Publications by Year: 2013

Pothou E a, Melliou E b, Skaltsounis A-L b, Liouni M c, Magiatis P b. Investigation of volatile constituents of beer, using resin adsorption and GC/MS, and correlation of 2-(3H)-benzoxazolone with wheat malt. Journal of the American Society of Brewing Chemists [Internet]. 2013;71:35-40. WebsiteAbstract
The volatile constituents of 22 samples of commercial beers (lager, ale, and lambic) were isolated using adsorption resin XAD-4 and analyzed by gas chromatography, using mass-spectrometric detection. The presence of 63 volatile components was examined in each sample. Major common compounds identified in all of the studied samples were 2-methylpropanol (0.77-12.9%), 3-methylbutanol (32.0-55.5%), phenylethanol (18.7- 58.8%), and tyrosol (0.69-5.82%), expressed as TIC percent. Most other components were found in various concentrations but their presence was not uniformly distributed in all the studied beers. One of the minor volatile compounds, 2-(3H)-benzoxazolone, was found only in beers made with wheat malt. Additionally, for the first time, tryptophol acetate was identified as beer constituent. Finally, principal component analysis of the volatile compounds was able to discriminate the group of beers containing wheat. © 2013 American Society of Brewing Chemists, Inc.
b Magiatis P a, Pappas P c, Gaitanis G d, Mexia N a, e Melliou E a, Galanou M c, d Vlachos C c, Stathopoulou K a, Skaltsounis AL a, Marselos M c, et al. Malassezia yeasts produce a collection of exceptionally potent activators of the ah (dioxin) receptor detected in diseased human skin. Journal of Investigative Dermatology [Internet]. 2013;133:2023-2030. WebsiteAbstract
Malassezia yeasts are commensal microorganisms, which under insufficiently understood conditions can become pathogenic. We have previously shown that specific strains isolated from diseased human skin can preferentially produce agonists of the aryl hydrocarbon receptor (AhR), whose activation has been linked to certain skin diseases. Investigation of skin scale extracts from patients with Malassezia-associated diseases demonstrated 10-to 1,000-fold higher AhR-activating capacity than control skin extracts. Liquid chromatography-tandem mass spectrometry analysis of the patients’ extracts revealed the presence of indirubin, 6-formylindolo[3,2-b]carbazole (FICZ), indolo[3,2-b]carbazole (ICZ), malassezin, and pityriacitrin. The same compounds were also identified in 9 out of 12 Malassezia species culture extracts tested, connecting their presence in skin scales with this yeast. Studying the activity of the Malassezia culture extracts and pure metabolites in HaCaT cells by reverse transcriptase real-time PCR revealed significant alterations in mRNA levels of the endogenous AhR-responsive genes Cyp1A1, Cyp1B1, and AhRR. Indirubin-and FICZ-activated AhR in HaCaT and human HepG2 cells with significantly higher, yet transient, potency as compared with the prototypical AhR ligand, dioxin. In loco synthesis of these highly potent AhR inducers by Malassezia yeasts could have a significant impact on skin homeostatic mechanisms and disease development. © 2013 The Society for Investigative Dermatology.
Karkoula E a, Melliou E b, Magiatis P a. A new method for the estimation of olive oil healthfulness. International News on Fats, Oils and Related Materials [Internet]. 2013;24:266-270. WebsiteAbstract
Several epidemiological studies have shown that the traditional Mediterranean diet is associated with a lower incidence of atherosclerosis, cardiovascular disease, neurodegenerative diseases, and certain kinds of cancer. These appreciable health-promoting properties have been partially correlated with the regular consumption of extra virgin olive oil as the principal source of fat. Olive oil is the most famous agricultural product in the Mediterranean, with a history as old as that region’s civilization. Olive fruits and olive oil not only are delicious but also have been considered as medicines since ancient times.
Myrianthopoulos V a, Kritsanida M a, Gaboriaud-Kolar N a, Magiatis P a, Ferandin Y b, Durieu E b, Lozach O b, Cappel D c, Soundararajan M e, Filippakopoulos P e, et al. Novel inverse binding mode of indirubin derivatives yields improved selectivity for DYRK kinases. ACS Medicinal Chemistry Letters [Internet]. 2013;4:22-26. WebsiteAbstract
DYRK kinases are involved in alternative pre-mRNA splicing as well as in neuropathological states such as Alzheimer’s disease and Down syndrome. In this study, we present the design, synthesis, and biological evaluation of indirubins as DYRK inhibitors with enhanced selectivity. Modifications of the bis-indole included polar or acidic functionalities at positions 5' and 6' and a bromine or a trifluoromethyl group at position 7, affording analogues that possess high activity and pronounced specificity. Compound 6i carrying a 5'-carboxylate moiety demonstrated the best inhibitory profile. A novel inverse binding mode, which forms the basis for the improved selectivity, was suggested by molecular modeling and confirmed by determining the crystal structure of DYRK2 in complex with 6i. Structure-activity relationships were further established, including a thermodynamic analysis of binding site water molecules, offering a structural explanation for the selective DYRK inhibition. © 2012 American Chemical Society.
b Lemonakis N a, Magiatis P b, Kostomitsopoulos N c, d Skaltsounis A-L b, Tamvakopoulos C a. Oral Administration of Chios Mastic Gum or Extracts in Mice: Quantification of Triterpenic Acids by Liquid Chromatography-Tandem Mass Spectrometry. Planta Medica [Internet]. 2013. WebsiteAbstract
Chios mastic gum, the resin obtained as an exudate from the trunk and branches of Pistacia lentiscus L var. chia, is used extensively as a constituent of herbal drugs or functional foods. The oral absorption of its major constituents still remains unclear. In the context of identifying the features of mastic gum that are responsible for either therapeutic effects or effects of nutritional value, a methodology based on high-performance liquid chromatography (HPLC) coupled to tandem mass spectrometry (MS/MS) was developed and applied for the quantification of mastic gum triterpenic acids, 24Z-isomasticadienonic acid (IMNA), and 24Z-isomasticadienolic acid (IMLA) in mouse plasma. The specific compounds were selected based on their biological activity and potential against Helicobacter pylori. Concentrations were determined simultaneously in mouse plasma after oral administration of mastic gum or total mastic extract without polymer (TMEWP) in order to evaluate the role of the natural polymer, poly-β-myrcene, in the absorption process. Following TMEWP administration in mice, circulating IMNA and IMLA plasma levels were significantly higher (approximately 10-fold) in comparison to IMNA and IMLA plasma levels following total mastic gum administration (CMG), suggesting that the polymer plays a critical role in the absorption process. More specifically following TMEWP administration, Cmax plasma values were 3300 ± 859 ng/mL for IMNA and 163 ± 58 ng/mL for IMLA. In comparison, following CMG administration, Cmax plasma values were 329 ± 57 ng/mL for IMNA and 28 ± 8 ng/mL for IMLA.The methodological approaches presented in this study, along with the findings, offer valuable information on the availability of bioactive components following ingestion of mastic and facilitate the uses of mastic either as an ingredient of functional foods or as a herbal drug. © Georg Thieme Verlag KG.
Stathopoulou K a, Valianou L b, Skaltsounis A-L a, Karapanagiotis I b, Magiatis P a. Structure elucidation and chromatographic identification of anthraquinone components of cochineal (Dactylopius coccus) detected in historical objects. Analytica Chimica Acta [Internet]. 2013;804:264-272. WebsiteAbstract
Cochineal is one of the most well known organic red dyes. Dactylopius coccus Costa (Dactylopiidae) is a scale insect that is used as the source of the dye known as Mexican cochineal. Although cochineal is today a natural food colorant (E120) and although it has been used in art objects (textiles and paintings) for centuries, its exact chemical consistency is not well clarified except for carminic acid which is the major component and kermesic and flavokermesic acids. Several minor components (typically less than 5% of the colouring material) remained unknown or partially studied, although their presence has been reported in numerous analytical works related to art objects. Chemical investigation of the methanol extract of the dried insects, after subsequent HPLC chromatographic separations, led to the isolation and structure elucidation of six new anthraquinones, along with the known compounds carminic acid, kermesic acid and flavokermesic acid. The new compounds formerly described as DCII and DCIII, were found to be the 2 C-glucoside of flavokermesic acid and 4-aminocarminic acid, respectively, while DCIV and DCVII were found to be the α/β C-glucofuranosides of kermesic acid, and were studied as a mixture due to equilibrium. In addition, 3 O-glucoside of flavokermesic acid (DCOFK), and 3,4-dideoxycarminic acid (DDCA) were identified. The structures of the new compounds were elucidated on the basis of their NMR and MS data. Finally, the new compounds were detected in silk dyed with cochineal, lake pigment and, furthermore, in historical objects of the cultural heritage (icon and textile) using LC-DAD and LC-MS. © 2013 Elsevier B.V.
Brennan JC a, Denison MS a, Holstege DM b, Magiatis P c, Dallas JL d, Gutierrez EG e, Soshilov AA a, Millam JR f. 2,3-cis-2R,3R-(-)-epiafzelechin-3-O-p-coumarate, a novel flavan-3-ol isolated from Fallopia convolvulus seed, is an estrogen receptor agonist in human cell lines. BMC Complementary and Alternative Medicine [Internet]. 2013;13. WebsiteAbstract
Background: The plant genus Fallopia is well-known in Chinese traditional medicine and includes many species that contain bioactive compounds, namely phytoestrogens. Consumption of phytoestrogens may be linked to decreased incidence of breast and prostate cancers therefore discovery of novel phytoestrogens and novel sources of phytoestrogens is of interest. Although phytoestrogen content has been analyzed in the rhizomes of various Fallopia sp., seeds of a Fallopia sp. have never been examined for phytoestrogen presence.Methods: Analytical chemistry techniques were used with guidance from an in vitro estrogen receptor bioassay (a stably transfected human ovarian carcinoma cell line) to isolate and identify estrogenic components from seeds of Fallopia convolvulus. A transiently transfected human breast carcinoma cell line was used to characterize the biological activity of the isolated compounds on estrogen receptors (ER) α and β.Results: Two compounds, emodin and the novel flavan-3-ol, (-)-epiafzelechin-3-O-p-coumarate (rhodoeosein), were identified to be responsible for estrogenic activity of F. convolvulus seed extract. Absolute stereochemistry of rhodoeosein was determined by 1 and 2D NMR, optical rotation and circular dichroism. Emodin was identified by HPLC/DAD, LC/MS/MS, and FT/ICR-MS. When characterizing the ER specificity in biological activity of rhodoeosein and emodin, rhodoeosein was able to exhibit a four-fold greater relative estrogenic potency (REP) in breast cells transiently-transfected with ERβ as compared to those transfected with ERα, and emodin exhibited a six-fold greater REP in ERβ-transfected breast cells. Cell type-specific differences were observed with rhodoeosein but not emodin; rhodoeosein produced superinduction of reporter gene activity in the human ovarian cell line (> 400% of maximum estradiol [E2] induction) but not in the breast cell line.Conclusion: This study is the first to characterize the novel flavan-3-ol compound, rhodoeosein, and its ability to induce estrogenic activity in human cell lines. Rhodoeosein and emodin may have potential therapeutic applications as natural products activating ERβ, and further characterization of rhodoeosein is necessary to evaluate its selectivity as a cell type-specific ER agonist. © 2013 Brennan et al.; licensee BioMed Central Ltd.