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Background Helichrysum italicum (Asteraceae) is a small shrub endemic to the Mediterranean Basin, growing in fragmented and diverse habitats. The species has attracted attention due to its secondary metabolite content, but little effort has as yet been dedicated to assessing the genetic and metabolite diversity present in these populations. Here, we describe the diversity of 50 H. italicum populations collected from a range of habitats in Sardinia.Methods H. italicum plants were AFLP fingerprinted and the composition of their leaf essential oil characterized by GC-MS. The relationships between the genetic structure of the populations, soil, habitat and climatic variables and the essential oil chemotypes present were evaluated using Bayesian clustering, contingency analyses and AMOVA.Key resultsThe Sardinian germplasm could be partitioned into two AFLP-based clades. Populations collected from the southwestern region constituted a homogeneous group which remained virtually intact even at high levels of K. The second, much larger clade was more diverse. A positive correlation between genetic diversity and elevation suggested the action of natural purifying selection. Four main classes of compounds were identified among the essential oils, namely monoterpenes, oxygenated monoterpenes, sesquiterpenes and oxygenated sesquiterpenes. Oxygenated monoterpene levels were significantly correlated with the AFLP-based clade structure, suggesting a correspondence between gene pool and chemical diversity.ConclusionsThe results suggest an association between chemotype, genetic diversity and collection location which is relevant for the planning of future collections aimed at identifying valuable sources of essential oil.

Biosensors based on Pt or Pt/Ir based needle-type microelectrodes have been successfully employed for continuous in vivo real-time brain biomonitoring of biomarkers such as glutamate and glucose. However, when implanted, these biosensors often bend, thereby damaging its surface and degrading its bioanalytical properties. In addition, downscaling of Pt and Pt/Ir needle-type biosensors, to improve the spatial resolution and decrease tissue damage, is technically challenging. In that sense, we investigated whether the use of a material with low malleability, tungsten (W), coated with a highly conductive material, gold (Au) could be as an alternative for conventional needle-type based biosensors.Therefore, we developed implantable needle-type (50 m Ø) gold coated tungsten (W-Au) amperometric microbiosensors. First, we evaluated electrochemically, the ability of W-Au microelectrodes (50 m Ø) to continuously monitor changes in H 2 O 2 . After, we functionalized, using a layer-by-layer assembly, the surface of W-Au microelectrodes. First with permselective membrane(s) (Nafion and Nafion-PPD) and after with an enzymatic hydrogel, containing an enzyme selective for glucose (glucose oxidase). Both the enzyme loading and the applied potential were optimized and the performance of functionalized W-Au microelectrodes and fully assembled biosensors was evaluated electrochemically. Additionally, the surface of bare and functionalized microelectrodes was also characterized by imaging techniques (scanning electron microscopy).In vivo experiments revealed that, W-Au based glucose biosensors, were able to accurately monitor, in real-time, changes in brain glucose in response to relevant pharmacological challenges.

Pancreatic triacylglycerol lipase (PL), α-amylase and α-glucosidase are interesting pharmacological targets for the management of dyslipidemia, atherosclerosis, and obesity-diabetes. Limonium spp (Plumbaginaceae) are endemic to Sardinia, Italy. Comparable with acarbose, aqueous extracts (AE) of L. contortirameum and L. virgatum, and their phytoconstituent gallic acid concentration gradients (mg/mL) were identified as in vitro potent ( p<0.001, n=3) and efficacious dual inhibitors of α-amylase and α-glucosidase with respective IC50 (mg/mL) values of 0.6 ± 0.1, 1.2 ± 0.1 and 0.15 ± 0.02. Equivalent to orlistat (PL IC50 of 0.114 ± 0.004 μg/mL), L. contortirameum, L. virgatum AE and their phytoprinciple gallic acid inhibited PL substantially ( p<0.001, n=3) in a dose-dependent manner in vitro with PL- IC50 (μg/mL) of 920.4 ± 105.2, 593.1 ± 56.8 and 8.4 ± 0.9, respectively. LC-MS analysis of extracts revealed the presence of several phenolic compounds in their aglycon and glycoside forms. These are catechins, flavones, epigallocatechins and flavonols. Flavonoid- and polyphenol-rich L contortirameum and L. virgatum, modulating gastrointestinal carbohydrate and lipid digestion and absorption, may be advocated as candidates for obesity-diabetes prevention and phytotherapy.