Design, Synthesis, and Examination of Neuron Protective Properties of Alkenylated and Amidated Dehydro-Silybin Derivatives

A series of C7-O- and C20-O-amidated 2,3-dehydrosilybin (DHS) derivatives ((±)-1a−f and (±)-2), as well as a set of alkenylated DHS analogues ((±)-4a−f), were designed and de novo synthesized. A diesteric derivative of DHS ((±)-3) and two C23 esterified DHS analogues ((±)-5a and (±)-5b) were also prepared for comparison. The cell viability of PC12 cells, Fe2+ chelation, lipid peroxidation (LPO), free radical scavenging, and xanthine oxidase inhibition models were utilized to evaluate their antioxidative and neuron protective properties. The study revealed that the diether at C7−OH and C20−OH as well as the monoether at C7−OH, which possess aliphatic substituted acetamides, demonstrated more potent LPO inhibition and Fe2+ chelation compared to DHS and quercetin. Conversely, the diallyl ether at C7−OH and C20−OH was more potent in protection of PC12 cells against H2O2-induced injury than DHS and quercetin. Overall, the more lipophilic alkenylated DHS analogues were better performing neuroprotective agents than the acetamidated derivatives. The results in this study would be beneficial for optimizing the therapeutic potential of lignoflavonoids, especially in neurodegenerative disorders such as Alzheimer's and Parkinson's disease.