Polymeric Micelles in the Delivery of Therapeutic Phytoconstituents

Abstract

Since ancient times, medicinal plants and their phytochemical constituents have been utilized to cure a number of diseases. Currently, various herbal formulations are available on market but the problem is many of the phytoconstituents of herbal product are hampered by their less bioavailability, the reason behind that is poor aqueous solubility, limited absorption, and hygroscopicity leads to degradation of the phytoconstituents. These problems can be overcome by combining the phytoconstituent with nanocarriers such as liposomes, polymeric micelles, dendrimers, organic nanoparticles, nanoemulsion, emulsomes, phytosomes, and nanocrystals. These nanocarrier systems help to increase the pharmacokinetic and bioavailability of phytoconstituent. Polymeric micelles are nanosized core-shell shape, self-assembly of amphiphilic macromolecules with lipophilic core and hydrophilic shell containing polymer including block and graft copolymer for favorable drug delivery. Polymeric micelles are between 10 and 100 nm in size They have unique characteristics such as increased bioavailability, biocompatibility, enhanced solubility of water-insoluble drug and enhance its absorption by minimizing the degradation rate. Polymeric micelles act as a targeted drug delivery because they target certain parts of body, for example, encapsulation of curcumin by polymeric micelles for the treatment of cancer. Traditional micelles have hydrophilic head and hydrophobic tail, they do not contain polymers. In polymeric micelles different polymers are used for the preparation. The stearic acid and chitosan are grafted with copolymers like diblock (poly(ethylene glycol), polystyrene) and triblock (poly(ethylene oxide)) copolymers respctively. These polymers protect the drug from degradation and provide in vivo stability, enhanced efficiency and biocompatibility. Polymeric micelles are more valuable than liposomes comparing their size, stability, and accumulation at target site. Polymeric micelles has highest percentage of entrapment efficiency and loading capacity. Polymeric micelles deliver various poorly soluble phytoconstituents like artemisinin and curcumin (anticancer), Piper methysticum G. Forst. (Kava-kava) for local anesthetic activity, berberine for anticancer and antibacterial activity.