The effects of sperminated pullulans on cornea permeability to puerarin and the toxicity.

To investigate the varied effects of sperminated pullulans (SP) with different amino residues on cornea permeability and its local toxicity. Three groups of rabbits were used: control, low-amino residue content SP (SP-L), and high-amino residue content SP (SP-H). The in vitro and in vivo spreading assays were combined with high performance liquid chromatography (HPLC) to measure the concentration of puerarin in the external medium or aqueous humor when 0% SP, 0.2% SP-L, and 0.2% SP-H were included. The toxicity of SP was determined by corneal hydration values, Draize score, aqueous humor protein concentration, corneal endothelial evaluation, as well as light microscopy and electron microscopy. The application of 0.2% SP-L and 0.2% SP-H to the cornea in vitro increased puerarin apparent permeability coefficient by 1.96-fold (P<0.05) and 2.95-fold (P<0.01), respectively. SP-H showed stronger effect than SP-L (P<0.05). For the in vivo assay, those were 1.81-fold (P<0.05) and 3.71-fold (P<0.01), respectively. With the SP application, the corneal hydration values were <83% and Draize scores were <4, with no apparent changes in histological observations. SP is one potential adjuvant promoting puerarin permeability to the cornea, and the high-content amino residue SP showed stronger effect, without ocular toxicity.