper nigrum L. (Piperaceae)], clove [Syzygium aromaticum (L.) Merr. & Perry (Myrtaceae)], geranium [Pelargonium graveolens L'Herit (Geraniaceae)], nutmeg [Myristica fragrans Houtt. (Myristicaceae), oregano [Origanum vulgare ssp. hirtum (Link) Letsw. (Lamiaceae)] and thyme [Thymus vulgaris L. (Lamiaceae)] were assessed for antibacterial activity against 25 different genera of bacteria. These included animal and plant pathogens, food poisoning and spoilage bacteria. The volatile oils exhibited considerable inhibitory effects against all the organisms under test while their major components demonstrated various degrees of growth inhibition.

Effect of thyme oil and thymol dietary supplementation on the antioxidant status and fatty acid composition of the ageing rat brain.

The present study measured changes in antioxidant enzyme activity in, and the phospholipid fatty acid composition of the ageing rat brain and tested whether dietary supplementation with thyme oil or thymol could provide beneficial effects. There were significant declines in superoxide dismutase (EC 1.15.1.1) and glutathione peroxidase (EC 1.11.1.9) activities and the total antioxidant status in the untreated rats with age, while thyme-oil- and thymol-fed rats maintained significantly higher antioxidant enzyme activities and total antioxidant status. The proportions of 18:2n-6, 20:1n-9, 22:4n-6 and 22:5n-3 in the brain phospholipids resulting from all three dietary treatments were significantly higher in 28-month-old rats than in 7-month-old rats. Only 20:1n-9 levels in 28-month-old thyme-oil- and thymol-treated rats were significantly higher than in the age-matched control. The proportion of 22:6n-3 in brain phospholipids, which declined with age in control rats, was also significantly higher in rats given either supplement. This latter finding is particularly important as optimum levels of 22:6n-3 are required for normal brain function. These results highlight the potential benefit of thyme oil as a dietary antioxidant.

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.

Antioxidant and antimicrobial activity of Foeniculum vulgare and Crithmum maritimum essential oils.

The essential oils obtained from Crithmum maritimum L. (marine fennel) and two samples of Foeniculum vulgare Miller (common fennel) were analysed by GC and GC-MS and assayed for their antioxidant and antibacterial activities. The antioxidant activity of the oils was evaluated by two lipid model systems: a modified thiobarbituric acid reactive species (TBARS) assay and a spectrophotometric detection of hydroperoxydienes from linoleic acid in a micellar system. The oils demonstrated antioxidant capacities, comparable in some cases to that of alpha-tocopherol and butylated hydroxytoluene (BHT), used as reference antioxidants. Concerning the antimicrobial tests the essential oils were assayed against twenty-five genera of bacteria, including animal and plant pathogens, food poisoning and spoilage bacteria. Oils from the two samples of F. vulgare showed a higher and broader degree of inhibition than that of C. maritimum.

Dietary supplementation of thyme (Thymus vulgaris L.) essential oil during the lifetime of the rat: its effects on the antioxidant status in liver, kidney and heart tissues.

This study aimed not only to identify age-related changes in certain antioxidant systems, but to assess whether dietary supplementation of thyme oil could address the unfavourable antioxidant-pro-oxidant balance that occurs with age. The present study has shown that there were significant declines in the superoxide dismutase activities in the liver and heart of old rats, although kidney showed no decline. Liver glutathione peroxidase (GSHPx) activity was found to have increased significantly in old rats, while a significant decrease was observed in kidney. Heart GSHPX activity was not found to differ significantly between young and old rats. There were also significant declines in the total antioxidant status in each tissue examined. A general feature of these various antioxidant parameters measured was that their activities remained higher in rats whose diets were supplemented with thyme oil, suggesting that they retained a more favourable antioxidant capacity during their life span.

Beneficial effects of thyme oil on age-related changes in the phospholipid C20 and C22 polyunsaturated fatty acid composition of various rat tissues.

The aim of this study was to determine any age-related changes in phospholipid polyunsaturated fatty acid composition, in particular C20 and C22 fatty acids in rat liver, brain, kidney and heart, and to assess and compare the effects of dietary supplementation (42.5 mg/kg body weight/day) of the natural antioxidant thyme oil and its major component thymol throughout the rat life span. The fatty acid composition in the various tissues from young (7 months) and aged (28 months) rats was determined and compared. Livers from aged control, thyme oil and thymol treated rats exhibited an increase in 22:6(n-3). In contrast, 22:6(n-3) content of brain, kidney and heart declined in aged rats in all three dietary groups. However, aged rats treated with thyme oil and thymol displayed significantly higher levels of 22:6(n-3) than the respective age-matched controls. Tissue compositions of 20:4(n-6) were found to be significantly lower in the liver and kidney from aged control rats but not those fed either thyme oil or thymol. In aged rats, the composition of 20:4(n-6) in all tissues was highest in rats fed either thyme oil or thymol. These results show that dietary supplementation with thyme oil tended to maintain higher PUFA levels in all tissues studied. The majority of protection provided by thyme oil was by virtue of its thymol component, which comprises 49% of the whole oil. Thymol administered alone did not provide significantly higher protection than the whole oil, suggesting that other components within thyme oil are also contributing antioxidant activity.

Bioactivity of selected plant essential oils against Listeria monocytogenes.

Ninety-three different commercial essential oils were screened for activity against 20 Listeria monocytogenes strains in vitro and the results correlated against the actual chemical composition of each oil. There was a substantial difference in the activity between different essential oils as expected, but there was also a difference in activity between different samples of the same essential oil. Strong anti-Listeria activity was often correlated with essential oils containing a high percentage of monoterpenes, eugenol, cinnamaldehyde, thymol, and sometimes with citronellol, limonene and geraniol. However, as there was often no correlation between the anti-Listeria activity and the main chemical components, it is possible that either there is a more complex relationship with the chemical composition (which includes the minor components) or that substantial adulteration had occurred in some essential oil samples.

Antimicrobial effects of hydrophilic extracts of Pelargonium species (Geraniaceae).

Methanolic extracts of representative species and cultivars of Pelargonium (Geraniaceae) were assessed for activity against 25 different species of bacteria and Aspergillus niger. All samples were active against at least 18 bacterial species and some were active against all 25 species, although there was very poor antifungal action. Antioxidant action was very pronounced, and this together with the strong antibacterial activity indicates that there is a potential usage in the food or other industry for Pelargonium extracts.

Antimicrobial activity of essential oil from Hoslundia opposita.

The essential oil from the leaves of Hoslundia opposite was extracted by hydrodistillation. GC/MS analysis of the volatile oil showed that it contains largely the sesquiterpenes and sesquiterpene alcohols. The essential oil was tested against eight different bacterial species and one fungal species. The antibacterial and antifungal properties of the essential oil from Hoslundia opposite were determined by using seeded agar plates with wells into which was placed the oil, and flasks of yeast extract and sucrose broth for mycelial growth of Aspergillus niger. After incubation for 24 hours, the diameter of the inhibition zone was measured for the antibacterial tests and after seven days, the dry weight of the mycelia was measured and a percentage of inhibition calculated using controls where no samples were added. The results obtained showed that the essential oil from this plant has significant activity against Aspergillus niger, Acinetobacter calcoacetica, Brochothrix thermosphacta and Flavobacterium suaveolens. These were most affected by the volatile oil from Hoslundia opposita.