Figure 3

Peptide transport results from the in vitro bovine BBB cell-based model assay obtained through RP-HPLC-PDA (in blue) or MALDI-TOF MS (in green) quantification; Data are expressed as mean ± SD, n = 3. (a) RP-HPLC-PDA transport quantification significance between L- and D-peptides (additionally, peptide 9D showed significant differences (*) with 7 + D and 8 D); (b) MALDI-TOF MS transport quantification results and significance. Differences in group means were assessed using a linear model fitted for each measurement method. In each case, Wald tests derived from the linear models were used to perform pairwise comparisons between experimental conditions. A 5% level was chosen for significance of group. In vitro human BBB model: (c) transport of 1 L, 7 − D and 8D peptides when assayed with Ringer-HEPES buffer or supplemented ECM medium. Extremely significant differences (****) are observed when peptides are assayed in buffer or medium; within peptides assayed in buffer, significant differences (*) are only observed between 1 L and 8 D; within peptides assayed in medium, significant differences (* or **) are observed between 1 L both retro-D-analogs (7 − D and 8 D). Significance: ns ≡ not significant (p ≥ 0.05), *significant (0.01 ≤ p < 0.05), **very significant (0.001 ≤ p < 0.01), ***extremely significant (0.0001 ≤ p < 0.001), ****extremely significant (p < 0.0001). Data analysis was done using the T test (non-parametric).