Globularia Alypum Research Articles

Net ecosystem exchange and whole plant isoprenoid emissions by a mediterranean shrubland exposed to experimental climate change

We tested the effect of forecasted soil drought and warming climate conditions for the next decades on emission rates of isoprenoids by mediterranean shrublands. We measured isoprenoid emissions by whole dominant mediterranean woody plants (Erica multiflora L. and Globularia alypum L.) inhabiting the studied shrublands. Monoterpene emissions were detected in both species, but isoprene was emitted only by E. multiflora. Maximum emission rates were found during the hottest periods (except for G. alypum, in which they occurred in autumn), and minimum emission rates in winter in E. multiflora. Terpene emission rates ranged from 0.08 μg/(g dry wt h) in winter in E. multiflora to 8.8 μg/(g dry wt h) in G. alypum in autumn. In E. multiflora, the terpene emission rates decreased in response to soil drought only in summer, but increased in response to warming in spring and autumn. Isoprene emissions ranged from 0.1 μg/(g dry wt h) in spring to 4.4 μg/(g dry wt h) in summer. The effect of the treatments was only detected in autumn when soil drought and warming had a negative effect on isoprene emission rates. These data might improve our knowledge of isoprenoid emissions at the canopy level and in response to climate change, soil drought, or warming.

Warming and drought alter C and N concentration, allocation and accumulation in a Mediterranean shrubland

AbstractWe investigated the effects of warming and drought on C and N concentrations, nitrogen use efficiency (NUE), and C and N accumulation in different ecosystem compartments. We conducted a 6‐year (1999–2005) field experiment to simulate the climate conditions projected by IPCC models for the coming decades in a Mediterranean shrubland. We studied the two dominant species, Globularia alypum and Erica multiflora, and an N‐fixing species, Dorycnium pentaphyllum, also abundant in this shrubland. Warming (1 °C) decreased N leaf concentrations by 25% and increased N stem concentrations by 40% in G. alypum. Although warming changed the available ammonium in soil in some seasons, it did not increase total soil N contents. Drought (19% average reduction in soil moisture) decreased leaf N concentrations in the two dominant shrub species, E. multiflora and G. alypum by 16% and 19%, respectively, and increased stem N concentrations by 56% and 40%, respectively. Neither warming nor drought changed the leaf N concentrations in the N‐fixing species D. pentaphyllum, although warming increased stem N concentration by 9%. In G. alypum, the increase of stem N concentrations contributed to the observed increase of N accumulation in stem biomass in drought treatments with respect to control plots (8 kg N ha−1). Neither warming nor drought changed NUE in the period 1999–2005. Warming increased soil organic C relative to drought. The effects of warming and drought on C and N concentrations, on N accumulation and on leaf/stem N distribution were not the result of dilution or concentration effects produced by changes in biomass accumulation. Other factors such as the changes in soil N availability, photosynthetic capacity, and plant internal C and N remobilization must be involved. These changes which differed depending on the species and the plant tissue show that the climate change projected for the coming decades will have significant effects on the C and N cycle and stoichiometry, with probable implications for ecosystem structure and function, such as changes in plant–herbivore relationships, decomposition rates or community species composition.

Changes in Ca, Fe, Mg, Mo, Na, and S content in a Mediterranean shrubland under warming and drought

In an evergreen Mediterranean shrubland we conducted a 6‐year field experiment simulating the warming and drought projected by general circulation models and ecophysiological models for the next decades: 20% reduction of soil moisture and 1°C of temperature increase. We tested whether warming and drought have effects on Ca, Fe, Mg, Mo, Na and S availability, concentrations and accumulation patterns in the three dominant plant species and in soil. Warming increased concentrations of Ca and Mo in leaves in Erica multiflora (42% and 65%, respectively) and in Dorycnium pentaphyllum (38% and 60%, respectively). Warming increased Mo accumulation in leaves and aboveground biomass in Globularia alypum (0.07 and 0.40 g ha−1) and in E. multiflora (0.12 and 0.4 g ha−1), and increased Fe accumulation in stem biomass of G. alypum (600 g ha−1), increasing the capacity to retain these nutrients in the ecosystem. The increase of Fe and Mo capture capacity under warming conditions was greater in G. alypum than in E. multiflora coinciding with its greater increases in photosynthetic capacity. Warming decreased soil total‐Fe concentration by 24% and increased Mg accumulation in soil exchange complex by 19%. Drought increased Na leaf and stem concentrations (93% and 50%, respectively) and accumulation in leaf and aboveground biomass (780 and 800 g ha−1, respectively) in G. alypum, allowing an increase of osmotic pressure which helps to prevent water losses and is related to its capacity to resist drought. Drought reduced S leaf and Mg leaf‐litter concentrations of G. alypum and increased them in leaves of E. multiflora and also increased Mo and Na concentrations in leaves of D. pentaphyllum. Drought increased Fe soil solubility by 65%. The results indicate different effects of climate change on nutrient status in the ecosystem depending on whether the main change is warming or drought. The changes in concentration and biomass accumulation were different depending on the nutrient and the species, changing the stoichiometry among these nutrients and modifying the nutritional quality of plant tissues.

Phenylethyl Glycosides from Globularia alypum Growing in Turkey

AbstractFrom the leaves of Globularia alypum, three new phenylethyl glycosides, namely galypumosides A (=2‐(3,4‐dihydroxyphenyl)ethyl O‐α‐rhamnopyranosyl‐(1→3)‐4‐O‐[(E)‐caffeoyl]‐6‐O‐[(E)‐p‐coumaroyl]‐β‐glucopyranoside; 1), B (=2‐(3,4‐dihydroxyphenyl)ethyl O‐α‐rhamnopyranosyl‐(1→3)‐4‐O‐[(E)‐caffeoyl]‐6‐O‐[(E)‐feruloyl]‐β‐glucopyranoside; 2), and C (=2‐(3,4‐dihydroxyphenyl)ethyl O‐α‐rhamnopyranosyl‐(1→3)‐4‐O‐[(E)‐caffeoyl]‐6‐O‐menthiafoloyl‐β‐glucopyranoside; 3), were isolated, together with two known phenylethyl glycosides, calceolarioside A and verbascoside. Eight iridoid glucosides, catalpol, globularicisin, globularin, globularidin, globularinin, globularimin, lytanthosalin, and alpinoside, a flavon glycoside, 6‐hydroxyluteolin 7‐O‐sophoroside, a lignan glycoside, syringaresinol 4′‐O‐β‐glucopyranoside, and a phenylpropanoid glycoside, syringin, were also obtained and characterized. The structures of the isolates were elucidated on the basis of 1D‐ and 2D‐NMR experiments as well as HR‐MALDI‐MS.

Secondary Metabolites from Globularia alypum

The genus Globularia (Globulariaceae) includes two species in Algeria. One of them is endemic, Globularia eriocephala (Pomel); the other Globularia alypum L., widespread in the Mediterranean region [1], is used in folk medicine. Its leaves are traditionally used as a hypoglycemic agent, laxative [2], cholagogue, stomachic, purgative, and sudorific [3]. In the present paper we report on the qualitative and quantitative analysis of secondary metabolites extracted from the medicinal plant G. alypum, which has been the subject of several chemical and pharmacological investigations [4–10]. Aerial parts of Globularia alypum L. were collected during the flowering season in eastern Algeria (April 2004). A voucher specimen for this material (VAREN/ SB BF Rv /04/04) was deposited at the Herbarium of the Faculty of Sciences, University MentouriConstantine. Air-dried and powdered aerial parts (1280 g) of G. alypum were macerated in an ethanolic solution (70%); the residue was filtered, concentrated, then successively extracted with petroleum ether, trichloromethane, ethyl acetate, and n-butanol. The AcOEt extract (10 g) was applied to a column of silica gel 60 and eluted with a gradient of CHCl3–CH3COCH3 with increasing polarity. Preparative TLC on silica gel 60 F254 using CHCl3–acetone–acetic acid (4:0.25:0.25) led to luteolin, para-coumaric acid, and cinnamic acid, while using CHCl3–acetic acid (4:0.25) led to apigenin. The para-coumaric acid and cinnamic acid have already been isolated from this plant [4, 5]. Flavonic compounds were identified using UV and 1H NMR spectra, chemical transformations, and comparison with authentic samples [11, 12]. Flavonoids 1, 2 have been isolated previously from another species of Globularia [13], but from G. alypum L. this was the first time. Apigenin, C15H10O5, mp 348–350°C, UV (λmax, MeOH, nm): 268, 335; +NaOH: 274, 324, 392; +AlCl3: 274, 300, 348, 382; AlCl3/HCl: 274, 300, 334, 380; NaOAc: 276, 306, 380. 1H NMR (250 MHz, CD3COCD3, δ, ppm, J/Hz ): 7.90 (2H, d, J = 8.7, H-2′, H-6′); 7.02 (2H, d, J = 8.7, H-3′, H-5′); 6.65 (1H, s, H-3); 6.55 (1H, d, J = 2.2, H-8); 6.26 (1H, d, J = 2.2, H-6). Luteolin, C15H10O6, mp 329–331°C, UV (λmax, MeOH, nm): 264, 350; +NaOH: 267, 329, 402; +AlCl3: 273, 303, 422; AlCl3/HCl: 274, 297, 358, 385; NaOAc: 254, 269, 352. 1H NMR (250 MHz, CD3COCD3, δ, ppm, J/Hz): 7.52 (1H, d, J = 2, H-2′); 7.49 (1H, dd, J = 8.4; 2, H-6′); 7.02 (1H, d, J = 8.4, H-5′); 6.62 (1H, s, H-3); 6.55 (1H, d, J = 2, H-8); 6.26 (1H, d, J = 2, H-8).

Contrasting Species‐Specific, Compound‐Specific, Seasonal, and Interannual Responses of Foliar Isoprenoid Emissions to Experimental Drought in a Mediterranean Shrubland

We aimed to test the effect of soil drought conditions projected by general circulation models and ecophysiological models for the next few decades on emission rates of isoprenoids by Mediterranean shrublands. We conducted a field experiment in which we generated soil drought (ca. 12%–20% decreased soil moisture) using automatically sliding curtains, and we measured foliar isoprenoid emissions in the three dominant species of the studied shrubland (Erica multiflora L., Globularia alypum L., and Pinus halepensis L.) in two different annual periods. Monoterpene emissions were detected in the three studied species, but isoprene emissions were significantly detected only in E. multiflora. Main volatile terpenes emitted by the three species were α‐pinene, β‐myrcene, limonene, and Δ3‐carene. In general, maximum isoprenoid emission rates were found in the hottest periods, and minimum emission rates were found in winter. Isoprene emissions in E. multiflora ranged between practically 0 μg g−1 (dry matter) h−1 in winter 2005 and 57 μg g−1 (dry matter) h−1 in summer 2003. Isoprene emissions were 75% lower during the dry second annual period, 2004–2005, than during the first year, 2003–2004. In E. multiflora, there was an overall decrease of 19% in isoprene emissions in response to soil drought. Conversely, monoterpene emissions increased by 26.4% in drought treatment. In G. alypum, there was an overall increase of 75% in terpene emissions in response to soil drought. In P. halepensis, drought treatment increased terpene emission rates by 156%. Drought treatment affected the emissions mainly in the hottest seasons, spring and summer. There were strong compound‐specific, species‐specific, interannual, and seasonal changes in the emission rates and in their response to the treatments. These data might help to improve prediction algorithms, inventories, and modeling of isoprenoid emissions and of their response to climate change (decreased isoprene emissions and increased monoterpene emissions under moderate or short‐term drought and decreased emissions under severe or long‐term drought), but the great variability highlights the difficulty of the task.

Precipitation-dependent flowering of Globularia alypum and Erica multiflora in Mediterranean shrubland under experimental drought and warming, and its inter-annual variability.

Relationships between autumn flowering, precipitation and temperature of plant species of Mediterranean coastal shrublands have been described, but not analysed experimentally. These relationships were analysed for two species of co-occurring, dominant, autumn-flowering shrubs, Globularia alypum and Erica multiflora, over 4 years and in experimentally generated drought and warming conditions. The aim was to improve predictions about the responses and adaptations of flowering of Mediterranean vegetation to climate change. Beginning of anthesis and date of maximum flowering intensity ('peak date') were monitored over 4 years (2001-2004) on a garrigue land type in the noth-east of the Iberian Peninsula. Two experimental treatments were applied, increased temperature (+0.73 degrees C) and reduced soil moisture (-17%) relative to untreated plots. Flowering of Globularia alypum and Erica multiflora differed greatly between years depending on the precipitation of the previous months and the date of the last substantial rainfall (>10 mm). Globularia alypum flowered once or twice (unimodal or bimodal) as the result of differences in the distribution and magnitude of precipitation in late-spring and summer (when floral buds develop). The drought treatment delayed and decreased flowering of Globularia alypum in 2001 and delayed flowering in 2002. Warming extended the period between the beginning of flowering and the end of the second peak for autumn flowering in 2001 and also increased peak intensity in 2002. Flowering of Erica multiflora was unaffected by either treatment. Autumn flowering of Globularia alypum and Erica multiflora is more dependent on water availability than on temperature. Considerable inter-annual plasticity in the beginning of anthesis and peak date and on unimodal or bimodal flowering constitutes a 'safe strategy' for both species in relation to varying precipitation and temperature. However, severe changes in precipitation in spring and summer may severely affect flowering of Globularia alypum but not Erica multiflora, thus affecting development/structure of the ecosystem if such conditions persist.

Beneficial effects of a methanolic extract of Globularia alypum on glycaemia, lipid peroxidation and antioxidant enzymes activities in rats with streptozotocin-induced diabetes

Beneficial effects of a methanolic extract of <i>Globularia alypum</i> on glycaemia, lipid peroxidation and antioxidant enzymes activities in rats with streptozotocin-induced diabetes

Beneficial effects of a methanolic extract of Globularia alypum on glycaemia, lipid peroxidation and antioxidant enzymes activities in rats with streptozotocin-induced diabetes

Beneficial effects of a methanolic extract of <i>Globularia alypum</i> on glycaemia, lipid peroxidation and antioxidant enzymes activities in rats with streptozotocin-induced diabetes

Drought and warming induced changes in P and K concentration and accumulation in plant biomass and soil in a Mediterranean shrubland

A field experiment involving drought and warming manipulation was conducted over a 6-year period in a Mediterranean shrubland to simulate the climate conditions projected by IPCC models for the coming decades (20% decreased soil moisture and 1°C warming). We investigated P and K concentration and accumulation in the leaves and stems of the dominant species, and in soil. Drought decreased P concentration in Globularia alypum leaves (21%) and in Erica multiflora stems (30%) and decreased K concentration in the leaves of both species (20% and 29%, respectively). The general decrease of P and K concentration in drought plots was due to the reduction of soil water content, soil and root phosphatase activity and photosynthetic capacity that decreased plant uptake capacity. Warming increased P concentration in Erica multiflora leaves (42%), but decreased it in the stems and leaf litter of Erica multiflora and the leaf litter (33%) of Globularia alypum, thereby demonstrating that warming improved the P retranslocation and allocation from stem to leaves. These results correlate with the increase in photosynthetic capacity and growth of these two dominant shrub species in warming plots. Drought and warming had no significant effects on biomass P accumulation in the period 1999–2005, but drought increased K accumulation in aboveground biomass (10 kg ha−1) in Globularia alypum due to the increase in K concentration in stems. The stoichiometric changes produced by the different responses of the nutrients led to changes in the P/K concentration ratio in Erica multiflora leaves, stems and litter, and in Globularia alypum stems and litter. This may have implications for the nutritional value of these plant species and plant–herbivore relationships. The effects of climate change on P and K concentrations and contents in Mediterranean ecosystems will differ depending on whether the main component of change is drought or warming.

Changes in soil enzymes related to C and N cycle and in soil C and N content under prolonged warming and drought in a Mediterranean shrubland

In a Mediterranean shrubland, we investigated the effects of the projected warming and drought on soil urease, protease and β-glucosidase activities and the relation of the possible changes in the activities of these enzymes with the observed changes in soil moisture, soil pH and in C and N stocks in soils, leaves and leaf litter during 1 year (April 2004–May 2005). This investigation was conducted in a long-term experiment of warming and drought manipulation that began in 1999 and is lasting until now. Warming increased soil urease activity by 10% in the study period, mainly by increasing soil urease activity 30% in winter and 10% in spring, and increased β-glucosidase activity 38% in spring. Soil urease and β-glucosidase activities were positively correlated with soil temperatures in winter and negatively in summer. Warming increased soil enzyme activities in winter when soil moisture was highest and in spring coinciding with the greatest biological activity. Warming decreased NH 4 + soil concentration in the spring of 2004 (by 30%) and 2005 (by 72%), in consonance with the increase in N uptake by plants. Warming decreased N concentration in Globularia alypum leaf litter, increasing C/N leaf ratio by 30% showing an increase in N mobilization and contributing to a greater total N accumulation in plants. However, the greater NO 3 − availability in soil observed under warming, probably by an increase in nitrification, may lead to a net N loss by leaching under the torrential rainfalls typical of the Mediterranean climate regions. Drought reduced soil protease activity (9%) in the study period, mainly by decreasing it in spring by 13–21%, but did not affect N soil contents because N turn-over reduction was counterbalanced by a decrease in N leaf concentrations. Soil protease activity was positively correlated with soil water content showing a strong dependence of this enzyme on soil water content. Drought did not affect β-glucosidase activity but tended to increase C contents in soils, which together with the increase in C/N in leaves indicate a reduction of C turn-over and a trend to increase C stocks in soil at long term. The effects of warming and drought on soil enzyme activities were due to a direct effect on soil temperature and soil water content, respectively, and not to changes on soil organic matter quantity and nutritional quality.

Response of plant species richness and primary productivity in shrublands along a north–south gradient in Europe to seven years of experimental warming and drought: reductions in primary productivity in the heat and drought year of 2003

AbstractWe used a nonintrusive field experiment carried out at six sites – Wales (UK), Denmark (DK), the Netherlands (NL), Hungary (HU), Sardinia (Italy – IT), and Catalonia (Spain – SP) – along a climatic and latitudinal gradient to examine the response of plant species richness and primary productivity to warming and drought in shrubland ecosystems. The warming treatment raised the plot daily temperature by ca. 1 °C, while the drought treatment led to a reduction in soil moisture at the peak of the growing season that ranged from 26% at the SP site to 82% in the NL site. During the 7 years the experiment lasted (1999–2005), we used the pin‐point method to measure the species composition of plant communities and plant biomass, litterfall, and shoot growth of the dominant plant species at each site. A significantly lower increase in the number of species pin‐pointed per transect was found in the drought plots at the SP site, where the plant community was still in a process of recovering from a forest fire in 1994. No changes in species richness were found at the other sites, which were at a more mature and stable state of succession and, thus less liable to recruitment of new species. The relationship between annual biomass accumulation and temperature of the growing season was positive at the coldest site and negative at the warmest site. The warming treatment tended to increase the aboveground net primary productivity (ANPP) at the northern sites. The relationship between annual biomass accumulation and soil moisture during the growing season was not significant at the wettest sites, but was positive at the driest sites. The drought treatment tended to reduce the ANPP in the NL, HU, IT, and SP sites. The responses to warming were very strongly related to the Gaussen aridity index (stronger responses the lower the aridity), whereas the responses to drought were not. Changes in the annual aboveground biomass accumulation, litterfall, and, thus, the ANPP, mirrored the interannual variation in climate conditions: the most outstanding change was a decrease in biomass accumulation and an increase in litterfall at most sites during the abnormally hot year of 2003. Species richness also tended to decrease in 2003 at all sites except the cold and wet UK site. Species‐specific responses to warming were found in shoot growth: at the SP site, Globularia alypum was not affected, while the other dominant species, Erica multiflora, grew 30% more; at the UK site, Calluna vulgaris tended to grow more in the warming plots, while Empetrum nigrum tended to grow less. Drought treatment decreased plant growth in several studied species, although there were some species such as Pinus halepensis at the SP site or C. vulgaris at the UK site that were not affected. The magnitude of responses to warming and drought thus depended greatly on the differences between sites, years, and species and these multiple plant responses may be expected to have consequences at ecosystem and community level. Decreases in biodiversity and the increase in E. multiflora growth at the SP site as a response to warming challenge the assumption that sensitivity to warming may be less well developed at more southerly latitudes; likewise, the fact that one of the studied shrublands presented negative ANPP as a response to the 2003 heat wave also challenges the hypothesis that future climate warming will lead to an enhancement of plant growth and carbon sequestration in temperate ecosystems. Extreme events may thus change the general trend of increased productivity in response to warming in the colder sites.

Warming and drought change trace element bioaccumulation patterns in a Mediterranean shrubland

A field experiment consisting of drought and warming manipulation was conducted in a Mediterranean shrubland dominated by the shrubs Erica multiflora and Globularia alypum. The aim was to investigate the effects of the climatic changes predicted by IPCC models for the coming decades on trace element concentration and accumulation in aboveground biomass, plant litter, and soil. Warming increased concentrations and aboveground accumulation of some trace elements related to plant root uptake, such as Al, As, Cr, Cu, and partially Pb. This effect was more general in E. multiflora than in G. alypum. The stronger effects were increases in Al leaf concentrations (42%) and aboveground accumulation (500 g ha −1) in E. multiflora, in As stem biomass accumulation (0.2 g ha −1) in E. multiflora, and in Cr leaf concentrations (51%) in G. alypum and stem aboveground accumulation in E. multiflora (1.1 g ha −1). These species-specific increases were related to greater retranslocation, photosynthetic capacity and growth in E. multiflora than in G. alypum. Warming decreased the concentrations of some trace elements in leaf litter, implying the existence of an increased leaf retranslocation. Drought increased As (40%) and Cd (55%) in E. multiflora stems, whereas it decreased Cu (50%) in leaves, Ni (28%) in stems and Pb (32%) in leaf litter of G. alypum. The increasing concentrations of some trace elements in E. multiflora and not in G. alypum were related to a greater growth reduction in E. multiflora than in G. alypum. Warming increased As soil solubility (67%) and decreased total soil As (21%). Those changes were related to a greater Fe mobilization in warming plot and to a greater plant capture. Drought increased Hg (350%) concentrations in soils but had no significant effects on trace element accumulation in aboveground biomass. The different response to warming and drought in the two dominant species implies uneven changes in the quality of the plant tissues that may have implications for herbivores. This may be specially important for the performance of the studied Mediterranean ecosystems under the warmer and drier conditions predicted by the next decades by the GCM and ecophysiological models.

Seasonal patterns of root-surface phosphatase activities in a Mediterranean shrubland. Responses to experimental warming and drought

Mediterranean ecosystems are water limited and the current general circulation Models (GCM) and ecophysiological models forecast a warming and a further increase of drought in the next decades. A stronger water stress can decrease the capacity for nutrient absorption by plants. We conducted a field experiment to simulate forecasted drought and warming in a Mediterranean calcareous shrubland to assess the performance of root-surface phosphatase activities of the dominant shrub Globularia alypum. These enzyme activities were higher in autumn and spring, when the climate conditions were optimal for plant activity, than in summer or winter, when there was either lack of water or cold temperatures. A decrease in soil moisture in drought plots decreased root-surface phosphatase activity (29% in summer and 25% in autumn). The decrease in root-surface phosphatase activity in drought plots coincided with a decrease in P leaf concentrations and P accumulation in aboveground biomass and loss of photosynthetic capacity of some dominant shrub species of this ecosystem, and with a tendency to increase total soil-P. These results suggest that the expected drier conditions in this Mediterranean shrubland in the next decades will slow down the P uptake by plants, thereby, diminishing the P contents in biomass and increasing total P contents in soil in non-available forms and that this can be, in part, attributable to a result of the decrease in root-surface phosphatase activity.

New phenylethanoid glycosides from Globularia alypum

Globularia alypum L. (formerly Globulariaceae, now „new“ Plantaginaceae) is a shrub distributed to the Mediterranean area [1]. It is widely utilized in indigenous systems of medicine in some Mediterranean countries, especially in Morocco as a hypoglycaemic agent, laxative, cholagogue, and stomachic [2]. Recent researches on this plant have resulted in the isolation of various types of iridoid glucosides, phenylethanoid glycosides and flavonoids [3, 4]. As a part of our continuing phytochemical investigation of members of the genus Globularia growing in the flora of Turkey, we have investigated the chemical constituents of G. alypum. Our current investigation on the MeOH extract of the leaves led to the isolation and identification of two new phenylethanoid glycosides (1 and 2), in addition to two known phenylethanoid glycosides, calceolarioside A and verbascoside. Eight iridoid glucosides (lytanthosalin, catalpol, globularicisin, globularin, globularidin, globularinin, globularimin, and alpinoside), a flavon glycoside (6-hydroxyluteolin 7-O-sophoroside), a lignan glycoside (syringaresinol 4' -O-β-D-glucopyranoside), and a phenylpropanoid glycoside (syringin) were also obtained and characterized. The structures of the isolates were elucidated on the basis of 1D and 2D NMR experiments as well as HR-MS. Compounds 1 and 2 are rare examples of phenylethanoid glycosides bearing two aromatic acyl units.

In Vitro. Antimicrobial Activity of Some Libyan Medicinal Plant Extracts

In vitro. antimicrobial activity of 32 extracts (ethanol, hexane, chloroform, and methanol) from eight different Libyan medicinal plants, namely Artemisia herba-alba. Asso (Compositae), Globularia alypum. L. (Globulariaceae), Helichrysum stoechas., DC. (Compositae), Peganum harmala. L. (Zygophyllaceae), Polygonum equisetiforme. Sibth. & Sm. (Polygonaceae), Pulicaria crispa. (Forssk.) Oliv. (Compositae), Rosmarinus officinalis. L. (Labiatae), and Thymus capitatus. Hoffmanns & Link. (Labiatae), was determined against seven bacteria and one yeast strain using the broth microdilution method. The results show that all plants tested possessed antimicrobial activity against at least one of the examined strains at a concentration ≤8 mg/ml. The extracts from H. stoechas., P. equisetiforme., P. crispa., R. officinalis., and T. capitatus. exhibited strongest activity against Gram-positive bacteria with minimum inhibitory concentrations (MICs) ranging from 0.5 to 8 mg/ml. Only a few extracts showed inhibitory activity against Gram-negative strains in this test, whereas those of the H. stoechas. and P. harmala. were among the strongest ones (MICs range 4–8 mg/ml). High anticandidal activity was observed for P. harmala., P. crispa., and T. capitatus., with MICs ranging from 0.25 to 1 mg/ml.

Warming and drought alter soil phosphatase activity and soil P availability in a Mediterranean shrubland

We conducted a field experiment simulating the warming and drought in a Mediterranean shrubland dominated by Erica multiflora and Globularia alypum with the aim to simulate the next future climate conditions predicted by the IPCC and ecophysiological models. As P is frequently a limiting nutrient in Mediterranean ecosystems, we investigated the drought and warming effects on soil phosphatases activities, soil P contents and availability, litter and leaf P concentration, and the capacity of this community to maintain soil P reserves and retain this nutrient in the ecosystem. Warming treatment increased soil and air temperature (an average of 1°C) and drought treatment decreased soil water content in one of the seasons analysed (28% in autum 2004). Warming increased (68%) the activities of soil acid phosphatases in summer and alkaline phosphatase activity (22%) in spring 2004, and increased P concentrations in E. multiflora. Instead, warming decreased P concentrations in litterfall of this same species, E. multiflora, and soil HCO3-extractable Pi (Olsen-Pi) in some seasons, decreasing total P soil concentration (37%) after 6 years of treatment. The drought treatment did not change soil phosphatase activities, nor available Pi. The effects of climate change on soil P dynamics in Mediterranean areas will thus be strongly dependent on whether the main variable involved in the local change is warming or drought. If warming is the main change without significant changes in water availability, the increases of biological activity can accelerate plant growth, P capture by plants and increase soil-phosphatase activity, altogether decreasing P contents in soil. If drought is the main change, a reduction in P demands by plants is expected, increasing P stocks in soils.

Antioxidative effect of compounds isolated from Globularia alypum L. structure–activity relationship

The antioxidant activity of the Globularia alypum phytochemicals were evaluated for their capacity to scavenge the 1,1-diphenyl-2-dipicrylhydrazyl (DPPH°) free radical and some structure–activity relationships were obtained. Assay guided fractionation led to the isolation of syringin, four phenylethanoids, four flavonoids and six iridoids as the main constituents of the extract and their antioxidant activity was determined. The obtained results showed that the activity towards the DPPH° free radical was mainly due to the flavonoid and phenyl ethanoid constituents which were most active free radical scavengers than iridoids. Among the tested flavonoids, 6-hydroxyluteolin glycosides showed the strongest activity, suggesting that the presence of the 6-hydroxyl group was a favourable structural feature of flavonoids with regard to DPPH° scavenging effect. The isolated phenylethanoid glycosides all showed potent antioxidant activity and their capacity to scavenge free DPPH° radical was greater than BHT. Their high antioxidant activity could be attributed to the caffeoyl moieties contained in them, while iridoids showed moderate free radical scavenging activity. The obtained results demonstrated that some of the isolated compounds play an important role for the antioxidant activity of G. alypum and give a scientific basis to the use of this plant in traditional medicine. The hydromethanolic extract of G. alypum could thus be considered as a source of potential antioxidants and will promote the reasonable usage of this plant in food technology and processing as well as for medical use.

Iridoid Glucosides from the Aerial Parts of Globularia alypum L. (Globulariaceae).

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Seasonal contrasting changes of foliar concentrations of terpenes and other volatile organic compound in four dominant species of a Mediterranean shrubland submitted to a field experimental drought and warming

To test the effect of forecasted drought and warming conditions for the next decades by GCM and ecophysiological models on foliar concentrations of volatile organic compounds (VOCs) and especially of volatile terpenes, we studied four typical Mediterranean woody plants (Pinus halepensis L., Pistacia lentiscus L., Rosmarinus officinalis L. and Globularia alypum L.) under a field experimental drought and warming generated using automatically sliding curtains. Terpenes were detected in the four studied species (R. officinalis L., P halepensis L., Pistacia lentiscus L. and G. alypum L.). In general, maximum concentrations of terpenes were found in the coldest periods and minimum concentrations in the summer. Their concentrations ranged between 0.003 mg g−1 DM (eugenol) in G. alypum under drought conditions and 37 mg g−1 DM in R. officinalis under control conditions. Main volatile terpenes found in all studied species except in G. alypum were α‐pinene, camphene, β‐pinene, β‐phellandrene and caryophyllene. In general, VOC leaf concentrations increased when soil moisture increased and decreased when air temperature increased. However, contrasting not consistent responses to the drought and warming treatments were found among species, seasons and years. For example, in P. halepensis, the concentrations decreased in response to drought in winter and instead increased in summer. Contrarily, drought decreased concentrations in summer and increased them in winter in Pistacia lentiscus. In any case, the data on seasonal VOC concentration in Mediterranean woody species provided here will add new knowledge of seasonal variation in essential oil contents of these species. These data might help in the study of flammability of Mediterranean ecosystems and in improving prediction algorithms, inventories and modelling of monoterpene emissions in response to climate change, which mostly do not consider the changes in concentration under drought stress. However, the lack of general and consistent response patterns to increasing drought and warming among species, seasons and years found here makes this task difficult.