Heparin reduces Fe(II)-catalyzed peroxidation of linolenic acid

Abstract

In addition to having a putative role in OH' generation through Fenton reactions, and therefore perhaps in fust-chain initiation of lip'd peroxidation. transition metal ion complexes (particul ly of Fei+ and Cu+v and, although they react more slowly, of F e g and Cu2+), accelerate decomposition of lipid peroxides to alkoxyl and peroxyl radicals. Both of these are capable of abstracting methylene group hydrogen atoms and so stimulating further lipid peroxidation. Heparins are strongly anionic glycosaminoglycan components of mast cell granules, from which they are released during inflammatory reactions to tissue damage. They possess a variety of anionic groups which allow the molecules to interact with a range of biologically relevant micro-and macro-cations. These molecules might therefore influence the activity of radicals by modulating the availability or reactivity of such ions. The present &ansaction uses a simple in vitro model to investigate the possible effects of heparin on lipid peroxidation. The source, preparation and properties of the heparin have been described previously [ 1.21. y-Linolenic acid (6,9,12octadecatrienoic acid), polyoxyethylene ether W-1 (a-dodecyl-ohydroxpoly (oxy-l,2-ethanediyl)), chondroitin 4-sulphate (from whale cartilage), chondroitin 6-sulphate (from shark cartilage), dermatan sulphate (from pig skin), heparan sulphate (from bovine kidney) and hyaluronic acid (from human umbilical cord) were obtained from Sigma Chemical Co., Poole. U.K. Ferrous ammonium sulphate (Specpure grade) was from Johnson Matthey, Royston. U.K. Assay of an early stage in linolenic acid peroxidation, the formation of u.v.-absorbing conjugated dienes, was essentially by the method of Knight & Voorhees [3]. Na+ forms of the glycosaminoglycans (1 mmol.dm-3 with regard to deoxygenated) was then added, and the absorbance measured at 233 nm after 10 min. Absorbancies measured in control experiments canied out in h e absence of linolenic acid wen subtracted from 0.05 -0.04 -0 0 5 0.03e s 0 4 0.02 -0.01nnn 0 Fig. 1 Effect of heparin on conjugatediene pro uction N u n l m o n J l e~l e l a~M~( r m n L d m 4 ,nrmSd ~d i n s ) d~p e s a t i n h e &~ Y V c 0 e z P a 0.03 0.02 0.01 0.00 Fig. 2 Effect of glycosaminoglycans on conjugate diene Final concentration of glycosaminoglyc s (in terms of hydrated production h e r ) in the reaction mix was 1 mmol.dm-b . those recorded in its presence. Reagents were made up in deionized distilled water and ad the above noted concentrations in a final in U.V. absorption of the reaction mix following addition of F F m y-linolenic acid in polyoxyethylene ether either alone or in the presence of various concentrations of heparin. No change in absorption was detected when any combination of th components of the reaction mix was incubated in the absence of Fe3+ (n t shown). Further, addition of EDTA to the reaction mix before Fef+ addition inhibited the subsequent increase in absorption in a [EDTAI-dependent manner the presence of sufficient EDTA to produce a [EDTA]/[Fe2+] ratio of one co...

Heparin inhibits production of thiobarbituric acid-reactive substances in the the presence of linolenic acid and Fe2+ ions

“…Because heparins and heparan sulphates also bind such ions, these polyanions might therefore also modulate their availability or reactivity. In accordance with this possibility, it has been shown t h a t heparin, in a concentration-dependent manner, inhibits an early stage in Fe2+-catalyzed linolenic acid peroxidation, the production of u.v.-absorbing conjugated dienes [6,7]. In this transaction, we demonstrate the effect of heparin on a later stage of lipid peroxidation, the production of thiobarbituric acid-reactive substances.…”

EPA and DHA Levels in Whole Blood Decrease More Rapidly when Stored at −20 °C as Compared with Room Temperature, 4 and −75 °C

“…BHT condition, 50 lg of BHT in methanol (2 lg/lL) was added to the aliquot just prior to storage [16][17][18]. This storage condition was designed to provide maximum protection against fatty acid peroxidation in which peroxidation protection is provided by both BHT and heparin [19,20].…”

Cu2+-heparin interaction studied by polarimetry

“…Of these, Cu2l has been reported to bind strongly to heparin, and a direct relationship between Cu2+-binding capacity and anticoagulant activity in heparin has been reported (Stivala, 1977), although the presence of Cu21 does not affect this activity (Stivala et al, 1973). Heparin acquires angiogenic activity in vivo upon complex-formation with Cu2+ (Raju et al, 1982;Alessandri et al, 1983;Bergendal et al, 1988), and it has been suggested that heparins may play a role in limiting free-radical damage by sequestering transition-metal ions such as those of copper (Ross et al, 1991).…”