Establishment of purification techniques for alpha-lipoic acid derivative, sodium zinc histidine dithiooctanamide using ethanol-based crystallization and suspension methods

Alpha-lipoic acid (LA) has become a common ingredient in multivitamin formulas, anti-aging supplements, and even pet food. It is well defined as a therapy for preventing diabetic polyneuropathies, scavenges free radicals, chelates metals, and restores intracellular glutathione levels which otherwise decline with age. Sodium zinc histidine dithiooctanamide (DHL-HisZn_Na) is a water-soluble substance, with strong antioxidant and anti-inflammatory properties, similar to α-lipoic acid with histidine bound to α-lipoic acid and zinc chelated with sulfur atoms. DHL-HisZn_Na slowly loses its stability under dry conditions in the dark and under refrigeration. Purification is essential for use after long-term storage. In this study, ethanol crystallization and suspension methods were utilized in development for the first time as purification methods for DHL-HisZn_Na.