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Antifeedant Activity (antifeedant + activity)
Selected AbstractsBIOACTIVITIES AND MECHANISM OF SPIRO ENOL ETHER ANALOGUES AGAINST PIERIS RAPAEINSECT SCIENCE, Issue 1 2004Zhi-xiang Zhang Abstract, Nineteen kinds of spiro enol ether analogues were screened with larvae of Pieris rapae for antifeedant activity. The results showed that the antifeedant activity of compounds No.20 and No. 12 was higher than others. In non-choice test, AFC50 values within 24 h of compounds No.20 and No. 12 against 3rd instar larvae of P. rapae were 226.93 ,g/mL and 370.00 ,g/mL, and that in choice test against 4th larvae were 280.54 ,g/mL and 398.88 ,g/mL, respectively. Compd. No.20 could prolong the eggs hatch time and reduce the haemolymph content and the protein content in haemolymph of 4th instar larvae obviously. Compd. No.20 could protect tested leaves and control larvae of P. rapae effectively. [source] Insect growth-reducing and antifeedant activity in Eastern North America hardwood species and bioassay-guided isolation of active principles from Prunus serotinaAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 4 2000S. Omar Abstract 1 Thirty extracts of wood and bark of hardwood trees from Eastern North America were examined for insect growth-reducing activity in a bioassay with European corn borer, Ostrinia nubilalis, and an antifeedant bioassay with the rice weevil, Sitophilus oryzae. 2 Nine of the bark extracts and four of the wood extracts showed significant growth reducing effects at 0.5% in meridic diets, whereas only two bark extracts and one wood extract showed significant antifeedant effect at the same concentration. 3 Slower growing tree species were more biologically active than fast growing ones. Isolation of the bioactive compounds in one of the active species, Prunus serotina, showed that naringenin, its derivative methoxynaringenin, and eriodictyol were responsible for the antifeedant effects. [source] Insecticidal activity of deoxypodophyllotoxin, isolated from Juniperus sabina L, and related lignans against larvae of Pieris rapae LPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 11 2004Rong Gao Abstract In the course of screening for naturally occurring insecticides from plants from the northwestern part of China, a petroleum ether extract of Juniperus sabina L was found to show insecticidal activity against fifth-instar larvae of Pieris rapae L. From the extract, an insecticidal compound was isolated by bioassay-guided fractionation. The compound was identified as deoxypodophyllotoxin (1) by comparison of its spectroscopic characteristics with literature data. In bioassays, 1 showed antifeedant activity against fifth-instar larvae of P rapae at 0.05,1.00 g litre,1 and its AFC50 (concentration for 50% antifeedant activity) values at 12 and 48 h were 0.170 and 0.060 g litre,1, respectively. In that concentration range, all treated insects died within 48 h after treatment and compound 1 showed delayed insecticidal activity. At 0.015,0.100 g litre,1, 1 showed insecticidal activity, with an LC50 of 0.020 g litre,1. The related compound deoxypicropodophyllotoxin (2), however, showed lower antifeedant and insecticidal activities than 1 in bioassay. This indicated that the trans -lactone ring is an important moiety for enhancing activity in these compounds. Comparison of the insecticidal activities of 1 and another related compound, podophyllotoxin (3), suggested that varying the substituent at C-4 is an exciting possibility for synthesizing more potent analogues. Copyright © 2004 Society of Chemical Industry [source] Chemical modification of chitosan: synthesis and biological activity of new heterocyclic chitosan derivativesPOLYMER INTERNATIONAL, Issue 2 2008Mohamed EI Badawy Abstract BACKGROUND: Numerous works have been published on the chemical modification of chitosan; this polymer is still being modified, leading to various derivatives with improved properties. In the present study, heterocyclic aldehydes including furan-2-carbaldehyde, 5-methylfuran-2-carbaldehyde, 3-pyridine carboxyaldehyde, benzo[d][1,3]dioxole-5-carbaldehyde and 4-oxo-4H -chromene-3-carbaldehyde were reacted with chitosan by a reductive alkylation reaction to produce for the first time five new N -heterocyclic chitosan derivatives to improve the biological activity of chitosan against the most important economic plant pests including fungi and insects, in particular the cotton leafworm Spodoptera littoralis. RESULTS: The chemical structures of the synthesized compounds were confirmed by 1H NMR spectroscopy and the degree of substitution ranged from 0.30 to 0.43. The fungicidal assessment was investigated in vitro using a mycelia radial growth inhibition technique against soil-borne pathogenic fungi Fusarium oxysporum and Pythium debaryanum and the rice leaf blast Pyricularia grisea. The results showed that N -[(5-methylfuran-2-yl)methyl] chitosan was the most active against P. grisea with an EC50 value of 0.919 mg mL,1 while N -(benzo[d][1,3]dioxol-5-ylmethyl) chitosan and N -(methyl-4H -chromen-4-one) chitosan exhibited the most potent fungicidal activity against P. debaryanum and F. oxysporum. An insecticidal bioassay against the larvae of S. littoralis showed that N -(methyl-4H -chromen-4-one) chitosan exhibited a significant growth inhibition and antifeedant activity among the synthesized compounds. CONCLUSION: The chemical modification of chitosan molecule with a heterocyclic moiety led to an enhancement in the biological activity against the plant pathogenic fungi F. oxysporum, P. debaryanum and P. grisea and the cotton leafworm insect S. littoralis. Copyright © 2007 Society of Chemical Industry [source] Xylogranatins F,R: Antifeedants from the Chinese Mangrove, Xylocarpus granatum, A New Biogenetic Pathway to TetranortriterpenoidsCHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2008Jun Wu Dr. Abstract Thirteen limonoids with a new carbon skeleton, the xylogranatins,F,R (1,13), have been isolated from the seeds of a Chinese mangrove, Xylocarpus granatum; two recently reported compounds, xylogranatins,C and,D were also isolated. Their structures were elucidated on the basis of spectroscopic data and chemical methods. The absolute configurations of these compounds were determined by using the modified Mosher MTPA ester method and by quantum chemical circular dichroism (CD) calculations. Xylogranatins,F,Q are the first aromatic B-ring limonoids found in nature. They belong to two substructural classes, of which one (1,3) contains a pyridine ring while the other one (4,12) contains a central furan core. Xylogranatins,C and,R can be considered to be key biosynthetic intermediates, while xylogranatin,D, the only limonoid found so far with a carbon skeleton that conatains a C30C9 linkage, is apparently an artifact. The structures of these compounds suggest a new biogenetic pathway to tetranortriterpenoids. Xylogranatins,F, G and R were found to exhibit marked antifeedant activity against the third instar larvae of Mythimna separata (Walker) at a concentration of 1,mg,mL,1. The most potent compound tested was xylogranatin,G. Its AFC50 (concentration for 50,% antifeedant activity) values at the exposure times of 24 and 48,h were 0.31 and 0.30,mg,mL,1, respectively. [source] Synthesis and Bio-activities of Pyrazolyl or Pyridinyl Substituted Tonghaosu AnalogsCHINESE JOURNAL OF CHEMISTRY, Issue 6 2007Biao-Lin Yin Abstract 11 pyrazolyl or pyridinyl substituted tonghaosu analogs were synthesized. Structures of all the new compounds were confirmed by 1H NMR, IR, MS, HREIMS or elemental analysis. Their antifeedant activity against larvae of large white butterfly (Pieris brassicae L.), larvicidal activity toward mosquito (Culex quinquefasciatus Say) and growth control activity toward larvae of Spodoptera litura Fab were examined. Some of them exhibited antifeeding activities comparable to or stronger than tonghaosu Z-1. Based on the activity data, the preliminary structure-activity relationship was also discussed, which might be instructive for finding out lead compounds with better bioactivities in the future. [source] | ||||||||||