Preparation and analysis of nanocarriers for brain delivery of neuroprotective andrographolide

Andrographolide (AG) is a major diterpenoid of Andrographis paniculata (Burm. f.) Nees, the clinical utility of which has been demonstrated in the treatment of inflammation-related neurodegenerative disorders [1]. Low bioavailability and poor water solubility limit the further development of the compound. To overcome these limitations AG was loaded into albumin based nanoparticles (HSA NPs) and polyethylcyanoacrylate nanoparticles (PECA NPs). NPs were prepared by coacervation using thermal cross-linking, and by emulsion-polymerization, respectively. Both NPs appeared as spherically shaped with an average diameter of 255,4 ± 8,9nm, a polydispersity (PD) of 0,19 ± 0,02, and a zeta potential of -4,77 ± 0,18 mV for PECA NPs. HSA NPs showed a mean diameter of 202.15 ± 6.15nm, with a PD of 0.17 ± 0.01, and a zeta potential of -10.20 ± 0.15 mV. The average drug-entrapment efficiency (EE) and loading capacity (LC) were 94,6 ± 0,41% and 13,2 ± 0,36%, respectively, for PECA NPs, and 98.21 ± 0.01% and 8.50 ± 0.01% for HSA NPs. The ability of free AG and AG-loaded NPs to cross the blood-brain barrier (BBB) was evaluated with two in vitro BBB models based on human hCMEC/D3 and murine bEnd5 endothelial cells. For that purpose, a quantitative LC-MS/MS method for AG in Ringer HEPES buffer, in the range of 10 – 2000 ng/mL, and with forskolin as internal standard was developed and validated according to FDA/EMA guidelines [2 – 3]. Apparent permeability coefficients (Papp) in apical-to-basolateral (A-B) direction across cell monolayers cultured on 24-well format will be discussed.