Abstract: The invention relates to a neuroactive substance which is characterised in that it has formula (O), wherein R1, R2, R3 and R4 are identical or different and are methyl or ethyl radicals. Preferably, the neuroactive substance comprises 6S-acetyl-4R,5R-dimethyl-1R(10S)-epoxy-2R-hy-droxy-7R-acetoxydecahydro naphthalene which can be isolated from Rhytisma fulvum cnidaria. The inventive neuroactive substance can be used as a pharmacological reagent in research work and is also suitable for use in the fields of industry (insecticides) and health.

Abstract: The invention relates to a neuroactive substance which is characterised in that it has formula (O), wherein R1, R2, R3 and R4 are identical or different and are methyl or ethyl radicals. Preferably, the neuroactive substance comprises 6S-acetyl-4R,5R-dimethyl-1R(10S)-epoxy-2R-hy-droxy-7R-acetoxydecahydro naphthalene which can be isolated from Rhytisma fulvum cnidaria. The inventive neuroactive substance can be used as a pharmacological reagent in research work and is also suitable for use in the fields of industry (insecticides) and health.

Abstract: Bistramide derivatives with virtually no toxic effects, of formula (I) wherein --R.sub.1, X, Y and R.sub.2 are a saturated or unsaturated hydrocarbonaceous chain having from 1 to 20 carbon atoms, substituted by at least one --OH group and/or a ketone function, including, if need be, at least one ring (a), the ring including one more unsaturations; --R.sub.3, R.sub.4 and R.sub.5 are the same or different and are selected from hydrogen, alkyl or alkoxy radicals having from 1 to 4 carbon atoms, a group --COOH, --OH, --NH or --NO.sub.2, or a halogen atom. The invention also concern bistramide derivatives of formula (I) such as ethers or esters and their isomers, excluding A, B and C bistramides. Said bistramides are useful especially as drugs having a cytostatic effect, in particular as antitumour or anti-parasitic drugs.