Thymoquinone (2-isopropyl-5-methyl-1,4-benzoquinone) is a herbal-derived drug with potential chemopreventive and chemotherapeutic activity. However, thymoquinone suffers from high hydrophobicity causing poor solubility which limits its bioavailability and high lipophilicity causing poor formulation characteristics. Liposomes are versatile drug carriers that can be used to solve problems of drug solubility, instability, and bio-distribution. In this study, we were able to prepare thymoquinone-loaded liposomes (TQ-LP) and thymoquinone loaded in liposomes modified with Triton X-100 (XLP) with diameters of about 100 nm, and entrapment efficiency of more than 90% for TQ-LP and of 49.6% for XLP. The TQ-LP liposomes were effective in suppressing the proliferation of breast cancer cell lines MCF-7 and T47D, and at the same time exerting very low toxicity on normal periodontal ligament fibroblast. Altogether, this report describes the first successful encapsulation of thymoquinone into liposome; which maintains stability, improves bioavailability and maintains its anticancer activity.

The inhalation route is of increasing interest for both local and systemic drug delivery, including macromolecular biopharmaceuticals, such as peptides, proteins, and gene therapeutics. In addition to appropriate aerosolization for deposition in relevant areas of the respiratory tract, therapeutic molecules may require an advanced carrier system for safe and efficient delivery to their target. Two approaches to obtain novel carrier systems for pulmonary drug delivery are large porous microparticles with a low aerodynamic diameter and lectin-functionalized liposomes. Epithelial cells of alveolar or bronchial origin, obtained either from patient material or from established cell lines, can be grown on permeable filter supports, resulting in polarized monolayers with functional intercellular junctions. With such in vitro models, transport of drugs into pulmonary epithelial cells and/or across the air-blood barrier, as well as the effect and efficacy of novel drug carrier systems can be systematically studied.