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Essential oil from the leaves of Chloroxylon swietenia DC. was obtained by hydrodistillation and cold extraction, and the chemical composition was determined by gas chromatography and gas chromatography-mass spectrometry. The major identified components were limonene, geijerene, pregeijerene, germacrene D and trans-beta-ocimene. Laboratory bioassays of the essential oil and four constituents of essential oil isolates were evaluated for insecticidal, antifeedant and oviposition deterrent effects on tobacco cutworm, Spodoptera litura (F.). Toxicity was determined by topical application of the isolates at varying concentrations. Pure oil, geijerene and pregeijerene were found to be more toxic, with LD50 values of 28.6, 35.4 and 40.7 microg per larva respectively. Maximum feeding deterrence was noted for geijerene and pregeijerene, with DC(50) values of 82.5 and 95.1 microg cm(-2) respectively. Furthermore, pure oil, geijerene and pregeijerene displayed oviposition deterrence, even at low concentrations. These results indicate that these natural products may lead to useful, biodegradable, environmentally safe insect control agents.

Growing awareness in using ecofriendly and biologically compatible phytoconstituents as natural insecticides and repellents for the safety of life and ecological balance led to conscientious efforts by scientists all over the world to search for alternative sources of plant derivatives for effective use as mosquitocides. Encouraged by this, the essential oil and the sesquiterpenes isolated from the leaves of Chloroxylon swietenia DC. were screened for mosquitocidal activity by fumigant toxicity against three mosquito species, Anopheles gambiae, Culex quinquefasciatus and Aedes aegypti. The essential oil had pronounced mosquitocidal activity with LD50 of 1.0, 1.2 and 1.7 x 10(-3) mg/cm(-3), respectively, for the three vector species. Furthermore, the major sesquiterpenes were tested at different doses, which again showed varying levels of toxicity. However, germacrene D performed better and proved to be the potential candidate with LD50 values of 1.8-2.8 x 10(-3) mg/cm(-3) followed by pregeijerene and geijerene. Nevertheless, the oil and the isolated compounds were particularly active against A. gambiae. The essential oil from the leaves was obtained by hydrodistillation, and the chemical composition was determined by GC and GC-MS. The main compounds identified were limonene, germacrene D, geijerene, pregeijerene, trans-beta-ocimene and methyl eugenol. The present study indicates that the oil and the isolated compounds of C. swietenia displayed remarkable mosquitocidal activity suggesting that the method could be extended for future field trials in various mosquito control programmes, and the results are compared with synthetic insecticides.

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Background: Pharmacognostic study of medicinal plants is an important parameter for standardization and authentication of plants, with the help of which adulteration and substitution can be prevented. The present study deals with pharmacognostic profile of leaf of Bridelia scandens (Roxb).Willd. an important traditional plant, belonging to family Euphorbiaceae used to treat various ailments. Methods: The present study includes macroscopic and microscopic studies, quantitative microscopy, and physiochemical characters such as ash value, extractive values, fluorescence analysis, and total phenol and flavonoid content. Results: Macroscopically, the leaves are B. scandens are elliptic –oblong or obavate, dark green above, pale green below lateral veins. Microscopically, leaf consists of thick semicircular midrib and the lamina, cortical zone ending with thick continuous cylinder of sclerenchyma cells. Sclerenchyma cylinder completely enclosed the vascular cylinder of the midrib, consists of only continuous thick layer of phloem. Xylem cylinder consists of numerous short or long radial chains of vessels. The lateral vein is flat on the adaxial side and prominently projecting hemispherical body on the adaxial side. Powder microscopy of leaf revealed the presence of spiral xylem vessels, rosette and prismatic calcium oxalate crystals and trichomes. A Physiochemical characteristic was also determined. Conclusion: Existing literature revealed that so far, no Pharmacognostic study has been reported on the leaf of B. scandens. Findings from this investigation can be used for its identification and determination of quality and purity of medicinally important plant. Thus exploring the usefulness of pharmacognostic evaluation to validate and authenticate drug