Lichens (Lichenophyta phylum), the least exploited subdivision of fungus, are composite plants used in folk medicine for the treatment of diverse pathologies, from respiratory to digestive diseases, as they contain over 500 potentially bioactive compounds identified up-to-date. Lichen acids, such as usnic acid, lobar acid, lecanoric acid or salazinic acid, are among these compounds, with biopharmaceutical applications as antimicrobial, antioxidant and cytotoxic agents. The objectives of this study were to extract usnic acid from Romanian Cetraria islandica, (Parmeliaceae family), to characterize the extracts and to evaluate their antioxidant and antimicrobial potential. The extracts were characterized using FTIR spectroscopy and HPTLC techniques. The extracts and pure usnic acid have shown high antioxidant activity and have activity against certain Gram-positive and Gram-negative bacteria and fungi such as Candida albicans. Therefore, the analyzed bioactive compounds could be used as the basis of pharmaceutical formulations to treat various respiratory and digestive disorders.

Actin filaments play essential roles in many kinds of cellular functions by interacting with hundreds of actin binding proteins. Here we probe the interaction between actin filament and a binding protein, α-actinin, using an atomic force microscopy (AFM) and dynamic force spectroscopy (DFS). The distribution of rupturing events including specific and non-specific interactions of actin filament/α- actinin and BSA/α-actinin were analyzed. The rupture force of the actin filament/α-actinin binding was significantly larger than that of the BSA/α-actinin non-specific interaction, and the peaks represent typical multiple parallel bonds. In addition, based on the rupture forces in different loading rate DFS experiments, the dissociation constant of actin filament/α-actinin binding was estimated. The value is in good agreement with a previously reported value obtained by optical tweezer measurement. We expect that the present method will be useful for interaction measurement of actin filaments and many kinds of binding protein.

Microtubules are cylindrical protein polymers that play important roles in a number of cellular functions. The properties of microtubules are dynamically changed by interacting with many microtubule-related proteins and drugs. In this study, we used atomic force microscopy to evaluate the changes in microtubule mechanical properties induced by treatment with nocodazole, which is a microtubule-destabilizing drug. The average spring constant of the microtubules, which was used as a measure of microtubule lateral stiffness, was drastically decreased by treatment with nocodazole within 30 min from 0.052 +/- 0.014 N/m to 0.029 +/- 0.015 N/m. Our findings will aid in the understanding of microtubule dynamics, protein interactions in response to drug treatment, microtubule-related diseases, and drug development.

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<p class="PaperAbstract"><span lang="EN-GB">The interaction between pyridinium ligands derived from 4,4’-bipyridine (N,N’-bis(p-bromophenacyl)-4,4’-bipyridinium dibromide – Lr) and (N,N’-bis(p-bromophenacyl)-1,2-bis (4-pyridyl) ethane dibromide – Lm) with lipase enzyme was evaluated. The stability of the pyridinium ligands, having an essential role in biological systems, in 0.1 M KNO₃ as supporting electrolyte is influenced by the lipase concentration added. The pH and conductometry measurements in aqueous solution suggest a rapid ionic exchange process. The behavior of pyridinium ligands in the presence of lipase is investigated by cyclic voltammetry and UV/Vis spectroscopy, which indicated bindings and changes from the interaction between them. The voltammograms recorded on the glassy carbon electrode showed a more intense electronic transfer for the Lr interaction with lipase compared to Lm, which is due to the absence of mobile ethylene groups from Lr structure.</span></p>