Phosphatidylcholines (PC) are a class of phospholipids that incorporate choline as a headgroup. They are a major component of biological membranes and can be easily obtained from a variety of readily available sources, such as egg yolk or soybeans, from which they are mechanically or chemically extracted using hexane.
Fig.1 The chemical structure of 1-Oleoyl-2-palmitoyl-phosphatidylcholine.
Chitosan and ePC were used as a unique combination to prepare composite films for localized drug delivery. ePC was found to be unique in comparison to other phospholipids, as it combined with chitosan to produce films with minimal swelling and a high degree of stability. FTIR confirmed that the chitosan-ePC blends are stabilized largely by ionic and hydrogen bonding interactions. The non-cytotoxicity of the chitosan-ePC films was confirmed in both SKOV-3 human ovarian cancer and K1-CHO fibroblast cells. This film was also found to be a promising system for the localized delivery of the highly lipophilic anticancer agent, PTX. This agent was loaded into the film at a drug: material ratio of 1:8 (wt/wt), and the film was found to provide a sustained release of this drug over a 4 months period.
Fig.2 Scanning electron micrograph of the PTX loaded chitosan-ePC film prior to incubation (a) and following 2 months incubation in buffer containing lysozyme (2 mg/mL) at 37oC (b). (Grant, 2005)
Shikonin was effectively incorporated into several liposomes and many processes and composition parameters were evaluated. Both DPPC and EPC lipids produced shikonin-loaded liposomes with favorable physicochemical characteristics and controlled drug release profiles. DPPC liposomes showed higher entrapment efficiency and released greater amounts of a drug during the in vitro dissolution experiments, while EPC lipids produced liposomes with smaller mean particle sizes and higher potential values. Reducing the initial drug loading resulted in lower z-potential values and a faster shikonin release rate. The results indicated the successful incorporation of shikonin into liposomes, using both 1,2-dipalmitoylphosphatidylcholine and EPC lipids. In vitro cytotoxicity of liposomes was additionally tested against three human cancer cell lines (breast, glioma, and non-small cell lung cancer) showing a moderate growth inhibitory activity. The prepared shikonin-loaded liposomal formulations are novel and could be able to reduce the adverse effects of the free drug, enhance its aqueous solubility and therapeutic index and protect it from internal biotransformations.
Fig.3 Composition of the prepared shikonin-loaded liposomes. (Kontogiannopoulos, 2011)
Fig.4 Physicochemical characteristics of the prepared shikonin-loaded liposomes. (Kontogiannopoulos, 2011)
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