Vesicles and micelles: Two versatile vectors for the delivery of natural products

Natural plant-based extracts and isolated constituents have been widely used around the world since ancient times for both treatment and prevention of human diseases. Currently, the importance of natural products in clinical practice is highlighted by the number of herbal medicinal products on the market. However, formulation development of many active constituents of plant extracts is often hampered by their limited bioavailability due to several issues among which low water solubility, poor absorption and degradation are the most frequent. To overcome these issues, several research studies proposed to combine herbal medicinal products with nanocarriers widely used as drug delivery systems. The nanotechnology approach is especially attractive because colloidal carriers can modify the payload pharmacokinetic and biodistribution, as well as increase solubility, stability, and efficacy. Moreover, nanoencapsulation may decrease toxicity and modulate drug release. In recent years, delivery systems such as micelles and vesicles, obtained by the self-assembly of biocompatible surfactants, have attracted increasing attention as carriers for various herbal products. Thus, the aim of this paper is to review the main investigations developed by Italian research groups on formulations of natural products, including isolated compounds, extracts and essential oils, using micelles and vesicles as carriers.