Evaluation of hypericin-loaded solid lipid nanoparticles: physicochemical properties, photostability and phototoxicity.
Hypericin (HYP), a natural photosensitizer, has powerful photo-oxidizing ability, tumor-seeking characteristics, and minimal dark toxicity; nevertheless, it has proven high lipid solubility compared to its sparingly water soluble nature. Therefore, its formulation into solid lipid nanoparticles (SLNs) has attracted increasing attention as a potential drug-delivery carrier. Two HYP-loaded SLNs formulations were prepared utilizing microemulsion-based technique. Thereafter, the physicochemical properties of the formulations were investigated and evaluated. HYP-loaded SLNs showed spherical shape with mean particle size ranging from 200-300 nm for both formulations (FA and FB). The encapsulation efficiencies reached above 80% and FA showed significant higher encapsulation than FB (P<0.05), also, the thermal analysis using differential scanning calorimetry (DSC) indicated good compatibility between hypericin and lipids forming the cores in both formulations. Spectroscopic measurements of the photostability study showed that hypericin encapsulation into SLNs improved its photostability, compared to free HYP in 0.1% ethanolic solution. However, photocytotoxicity studies on HepG2 cells revealed an evident inhibition of the photodynamic efficacy of HYP-loaded SLNs, compared to free HYP. In conclusion, although the elevated entrapment efficiency of HYP into SLNs increased its photostability, it decreased its phototoxicity which might be due to the quenching deactivation of HYP molecules resulting from SLN compactness and thickness structure.
Photochemistry and Photobiology Unit, National Institute of Laser Enhanced Sciences, Cairo University, Egypt.
Tareq
T
Youssef
Maha
M
Fadel
Rania
R
Fahmy
Kawser
K
Kassab
D000873:Anthracenes; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy; D002470:Cell Survival / Q000187:drug effects; D004337:Drug Carriers / Q000737:chemistry*; D004355:Drug Stability; D056945:Hep G2 Cells; D006801:Humans; D008055:Lipids / Q000737:chemistry; D008113:Liver Neoplasms / Q000188:drug therapy; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D010569:Perylene / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D010778:Photochemotherapy; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage* / Q000737:chemistry / Q000494:pharmacology*
D000873:Anthracenes; D004337:Drug Carriers; D008055:Lipids; D011838:Radiation-Sensitizing Agents; D010569:Perylene; C004965:hypericin