INSECT FEEDING INDUCED CHEMICAL AND BIOCHEMICAL DEFENSES ADOPTED BY PLANTS

Plants are sedentary living organisms performing vivid roles in life cycle from germination to reproduction. During this journey they encounter several distinct obstacles right from the exposure to various unsuitable climatic conditions, to unwanted attackers such as insects, pathogens or even the manmade chemicals. Though the plants are motionless and inactive in appearance often they wisely defend themselves. Majority of the insects depend on plants for their feeding, oviposition and sometimes whole survival itself. Plants when attacked by an insect or a pathogen, respond to resist the intrusion in its life and overcome it in several ways. Plant chemicals and hormones are important shielding molecules present in them that stimulate responses against herbivores. Plants utilize cost effective methods to administer its energy for either growth or defense against insect feeding. They defend themselves utilizing the plant variability of primary metabolites, secondary metabolites, alkaloids and plant enzymes that detoxify the reactive oxygen species. Thus they have either antinutritive or antidigestive effects that play a major role in inhibiting the invasion of insects. These mechanisms help plants defend themselves from feeding insector animal attack and this area of research is gaining interest in scientific community of late

TAGETES ERECTA (L.) ESSENTIAL OIL FLORAL AND FOLIAR EXTRACTS AS POTENTIAL GRAIN PROTECTANTS AGAINST THREE SPECIES OF STORED PRODUCT PESTS

Laboratory tests were carried out using population of Tribolium castaneum, (Herbst), Sitophilus oryzae (L.), Callasobruchus chinensis to evaluate the effectiveness of the African marigold, Tagetes erecta (L.) (Asteraceae) floral, foliar extracts and the essential oil, (floral, foliar extracts and the essential oil)for their toxic effects. The effects of the treatments on adult mortality were observed in contact and vapor toxicity methods. Floral and foliar extracts of T. erecta at dosage of 100 mg/ 20 g diet and the essential oil at 30 ul/ 20 g diet, produced 100% mortality (was observed) in all the test insects, one day after application in contact toxicity method. The low doses of the samples were also effective in causing the mortality but the effects were delayed. However, all the dilutions of T.erecta were highly potent in producing the toxicity in the vapor form. There was 100% mortality of the test insects (was observed) even at very low dosages of floral and foliar extracts (80 mg/ 200 cc) and also the essential oil of T. erecta (25ul/ 200cc) in fumigation method within one day after treatment. The dosages lesser to this, showed a comparatively less toxicity to S. oryzae, T. castaneum and C. chinensis. These results suggest that the essential oil, floral and foliar extracts of T. erecta act as good protectants of the stored grain and can be considered as an alternative to synthetic insecticides

Identification of Naphthol Derivatives as Novel Antifeedants and Insecticides. 1

A series of β-naphthol-derived 2-aminobenzothiazolomethylnaphthol derivatives (<b>4a</b>–<b>4q</b>) were synthesized and purified in excellent yields (86–94%) using green protocols and screened for their antifeedant and toxic activities against tobacco caterpillar (Spodoptera litura) and castor semilooper (Achaea janata) using no-choice leaf disk and topical bioassay methods. Four of them, <b>4d</b>, <b>4f</b>, <b>4i</b>, and <b>4j</b>, were identified to be potent antifeedants with ED₅₀ values of 16.4, 19.3, 7.0, and 5.2 μg/cm² against <i>S. litura</i> and 13.9, 17.2, 10.2, and 7.7 μg/cm² against <i>A. janata</i>, respectively, and the mortality rate is >95% for <b>4i</b> and <b>4j</b> in the case of <i>S. litura</i> and <b>4j</b> in case of <i>A. janata</i> at a dosage of 0.2 μg/insect. Compounds <b>4d</b>, <b>4i</b>, and <b>4m</b> are moderately toxic to <i>A. janata</i> only. Overall, this study identified a novel class of synthetic compounds that do not belong to organochlorides, organophosphates, carbamates, or neonicotinoids as strong antifeedants as well as insecticides

New seco-limonoids from Cipadessa baccifera: Isolation, structure determination, synthesis and their antiproliferative activities

International audienceA comprehensive reinvestigation of chemical constituents from CHCl3-soluble extract of Cipadessa baccifera led to the isolation of two new limonoids 1, 2 together with six known compounds 3-8. Their structures were established on the basis of extensive analysis of spectroscopic (IR, MS, 2D NMR) data. Further, a series of cipaferen G (3) derivatives were efficiently synthesized utilizing Yamaguchi esterification (2, 4, 6-trichlorobenzoyl chloride, Et3N, THF, DMAP, toluene) at the C-3 position of the limonoids core, which is being reported for the first time. The anti-proliferative activity of the isolates and the synthetic analogues were studied against HeLa, PANC 1, HepG2, SKNSH, MDA-MB-231 and IMR32 cancer cells using the sulphorodamine B assay. Among the tested compounds, 13d and 13h manifested potent activity against IMR32, HepG2 cell lines with GI50 0.013 and 0.01μM, respectively