Isolation, Total Synthesis, and Absolute Configuration Determination of Renoprotective Dimeric N-Acetyldopamine–Adenine Hybrids from the Insect Aspongopus chinensis

Aspongdopamines A and B (1 and 2), unusual adducts composed of N-acetyldopamine and adenine were isolated from the insect Aspongopus chinensis. Compounds 1 and 2 are positional isomers both isolated as racemates. Chiral separation assisted by 14-step total synthesis and computation including vibrational circular dichroism calculations allowed us to unambiguously assign the absolute configurations of eight stereoisomers. Renal fibrosis inhibition of the stereoisomers was evaluated in TGF-β1-induced rat kidney epithelial cells.