Mosquitocidal activity of acetylenic compounds from Cryptotaenia canadensis

As part of an on-going program to identify natural products from plants wit h mosquitocidal activity, two acetylenic compounds were isolated from Crypt otaenia canadensis, a native North American umbellifer frequently encounter ed in moist woodlands. Fresh foliage, roots, and fruits were extracted with a hot methanol and water mixture and then dried. The extract was partition ed into chloroform and water, and both phases were bioassayed against fourt h instars of Culex pipiens at concentrations between 5 and 50 ppm. Only the organic phase was active. Gas-liquid chromatography revealed that the two main components of the organic phase were polyacetylenes. The compounds wer e isolated by vacuum chromatography on silica gel and identified as falcari nol and falcarindiol based on GC-MS-EI and GC-MS-CI fragmentation patterns, high-resolution MS, and H-1 and C-13 NMR spectrometric data. The dose-resp onse curves with mosquito larvae were determined by probit analysis. The LC 50 values were 3.5 ppm for falcarinol and 6.5 ppm for falcarindiol. The dis tribution of polyacetylenes varied among plant parts. Fruits contained an u nknown compound not found in either the foliage or roots.