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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.

Three extraction methods were compared for their efficiency to analyze sitagliptin and simvastatin in rat plasma by LC–MS/MS, including (1) liquid–liquid extraction (LLE), (2) solid phase extraction (SPE) and (3) supported liquid extraction (SLE). Comparison of recoveries of analytes with different extraction methods revealed that SLE was the best extraction method. The detection was facilitated with ion trap-mass spectrometer by multiple reactions monitoring (MRM) in a positive ion mode with ESI. The transitions monitored were m/z 441.1→325.2 for simvastatin, 408.2→235.1 for sitagliptin and 278.1→260.1 for the IS. The lower limit of quantification (LLOQ) was 0.2 ng/mL for sitagliptin and 0.1 ng/mL for simvastatin. The effective SLE offers enhanced chromatographic selectivity, thus facilitating the potential utility of the method for routine analysis of biological samples along with pharmacokinetic studies.

Conjugated trienoic FA-α-eleostearic, β-eleostearic, and punicic acids-were preferentially isolated in pure form from the total methyl esters of the respective oils by simple silica gel TLC using hexane/diethyl ether as the mobile phase (94:6). The subsequent saponification of the separated methyl ester fractions upon cooling at -20°C yielded individual acids in crystalline form. Melting points, conventional UV spectroscopy, and GLC confirmed the identity of the conjugated trienoic FA. The method finds potential application in benchscale reaction optimization using pure FA and in the preparation of standard reference materials of these acids, as these oils are widely used in the coatings industry.Paper no. J10335 in JAOCS 80, 315-318 (April 2003).Conjugated trienoic FA such as α-eleostearic, punicic and licanic acids are an industrially important group of compounds found in vegetable oils. They are not very common in yeasts, bacteria, fish oil, or animal fats, but conjugated dienoic, trienoic, and tetraenoic FA and their oxygenated derivatives are encountered in various seed oils in abundance (1-3). The oils containing these FA are very important raw materials in the manufacture of organic coatings and polymers (4-7), as the conjugated unsaturation facilitates good polymerization and imparts adhesive properties when properly treated. As these acids are heat and light sensitive, they cannot be stored for long times and thus standard reference materials are difficult to procure. The isolation and purification of conjugated acids were effected by the crystallization technique devised by earlier workers (8). Silver-ion TLC was used to achieve separation of conjugated esters from other esters (9). Also, the separation of positional and geometrical isomers was facilitated by HPLC by using the silver-ion mode again (10). Further, the characterization of hydroxy eicosatetraenoic acids and conjugated dienes was carried out by a UV spectroscopic method (11). The analysis of carotenoids using nonaqueous reversed-phase HPLC with photodiode array (PDA) detection was accomplished by Tan et al. (12). However, isolation by direct silica gel TLC has not been reported before for the enrichment of α-eleostearate.Four varieties of bittergourd [Momordica charantia: varieties, Long Green Monsoon, Summer Crop (S.C), Coimbatore Long (C.L), and Local] and one variety of snake gourd (Trichosanthus anguina) were studied in our laboratory for the content of conjugated FA in the respective seed oils, and different analytical methods were used for identification and quantification. Interestingly, simple TLC yielded very useful results because the methyl esters of the above oils, when separated by TLC using normal silica gel plates, presented wellresolved bands accounting for approximately 96% of conjugated trienoic FA of any geometrical configuration. We first attempted to isolate α-eleostearate in clean form by using hexane/ether (94:6) as the mobile phase system to monitor the biosynthetic pathway of conjugated FA (13). We extended this wor...