Alkyl-modified nucleobases with 6/5/7/5 ring systems from the insect Cyclopelta parva

Abstract

(±)-Cyclopeltains A and B (1 and 2), two pairs of unusual alkylated adenine derivatives, were isolated from the insect Cyclopelta parva and structurally characterized. 1 and 2 both possess a 6/5/7/5 ring system arising from the alkylation of N⁷ and N¹⁰ by a C₆ unit and the formation of a furan ring. A plausible biosynthetic pathway for 1 and 2 was proposed. Biological evaluation of the enantiomers of 1 and 2 revealed that (−)-1 and (+)-2 could inhibit the production of TNF-α and IL-6 and the expression of iNOS, COX-2, and p-NF-κB.