title: Modulation of oxidative stability of haemoglobin inside liposome-encapsulated haemoglobin.
abstract: The major hurdle in the formulation of liposome-encapsulated haemoglobin (LEH) is the oxidation of haemoglobin (Hb) into methaemoglobin during storage and after administration. In order to reduce this oxidative degradation, we tested various reducing conditions in the presence of catalase. We found that at 37°C more than 50% of Hb oxidized to methaemoglobin within 24 h, whereas in presence of catalase, the oxidation was significantly reduced. The effect of catalase was further enhanced by a reduction mixture containing β-NAD, d-glucose, adenine, inosine, MgCl2, KCl, KH2PO4 and Na2HPO4; only 14% methaemoglobin was generated in the presence of catalase and reduction mixture. Contrary to the expectation, glutathione, deferoxamine and homocysteine enhanced Hb oxidation. The presence of CRM inside liposomes (250 nm) significantly decreased Hb oxidation. The results suggest that catalase and a well-defined mixture of co-factors may help control Hb oxidation for improvement in the functional life of LEH.
authors.affiliation: College of Pharmacy, University of Oklahoma Health Sciences Center, 1110 North Stonewall Avenue, Oklahoma City, OK 73117, USA. vawasthi@ouhsc.edu
authors.forename: Vibhudutta
authors.initials: V
authors.lastname: Awasthi
authors.forename: Vivek R
authors.initials: VR
authors.lastname: Yadav
authors.forename: Beth
authors.initials: B
authors.lastname: Goins
authors.forename: William T
authors.initials: WT
authors.lastname: Phillips
mesh_terms: D000818:Animals; D001802:Blood Substitutes / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D002417:Cattle; D006454:Hemoglobins / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008081:Liposomes / Q000737:chemistry*; D008706:Methemoglobin / Q000737:chemistry / Q000378:metabolism; D055550:Protein Stability
chemical_list: D001802:Blood Substitutes; D006454:Hemoglobins; D008081:Liposomes; D008706:Methemoglobin; D002374:Catalase