(+/-)-Kituramides A and B, pairs of enantiomeric dopamine dimers from the two-spotted cricket Gryllus bimaculatus

Abstract

Two-spotted cricket Gryllus bimaculatus is one of many cricket species, and it is widely used as a food source for insectivorous animals. Moreover, this species is one of the edible insects approved by the Korea Food and Drug Administration (KFDA). (+/-)-Kituramides A (1) and B (2), which are pairs of novel enantiomeric dopamine dimers possessing a formamide group, were isolated from the two-spotted cricket, together with four other known biosynthetically related compounds (3-6). The chemical structures of 1 and 2 were elucidated using a combination of 1D and 2D NMR spectroscopic experiments and HR-ESIMS data. Compounds 1 and 2 were identified as racemic mixtures; the enantiomers (+)-1/2 and (-)-1/2 were successfully separated by utilizing a chiral HPLC column. The absolute configurations of (+/-)-1 and (+/-)-2 were unambiguously delineated by the application of quantum chemical ECD calculations. Further, these insect-derived substances were evaluated to understand their effects on cytokine expression in adipocytes. Treatment with (-)-1, (+)-2, and (-)-2 during adipocyte differentiation significantly promoted the expression of Leptin and IL-6, which resembles the actions of dopamine.