Design, synthesis and anti-inflammatory activity of diterpenoid alkaloids and non-steroidal anti-inflammatory drug hybrids based on molecular hybridization strategy

Molecular hybridization is a widely employed approach in pharmaceutical chemistry for modifying drugs with the aim of improving pharmacological efficacy and reducing adverse effects. A prime example of this is the case of benorylate, which was created by combining aspirin and acetaminophen, two non-steroidal anti-inflammatory drugs (NSAIDs). Diterpenoid alkaloids, which exhibit potent anti-inflammatory activity, have limitations in their application due to their toxicity and side effects. Thus, we aimed to design new anti-inflammatory lead compounds through the molecular hybridization of the anti-inflammatory active skeletons (lappaconitine, aconorine, and bulleyaconitine A) of diterpenoid alkaloids with classical NSAIDs. In this study, we synthesized 25 diterpenoid alkaloid derivatives with NSAIDs, organized into four series. Among these derivatives, lappaconitine derivative 1e demonstrated the strongest inhibition of lipopolysaccharide (LPS)-induced NO production in RAW 264.7 cells with minimal cytotoxicity. Additionally, 1e effectively suppressed the inflammatory response induced by carrageenan in vivo, with a swelling rate of only 1%. This anti-inflammatory potency was found to be significantly superior to that of naproxen. The molecular docking analysis revealed that the binding affinity of 1e was scored as -10.3 kcal/mol, suggesting that it forms a stable complex with cyclooxygenase-2 (COX-2). Therefore, compound 1e holds potential as a lead anti-inflammatory compound that could be further developed.