Structure‐activity relationships of insecticidal amides from Piper guineense root

Abstract

The structure‐activity relationships between five amides previously isolated from the root extract of Piper guineense Schum and Thonn were studied. The methyl‐terminated amides, pellitorine and kalecide, were found to be more polar and caused higher knockdown, but showed less lethal action against insects than their methylenedioxyphenyl‐terminated counterparts, pipercide and guineensine. Guineensinamide showed weak activity and this was correlated with higher unsaturation and the presence of a pyrrolidyl group in the molecule. There was an association between the polarity of the amides and the recovery of the insects from their effects, much more recovery being observed with the methylterminated than with the methylenedioxyphenyl‐terminated amides. Electrophysiological investigations of the effects of pellitorine and pipercide on miniature excitatory postsynaptic potentials (MEPSPs) from the locust retractor unguis nerve‐muscle preparation showed that the amides caused a reduction in both the frequency and amplitude of MEPSPs, pipercide being between 100 and 1000 times more effective than pellitorine. An action of the amides on presynaptic transmission is suggested. The effects of pipercide and pellitorine on the isolated nerve‐muscle preparation were correlated with the symptoms of poisoning at the whole animal level.

Insecticidal Neolignans from Piper decurrens

“…In addition, the chemistry of this species had not previously been investigated. Knowing that the bioactivity of Piper species can generally be attributed to the presence of lignans and/or amides, such as alkyl or olefinic isobutylamides, 1,3,4 it was of interest to determine which of the two preceding types of compounds would be present in P. decurrens. Bioassay-guided fractionation of the crude ethanol extract of this species led to the isolation of four compounds new to the Piperaceae, 2,3-dihydro-2-(4′-hydroxyphenyl)-3-methyl-5(E)-propenylbenzofuran (1), 2-(4′-hydroxy-3′-methoxyphenyl)-3-methyl-5(E)propenylbenzofuran (2), 2-(4′-hydroxyphenyl)-3-methyl-5(E)-propenylbenzofuran (3), and 2,3-dihydro-5-formyl-2-(4′-hydroxyphenyl)-3-methylbenzofuran (4), as well as 3,7,11,15-tetramethyl-2(E)-hexadecen-1-ol, or trans-phytol, which has been identified previously in the extracts of other Piper species.…”

“…In addition, the chemistry of this species had not previously been investigated. Knowing that the bioactivity of Piper species can generally be attributed to the presence of lignans and/or amides, such as alkyl or olefinic isobutylamides, ,, it was of interest to determine which of the two preceding types of compounds would be present in P . decurrens .…”

One-Step Synthesis of α-Pyrones from Acyl Chlorides by the Stille Reaction

“…Calcd for C11H8O2: C, 76.73;H,4.68. Found: C,76.79;H,4.75. 6-Isopropylpyran-2-one (3b): isolated in 66% yield as a colorless liquid; IR (neat) 3096,2983,2897,1738,1641,1570, 1098 cm -1 ; 1 H NMR (CDCl3, 200 MHz) δ 1.18 (d, J ) 7.1 Hz, 6H), 2.68 (m, J ) 7.1 Hz, 1H), 5.96 (d, J ) 6.0 Hz, 1H), 6.10 (d, J ) 9.3 Hz, 1H), 7.26 (dd, J ) 9.3 Hz, 6.6 Hz, 1H); 13 C NMR (CDCl3, 50.5 MHz) δ 18.4 (2C), 33.6, 100.6, 112.8, 144.3, 163.1, 170.9; MS (70 eV, EI) 138 (M + , 12), 83 (13), 75 (100), 73 (26), 59 (79), 49 (69), 47 (25), 45 (17), 31 (35), 29 (25), 27 (10). Anal.…”

“…Finally, the synthesis of sibirinone 3f isolated from a culture of Hypomyces semitranslucens G. Arnold, ( E )-6-pent-1-enyl-pyran-2-one 3i extracted from Solenopsis invicta , 6-pentylpyranone 3d found in a number of plants and as a pheromone of ant , and Paracotoin 3m , an intermediate in the biosynthesis of shikimic acid, was realized by this procedure.…”

Sesamin a potent antifeedant principle fromPiper mullesua

“…The leaves of P. futokadzura deter feeding by the larvae of Spodoptera litura (Matsui and Munskata, 1975). Neurotoxic amides and lignans appear to be mainly responsible for the anti insect activities of Piper species (Greger, 1988;Gbewonyo et al, 1993).…”