J. Brito

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.

Main Components of the Essential Oils from Wild Portuguese Thymus mastichina (L.) L. ssp. mastichina in Different Developmental Stages or Under Culture Conditions

Abstract The aerial parts of wild Thymus mastichina (L.) L. ssp. mastichina were collected during the flowering (May) and vegetative phases (October) at Sesimbra (southwest Portugal). The aerial parts of cultivated plants of T. mastichina maintained in two different substrates, obtained from those plants growing wild at Sesimbra, were collected during the flowering phase (May) at Algarve (southern Portugal). The oils were isolated by hydrodistillation and analyzed by GC and GC/MS. In the wild plants, it was found that harvesting time had a significant effect on the oil yield, but did not greatly affect the composition. The highest oil yield isolated from the wild plants was found to be at the time of full flowering (2.1%, v/w). The oils were comprised mainly of oxygenated monoterpenes, among which linalool (58.7–69.0%) was the most abundant. In the wild plants, α-pinene, (E)-β-ocimene, γ-cadinene and elemol were the compounds that showed the most important variations, according to the harvesting month. The effect of nutritive elements (NPK) on the yield and on the oil composition was investigated in cultivated plants in two different substrates: a non-fertilized substrate (without N:P:K supply) and a fertilized substrate (with N:P:K, 1:1:1 supply). This study was carried out only in May. In the cultivated plants the highest oil yield (2.7%, v/w) was registered in the plants maintained in the non-fertilized substrate. Although the qualitative composition of the wild and cultivated oil plants was similar, the results showed quantitative variability among the components. The fertilized substrate proved to be the best to obtain a higher concentration of linalool (69.0%), while the non-fertilized substrate provided the lowest percentage (58.7%). The non-fertilized substrate induced a higher accumulation of (E)-β-ocimene, γ-terpinene, sesquiterpene hydrocarbons and oxygenated sesquiterpenes than the fertilized substrate, while this latter supported higher p-cymene and linalool content formation. The wild plant oils were found to be richer in α-pinene, camphene, β-pinene, 1,8-cineole and camphor and poorer in p-cymene, γ-terpinene, and in sesquiterpene hydrocarbons and oxygenated sesquiterpenes, than the cultivated plant oils. Nevertheless, such quantitative differences can be also explained by the different maturity stage of the wild and cultivated plants though both were in the same developmental stage.

Essential oils of Portuguese Thymus mastichina (L.) L. subsp. mastichina grown on different substrates and harvested on different dates

Summary The effects of harvesting date and different substrates on the yield and chemical composition of the essential oils of Portuguese Thymus mastichina (L.) L. subsp. mastichina were compared with samples grown in pots. The best oil yields were obtained in June (3.2, 3.6 and 4.9% in the local sandy soil, in non-fertilized peat, and in fertilized peat, respectively). The essential oils were dominated by 1,8-cineole, the highest concentration of which was detected in June (58.6%) in samples kept in non-fertilized peat, and the lowest values were from plants growing in fertilized peat during April and June (45.1%). The remaining samples always reached the highest percentages in October (around 54% in both oil samples), although the concentration profile over time was similar in every sample. Concerning the monoterpene hydrocarbons, ケ-pinene, camphene, sabinene and ゲ-pinene were the most significant components. While the amounts of ケ-pinene tended to decrease from April to June, for ゲ-pinene such tendency was observed from October to January, independently of the growing material used. Amounts of camphene, being similar to those of ケ-pinene, decreased successively from October to April. Elemol and intermedeol were the most representative sesquiterpene components, although the concentrations never exceeded 2.2% and 1.3%, respectively. The results obtained in this work suggest that the harvesting dates of Portuguese T. mastichina influence oil yields and their chemical compositions much more than the different growing media used, although a higher oil yield was obtained with the fertilized growing material.

Grass response to municipal wastewater reuse as compared to nitrogen and water application

Bermuda grass (Cynodon dactylon, L. Pers) is used very often in the fairways of golf courses, due to its tolerance to drought, high temperatures and treading damage. The objective of this work was to study the response of this grown cultivar with Dallis grass (Paspalum dilatatum, Poiret), to several levels of municipal wastewater. An experimental setup known as sprinkle point source was used to simulate the various levels of water application, expressed by the crop coefficient kc and the crop evapotranspiration rate. Results were compared with those obtained for sprinkle irrigated plots under nitrogen fertilization. At lower water application rates (kc 1), grass yield response to wastewater was comparable to potable application combined with nitrogen application between 0 and 25 kg ha−1.month−1. Visual appearance of the lawngrass was good for kc values > 1.2, when wastewater was applied.

Study of the substrate and fertilization effects on the production of essentials oils by Thymus mastichina (L.) L. ssp. mastichina cultivated in pots

Thymus mastichina (L.) L. subsp. mastichina is endemic in the Iberian Peninsula, largely spread in Portugal and growing in stony and arid places. Plants growing either wild in Algarve fields or maintained in pots, using three different substrates: fertilised turf (TTUFF2), non-fertilised turf (TTUNFF2) and a sandy soil (TTF2), were analysed for their essentiel oil composition. In all samples, oxygenated monoterpenes were the main components of T. mastichina essential oils, 1,8-cineole being the most representative component. TTF2 and TTUNFF2 showed the highest concentrations of sabinene, trans-sabinene hydrate and linalool and the lowest concentrations of p-cymene and camphor. The highest concentration of 1,8-cineole was found in the essential oils of TTUFF2 samples whilst the highest amount of borneol was registered in the essential oils of TTF2 samples. Essential oils of plants kept in pots seem to be characterised by higher intermedeol levels than those maintained wild in field.

Study of the substrate and fertilisation effects on the production of essential oils of Rosmarinus officinalis L. cultivated in pots

Rosmarinus officinalis L. is a perennial sub-shrub growing wild in all of the coastal regions of the Mediterranean Sea, and cultivated in some Mediterranean countries. In Portugal, rosemary grows wild and is very appreciated in culinary preparations as a spice and in herbal teas. This work submits studies on the essential oil composition leaves of R. officinalis kept in pots using three different substrates: fertilised turf (RTUFF2), non-fertilised turf (RTUNFF2) and a sandy soil (RTF2). These treatments were fertigated every fifteen days. These essential oils show high percentages of terpene hydrocarbons and oxygenated monoterpenes independently of the substrate used. In all cases, the main component was myrcene. RTF2 samples present the lowest concentrations of myrcene and camphor and the highest percentage of verbenone.

Effect of Substrate on the Essential Oils Composition of Thymus mastichina (L.) L. Subsp. mastichina Collected in Sesimbra Region (Portugal)

The effect of fertilization on the chemical composition of the oils isolated from different parts Thymus mastichina was evaluated. The essential oils were mainly constituted by oxygenated monoterpenes, being the flower oils richest in this group of compounds, independently of the fertilization conditions. Linalool was the most representative component belonging to this group of compounds. Regarding the monoterpene hydrocarbons, the essential oils isolated from the flower oils were poorest in γ-terpinene and p-cymene, regardless of the fertilization conditions. In the sesquiterpene group of compounds, elemol and T-cadinol were the most representative compounds in the essential oils. Lower concentrations of T-cadinol were always found in the flower oils, independently of the fertilization conditions.

The influence of waste water treatment on irrigation water quality

Reclaimed wastewater has been used extensively as a source of irrigation water for centuries. In addition to provide a low water source cost, other side benefits include increases in crop yields and decreased reliance on chemical fertilizers. One of the main aspects of the wastewater related to its quality is the kind of treatment used. Thus, three wastewater plants were studied. The quality of the final effluents of three different reclamation plants was analysed, in order to apply them on irrigated crops. From these final effluents, it was shown that two of them had good quality to be reused on irrigation, and the characteristics of the one were not good enough to be reused, due to the large concentration of pathogens. Those effluents of better quality were applied to lawngrass, composed by Bermuda grass and Dallis grass, in order to study the response of this lawngrass to the application of this final effluent. It was concluded that for a crop coefficient around 1.2, the lawngrass had a good visual rating, though a lower yield; additionally a very low soil and plant contamination was verified.