Thus, it seems that the assumptions described
for sugars and acids are transferable to folates, including the effects
of electrostatic repulsion with cell walls. Moreover, folate interactions
with macromolecules such as proteins could limit their diffusion
under these pH conditions. Interaction between folates and
proteins did not seem to be involved in our study because similar
diffusivity constants were obtained for folates and sugars. The pH
does not seem to be an important physico-chemical parameter
for the diffusion of sugars, acids and folates.