The repellent properties of different fractions isolated from Lantana camara flowers by using steam distillation, solvent partition and chromatographic methods were evaluated against Aedes mosquitoes. Maximum protection time of one fraction eluted by chloroform from a silica gel column was 3.45 h. One application of this fraction gave 100% protection for 2 h and may protect 75.8% at 7 h (t ¼ 7.00, P < 0.001) against the bites of Aedes mosquitoes. Further purification of the most efficient fraction into pure compounds did not result in any increase in repellency.

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The diversity and density of methanogenic archaea and methane production were investigated ex situ at different growth stages of rice plant cultivated in compost-treated tropical rice fields. The qPCR analysis revealed variation in methanogens population from 3.40 × 10(6) to 1.11 × 10(7)  copies g(-1)  dws, in the year 2009 and 4.37 × 10(6) to 1.36 × 10(7)  copies g(-1)  dws in the year 2010. Apart from methanogens, a large number of bacterial (9.60 × 10(9) -1.44 × 10(10)  copies g(-1)  dws) and archaeal (7.13 × 10(7) -3.02 × 10(8)  copies g(-1)  dws) communities were also associated with methanogenesis. Methanogen population size varied in the order: flowering > ripening > tillering > postharvest > preplantation stage. The RFLP-based 16S rRNA gene-targeted phylogenetic analysis showed that clones were closely related to diverse group of methanogens comprising members of Methanomicrobiaceae, Methanosarcinaceae, Methanosaetaceae and RC I. Laboratory incubation studies revealed higher amount of cumulative CH(4) at the flowering stage. The integration of methanogenic community structure and CH(4) production potential of soil resulted in a better understanding of the dynamics of CH(4) production in organically treated rice-field soil. The hypothesis that the stages of plant development influence the methanogenic community structure leading to temporal variation in the CH(4) production has been successfully tested.

From the roots of VERNONIA CINEREA Less. (Compositae) a new triterpenoid has been isolated and characterised as 3beta-acetoxyurs-19-ene ( 1). A further constituent has been identified as lupeol acetate. Structure elucidation has been made with the help of spectral analyses.

Cassia, a large genus of the Leguminosae, contains four sections. The section Fistula possesses 28 tropical trees, and six of these are represented in the Indian flora. Phytochemical investigations reveal that all six of these species contain kaempferol and a mixture of anthraquinones (chrysophanol, rhein, and physcion). Rhein is absent from many other Cassia species. EXPERIMENTALPlant materials and ISOLATION.-Leaves were collected from the Horticultural Research Institute, Saharanpur (India), shade-dried, and extracted with EtOH. Extracts after concentration at reduced pressure (temperature below 40°) were saponified, chromatographed, and analyzed for anthraquinones and