Triple Action of Lignosulfonic Acid Sodium: Anti-protease, Antioxidant, and Anti-inflammatory Effects of a Polymeric Heparin Mimetic.

Background: Heparins are sulfated glycosaminoglycans that are used as anticoagulants to treat thrombosis. Heparins exhibit other potential therapeutic effects, such as anti-inflammatory, anti-viral, and anti-malarial effects. However, the strong anticoagulant activity of heparins poses a risk of life-threatening bleeding, limiting their therapeutic use for other diseases beyond thrombosis. To exploit the other effects of heparins and eliminate the bleeding risk, we explored an alternative polymer called lignosulfonic acid sodium (LSAS), which acts as a sulfonated heparin mimetic. LSAS targets factor XIa to exert an anticoagulant effect, and thus, unlike heparins, it is unlikely to cause bleeding.

Methods: This study investigated the multiple effects of LSAS to identify potential leads for complex pathologies treatment. A series of chromogenic substrate hydrolysis assays were used to evaluate the inhibition of three inflammation-related proteases by LSAS. Its chemical antioxidant activity against the system of ABTS/hydrogen peroxide/metmyoglobin was also determined. Lastly, the effect of LSAS on TNFα-induced activation of the NF-κB pathway in HEK-293 cells was also tested to determine its cellular anti-inflammatory activity.

Results: The results showed that LSAS effectively inhibited human neutrophil elastase, cathepsin G, and plasmin, with IC₅₀ values ranging from 0.73 to 212.5 μg/mL. Additionally, LSAS demonstrated a significant chemical antioxidant effect, with an IC50 value of 44.1 μg/mL. Furthermore, at a concentration of approximately 530 μg/mL, LSAS inhibited the TNFα-induced activation of the NF-κB pathway in HEK-293 cells, indicating a substantial anti-inflammatory effect. An essential advantage of LSAS is its high water solubility and virtual non-toxicity, making it a safe and readily available polymer.

Conclusion: Based on these findings, LSAS is put forward as a polymeric heparin mimetic with multiple functions, serving as a potential platform for developing novel therapeutics to treat complex pathologies.