8 research outputs found
On equality of two classes of homomorphism-homogeneous relational structures
No full textThis talk provides a story of equality of homomorphism-homogeneous classes. Cameron and Nesetril [1] suggested a novel notion of homomorphism-homogeneity for relational structure that requires every local homomorphism between finite induced substructures extends to homomorphism to the whole structure extending thus a classical notion of ultrahomogeneity in sense of Fraisse. Depending on types of local homomorphism as well as the extending one it is possible to define various types of homomorphism-homogeneity, e.g. monomorphism-homogeneity extending local monomorphism to homomorphism. Mentioned work was an onset of wide classification program attempting to describe corresponding homogeneity classes. Already in this work there was a question about equality of classes HH and MH which was answered by Rusinov and Schweitzer 4 years later for countable undirected grahs. Later, with Hubicka and Masulovic [3] we studied L-colored graphs, graphs having their edges as well as vertices colored by partial ordered set L, and showed conditions under which classes HH and MH are equal for finite L-colored graphs. We extend this result by considering countably infinite P,Q-colored graphs, graphs coloring vertices and edges by two different partially ordered sets P and Q, and showed that necessary as well as suffcient condition for equality of classes MH and HH is that Q is a linear order [4].
Joint work with Andres Aranda.
[1] P. J. Cameron, J. Nesetril (2006), Homomorphism-homogeneous relational
structures, Combinatorics, probability and computing 15(1-2): 91{103.
[2] M. Rusinov, P. Schweitzer (2010), Homomorphismhomogeneous graphs, Journal of Graph Theory 65(3):253{262.
[3] D. Hartman, J. Hubicka, D. Masulovic (2014) Homomorphism-homogeneous
L-colored graphs, European Journal of Combinatorics 35: 313{32.
[4] A. Aranda, D. Hartman (2018), Morphism extension classes of countable L-colored graphs. Preprint at arXiv:1805.01781.Non UBCUnreviewedAuthor affiliation: Charles University in PragueResearche
Assessing the pharmacological potential of selected xanthene derivatives
No full textA convenient and efficient approach toward the synthesis of seven aromatically substituted xanthendiones 1‒7 and one structurally-related xanthenone 8 through condensation of dimedone and the appropriate aromatic aldehyde is reported. Further, their chemical structure was confirmed by melting points, elemental analysis, FT-IR, 1H-, 13C-NMR and UV–Vis spectroscopic methods. The relationship between the chemical structure and pharmacological activity was determined empirically using appropriate software packages and in vitro using the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) method. The results of in silico prediction suggested that all investigated compounds possess good oral bioavailability. The results of the ABTS assay indicate that five compounds possess the ability to scavenge the ABTS•+ radical cation. Based on the comparison of the IC50 values, the activity of the compounds was found to be as follows: 6 > 1 > 7 > 2 > 8. The effects of solvent dipolarity/polarizability and solute solvent–hydrogen-bonding interactions on the shifts of the absorption maxima were rationalized by means of the linear solvation energy relationship concepts proposed by Kamlet–Taft and Catalán.U ovom radu, predstavljena je jednostavna metoda u dva koraka za sintezu sedam derivata ksantendiona i jednog derivata ksantenona koji sadrže različite aromatične supstituente, polazeći od dimedona i odgovarajućih aromatičnih aldehida. Karakterizacija sintetisanih jedinjenja izvršena je određivanjem temperature topljenja, kao i primenom elementalne analize, FT-IR, 1 H-NMR i 13C-NMR spektroskopskih metoda. Veza između hemijske strukture ovih jedinjenja i njihove farmakološke aktivnosti uspostavljena je empirijski korišćenjem odgovarajućih softverskih paketa (za predikckciju farmakološke aktivnosti) i in vitro određivanjem njihove antioksidativne aktivnosti primenom ABTS metode. Rezultati ABTS metode pokazuju da od celokupne serije testiranih jedinjenja, pet jedinjenja pokazuje značajnu antioksidativnu aktivnost. Na osnovu međusobnog poređenja IC50 vrednosti ispitivanih jedinjenja pokazano je da njihova antioksidativna aktivnost opada u sledećem nizu: 6 > 1 > 7 > 2 > 8. Jedinjenje 6 je najaktivnije u analiziranoj seriji i ima IC50 vrednost približne vrednosti kao askorbinska kiselina. Rezultati solvatohromnih jednačina koje su razvili Kamlet (Kamlet), Taft (Taft) i Katalan (Catalán), ukazuju da položaj apsorpcionih maksimuma proučavanih jedinjenja zavisi od prirode (polarnosti i kiselo-baznih svojstava) upotrebljenih rastvarača. Sa visokim vrednostima antioksidativne aktivnosti i dobrom oralnom bioraspoloživošću, derivati ksantendiona i ksantenona sa aromatičnim supstituentima, predstavljaju dobru polaznu osnovu za sintezu novih farmakološki aktivnih jedinjenja i bolje razumevanje uticaja strukture na farmakološku aktivnost.Supplementary information: [https://technorep.tmf.bg.ac.rs/handle/123456789/6810
