Authors:Paula Nunes, Marília Bezerra, L. Costa, Juliana Cardoso, R. Albuquerque, M. Rodrigues, Gabriela Barin, Francilene da Silva and A. Araújo
The purpose of this study was to evaluate the physical–chemical properties of collagen (CL) and usnic acid/collagen-based
(UAC) films, using differential thermal analysis (DTA), thermogravimetry (TG/DTG), infrared spectroscopy (FTIR), and scanning
electron microscopy (SEM). Both films were prepared by casting process using polyethylene glycol 1500 (PEG 1500) as plasticizer.
In the spectrum of UAC, similar bands of the usnic acid are observed, indicating that the polymerization (film formation)
did not affect the stability of the drug. Distinctly, DTA curve of UAC did not show an endothermic peak at 201 °C, indicative
that the drug was incorporated into the polymeric system. These results were corroborated by the scanning electron microscopy
(SEM). The TG/DTG curves of UAC presented a different thermal decomposition profile compared to the individual compounds and
CL. These findings suggest the occurrence of molecular dispersion or solubilization of the drug in the collagen film.
Authors:K. Andjelković, M. Šumar and I. Ivanović-Burmazović
Results of our research on synthesis and characterization of complexes with acylhydrazone derivatives are described in this
review paper. Structural characterization of newly synthesized complexes by thermal analysis (TG, DTA, DSC) is particularly
emphasized in this paper. Thermal analysis enabled us to study not only structural changes of substances during thermal treatment,
but also the mode of coordination and degree of deprotonation of acylhydrazones, as well as geometry of the coordination sphere
of complexes, the structure of which had not been determined by X-ray analysis. Topics in this paper are as follows: complexes
of dioxomolybdenum(VI) with tridentate hydrazones, usnic acid derivatives and their Cu(II) complexes, as well as transition
metal complexes with 2,6-diacetylpyridine bis(hydrazones).
Cansaran, D., Atakol, O., Halıcı, M. G. and Aksoy, A. (2007): HPLC analysis of usnicacid in some Ramalina species from Anatolia and investigation of their antimicrobial activities. — Pharm. Biol. 45 : 77–81.
., Boehm, F., Troppens, S., Lademann, J., Truscott, T. G. (2010) Prooxidant and antioxidant behaviour of usnicacid from lichens under UVB-light irradiation-studies on human cells. J. Photochem. Photobiol. B Biol. 101 , 97