Antioxidant Polymers with Enhanced Neuroprotection Against Insulin Fibrillation

• Published in: Macromolecular bioscience 2023-07, Vol.23 (7), p.e2300100-n/a
• Main Authors: Bera, Avisek, Ghosh, Pooja, Ghosh, Shilpendu, Mukherjee, Arindam, De, Priyadarsi
• Format: Article
• Language: English
• Subjects: Amyloid; Amyloidogenesis; antioxidant polymers; Antioxidants; Antioxidants - chemistry; Antioxidants - pharmacology; Block copolymers; Carboxylates; Cell membranes; Cell viability; Dihydrolipoic acid; dihydro‐lipoic acid; Disintegration; fibril inhibition; Fibrillation; Free radicals; Insulin; insulin fibril; Lipoic acid; Neuroprotection; Pharmacology; Polyethylene glycol; Polymers; Proteins; Reactive Oxygen Species; Scavenging; Thioctic Acid - pharmacology
• ISSN: 1616-5187; 1616-5195
• DOI: 10.1002/mabi.202300100

Lipoic acid (LA) and dihydrolipoic acid (DHLA) are well established antioxidants to scavenge reactive oxygen species (ROS). However, they are carboxylates with ≈4.7 pKa making them negatively charged at physiological pH (7.4) reducing their passive diffusion through cell membranes. LA is known to be capable of reducing protein fibrillation. Incorporation of LA and especially DHLA in polymer side chains are scarce. Herein, the first examples of the anti‐amyloidogenic effect of LA and DHLA incorporated into the side‐chain of a block copolymer with a water‐soluble poly(polyethylene glycol methyl ether methacrylate) (PPEGMA) segment are presented. The resultant polymers show improved ROS scavenging activity and improved ability to reduce insulin fibrillation compared to free LA and DHLA. Furthermore, the resultant polymers are also capable of disintegrating preformed insulin firbrils. Interestingly, polymers with dihydro‐lipoate moieties showed 93% free radical scavenging activity with 91% anti‐fibrillating efficacies for insulin protein confirmed by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) assay and Thioflavin T (ThT) dye binding study, respectively. Further, the antioxidant polymers increase the cell viability against fibrillar insulin aggregates that may be involved in the etiology of several diseases. Overall, this work reveals that antioxidant polymer‐based therapeutic agents can serve as a powerful modulation strategy for developing novel drugs in future against amyloid‐related disorders. Side‐chain lipoic acid and dihydro‐lipoic acid‐containing polymers are fabricated to explore their potential antioxidant properties as well as anti‐amyloidogenic role in preventing the insulin fibrillation process. The enthralling upshots based on the experimental results eventually endow dihydrolipoic acid‐tethered polymers to act as novel effective anti‐amyloidogenic agents.