Two new insecticidal amide dimers from fruits of Piper nigrum LINN.

The methanolic extract of dried ground seeds of Piper nigrum LINN. afforded fourteen compounds, of which thirteen were amides, including two new isomeric insecticidal amides, pipsaeedine (1) and pipbinine (2), along with eleven known amides and piptaline; (this is the first report of isolation of these compounds from this plant). The structures of 1 and 2 have been elucidated as (E,E)-1-[(E)-5-(7-(6-[5-(piperidin-1-yl)-5-oxopent-3enyl]-1,3-benzodioxol-4-yl)-1,3-benzodioxol-5-yl)-1-oxopenta-2,4-dienyl]piperidine and (E,E)-1-[(E)-5-(4-(6[5(piperidin-1-yl)-5-oxopent-3-enyl]-1,3-benzodioxol-4-yl)-1,3-benzodioxol-5-yl)-1-oxopenta-2,4-dienyl]piperidine, respectively, through extensive 1D- and 2D-NMR spectral studies, while the known constituents have been identified through comparison of their spectral data with those reported in the literature. Compounds 1 and 2 exhibited toxicities of 45.0 and 40.0 ppm, respectively, against fourth instar larvae of Aedes aegypti Liston.