In vitroandin vivoproperties of usnic acid encapsulated into PLGA-microspheres

Abstract

Microparticles will probably play a promising role in the future of chemotherapy. These polymeric delivery systems are capable of maximizing the therapeutic activity while reducing side effects of anti-cancer agents. Usnic acid (UA) is a secondary metabolite produced by lichens, which exhibits an anti-tumour activity. In this study, PLGA-microspheres containing usnic acid from Cladonia substellata were prepared by the double emulsion method, with or without PEG as stabilizer. The morphology of the microspheres was examined by optical and scanning electron microscopy. The in vitro kinetic profile of usnic acid loaded-microspheres was carried out by dissolution testing. The usnic acid content was analysed by HPLC. The cytotoxicity of free and encapsulated usnic acid was evaluated against HEp-2 cells using the MTT method. The anti-tumour assay was performed in mice against Sarcoma-180 tumour (UA 15 mg kg(-1) weight body/day) during 7 days. Animals were then sacrificed and tumour and organs were excised for histopathological analysis. Microspheres presented a smooth spherical surface with a mean diameter of 7.02 +/- 2.72 microm. The usnic acid encapsulation efficiency was approximately 100% (UA 10 mg 460 mg(-1) microspheres). A maximum release of 92% was achieved at the fifth day. The IC50 values for free and encapsulated usnic acid were 12 and 14 microg ml(-1), respectively. The encapsulation of usnic acid into microspheres promoted an increase of 21% in the tumour inhibition as compared with the free usnic acid treatment. In summary, usnic acid was efficiently encapsulated into PLGA-microspheres and the microencapsulation improved its anti-tumour activity.

Validação de método analítico espectrofotométrico UV para determinação de ácido úsnico em lipossomas

“…Ao comparar os resultados obtidos com mé-todos analíticos para determinação de ácido úsnico por CLAE, o método espectrofotométrico proposto apresenta capacidade similar de determinar o analito em questão, uma vez que a faixa de linearidade do método desenvolvido, pode ser considerada equivalente àquela dos métodos CLAE, utilizados para microesferas (1-10 µg.mL -1 ) (Ribeiro-Costa et al, 2004) e nanocápsulas (2-20 µg.mL -1 ) (Santos et al, 2005). Além disso, outro método CLAE associado a detector UV com arranjo de diodos para doseamento do ácido úsnico em matéria-prima e produtos acabados, apresentou resposta linear entre 1,4 e 570 µg.mL -1 e um limite de detecção de 0,4 µg.mL -1 (Ji, Khan, 2005), valor este próximo do limite de detecção encontrado no presente trabalho (LD = 0,34 µg.mL -1 ).…”

“…O ácido úsnico, como agente antimicrobiano, é constituinte de diversas preparações farmacêuticas, tais como: dentifrício (Grasso et al, 1989), colutório (Ferrarri et al, 1988;Ghione et al, 1988;Lodetti et al, 2000), óvulos vaginais (Scirpa et al, 1999), antitranspirante e desodorante (Clothier et al, 2002;Elliott et al, 2005); em cápsulas como suplemento dietético -LipoKinetix ® (Neef et al, 2004), atualmente fora do mercado devido à hepatoxicidade; em microesferas (Ribeiro-Costa et al, 2004) e nanocápsulas (Santos et al, 2005) como antineoplásico.…”

“…Métodos de doseamento do ácido úsnico utilizando cromatografia líquida de alta eficiência (CLAE) com detecção UV são descritos para doseamento de matéria-prima e produtos farmacêuticos -cápsulas, comprimidos e preparações líquidas (Ji, Khan, 2005), microesferas e nanocápsulas (Ribeiro-Costa et al, 2004;Santos et al, 2005) e em plasma (Venkataramana, Krishna, 1992).…”

Hepatic toxicity caused by PLGA-microspheres containing usnic acid from the lichen C ladonia substellata (AHTI) during pregnancy in Wistar rats

“…Although the usnic acid has remarkable pharmacological activity, its therapeutic application in the conventional manner is limited due to their unfavorable physicochemical properties, including low hydrosolubility, difficult interaction with biological barriers and high prevalence of hepatotoxicity (Cocchietto et al 2002, Fraveau et al 2002, Han et al 2004, Pramyothin et al 2004, Ribeiro-Costa et al 2004, Sanchez et al 2006, Santos et al 2006.…”

“…A promising alternative related to the incorporation of new drugs on the market (Ribeiro-Costa et al 2004, 2009, Santos et al 2006, Siqueira-Moura et al 2008, Grumezescu et al 2014, Martinelli et al 2014.…”