Abstract
Purpose: :
One of the most important properties of ophthalmic preparations for the amelioration of dry eye syndrome is their residence on the ocular surface. Arabinogalactan (AG), a natural polysaccharide present in conifers of the genus Larix (Larch), was recently shown to exert a corneal protective action. Mucins are the main glycoproteins which protect the corneal surface, so a relevant investigation is the assessment of the mucoadhesive properties of AG by evaluating its ability to interact with mucins.
Methods: :
Mucin MUC1, a transmembrane glycoprotein isolated from submaxillary glands was purchased from Sigma-Aldrich. AG, pharmaceutical grade, was supplied by Opocrin S.p.A. AG content was evaluated spectrophotometrically upon reaction with the anthrone reagent.
Results: :
The interaction between AG and mucin was studied through a gel filtration chromatography approach. The two molecular species displayed, when chromatographed separately on Sephacryl S-300, well distinct elution peaks. However, a significant change in the elution profile of AG, compatible with a transient coelution of the two molecules, was observed when the polysaccharide was chromatographed in the presence of mucin, at different ratios mucin:AG (w:w). On the contrary, no effect was exerted on the elution profile of AG by different proteins or glycoproteins with molecular mass comparable with mucin.
Conclusions: :
Mucin and Arabinogalactan do interact, giving rise to reversible adduct formation. This is supportive of the possibility of temporarily retention of AG preparation on the ocular surface.
Keywords: cornea: surface mucins • cornea: tears/tear film/dry eye • protective mechanisms