Diversity-oriented synthesis of diterpenoid alkaloids yields a potent anti-inflammatory agent

•18 novel compounds with unprecedented ring systems were prepared from the diterpenoid alkaloids deltaline and talatisamine.•Deltanaline was found to exhibit the most potent anti-inflammatory activity after optimization and screening.•Deltanaline inhibited the production of inflammatory mediators and NF-κB/MAPK pathway in activated macrophages.•Deltanaline alleviated inflammation in ear edema, AKI, and CIA.