Dimeric N-Acetyldopamine Derivatives Featuring a Seco-Benzene System from the Insects Aspongopus chinensis and Periostracum cicadae

Aspongamide F (1), a novel N-acetyldopamine (NADA) dimer possessing a 6/6/6 ring system, and (+/-)-aspongamides G (2) and H (3), rare NADA derivatives with fragmented benzene rings, were isolated from Aspongopus chinensis. (+/-)-Cicadamides C (4) and D (5), the first 1,4-Benzodioxane NADA dimers featuring a seco-benzene system, and (+/-)-cicadamides E (6) and F (7), the NADA dimers derivatives, were isolated from Periostracum cicadae. The structures of all compounds were elucidated by spectroscopic analyses and computational methods. A plausible biosynthetic pathway for compounds 1-5 was proposed. The biological assay revealed that (+)-4 and (-)-4 exhibit renal protection in a dose-dependent manner.