Interakcije antitumorskog seskviterpenskog hidrohinona avarola sa DNA in vitro

Changes in electrophoresis pattern after interaction of supercoiled plasmid pBR322 DNA with avarol was studied at a micromolar concentration of reactants under mild reaction conditions. Interactions of avarol with linear high-molecular CT-DNA at millimolar concentrations were analyzed by electrophoresis and UV spectrophotometry. It was observed that avarol is capable of quenching ethidium bromide fluorescence in DNA bands. An increase in the absorbance of DNA was detected. The results indicate the binding of avarol to DNA and/or modification of nucleotide bases.Proučavane su promene elektroforetskog ponašanja DNA posle interakcija superhelikoidalnog plazmida pBR322 s avarolom pri mikromolarnim koncentracijama reaktanata pod blagim reakcionim uslovima. Interakcije avarola sa linearnom visokomolekulskom CT-DNA pri milimolarnim koncentracijama analizirane su elektroforezom i UV spektrofotometrijom. Uočeno je da je avarol u stanju da gasi fluorescenciju etidijum-bromida u trakama koje potiču od DNA. Detektovan je porast apsorbancije DNA. Rezultati ukazuju na vezivanje avarona za DNA i/ili modifikaciju nukleotidnih baza

Bioconjugate of Lysozyme and the Antibacterial Marine Sesquiterpene Quinone Avarone and Its Derivatives

A conjugate of lysozyme with avarone, a bioactive sesquiterpene quinone of marine origin, and its three derivatives were synthesized. MALDI TOF mass spectral analysis and tryptic digestion showed that the only residue in lysozyme that was modified by all derivatives was lysine 97. The identity of the residue was in full correlation with the prediction obtained by molecular modeling. All bioconjugates preserved most of the enzymatic activity of lysozyme. The melting point of the conjugates was slightly increased in comparison to lysozyme, indicating a slight stabilization of structure. The antibacterial activity of all the conjugates to both Gram positive and Gram negative bacteria was stronger than the activity of either lysozyme or the quinones, the MIC values being in low micromolar range for some conjugates.This is the peer-reviewed version of the article: Novaković, I., Anđelković, U., Zlatović, M., Gašić, M.J., Sladić, D., 2012. Bioconjugate of Lysozyme and the Antibacterial Marine Sesquiterpene Quinone Avarone and Its Derivatives. Bioconjugate Chem. 23, 57–65. [https://doi.org/10.1021/bc200330m

Molecular orbital study of the oxidation of steroidal phenols into quinols and epoxyquinols

The MO study showed that the radical oxidation of phenols into quinols occurs readily. Further radical oxidation (in the m-CPBA / (BzO)2 /hn system) of quinols occurs through appropriate biradical species with an activation energy of 79.5 kJ/mol yielding syn-epoxyquinols. The stereochemical outcome presented in this study is in full agreement with the experimental results

Regioselectivity of conjugate additions to monoalkyl-1,4-benzoquinones

The regioselectivity of the reaction of conjugate addition of thiols, amines, methanol and hydrogen chloride with the monoalkyl-1,4-benzoquinones avarone and 2-tert-butyl-1,4-benzoquinone was investigated. It was shown that the regioselectivity of the reaction is influenced by the electrophilicity of position 5 in unprotonated 2-alkylquinones, the increased electrophilicity of position 6 in acidic medium, and by the acidity of the intermediate hydroquinones

Studies on the interactions of bioactive quinone avarone and its methylamino derivatives with calf thymus DNA

The interactions of avarone, a quinone from the marine sponge Dysideaavara, and the methylamino derivatives of avarone (2), 3'-(methylamino)avarone (3) and 4'-(methylamino)avarone (4) with calf thymus DNA (CT-DNA) were studied. Agarose gel electrophoreticanalysis showed that binding of the quinones quenched fluorescence of ethidium bromide (EB). The extent of fluorescence quenching of intercalator EB by competitive displacement from EB-CT-DNA system and of groove binder Hoechst 33258 (H) from H-CT-DNA system with the quinones was analyzed by fluorescence spectroscopy. The obtained results demonstrated that the quinones reduced binding of both the intercalator EB and the minor groove binder H, indicating possible degradation of DNA. The substituent on the quinone moiety determined the extent of DNA damaging effect of the quinone, which was the most extensive with 3'-(methylamino)avarone and the least extensive with its regioisomer 4'-(methylamino)avarone. The results were confirmed by the observed hyperchromic effects in UV-visible spectra measured after interactions of the derivatives with CT-DNA

Risk for Major Bleeding in Patients Receiving Ticagrelor Compared With Aspirin After Transient Ischemic Attack or Acute Ischemic Stroke in the SOCRATES Study (Acute Stroke or Transient Ischemic Attack Treated With Aspirin or Ticagrelor and Patient Outcomes)

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