Anticancer efficacy of cyclodextrin-based hyperbranched polymer nanoparticles containing alpha-mangostin

Abstract

Alpha-mangostin (MGS) is a natural xanthone compound extracted from mangosteen pericarps. It has great potential as an excellent anticancer agent. However, the extremely low solubility of MGS in water seriously impedes its medical application. Previously, we found that cyclodextrin (CD)-based hyperbranched polymer nanoparticles (CDNPs) solubilize MGS by encapsulating it in the CD cavity and that their binding constants are 100 times higher than those of native CDs. Our findings suggested that CDNPs could be good carriers of MGS. Here, we prepared three types of CDNP from α-, β-, and ɣCDs and compared them in terms of MGS release and in vitro and in vivo anticancer efficacy. βCDNP/MGS demonstrated the greatest anticancer efficacy, while no efficacy was observed for the other CDNPs. MGS release from CDNPs/MGS can be explained by a model in which the slow and rapid modes are connected in series; before release, MGS must shift from the slow to the rapid mode. We assumed that the slow and rapid modes are related to the interior and surface CDs of CDNPs. βCDNP/MGS showed the slowest release in the slow mode. We assume that slow release in the slow mode is essential for MGS retention until the cancerous region is reached. We examined drug release behavior and anticancer efficacy of cyclodextrin-based nanoparticles (CDNPs) containing alpha-mangostin (MGS) in three different type of CDs (α-, β-, and γ-CD). βCDNP containing MGS demonstrated the best anticancer efficacy, while no efficacy was observed for the other CDNPs. Our findings suggested the anticancer efficacy might depend on the drug retention capability in which the interior and surface CDs in the CDNPs relate to the slow and rapid release modes, respectively. We assume the drug retention capability of slow release mode is important for performing the anticancer efficacy.