title: Alginate/polymethacrylate copolymer microparticles for the intestinal delivery of enzymes.
abstract: Proteins administered orally must pass through the gastric environment in order to reach their site of absorption in the intestine. How to protect these exogenously administered proteins from the damaging effects of gastric acid and pepsin proteolytic activity, which often induce irreversible structural and functional alterations to the molecules, is an intriguing challenge. Another problem is the physical and chemical instability of proteins during some technological processes, which often involve the use of organic solvents or high temperatures. In this study we investigated the use of alginate microparticles containing one of two enzymes, an enteric polymer and a lyoprotectant for the intestinal delivery of proteins. The two enzymes tested in this protein delivery system were lactate dehydrogenase and alpha-amylase: the former was chosen because of its sensitivity to denaturation, the latter for its relevance in nutrition and medicine. A sodium alginate aqueous solution containing the enteric polymer, a lyoprotectant and the enzyme was either extruded or sprayed into a calcium chloride solution, with the resultant formation of beads and microspheres which were freeze-dried. About 90% of the enzyme activity was maintained during the process of loading the proteins into the microparticles and the subsequent freeze-drying process. The stability of the encapsulated enzyme in an acid medium and the enzymatic activity in an intestinal environment were then investigated by a dissolution test. This consisted of exposing the microparticles to simulated gastric fluid (pH 1.2) for 2 hours and to simulated intestinal fluid (pH 7.5+/-0.1) for 1 hour. The morphology of the microparticles did not change in the acid environment, whereas they completely dissolved within 3 min in the simulated intestinal fluid. Residual enzymatic activity after the test remained satisfactory for both enzymes. In conclusion, these microparticle systems offer promise for applications in human and veterinary medicine as well as in human and animal nutrition.
authors: Dipartimento di Scienze e Tecnologie Veterinarie per la Sicurezza Alimentare, Milano, Italia.
authors: Sarah
authors: S
authors: Scocca
authors: Massimo
authors: M
authors: Faustini
authors: Simona
authors: S
authors: Villani
authors: Eleonora
authors: E
authors: Munari
authors: Ubaldo
authors: U
authors: Conte
authors: Vincenzo
authors: V
authors: Russo
authors: Alessia
authors: A
authors: Riccardi
authors: Daniele
authors: D
authors: Vigo
authors: Maria Luisa
authors: ML
authors: Torre
mesh_terms: D000284:Administration, Oral; D000464:Alginates / Q000737:chemistry*; D002122:Calcium Chloride / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D004339:Drug Compounding; D004795:Enzyme Stability; D004798:Enzymes / Q000008:administration & dosage / Q000737:chemistry* / Q000378:metabolism; D005612:Freeze Drying; D005750:Gastric Juice / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption; D007419:Intestinal Secretions / Q000737:chemistry; D007770:L-Lactate Dehydrogenase / Q000737:chemistry / Q000378:metabolism; D007785:Lactose / Q000737:chemistry; D008863:Microspheres; D010316:Particle Size; D011109:Polymethacrylic Acids / Q000737:chemistry*; D012995:Solubility; D013678:Technology, Pharmaceutical; D000516:alpha-Amylases / Q000737:chemistry / Q000378:metabolism
chemical_list: D000464:Alginates; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D004798:Enzymes; D006603:Hexuronic Acids; D011109:Polymethacrylic Acids; C038300:methylmethacrylate-methacrylic acid copolymer; D020723:Glucuronic Acid; D007770:L-Lactate Dehydrogenase; D000516:alpha-Amylases; D007785:Lactose; D002122:Calcium Chloride