PERFORMANCE OF ALGINATE FILMS FOR RETENTION OF L-(+)-ASCORBIC ACID

DE NOBILI, M.D; CURTO L.M.; DELFINO J.M.; SORIA, M; FISSORE, E.N.; ROJAS, AM

INTERNATIONAL JOURNAL OF PHARMACEUTICS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2013 vol. 450 p. 95 - 103

0378-5173

Alginate films of different copolymer composition and glycerol plasticizer levels (26.7, 35.6, 52.3%w/w) were developed in Ca2+ presence with the purpose of achieving higher stability of L-(+)-ascorbic acid (AA), in view of acting as controlled delivery systems for nutritional supplementation, therapy or antioxidant activity at interfaces. The ability of the alginate network to preserve AA from hydrolysis, tested after vacuum storage at constant relative humidity (RH: 33.3, 57.7, 75.2%) and 25ºC, only decreased with the RH increase when alginates were mainly constituted by guluronic-guluronic acid blocks (GG), whereas also decreased with the glycerol level increase when mannuronic-mannuronic acid (MM) and/or alternating guluronic-mannuronic (GM+MG) flexible blocks were also present in important proportions. The latter results could be probably related to lower capability of alginates with MM and GM+MG blocks to immobilize water in the network as they are not able to constitute Ca2+ mediated junction zones where water molecules are retained and behave as unfreezable bound water. Films made with a GG or a GM+MG enriched alginate and 35.6 or 52.3% glycerol, previously evaluated for AA hydrolysis, were also studied at 57.7 or 75.2% RH under air. Even at these less favorable conditions, alginate networks in general preserved AA from oxidation.