Of AO, as well as the parent Aintermediate macroradical, form a collection of very reactive compounds, i.e., the initiators of subsequent self-perpetuating free-radical degradation of high-molar-mass HA. three.1.two. Transfer with the Free-Radical Centre and Fragmentation Reaction(s) As is well-known in macromolecular chemistry, a lengthy chain alkoxy-type macroradical freely undergoes the strand scission on account of the -cleavage. Hence the scission at, e.g., C(1) onCholesteryl sulfate Epigenetic Reader Domain Scheme two. An intact HA macromolecule (upper panel) reacts with H radical yielding an interm diate A i.e., a C-centered hyaluronan macroradical (reduced panel), which immediately reacts wform a collection of highly reactive compounds, i.e., the initiators of subsequent selfpetuating free-radical degradation of high-molar-mass HA. 3.1.two. Transfer of the Free-Radical Centre and Fragmentation Reaction(s)Pharmaceutics 2021, 13, 1815 5 ofAs is well-known in macromolecular chemistry, a lengthy chain alkoxy-type macro ical freely undergoes the strand scission on account of the -cleavage. Hence the scission at, C(1) on the ring of D-glucuronic acid, yields polymer fragments, namely a macromole the ring a terminal C=O group polymer fragments, namely a macromolecule bearing bearingof D-glucuronic acid, yieldsand a novel alkoxy-type macroradical (cf. Scheme three). A a terminal C=O group along with a novel alkoxy-type macroradical (cf. Scheme 3). As a rule of rule of such a degradation reaction each fragments have decreased molar mass.such a degradation reaction both fragments have lowered molar mass.OH HO O O CH3OC O NH HO OC OH OH C O . O CH3OC C NH O O OH OC HO OH O OHO HOOH HO O O CH3OC O NH HO OC OH OH C O O . OCH3OC C NH O O OH OC HOOH O OHHOScheme3. The lengthy chain alkoxy-type macroradical AOundergoes a transfer a transfer of 1 electro Scheme three. The extended chain alkoxy-type macroradical AOundergoes of 1 electron at, e.g., C(1) around the ring of D-glucuronic acid (upper The decay of the native chain alkoxy-type e.g., C(1) on the ring of D-glucuronic acid (upper panel). panel). The decay on the native chain alkoxymacroradical AOyields two polymer fragments (decrease (lower panel) possessing lowered molar macroradical AOyields two polymer fragments panel) possessing reduced molar masses. The masses. newly formed alkoxy-type macroradical of 38shorter molar ) naturally naturally the newly formed alkoxy-type macroradical of shorter molar size (AO ize (AOcould act as could act a initiator in the self-perpetuating free-radical HA degradation. initiatorof the self-perpetuating free-radical HA degradation.The initiating OH radical(s) (cf. Scheme 1) can react together with the D-glucuronate/DThe initiating H radical(s) (cf. Scheme 1) can react by opening the alkyl glucuronic acid and N-acetyl-D-glucosamine functional moieties using the D-glucuronate/Dcuronic acid and N-acetyl-D-glucosamine functional moieties by opening the alkyl r rings [525] with no breaking the HA chain.[525] without having breaking the HA chain.three.1.3. Termination Reaction(s) The free-radical degradation three.1.three. Termination Reaction(s) reactions with the native high-molar-mass hyaluronanbelong to self-perpetuating reactions. Just about the most helpful procedures terminating the The free-radical degradation reactions of the the really phase of their initiation. self-perpetuating reactions will be to scavenge this sequence in native high-molar-mass hyaluronan extended to self-perpetuating reactions. Just about the most by H2 O2 decomposition, can Reactions represented in Scheme 1, subsequently Benidipine In Vivo followed eff.
