Uroleuconaphins A2a, A2b, B2a, and B2b:: four yellowish pigments from the aphid Uroleucon nigtrotuberculatum (Olive)

Four novel yellowish pigments, uroleuconaphins A(2a), A(2b) (3a, 3b), and B-2a, B-2b (4a, 4b), were isolated from the aphid Uroleucon nigrotuberculatum (Olive). Their structures were established by detailed analyses of 1D and 2D NMR spectra and mechanistic consideration of the interconversion between 3 (or 4) and Uroleuconaphin A(1) (1) (or B-1 (2)). (C) 2008 Elsevier Ltd. All rights reserved.