Laurus Novocanariensis Research Articles

Ramomarthamyces octomerus sp. nov. and Insights into the Evolution and Diversification of Ramomarthamyces (Ascomycota, Leotiomycetes, Marthamycetales).

The apothecial fungus Ramomarthamyces octomerus sp. nov. is described from specimens collected in Mediterranean climate regions in southern Portugal, Spain (Canary Islands), and the Dalmatian region of Croatia. Presumably saprobic, R. octomerus occurs on intact, decorticated wood of Laurus novocanariensis and Olea europaea. Ascospores are cylindric-ellipsoid and seven-septate. Surprisingly, in our four-locus phylogenetic analysis (nuSSU, ITS1-5.8S-ITS2, LSU, mtSSU), this fungus clusters among species of Cyclaneusma, Marthamyces, Naemacyclus, and Ramomarthamyces in a core Marthamycetaceae clade that circumscribes primarily leaf-inhabiting, filiform-spored species. In addition, the asci of R. octomerus possess an amyloid pore, but the reaction varies between specimens collected in the Canary Islands and those collected in Portugal and Croatia. The occurrence of an amyloid reaction in the asci of R. octomerus challenges the characterization of Marthamycetales taxa as possessing inamyloid asci. In our discussion we provide background and analysis of these notable observations.

Land-use change and windstorms legacies drove the recolonization dynamics of laurel forests in Tenerife, Canary islands

Laurel forests are quite relevant for biodiversity conservation and are among the island ecosystems most severely damaged by human activities. In the past, Canary laurel forests have been greatly altered by logging, livestock and agriculture. The remains of laurel forests are currently protected in the Canary Islands (Spain). However, we miss basic information needed for their restoration and adaptive management, such as tree longevity, growth potential and responsiveness to natural and anthropogenic disturbances. Using dendrochronological methods, we studied how forest dynamic is related to land-use change and windstorms in two well-preserved laurel forests on Tenerife Island. Wood cores were collected from over 80 trees per stand at three stands per forest. We used ring-width series to estimate tree ages and calculate annual basal area increments (BAI), cumulative diameter increases, and changes indicative of released and suppressed growth. Twelve tree species were found in all stands, with Laurus novocanariensis, Ilex canariensis and Morella faya being the most common species. Although some individuals were over 100 years old, 61.8%–88.9% of the trees per stand established between 1940 and 1970, coinciding with a post-war period of land abandonment, rural exodus and the onset of a tourism economy. Some trees have shown growth rates larger than 1 ​cm diameter per year and most species have had increasing BAI trends over the past decades. Strong growth releases occurred after windstorms at both sites, but the effects of windstorms were site-dependent, with the 1958 storm affecting mainly the eastern tip of the island (Anaga massif) and the 1991 storm the western tip (Teno massif). Given the great ability of laurel forest trees to establish after land use cessation and to increase growth after local disturbances such as windstorms, passive restoration may be sufficient to regenerate this habitat in currently degraded areas.

Together Apart: Evaluating Lichen-Phorophyte Specificity in the Canarian Laurel Forest.

The effects of host tree identity on epiphyte lichen communities are a controversial issue, as the results obtained in different forest environments studied are not consistent. We investigated the host preferences for lichens in the laurel forest of Macaronesia. For this purpose, we analyzed the lichen communities growing on the four most common trees (Erica canariensis Rivas-Mart., M. Osorio and Wildpret, Morella faya (Aiton) Wilbur, Laurus novoca-nariensis Rivas-Mart., Lousa, Fern. Prieto, E. Días, J.C. Costa and C. Aguiar, and Ilex canariensis Poir. in Lamarck) in the laurel forest of the Canary Islands. The diversity, richness, and lichen composition showed a repetitive and common pattern with the functional traits studied. Although the existence of specificity with respect to the phorophyte species was not demonstrated, there was a clear affinity of the epiphytic lichens to the physico-chemical features of the bark (texture and pH), canopy architecture, foliar characteristics, etc. Our results highlight the importance of the natural diversity of tree species in the laurel forest. Due to the diversity and uniqueness of the lichen species that support each of the phorophytes, this fact should be taken into account in landscape protection and restoration actions, especially in those islands where the forest is highly fragmented.

Tree-ring distinctness, dating potential and climatic sensitivity of laurel forest tree species in Tenerife Island

Macaronesian laurel forests are the only remnants of a subtropical palaeoecosystem dominant during the Tertiary in Europe and northern Africa. These biodiverse ecosystems are restricted to cloudy and temperate insular environments in the North Atlantic Ocean. Due to their reduced distribution area, these forests are particularly vulnerable to anthropogenic disturbances and changes in climatic conditions. The assessment of laurel forest trees’ response to climate variation by dendrochronological methods is limited because it was assumed that the lack of marked seasonality would prevent the formation of distinct annual tree rings. The aims of this study were to identify the presence of annual growth rings and to assess the dendrochronological potential of the most representative tree species from laurel forests in Tenerife, Canary Islands. We sampled increment cores from 498 trees of 12 species in two well-preserved forests in Tenerife Island. We evaluated tree-ring boundary distinctness, dating potential, and sensitivity of tree-ring growth to climate and, particularly, to drought occurrence. Eight species showed clear tree-ring boundaries, but synchronic annual tree rings and robust tree-ring chronologies were only obtained for Laurus novocanariensis, Ilex perado subsp. platyphylla, Persea indica and Picconia excelsa, a third of the studied species. Tree-ring width depended on water balance and drought occurrence, showing sharp reductions in growth in the face of decreased water availability, a response that was consistent among species and sites. Inter-annual tree-ring width variation was directly dependent on rainfall input in the humid period, from previous October to current April. The four negative pointer years 1995, 1999, 2008 and 2012 corresponded to severe drought events in the study area. This study gives the first assessment of dendrochronological potential and tree-ring climate sensitivity of tree species from the Tenerife laurel forest, which opens new research avenues for dendroecological studies in Macaronesian laurel forests.

Assessing the In Vitro Inhibitory Effects on Key Enzymes Linked to Type-2 Diabetes and Obesity and Protein Glycation by Phenolic Compounds of Lauraceae Plant Species Endemic to the Laurisilva Forest.

Methanolic leaf extracts of four Lauraceae species endemic to Laurisilva forest (Apollonias barbujana, Laurus novocanariensis, Ocotea foetens and Persea indica) were investigated for the first time for their potential to inhibit key enzymes linked to type-2 diabetes (α-amylase, α-glucosidase, aldose reductase) and obesity (pancreatic lipase), and protein glycation. Lauraceae extracts revealed significant inhibitory activities in all assays, altough with different ability between species. In general, P. indica showed the most promissing results. In the protein glycation assay, all analysed extracts displayed a stronger effect than a reference compound: aminoguanidine (AMG). The in vitro anti-diabetic, anti-obesity and anti-glycation activities of analysed extracts showed correlation with their flavonols and flavan-3-ols (in particular, proanthocyanins) contents. These Lauraceae species have the capacity to assist in adjuvant therapy of type-2 diabetes and associated complications, through modulation of the activity of key metabolic enzymes and prevention of advanced glycation end-products (AGEs) formation.

Seedling bank demography over 11 years in an island laurel forest, Tenerife, Canary Islands

Confined to the humid cloud belt of the Macaronesian Islands the Laurel-forests are sensitive to climate changes. Intense natural disturbances are rare and regeneration includes asexual regeneration and dominance of shade intolerant species in the seedling bank. Long-term monitoring of the seedling bank showed that even under these relatively stable conditions high variations occurred. Studies point out to a downward shift of the trade winds cloud belt that confined laurel cloud forests. Only long-term studies can detect the effects of rare extreme events or the influence of slow processes on seedling dynamics. In nine 10 × 10 m plots (six in windward and three in leeward) we monitored the seedling bank monthly from 2000 to 2003 and recount it in 2005 and 2011. Our aim was to estimate seedling dynamics in a Laurel forest. We hypothesized that this forest seedling bank is relatively stable over time. Under present mild temperate climate, we hypothesized that this forest seedling bank is relatively stable over time; seedling recruitment will be positively related to rainfall; sprouting-species will be poorly represented in the seedling bank and growth rate will be higher than observed in other forests. Composition and abundance in seedling bank were stable across 2000–2003. The fluctuation in density, recruitment and mortality for Laurus novocanariensis was determinant for seedling community dynamic, and composition and abundance in seedling bank were stable across first three years and relative seeding growth rate is higher than observed in another subtropical wet montane forests. There was no significant relationship between mortality and recruitment and precipitation. However, in the 2011 count, an increase in density for all species. Except for a hot year in 2010 and a humid one in 2009 for the Canary Islands, there was no record of exceptional weather events or large-scale disturbance episodes in the previous eight years, and these are unlikely to explain the observed increase. Species with seedling banks were more abundant. Nonetheless, few seedlings survive more than two years. We emphasise the importance of long-term studies with fine-scale disturbance monitoring for understanding the dynamic processes of this unique forest.

Linking Dendrometry and Dendrochronology in the Dominant Azorean Tree Laurus azorica (Seub.) Franco

As in many archipelagos, the Azorean primary forest was largely cleared and replaced by secondary forest and grassland, the Azorean tree Laurus azorica (Seub.) Franco being one of the dominant trees in the remaining natural forests. Dendrochronological and dendrometric studies in the Azores mainly focused on non-indigenous trees, either used for timber (e.g., Cryptomeria japonica D. Don) or considered as invasive (Pittosporum undulatum Vent.). Therefore, this study aims to describe the growth ring anatomy of L. azorica, and to understand the relationship between dendrometric traits (e.g., trunk diameter at breast height; tree height), and the number of growth rings. Growth ring anatomy was accessed by wood anatomical preparation of microcore samples while tree age estimation was based on growth ring counts in wood cores taken at breast height and at base. A total of 145 trees were sampled, resulting in 262 increment cores, at six representative stands of laurel forest in São Miguel Island (Azores). The wood anatomical analysis confirmed the presence of clear annual ring boundaries, and a high structural similarity towards Laurus novocanariensis Rivas Mart., Lousã, Fern.Prieto, E.Días, J.C.Costa & C.Aguiar. Age at tree base averaged 33 years, with 60% of the trees between 25 and 50 years old, and only about 15% above 50 years old. This suggests the existence of a secondary forest that is more recent than expected, probably due to human disturbance. The allometric models showed best fit when calculated by stand, suggesting the effect of local environmental conditions on growth rate. Radial growth rate was estimated at 0.68 cm.year−1. Given the known dominance of this species and the threats affecting natural forests, this baseline study will allow a better understanding of forest distribution and dynamics, and support a more effective forest management approach.

Studies on the sesquiterpene lactones from Laurus novocanariensis lead to the clarification of the structures of 1-epi-tatridin B and its epimer tatridin B

The germacranolide 1-epi-tatridin B has been isolated from the aerial parts of Laurus novocanariensis. We have observed that the identification of this lactone and its epimer tetradin B in the scientific literature is confusing and contradictory. We have therefore studied this issue clarifying errors and contributing to the structural elucidation of other related products. Moreover, we have isolated from this plant a lactone with an 1,5-ether bridge, previously obtained from Austrolabium candidum. We have now named it austroliolide, reassigned its 13C NMR spectrum and compared its structure with that of badgerin. In addition, we have also isolated from L. novocanariensis the known germacranolides artemorin, costunolide, tatridin A, tulirinol and verlotorin, the eudesmanolides β-cyclopyrethrosin, 1β-hydroxy-arbusculin A, magnoliaolide and reynosin, and the guaianolide dehydrocostus lactone.

Phenolic profiles of Lauraceae plant species endemic to Laurisilva forest: A chemotaxonomic survey

In this work, the phenolic composition of several trees endemic to Madeira archipelago (Portugal) was studied. Specifically, the leaves of the most relevant species of the Lauraceae family (Laurus novocanariensis, Apollonias barbujana, Ocotea foetens, and Persea indica) have been analyzed. The screening of the main phenolic compounds in their methanol extracts has been performed by high-performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC-ESI–MSn), identifying or tentatively characterizing almost 100 compounds, including a high number of proanthocyanidins (A- and B-type), which have been reported to present remarkable health benefits. Thirty-four compounds have been quantified, observing total individual phenolic contents (TIPCs) between 18.43 and 88.99mgg−1 dry extract, with the lowest TIPC in O. foetens and the highest in A. barbujana.

Diversity hotspots of the laurel forest on Tenerife, Canary Islands: a phylogeographic study of Laurus and Ixanthus.

Macaronesian laurel forest is among the worldwide hotspots of threatened biodiversity. With increasing evidence that woodland composition on the Canary Islands changed dramatically during the last few thousand years, the aim of this study was to find evidence for substantial recent population dynamics of two representative species from laurel forest. Amplified fragment length polymorphism (AFLP) was used to evaluate fine-scaled genetic variation of the paradigmatic tree Laurus novocanariensis (Lauraceae) and a long-lived herbaceous gentian from core laurel forest, Ixanthus viscosus (Gentianaceae), on Tenerife. Bioclimatic variables were analysed to study the respective climate niches. A chloroplast DNA screening was performed to evaluate additional genetic variation. Genetic diversity of the laurel tree showed severe geographic partitioning. On Tenerife, fine-scaled Bayesian clustering of genetic variation revealed a western and an eastern gene pool, separated by a zone of high admixture and with a third major gene pool. Compared with genetic clusters found on the other Canary Islands, the East-West differentiation on Tenerife seems to be more recent than differentiation between islands. This is substantiated by the finding of extremly low levels of chloroplast DNA-based polymorphisms. Ixanthus showed no geographic structuring of genetic variation. Genetic data from Tenerife indicate contemporary gene flow and dispersal on a micro/local scale rather than reflecting an old and relic woodland history. In particular for Laurus, it is shown that this species occupies a broad bioclimatic niche. This is not correlated with its respective distribution of genetic variation, therefore indicating its large potential for contemporary rapid and effective colonization. Ixanthus is more specialized to humid conditions and is mostly found in the natural Monteverde húmedo vegetation types, but even for this species indications for long-term persistence in the respective bioclimatically differentiated regions was not find.

Chemical composition of Laurus essential oils from different Macaronesian Islands and their ovicidal and larvicidal activities against armyworm

Essential oils (EO) from the fresh leaves of Laurus novocanariensis (LN) from Madeira and of L. azorica (LA) from four Azorean Islands (S. Miguel-SMI, S. Maria-SMA, Pico-PIC and S. Jorge-SJO) were analyzed by gas chromatography – mass spectrometry (GC-MS). A total of 51 components were identified, accounting for 99.5 to 99.9% of the total EO, respectively. All the Laurus' EO investigated were dominated by monoterpenes, and were significantly rich in oxygen-containing terpenes. However, the EO of LA and LN species showed a distinct chemical profile, being the first one more complex, particularly in SMA population followed by SMI population [1]. Interest in the plants' EO was renewed with emerging demonstration of their insecticidal properties. All the Laurus' EO tested showed a high ovicidal activity against Pseudaletia unipuncta eggs (> 95% of mortality). The same holds true for the pure components linalool, α-terpinyl acetate and trans-cinnamyl acetate; these are among the main components only in LA-SMA (the first two) and in LA-SJO (the last one). Also, all the Laurus' EO showed strong insecticidal effect on fourth instar larvae (> 66% of mortality), with the exception of the LA-SJO, that caused a mortality rate of 46%. LA-SMA was the most effective in killing the larvae and showed the highest toxicity at 96h after treatment (LC50 = 11.54 mg/mL) followed by LA-SMI (LC50 = 37.08 mg/mL). Among the pure components, α-terpinyl acetate was the most toxic (LC50 = 8.05 mg/mL) followed by linalool (LC50 = 25.27 mg/mL) and α-pinene (LC50 = 36.71 mg/mL), being the last one the major Laurus' EO components, except for LA-SMA. These data show that some of the Laurus' EO and/or their bioactive compounds could be used as agrochemical agent against P. unipuncta, a serious pest on the Azores's pastures. Further studies are required to determine the mode-of-action of these essential oil products, through semi-field trials.

Chemical composition and biological activities of Laurus essential oils from different Macaronesian Islands

Essential oils (EO) and eight pure components from the fresh leaves of Laurus novocanariensis (LN) from Madeira and of Laurus azorica (LA) from four Azorean Islands (S. Miguel-SMI, S. Maria-SMA, Pico-PIC and S. Jorge-SJO) were evaluated for fumigant and contact insecticidal effects on adult stage of Mediterranean fruit fly (medfly) and for inhibition of oviposition. The chemical composition of EO were analysed by GC/MS. Oxygen-containing mono- and sesquiterpenes (mainly 1,8-cineole) dominated in LN (50%), LA-SMA (88%) and LA-SMI (57%) and mono- and sesquiterpene hydrocarbons (mainly α-pinene) dominated in LA-PIC (61%) and LA-SJO (44%). Linalool and α-terpinyl acetate were also abundant in LA-SMA and trans-cinnamyl acetate in LA-SJO. These three components and all of the Laurus' EO showed high repulsive activity against medfly oviposition. In contact assays on medfly adults, a moderate degree of mortality was observed, being the most toxic samples, in decreasing order, trans-cinnamyl acetate > α-terpinyl acetate > LA-SMI ∼ LA-SMA > LA-SJO ∼ linalool. In fumigant assays, α-terpinyl acetate was the only compound that showed some toxicity on medfly adults. According to the obtained results, the Laurus EO seem promising to be used against medfly oviposition in integrated pest management strategy.

A comparison of micronutrients (Mn, Zn, Cu, Mo, Ni, Na) within rocks, soils, and leaves, from fallow agricultural lands and natural laurel forest areas (Tenerife, Canary Islands, Spain)

The laurel forest in Tenerife is an important ecosystem and the habitation of several sensitive and endangered endemic species. Its mountainous areas at the border of the laurel forest vegetation zone, with suitable climatic conditions, have been intensively influenced, over the last decades, by logging and harnessing of agricultural areas. Many areas which were formerly used for agriculture have been abandoned for many decades and can be seen as potential areas for a natural resettlement of laurel forest. In order to classify these fallow areas, total nutrient element contents of rocks, soils and leaves were compared with published geochemical backgrounds, natural laurel forest results and with sufficient nutrient amounts for plant growth. The method determined whether a fallow agricultural sample site contains sufficient, insufficient or excessive micronutrient concentrations. The method indicated that the fallow agricultural sample sites contain Mn, Zn, Cu and Na in the normal range for a sufficient growth of Laurus novocanariensis. Whether agricultural or natural, Mo is mostly below and Ni significantly above the sufficient amount. In any case, the micronutrient results have determined that abandoned agricultural areas near the border of the laurel forest vegetation zone are comparable to the laurel forest and suitable for a resettlement of L. novocanariensis.

In vitro and in vivo assessment of the effect of Laurus novocanariensis oil and essential oil in human skin

Laurus novocanariensis is an endemic plant from the Madeira Island forest that derives a fatty oil, with a strong spicy odour, from its berries that has been used for centuries in traditional medicine to treat skin ailments. This work aimed to investigate the effect of the application of both the oil and its essential oil on normal skin, to assess their safety and potential benefits. Diffusion studies with Franz cells using human epidermal membranes were conducted. The steady-state fluxes of two model molecules through untreated skin were compared with those obtained after a 2-h pre-treatment with either the oil or the essential oil. Additionally, eleven volunteers participated in the in vivo study that was conducted on the forearm and involved daily application of the oil for 5 days. Measurements were performed every day in the treated site with bioengineering methods that measure erythema, irritation and loss of barrier function. Slightly higher steady-state fluxes were observed for both the lipophilic and the hydrophilic molecule when the epidermal membranes were pre-treated. Nevertheless, such differences had no statistical significance, which seems to confirm that neither the oil nor the essential oil impaired the epidermal barrier. Results collected with the Chromameter, the Laser Doppler Flowmeter and the visual scoring are in agreement with those established in the in vitro study. They indicate that the repeated application of the oil did not cause erythema, because the results observed in the first day of the study were maintained throughout the week. Application of the oil did not affect the skin barrier function, because the transepidermal water loss remained constant throughout the study. The stratum corneum hydration was slightly reduced on days 4 and 5. This work shows that both the oil and the essential oil were well tolerated by the skin and did not cause significant barrier impairment or irritation.

PLANT SPECIES MONITORING IN THE CANARY ISLANDS USING WORLDVIEW-2 IMAGERY

Abstract. The physical and climatic features of a relatively small volcanic island such as Tenerife (Canary Islands, Spain) cause increased difficulties to vegetation monitoring by means of moderate resolution satellite data. The use of multispectral very high resolution WorldView-2 (WV2) imagery provides promising perspectives for vegetation mapping in such a heterogeneous landscape. In order to assess its potential to estimate the cover fraction of dominant plant species in endemic Macaronesian laurel forests and heathlands, a hierarchical Multiple Endmember Spectral Mixture Analysis (MESMA) was performed within a study area where different patches from mature forest, to degraded forest and pine plantations can be found. First, a selection of pure pixels in the WV2 image for fern, Morella faya Ait., Laurus novocanariensis and the introduced species Pinus radiata were used to build a spectral library for each species. Last species Erica arborea L. was characterized in field by means of an ASD FieldSpec spectroradiometer, due to the rarity of pure pixels in this case, and to the simultaneous presence of two spectral subclasses depending on its flowering onset; WV2-adjusted spectral signatures from field reflectances were estimated by empirical calibration. Preliminary results showed a good separation of degraded from mature native forests and from plantations, although pine cover fraction is, in general, underestimated. The second MESMA cycle was useful to tell between most similar species, like in case of M. faya and L. novocanariensis.

The role of metals in soils and accumulation in the laurel forest of La Gomera (Canary Islands, Spain): preliminary results

The present study investigated the content of Al and various heavy metals (Cr, Cu, Fe, Mn, Ni and Zn) in soils and plant tissues of a sub‐tropical laurel forest in the Canary Islands and their relationship to the composition and structure of the forest. The content of different Al‐fractions and bioavailable (NH4Ac‐EDTA extractable) metals was analysed in a large number of soil samples and related to lithological and topographic factors. Seasonal variation of the metal content in the soil, phytomass and litter was studied at sites with different degrees of maturity or sites affected by forest dieback. Extremely large contents of bioavailable Al, Fe and Mn were observed in soils. The Al and Mn contents exert a considerable influence on ecosystem composition. The results of this study reveal the bioaccumulation of Al in Ilex canariensis Poir. and Viburnum rigidum Vent. and suggest the accumulation of Mn in Laurus novocanariensis Rivas Mart. The bioaccumulation patterns of Al were closely related to the NH4Ac‐EDTA‐extractable soil content but not as closely tied to KCl‐extractable Al, suggesting the greater importance of humic complexes in the regulation of aluminium toxicity in comparison with hydroxy‐Al interlayered 2:1 silicates. Bioaccumulation gives rise to Al‐rich litterfall inputs, allowing the exclusion of Al‐intolerant species from the understory or neighbouring vegetation.

Epiphytic bryophyte diversity on Madeira Island: Effects of tree species on bryophyte species richness and composition

The Madeiran laurel forest (Laurisilva) is a subtropical forest with a very rich bryophyte flora and is considered as one of the most important remnants of the evergreen laurel forest from the Tertiary period. The effect of the laurel forest tree species on the epiphytic bryophyte species richness and composition in Madeira Island was studied in 40 sites. A total of 160 trees, belonging to 19 different tree species were assessed in the laurel forest. For subsequent analyses, we focused on seven tree species, for which at least nine individuals were sampled. A total of 137 trees from 40 sites were thus available for statistical analyses. We recorded 110 epiphytic bryophyte taxa (59 species and one variety of mosses and 50 liverworts). Accumulation curves showed clear differences in bryophyte species richness between the different tree species, with typical laurel forest tree species harboring more bryophytes. Tree species also had highly significant effects on species density (mean species richness per 10 × 20 cm plot), with densities higher on the typical laurel forest trees. This was especially true for the liverworts and the endemics for which Clethra arborea, Laurus novocanariensis, Ocotea foetens and Persea indica exhibited higher species density than the two Erica species and Myrica faya. For mosses species density of the tree species tended to be more similar, only O. foetens showed a higher density and M. faya a lower. Endemic bryophytes were lacking on Erica species and almost lacking on M. faya. Concerning species composition, we found significant effects of the tree species sampled. There was a rather clear gradient from the two Erica species to the typical laurel forest tree species such as L. novocanariensis, O. foetens, and P. indica. An analysis of indicator species revealed ten significant indicator species for the typical laurel forest trees, C. arborea, L. novocanariensis, O. foetens and P. indica. Our results reinforced the importance of the laurel forest of Madeira as a hotspot of epiphytic bryophyte diversity whose species distribution is strongly shaped by the nature of the tree species.

Exploring the effect of host tree identity on epiphyte bryophyte communities in different Canarian subtropical cloud forests

This study explores the host tree preferences of epiphyte bryophyte communities in two key types of evergreen cloud forests on La Gomera (Canary Islands, Spain): ericaceous versus broadleaved laurel forest. By comparing two pairs of tree species (Erica arborea and Myrica faya vs. Ilex canariensis and Laurus novocanariensis) that occur in both forest types, we quantitatively examined whether epiphyte-host relationships change with the type of forest. In 51 ancient forest stands, the low-trunk bryophyte composition on the two host tree groups was analysed with both non-parametric procedures and ordination analyses. Our results highlight that the influence of local environmental conditions on the structuring of epiphyte communities may be different depending on the host tree identity. Whilst the epiphyte composition of the host tree group formed by I. canariensis and L. novocanariensis differed significantly between forest types depending on solar exposure, we failed to find variations for the other host tree group, excepting in those localities wherein mist precipitation was extremely high. Our findings highlight the importance of the natural diversity of tree species along environmental gradients, as well as of water availability at different spatial scales for epiphytic bryophytes in montane cloud forests.

Quantitative analysis of costunolide and dehydrocostuslactone in rat plasma by ultraperformance liquid chromatography–electrospray ionization–mass spectrometry

Costunolide and dehydrocostuslactone are well-known sesquiterpene lactones contained in many plants used as popular herbs, such as Saussurea lappa and Laurus novocanariensis, and have been considered as potential candidates for the treatment of various types of tumor. In the present work, a sensitive UPLC-MS/MS for the quantification of costunolide and dehydrocostuslactone in biological matrices has been developed. The method is based on protein precipitation with acetonitrile followed by isocratic ultraperformance liquid chromatographic separation using methanol-formic acid (0.1% in water; 70:30, v/v) mobile phase. Detection was performed by ESI mass spectrometry in MRM mode with the precursor-to-product ion transitions m/z 233-187 and m/z 231-185, respectively. The calibration curves of analytes showed good linearity within the established range 0.19-760 ng/mL for costunolide and 0.23-908 ng/mL for dehydrocostuslactone. The lower limits of quantification of costunolide and dehydrocostuslactone were found to be 0.19 and 0.23 ng/mL, respectively. The intra-day and inter-day presicions of this method for the entire validation were less than coefficient of variation of 7% and the accuracy was within ±8% (relative error). The mean extraction recoveries were 73.8 and 75.3%, respectively. The method was found to be precise, accurate and specific during the study, and was successfully used to analyze the pharmacokinetics of costunolide and dehydrocostuslactone.

Effects of a hexane extract from Laurus novocanariensis leaves on the ethanol metabolism of Wistar rats

A hexane extract from the leaves of Laurus novocanariensis was investigated for its activity on ethanol metabolism in Wistar rats. The extract could interfere with blood ethanol elevation, the induction of gastric alcohol dehydrogenase (ADH) and the reduction of erythrocyte catalase (CAT). The sesquiterpene lactones dehydrocostus lactone and costunolide were identified in the active extract, and might represent its active constituents. These results support the use of L. novocanariensis in the traditional Madeira Island medicine to protect against ethanol injury.