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Authors: Paula Nunes, Marília Bezerra, L. Costa, Juliana Cardoso, R. Albuquerque, M. Rodrigues, Gabriela Barin, Francilene da Silva and A. Araújo

Abstract  

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.

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.1080/13880200600713808 Asplund , J. , Siegenthaler , A. and Gauslaa , Y. ( 2017 ): Simulated global warming increases usnic acid but reduces perlatolic acid in the mat-forming terricolous lichen Cladonia stellaris . – Lichenologist 49 ( 3 ): 269 – 274 . https

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Authors: I. Tas, A.B. Yildirim, E. Ozkan, G.C. Ozyigitoglu, M.Z. Yavuz and A.U. Turker

radical . Nature , 181 , 1199 . C ansaran , D. , A takol , O. , H alici , M.G. & A ksoy A. ( 2007 ): HPLC analysis of usnic acid in some Ramalina species from Anatolia and

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Abstract  

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).

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Cansaran, D., Atakol, O., Halıcı, M. G. and Aksoy, A. (2007): HPLC analysis of usnic acid in some Ramalina species from Anatolia and investigation of their antimicrobial activities. — Pharm. Biol. 45 : 77–81. Aksoy

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.2015.00903 Cocchietto , M. , Skert , N. , Nimis , P. L. and Sava , G. ( 2002 ): A review on usnic acid, an interesting natural compound . – Naturwissenschaften 89 : 137

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., Boehm, F., Troppens, S., Lademann, J., Truscott, T. G. (2010) Prooxidant and antioxidant behaviour of usnic acid from lichens under UVB-light irradiation-studies on human cells. J. Photochem. Photobiol. B Biol. 101 , 97

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2006 45 159 171 Farkas, E., Lőkös, L. and Molnár, K. (2012): Taxonomic revision of the usnic acid containing Xanthoparmelia species

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[ 3 ], carbodiimide [ 4 ], acylazides [ 5 ], citric acid, maleic acid derivatives [ 6 ], usnic acid [ 7 ], alginic acid [ 8 ], dialdehyde starch [ 9 ], and various other physical treatments like UV [ 10 ] and gamma irradiation [ 11 ] were used for

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, FA , Araújo , AAS . Thermal characterization of usnic acid/collagen-based films . J Therm Anal Calorim . 2010 ; 99 : 1011 – 1014 . 10.1007/s10973-009-0661-8 . 13. Ghebremeskel

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