Study of quercetin-loaded liposomes as potential drug carriers: in vitro evaluation of human complement activation.
Liposomes have been employed as potential drug carriers. However, after their in vivo administration, they can be destabilized by proteins of complement system, contributing to the clearance of vesicles from blood circulation. Antioxidant flavonoids such as quercetin have been reported to be beneficial to human health, but their low water solubility and bioavailability limit their enteric administration. Therefore, the development of appropriate flavonoid-carriers could be of great importance to drug therapy. The aim of the present study was to evaluate the activation of human complement system proteins by liposomes composed of soya phosphatidylcholine (SPC) and cholesterol (CHOL) or cholesteryl ethyl ether (CHOL-OET) loaded with quercetin or not. The consumption of complement, via classical (CP) and alternative (AP) pathways, by different vesicles was evaluated using a hemolytic assay and quantitative determination of iC3b and natural antibodies deposited on empty liposomal surfaces by ELISA. The main results showed that empty liposomes composed of large amounts of CHOL consumed more complement components than the others for both CP and AP. Furthermore, replacement of CHOL with CHOL-OET reduced complement consumption via both CP and AP. Incorporation of quercetin did not change CP and AP consumption. Deposition of iC3b, IgG and IgM in vesicles composed of SPC:CHOL-OET at a molar ratio of 1.5:1 was lower compared to the others. Taken together, these observations suggest that liposomes composed of SPC:CHOL-OET at a molar ratio of 1.5:1 are the most appropriate among the vesicles studied herein to be used as a drug carrier system in further investigations.
Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Avenida do Café s/n, Monte Alegre, Ribeirão Preto, SP 14040-903, Brazil. ana.landi@yahoo.com.br
Ana Paula
AP
Landi-Librandi
Taís Nader
TN
Chrysostomo
Ana Elisa
AE
Caleiro Seixas Azzolini
Cleni Mara
CM
Marzocchi-Machado
Carlos Alberto
CA
de Oliveira
Yara Maria
YM
Lucisano-Valim
D000818:Animals; D003167:Complement Activation; D015941:Complement Hemolytic Activity Assay; D004337:Drug Carriers / Q000737:chemistry*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008081:Liposomes / Q000097:blood / Q000737:chemistry*; D008297:Male; D011794:Quercetin / Q000097:blood / Q000737:chemistry*; D011817:Rabbits; D012016:Reference Values; D012756:Sheep; D013499:Surface Properties
D004337:Drug Carriers; D008081:Liposomes; D011794:Quercetin