No abstract

Ethanol extract of leaves of Poa ampla, either infected or uninfected with the symbiotic fungus Neotyphodium typhnium, were tested for bioactivity against the mosquito larvae. Results of these tests indicated that only the extracts obtained from endophyte-infected grass are active against mosquito larvae. Relatively high activity was detected in stromata, seeds, spikelets, and leaves of plants, while only weak or no activity was found in extracts of the isolated fungus. The ethyl acetate fraction had approximately the same activity as that of the crude extract, while the activities from 1-butanol and hexane were intermediate and low, respectively. Bioassay-guided fractionation of the ethyl acetate fraction yielded tricin (1), 7-O-(β-d-glucopyranosyl)tricin (2), and isoorientin (3) as the bioactive constitutents. A fourth compound, 7-O-[α-l-rhamnopyranosyl(1−6)−β-d-glucopyranosyl]tricin (4), was also isolated from the active fraction but showed little activity in this assay. Keywords: Poa ampla; turf; endophyte; Neotyphodium typhnium; insecticidal properties; bioactivity; flavonoid; flavonoid−glycoside

Four pyranocoumarins; dipetaline, alloxanthoxyletin, xanthoxyletin and xanthyletin; and two lignans; sesamin and asarinin were isolated from the northern prickly ash, Zanthoxylum americanum. To varying degrees, all inhibited the incorporation of tritiated thymidine into human leukaemia (HL-60) cells. Dipetaline was the most active with an IC(50) of 0.68 ppm, followed by alloxanthoxyletin (1.31 ppm), sesamin (2.71 ppm), asarinin (4.12 ppm), xanthoxyletin (3.48 ppm) and xanthylletin (3.84 ppm).

Alcoholic extracts of leaves and stems of Vanilla fragrans were fractionated with ethyl acetate and aqueous butanol. All three fractions of ethyl acetate, butanol, and water were screened for toxic bioactivity against mosquito larvae. The results of these experiments showed that the fractions from the ethyl acetate and butanol phases were both active in the bioassay. Bioactivity of the ethyl acetate fraction was found to be much greater than that from the butanol fraction in mosquito larvae toxicity. The water phase appeared to contain no substances that impaired mosquito larval growth. Repeated column chromatography of the ethyl acetate fraction on silica gel led to the isolation of 4-ethoxymethylphenol (1), 4-butoxymethylphenol (2), vanillin (3), 4-hydroxy-2-methoxycinnamaldehyde (4), and 3,4-dihydroxyphenylacetic acid (5). Compounds 4 and 5 were isolated from Vanilla species for the first time and 2 has not been reported to have been found in a natural form. 4-Ethoxymethylphenol (1) was the predominant compound, but 4-butoxymethylphenol (2) showed the strongest toxicity to mosquito larvae. The structures of the compounds were determined on the basis of their mass spectra and (1)H or (13)C NMR data.