Determining the critical quality attribute for the delivery of α–mangostin by β–cyclodextrin-based nanoparticles in cancer treatment

We previously developed cyclodextrin-based nanoparticles by utilizing a conventional polymerization method with α-, β-, γ cyclodextrin and epichlorohydrin, which successfully encapsulated a hydrophobic xanthone compound named α-mangostin (MGS). The drug release profile of MGS showed two release modes, quick release in the early stage and slow release in the late stage, which can be characterized by the lifetimes of complexes τ1 and τ2, respectively. Although these nanoparticles satisfied the demand of the Enhancement Permeation and Retention effect, only β–cyclodextrin-based nanoparticles containing MGS exhibited anticancer efficacy in vivo. Thus, the aims of the present study are to create libraries of β–cyclodextrin-based nanoparticles (CDNPs), characterize the CDNPs and clarify the relationships between the physical parameters, release behavior, and anticancer efficacy. When surfactants were present during the polymerization process, the radius of the obtained CDNPs could exceed 10 nm. τ2 was linearly dependent on the nanoparticle density and showed a relationship with anticancer efficacy. We assumed that MGS released from CDNPs would accumulate in the tumor region if the optimal range of τ2 was approximately 90–140 h. These results suggest that τ2 can be a critical quality attribute for designing our CDNPs. The relationships between the physical parameters of β–cyclodextrin-based nanoparticles (CDNPs), the behavior of α-mangostin release, and the anticancer efficacy were revealed in this study. It was found that the lifetime of complex (τ2) in slow-release mode was linearly dependent on the nanoparticle density and showed a relationship with anticancer efficacy. We assumed that MGS released from CDNPs would accumulate in the tumor region if the optimal range of τ2 was approximately 90 to 140 h. These results suggest τ2 can be a critical quality attribute for designing our CDNPs.