J. Kiviranta

Bioactivity of certain Egyptian Ficus species

The fruit extracts of Ficus sycomorus L., F. benjamina L., F. bengalensis L. and F. religiosa L. were screened for bioactivity. F. bengalensis and F. religiosa demonstrated activity in the brine shrimp test (Artemia salina) which indicates toxicity, whereas F. sycomorus and F. benjamina showed no activity. All the fruit extracts exhibited antitumor activity in the potato disc bioassay. None of the tested extracts showed any marked inhibition on the uptake of calcium into rat pituitary cells GH4C1. The extracts of the four tested Ficus species had significant antibacterial activity, but no antifungal activity. The results of this preliminary investigation support the traditional use of these plants in folk medicine for respiratory disorders and certain skin diseases.

Structure determination and toxicity of a new microcystin from Microcystis aeruginosa strain 205

A new hepatotoxic microcystin was isolated from the cyanobacterium Microcystis aeruginosa strain 205. Its structure was found to be [Dha7]microcystin-RR as determined by amino acid analysis, mass spectrometry and 1H NMR spectroscopy. LD50 value (i.p. mouse) of this toxin was 180 micrograms/kg. The 48 hr lethal concentration (48-hr-LC50) of the toxin for larvae of the yellow fever mosquito, Aedes aegypti, was 14.9 micrograms/ml.

Insecticidal compounds against mosquito larvae fromOscillatoria agardhii strain 27

It was found that Oscillatoria agardhii strain 27 produced compounds toxic against mosquito larvae (Aedes albopictus), therefore, these compounds were extracted and separated for insecticide development. Structural characterization of the toxic fraction by 1H‐NMR and GC‐MS showed that these compounds are not the neurotoxins or hepatotoxins conventionally produced by Oscillatoria, but it contained a mixture of unsaturated fatty acids, oleic, linoleic, and γ‐linolenic acids, as well as saturated fatty acids, myristic, palmitic, and stearic acids. In a bioassay developed for these hydrophobic compounds using mosquito larvae, authentic unsaturated fatty acids were shown to be toxic, whereas saturated ones were not active. The results suggested that it might be possible to use unsaturated fatty acids as environmentally safe and effective insecticides without the side effects of the chemically synthesized insecticides. © 2000 John Wiley & Sons, Inc. Environ Toxicol 15: 114–119, 2000

Volatile constituents of wild and in vitro cultivated Gloeophyllum odoratum

The brown-rot fungus Gloeophyllum odoratum was collected from spruce stumps in southern Finland. The volatiles in the fruiting body and fungal cultures grown in malt extract and liquid medium were investigated. Chitin, chitosan and D-(+)-glucosamine at a concentration of 450 mgl-1 medium were used as elicitors. Chitosan completely inhibited growth in the solid medium. The main volatile(s) according to GC and GC-MS analysis were either linalool, citronellol, geraniol and methyl p-methoxyphenylacetate or drimenol depending on the culture type and elicitor. The composition of volatiles in the natural fungus differed slightly from that of the cultivated fungus since the major compound was methyl p-methoxyphenylacetate. The volatile oils were toxic to larvae of the brine shrimp, Artemia salina, indicating that they may possess insecticidal and cytotoxic activity.

Algae in mosquito breeding sites and the effectiveness of the mosquito larvicide Bacillus thuringiensis H-14

The presence of cyanobacteria generally decreased the effectiveness of Bacillus thuringiensis H-14 (BTI) as a mosquito larvicide. The effect was more pronounced when the mosquito larvae were exposed to BTI in the presence of several cyanobacterial strains. No synergistic or antagonistic effect between the δ-endotoxin from BTI and the hepatotoxin from cyanobacteria was seen. Neurotoxic cyanobacterial strains caused very fast paralysis in mosquito larvae; the decreases in the effectiveness of BTI when tested in combination with a neurotoxic strain might be due to the effect of this paralytic action on the feeding rate of the mosquito larvae.