Preparation, physicochemical characterization, and cell viability evaluation of long-circulating and pH-sensitive liposomes containing ursolic acid.

Cancer is one of the leading causes of death worldwide. Although several drugs are used clinically, some tumors either do not respond or are resistant to the existing pharmacotherapy, thus justifying the search for new drugs. Ursolic acid (UA) is a triterpene found in different plant species that has been shown to possess significant antitumor activity.