Cell experiment:

BCECs are seeded in 96-well plates in 200 μL of DMEM medium to obtain a concentration of 2000 cells per well, and incubated for 24 h. The medium in each well is then incubated for 72 h with 200 μL medium containing blank vehicle, P-LPs/ZL006, T7-P-LPs/ZL006 and ZL006 (free drug dissolved in DMSO) with a series of concentrations ranging from 0.001 to 100 μg/mL. The MTT absorbance at 570 nm of each well is measured by a microplate reader.

Animal experiment:

ICR mice weighting 20 ± 2 g are divided into three groups at random (n=12). Free ZL006, P-LPs/ZL006 and T7-P-LPs/ZL006 (all containing ZL006 4 mg/kg) are administered to each group through intravenous route, respectively. At designated time intervals (0.5, 1 and 2 h), the mice are executed and the major organs samples including brain, heart, liver, spleen, lung and kidney are collected. Before pretreatment, these tissues are rinsed with cold saline solution to remove the blood and then blotted with paper towel. Protein precipitation of the samples is performed before analysis. Then the samples are injected into the LC-MS/MS systems for analysis. The LC-MS/MS system consists of an Agilent Series 1200 HPLC system and a 6410 Triple Quad LC/MS mass spectrometer. The data is collected and processed using the Agilent MassHunter Workstation Software.

ZL006 is a potent inhibitor of nNOS/PSD-95 interaction, and inhibits NMDA receptor-mediated NO synthesis.

ZL006 presents little cytotoxicity, and a growth inhibition of BCECs is not found at low concentration of 0.001, 0.01, 0.1, 1 and 10 μg/mL. The cytotoxicity of T7-P-LPs/ZL006 is significantly enhanced at the concentration of 10 μg/mL. Cellular uptake of ZL006 loads P-LPs and T7-P-LPs after incubation for 0.5 h at the concentrations range from 100 μg/mL to 600 μg/mL in BCECs[1]. ZL006 does not inhibit the nNOS-PDZ/PSD-95-PDZ interaction, or perturb the nNOS β-finger[2].

Compared with P-LPs/ZL006 and free ZL006, T7-P-LPs/ZL006 exhibits a significant increase of drug accumulation in the brain tissue due to its better brain targeting delivery. Compared with free ZL006, P-LPs/ZL006 and T7-P-LPs/ZL006 exhibit a significant decrease of drug accumulation in the liver and kidney[1].

[1]. Wang Z, et al. Enhanced anti-ischemic stroke of ZL006 by T7-conjugated PEGylated liposomes drug delivery system. Sci Rep. 2015 Jul 29;5:12651. [2]. Bach A, et al. Biochemical investigations of the mechanism of action of small molecules ZL006 and IC87201 as potential inhibitors of the nNOS-PDZ/PSD-95-PDZ interactions. Sci Rep. 2015 Jul 16;5:12157.