Comparison of the percent of protection of HESA-A and Amantadine on cell viability. Data analyzed by SPSS, one way ANOVA are averages of 4 independent experiments (mean ± SD). HESA-A showed a higher degree of protection towards cell viability in comparison with Amantadine treatments. It was significantly higher in co- and pre-penetration treatments. *: Significantly different from values obtained for co- & pre-penetration treatments compared to Amantadine treatments (p < 0.05).