Four pairs of novel dopamine enantiomer trimers, (±)-cryptamides A-D (1-4), and 10 pairs of previously described dopamine enantiomer dimers (5-14) were isolated from the Periostracum cicadae, the cast-off shell of the insect Cryptotympana pustulata. Aside from being pairs of enantiomers, the eight trimers were also elucidated to be regioisomers, most likely resulting from their mechanism of formation, [4 + 2] cycloaddition. The discovery of dopamine trimers is rarely reported when it comes to natural products derived from insects.
Keywords: Periostracum cicadae; anti-inflammatory; dopamine trimers; enantiomer; structure identification.