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Comparison of the antioxidant properties of HYAFF®-11p75, AQUACEL® and hyaluronan towards reactive oxygen species in vitro

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Title: Comparison of the antioxidant properties of HYAFF®-11p75, AQUACEL® and hyaluronan towards reactive oxygen species in vitro
Authors: Moseley, R.1 Moseleyr@cardiff.ac.uk, Leaver, M.1, Walker, M.2, Waddington, R.J.1, Parsons, D.2, Chen, W.Y.J.2, Embery, G.1
Source: Biomaterials. May2002, Vol. 23 Issue 10, p2255. 10p.
Subjects: Biomedical materials, Reactive oxygen species, Antioxidants
Abstract: In chronic wounds, a number of host factors are released which perpetuate the inflammatory process, including polymorphonuclear leukocyte (PMN)-derived reactive oxygen species (ROS), such as superoxide radical (O2⋅−) and hydroxyl radical (⋅OH) species. The glycosaminoglycan, hyaluronan, has been shown to act as an antioxidant towards ROS, although the potential for biomaterials, such as HYAFF®-11p75 (the 75% benzyl ester of hyaluronan) and AQUACEL® (carboxymethylcellulose), to act in this manner has yet to be elucidated. This study compared the antioxidant properties of high and low molecular weight hyaluronan (HMWT HA and LMWT HA), HYAFF®-11p75, AQUACEL® and an AQUACEL®/hyaluronan composite (AQUACEL®/HA) against O2⋅− and ⋅OH. The antioxidant capacities of each material were assessed by their ability to inhibit cytochrome C reduction by O2⋅− fluxes, generated via the oxidation of hypoxanthine by xanthine oxidase, and their inhibition of 2-deoxy-d-ribose degradation by ⋅OH fluxes, generated by the reaction of hydrogen peroxide (H2O2) and iron (Fe2+).All materials studied possessed dose dependent antioxidant properties towards O2⋅−, with HYAFF®-11p75 having the greatest antioxidant potential towards these species, followed by AQUACEL®, HMWT HA, AQUACEL®/HA and LMWT HA. Only HMWT HA exhibited dose dependent antioxidant properties towards ⋅OH at the fluxes examined.Gas chromatography/mass spectrometry analysis implied that ester bonds between the hyaluronan backbone and benzyl groups of HYAFF®-11p75 are highly susceptible to O2⋅− hydrolysis, with the de-esterified benzyl alcohol being rapidly degraded in the presence of ⋅OH. This data supports the hypothesis that HYAFF®-11p75 has greater antioxidant capacity towards O2⋅−, due to the esterified benzyl groups providing alternative sites for O2⋅− attack other than the hyaluronan backbone of HYAFF®-11p75 itself and explains the inability of HYAFF®-11p75 to scavenge ⋅OH, due to benzyl alcohol degradation by ⋅OH.The antioxidant activities of these biomaterials, particularly HYAFF®-11p75 and AQUACEL®, towards O2⋅− could be beneficial, as the scavenging of PMN-derived O2⋅− may remove initial sources of O2⋅− and further prevent the secondary formation of ⋅OH. These ROS are thought to be a primary causal factor for the extensive degradation and metabolic alterations observed in chronic wounds. [Copyright &y& Elsevier]
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Database: Engineering Source
Description
Abstract:In chronic wounds, a number of host factors are released which perpetuate the inflammatory process, including polymorphonuclear leukocyte (PMN)-derived reactive oxygen species (ROS), such as superoxide radical (O2⋅−) and hydroxyl radical (⋅OH) species. The glycosaminoglycan, hyaluronan, has been shown to act as an antioxidant towards ROS, although the potential for biomaterials, such as HYAFF®-11p75 (the 75% benzyl ester of hyaluronan) and AQUACEL® (carboxymethylcellulose), to act in this manner has yet to be elucidated. This study compared the antioxidant properties of high and low molecular weight hyaluronan (HMWT HA and LMWT HA), HYAFF®-11p75, AQUACEL® and an AQUACEL®/hyaluronan composite (AQUACEL®/HA) against O2⋅− and ⋅OH. The antioxidant capacities of each material were assessed by their ability to inhibit cytochrome C reduction by O2⋅− fluxes, generated via the oxidation of hypoxanthine by xanthine oxidase, and their inhibition of 2-deoxy-d-ribose degradation by ⋅OH fluxes, generated by the reaction of hydrogen peroxide (H2O2) and iron (Fe2+).All materials studied possessed dose dependent antioxidant properties towards O2⋅−, with HYAFF®-11p75 having the greatest antioxidant potential towards these species, followed by AQUACEL®, HMWT HA, AQUACEL®/HA and LMWT HA. Only HMWT HA exhibited dose dependent antioxidant properties towards ⋅OH at the fluxes examined.Gas chromatography/mass spectrometry analysis implied that ester bonds between the hyaluronan backbone and benzyl groups of HYAFF®-11p75 are highly susceptible to O2⋅− hydrolysis, with the de-esterified benzyl alcohol being rapidly degraded in the presence of ⋅OH. This data supports the hypothesis that HYAFF®-11p75 has greater antioxidant capacity towards O2⋅−, due to the esterified benzyl groups providing alternative sites for O2⋅− attack other than the hyaluronan backbone of HYAFF®-11p75 itself and explains the inability of HYAFF®-11p75 to scavenge ⋅OH, due to benzyl alcohol degradation by ⋅OH.The antioxidant activities of these biomaterials, particularly HYAFF®-11p75 and AQUACEL®, towards O2⋅− could be beneficial, as the scavenging of PMN-derived O2⋅− may remove initial sources of O2⋅− and further prevent the secondary formation of ⋅OH. These ROS are thought to be a primary causal factor for the extensive degradation and metabolic alterations observed in chronic wounds. [Copyright &y& Elsevier]
ISSN:01429612
DOI:10.1016/S0142-9612(01)00360-X