Juan Antonio Llorens-Molina

Effect of drought stress on essential oil composition of Thymus vulgaris L. (Chemotype 1, 8-cineole) from wild populations of Eastern Iberian Peninsula

Abstract 1,8-cineole defines a typical chemotype of Thymus vulgaris L. in Iberian Peninsula. This compound has a wide range of potentially useful bioactive properties. In order to study the influence of drought stress in the essential oil (EO) composition of this chemotype, sixty plants from six wild populations of Eastern Iberian Peninsula were distilled and analyzed by GC and GC/MS. The harvest dates (May and August) were selected in such a way that the typical summer drought in Mediterranean climates was the critical factor affecting EO composition. Despite the high intrapopulational variability, significant increases of 1,8-cineole were found after the drought period (21.8%–43.2%, in May, up to 42.6%–68.5% in August). On the other hand, individuals from one of the populations showed different profiles rich in linalool and camphor or sesquiterpenoid compounds, such as α-cadinol.

Seasonal variations in essential oil of aerial parts and roots of an Artemisia absinthium L. population from a Spanish area with supramediterranean climate (Teruel, Spain).

The seasonal variation of essential oil composition of aerial parts and roots of Artemisia absinthium L. has been investigated. It was obtained from individuals growing wild in Teruel (Spain) by means of hydrodistillation (aerial parts) or simultaneous distillation extraction (roots), and analyzed by GC/MS and GC/FID. Results showed a predominance of oxygenated monoterpenes (81.4–89.1%) in aerial parts; mainly (Z)-epoxyocimene (49.3–71.5%), (Z)-chrysanthemyl acetate (7.6–18%) and linalool (0.7–10.4%). In spite of the high intrapopulational variability, significant variations were observed for these three compounds. Root essential oil composition showed a high amount of hydrocarbon monoterpenes (43.8–55.1%) and monoterpenic esters (36.6–41.5%) with a noticeable seasonal stability except for some allelopathic oxygenated monoterpenes. As A. absinthium is a typical invasive species, knowing the seasonal variations of these compounds may be a first step to study their release in soil as a source for natural herbicides.

Variability of essential oil composition of wormwood (Artemisia absinthium L.) affected by plant organ

Abstract The essential oil composition of leaves and roots of twenty individuals of wormwood (Artemisia absinthium L.) belonging to different chemotypes has been investigated. They were obtained from two accesions coming from Hungarian and Spanish wild populations. Essential oils were extracted by hydrodistillation and analyzed by GC/MS and GC/FID. Results showed a great individual variability of wormwood accesions. Based on leaves, three chemotypes (sabinene + myrcene, β-thujone and new sesquiterpene type accounting up to 80.8% of sesquiterpenic fraction) were found in the Hungarian population and two chemotypes ((Z)-β-epoxyocimene and (Z)-β-epoxyocimene + (Z)-chrysanthemyl acetate types) were present in the Spanish one. The composition of EO of the roots from both locations was predominated by monoterpenic esters (14.5–80.2% and 59.9–90.3%, in Hungarian and Spanish samples respectively) but characteristic quantitative and qualitative differences were present. No relationship was found between the composition of EO of roots and leaves of the same plant.

Mentha suaveolens Ehrh. Chemotypes in Eastern Iberian Peninsula: Essential Oil Variation and Relation with Ecological Factors

Essential oil (EO) extracts coming from two representative populations of Mentha suaveolens Ehrh. subesp. suaveolens in Eastern Iberian Peninsula were analyzed by gas chromatography coupled with mass spectrometry and flame ion detector. Plant sampling was carried out in the morning and evening in order to study diurnal variation in EO profiles. Likewise, leaves and inflorescences were analyzed separately. Two chemotypes corresponding to each one of the populations were identified, with piperitenone oxide (35.2 – 74.3%) and piperitone oxide (83.9 – 91.3%), respectively, as major compounds. Once different chemotypes were identified, canonical correspondence analysis was employed to evaluate the effect of the bioclimatic and edaphic factors recorded in each location on the observed differences. Statistical analysis suggested that these chemotypes were closely related to specific environmental factors, mainly the bioclimatic ones. Concretely, piperitenone oxide chemotype can be associated to supramediterranean bioclimatic conditions and soils with major salinity and water field capacity. On the other hand, the most volatile fraction (hydrocarbon monoterpenes) reached its higher level in the morning; specifically, a noticeable amount of limonene was found in morning samples of flowers (4.8 – 10.6%). This fact can be related to ecological role of volatile compounds in order to attract pollinator insects.

Compositional variability in essential oils of twelve wormwood (Artemisia absinthium L.) accessions grown in the same environment

ABSTRACT One hundred and twenty individuals from twelve accessions of Artemisia absinthium grown in experimental plots were harvested during the vegetative period in order to evaluate volatile compositions. The essential oils were obtained by hydrodistillation and analyzed by the GCMS method. Evaluating the components higher than 1% of GC area, a total of sixty-nine compounds were identified, among them thirty monoterpenes and thirty-nine sequiterpenes. Major components of the oils were α-thujone (0–51.7%), β-thujone (0–89.8%), cis-epoxyocimene (0– 75.7%), trans-sabinyl acetate (0–94.5%), sabinene (0–33.8%), β-myrcene (0–68.4%), linalool 15 (0–52.1%), ect. Based on main compounds we defined different chemotypes. The components (Z)-iso-citral, selin-11-en-4-α-ol, (Z)- and (E)-nuciferol isobutyrate characterise new chemotypes of wormwood as they have never been mentioned before in its EO. A connection between chemotype and habitat can not be justified in most cases. Natural populations of the accessions may have similar heterogeneity to those purchased on market.