A comparative study of PEO-PBO content on the targeting and anti-glioma activity of annonaceous acetogenins-loaded nanomicelles.

Annonaceous acetogenins (ACGs) have great potential in the treatment of gliomas, but are extremely insoluble and difficult for delivery in vivo. Poly(ethylene oxide)-b-poly(butylene oxide) (PEO-PBO) is an amphiphilic polymer and can reduce the clearance of nanoparticles by mononuclear phagocyte system. To explore an efficient and safe nanomedicine for glioma, ACGs-loaded nanomicelles (ACGs/EB-NCs) was constructed using PEO-PBO as a carrier, and the effect of PEO-PBO content on the targeting and anti-glioma activity were also compared. ACGs/EB5-NCs, ACGs/EB10-NCs and ACGs/EB20-NCs, the three nanomicellels prepared with different ACGs/EB feeding ratios, had average particle sizes of 148.8±0.5 nm, 32.7±4.1 nm, and 27.1±0.3 nm, respectively. The three ACGs/EB-NCs were spherical in shape, with drug loading content close to the theoretical drug loading content, encapsulation efficiency greater than 97 %, and good stability in physiological media. The cumulative release rates of ACGs/EB5-NCs, ACGs/EB10-NCs and ACGs/EB20-NCs were 78.2 %, 63.4 %, and 56.3 % within 216 hours, respectively. The inhibitory effects of three ACGs/EB-NCs on U87 MG cells were similar and stronger than free ACGs (P<0.05), with half inhibitory concentration of 0.17, 0.18, and 0.16 ng/mL (P>0.05), respectively. In U87 MG tumor‑bearing mice, ACGs/EB5-NC, ACGs/EB10-NCs and ACGs/EB20-NCs showed a similar tumor inhibition rate of 61.1±5.9 %, 56.2±8.6 % and 64.3±9.4 % (P>0.05), with good safety. Three ACGs/EB-NCs exhibited excellent liver escape ability and tumor targeting ability, with the tumor targeting index greater than 1.5. Three ACGs/EB-NCs were successfully prepared with strong anti-glioma activity and tumor targeting properties, which are expected to provide new options for the clinical treatment of gliomas. The content of PEO-PBO in micelles did not have a significant effect on the tumor targeting and anti-glioma activity of ACGs/EB-NCs.