Essential Oil Composition of Five Thymus Species from Bulgaria.

In this study, the essential oil composition of five Thymus species, belonging to Sect. Hyphodromi (A. Kerner) Halácsy - Thymus atticus Celak., T. leucotrichus Halácsy, T. striatus Vahl, T. zygioides Griseb. and T. perinicus (Velen.) Jalas. was studied by GC/MS/FID. T. atticus, T. leucotrichus, and T. striatus were characterized by high amounts of sesquiterpenoids (57.7, 78.9 and 79.7 %, respectively) with ß-caryophyllene and caryophyllene oxide as the main constituents. Aromatic compounds (61.2 %) were the most abundant group in T. zygioides essential oil, with thymol (51.2 %) as the principal component. The essential oil from the endemic species T. perinicus contained almost equal amounts of monoterpenoids (37.8 %) and aromatic compounds (36.0 %) with borneol (17.9 %) and thymol (20.9 %) as the major components. The obtained results revealed the existence of new chemotypes of T. atticus (caryophyllene oxide/ß-caryophyllene), T. leucotrichus (ß-caryophyllene/elemol/germacrene D) and T. striatus (ß-caryophyllene/germacrene D/caryophyllene oxide). The essential oil content of endemic T. perinicus is reported for the first time. Principal component analysis (PCA) and cluster analysis (CA) were used to investigate the variations in the essential oils of different Thymus species from Sect. Hyphodromi (A. Kerner) Halácsy.

A Hybrid Nanomaterial Based on Single Walled Carbon Nanotubes Cross-Linked via Axially Substituted Silicon (IV) Phthalocyanine for Chemiresistive Sensors.

In this work, the novel hybrid nanomaterial SWCNT/SiPc made of single walled carbon nanotubes (SWCNT) cross-linked via axially substituted silicon (IV) phthalocyanine (SiPc) was studied as the active layer of chemiresistive layers for the detection of ammonia and hydrogen. SWCNT/SiPc is the first example of a carbon-based nanomaterial in which an axially substituted phthalocyanine derivative is used as a linker. The prepared hybrid material was characterized by spectroscopic methods, thermogravimetry, scanning and transmission electron microscopies. The layers of the prepared hybrid were tested as sensors toward ammonia and hydrogen by a chemiresistive method at different temperatures and relative humidity as well as in the presence of interfering gases like carbon dioxide, hydrogen sulfide and volatile organic vapors. The hybrid layers exhibited the completely reversible sensor response to both gases at room temperature; the recovery time was 100-200 s for NH3 and 50-120 s in the case of H2 depending on the gas concentrations. At the relative humidity (RH) of 20%, the sensor response was almost the same as that measured at RH 5%, whereas the further increase of RH led to its 2-3 fold decrease. It was demonstrated that the SWCNT/SiPc layers can be successfully used for the detection of both NH3 and H2 in the presence of CO2. On the contrary, H2S was found to be an interfering gas for the NH3 detection.

Caffeoylquinic Acids, Cytotoxic, Antioxidant, Acetylcholinesterase and Tyrosinase Enzyme Inhibitory Activities of Six Inula Species from Bulgaria.

Chlorogenic (5-CQA), 1,5-, 3,5-, 4,5- and 3,4-dicaffeoylquinic (DCQA) acids were identified and quantified in the methanol extracts of Inula oculus-christi L., I. bifrons L., I. aschersoniana Janka var. aschersoniana, I. ensifolia L., I. conyza (Griess.) DC. and I. germanica L. by HPLC analysis. The amount of 5-CQA varied from 5.48 to 28.44 mg/g DE and the highest content was detected in I. ensifolia. 1,5-DCQA (4.05-55.25 mg/g DE) was the most abundant dicaffeoyl ester of quinic acid followed by 3,5-DCQA, 4,5-DCQA and 3,4-DCQA. The extract of I. ensifolia showed the highest total phenolic content (119.92±0.95 mg GAE/g DE) and exhibited the strongest DPPH radical scavenging activity (69.41±0.55 %). I. bifrons extract was found to be the most active sample against ABTS.+ (TEAC 0.257±0.012 mg/mL) and the best tyrosinase inhibitor. The studied extracts demonstrated a low inhibitory effect towards acetylcholinesterase and possessed low cytotoxicity in concentration range from 10 to 300 µg/mL toward non-cancer (MDCK II) and cancer (A 549) cells.

Phytochemical Profile of Inula britannica from Bulgaria.

The flower heads of Inula britannica L. of Bulgarian origin afforded sesquiterpene lactones (gaillardin, britannin, I1, 13-dihydroinuchinenolide B, ivalin, pulchellin C), triterpenoids (3-0-palmitates of 160-hydroxylupeol, 16ß-hydroxy-ß-amyrin, and faradiol) and flavonoids (quercetin, luteolin, luteolin-7-0- glucoside). All compounds are known and they were identified by spectral methods. The observed differences in the chemical content of the chloroform and methanol extracts were also reflected in their free radical scavenging activity, evaluated by DPPH and ABTS assays. Intraspecific variability of L britannica is discussed.

Ensuring high quality in anti-doping laboratories.

The worldwide network of World Anti-Doping Agency (WADA)-accredited anti-doping laboratories plays a fundamental role in supporting the global fight against doping in sport. This role is dependent on the ability to provide accurate, reliable and comparable data in identifying and measuring the presence of prohibited substances and methods. The accredited laboratories participate in WADA's External Quality Assessment Scheme (EQAS) program, which provides the structure to continuously assess and improve laboratory performance in compliance to the requirements of the International Standard for Laboratories and related Technical Documents. The WADA EQAS is comprised of various programs, including a blind EQAS, a double-blind EQAS and an educational EQAS, each with specific goals with regard to monitoring and improving laboratory competence. In this article, the anti-doping rules and processes that govern granting and maintenance of WADA laboratory accreditation, aimed at ensuring a high-quality of laboratory operations within the framework of the global fight against doping in sport, are reviewed.

Harmonization of anti-doping rules in a global context (World Anti-Doping Agency-laboratory accreditation perspective).

This article provides a review of the leading role of the World Anti-Doping Agency (WADA) in the context of the global fight against doping in sport and the harmonization of anti-doping rules worldwide through the implementation of the World Anti-Doping Program. Particular emphasis is given to the WADA-laboratory accreditation program, which is coordinated by the Science Department of WADA in conjunction with the Laboratory Expert Group, and the cooperation with the international accreditation community through International Laboratory Accreditation Cooperation and other organizations, all of which contribute to constant improvement of laboratory performance in the global fight against doping in sport. A perspective is provided of the means to refine the existing anti-doping rules and programs to ensure continuous improvement in order to face growing sophisticated challenges. A viewpoint on WADA's desire to embrace cooperation with other international organizations whose knowledge can contribute to the fight against doping in sport is acknowledged.

Hydrogen peroxide induces stress granule formation independent of eIF2α phosphorylation.

In cells exposed to environmental stress, inhibition of translation initiation conserves energy for the repair of cellular damage. Untranslated mRNAs that accumulate in these cells move to discrete cytoplasmic foci known as stress granules (SGs). The assembly of SGs helps cells to survive under adverse environmental conditions. We have analyzed the mechanism by which hydrogen peroxide (H(2)O(2))-induced oxidative stress inhibits translation initiation and induces SG assembly in mammalian cells. Our data indicate that H(2)O(2) inhibits translation and induces the assembly of SGs. The assembly of H(2)O(2)-induced SGs is independent of the phosphorylation of eIF2α, a major trigger of SG assembly, but requires remodeling of the cap-binding eIF4F complex. Moreover, H(2)O(2)-induced SGs are compositionally distinct from canonical SGs, and targeted knockdown of eIF4E, a protein required for canonical translation initiation, inhibits H(2)O(2)-induced SG assembly. Our data reveal new aspects of translational regulation induced by oxidative insults.