Acute toxic effects of 8-epidiosbulbin E, a 19-norclerodane diterpene from yam Dioscorea antaly, on medaka Oryzias latipes embryos.

The fractionation of an aqueous extract of yam Dioscorea antaly from Madagascar led to the isolation of terpenoids and flavonoids. Compounds were identified on the basis of modern mass spectrometry and two-dimensional nuclear magnetic resonance (2D-NMR). Toxicological effects of the most abundant isolated compound, 8-epidiosbulbin E were studied on medaka Oryzias latipes embryo-larval development. The lethal concentration (killing 50%; LC(50) ) to embryos treated 24 h before hatching and for 3 days after hatching was estimated to be 0·56 mg ml(-1) (P< 0·05). No mortality was observed with O. latipes larvae exposed after hatching until day 4. Anatomo-pathological studies of embryos exposed to 0·56 mg ml(-1) showed development anomalies of the central nervous system, liver, muscle and intestine. The present data thus extend the model of O. latipes embryos as a useful animal model to analyse the effects of food toxins.

Natural occurrence of methionine sulfoximine in the Connaraceae family.

The toxic principle of Cnestis glabra, identified as methionine sulfoximine has been found as a permanent constituent of the soluble amino acid pool of this plant. In the roots the toxin concentration varies markedly according to the developmental stage of the plant. The poisonous principles of Cnestis polyphylla and Rourea orientalis, two other Connaraceae species, were purified to homogeneity. Similarity of their physiochemical and biological properties, their behaviour in thin-layer and gas chromatographies and their infrared spectra to those of the toxin of Cnestis glabra established their identity to methionine sulfoximine. This methionine derivative, never reported as a natural product, seems to be characteristic of toxic Connaraceae species.

Isolation and partial characterization of glabrin, a neurotoxin from Cnestis glabra (Connaraceae) root barks.

A neurotoxic compound, inhibiting protein synthesis in cell culture, was isolated in a yield of about 0.4 per cent from Cnestis glabra root barks (Connaraceae) by a five-step fractionation procedure (filtration on activated charcoal, treatment by neutral lead acetate and fractionations on Dowex 50 X 8 in H+ and NH+4 forms). The purified toxin appeared homogeneous on thin-layer and in gas chromatography. The compound has a low molecular weight (less than 500). It is heat-stable, insoluble in usual organic solvents and gives a positive reaction with ninhydrin. Acidic hydrolysis does not change its behaviour on an amino acid analyzer. Its possible amino acid nature is discussed. It is temporarily named glabrin.

[Demonstration and partial purification of a convulsant from Cnestis glabra (Connaracea): effect on cells in culture]. / Mise en évidence et purification partielle d'un convulsivant à partir de Cnestis glabra (Connaracées): effet sur des cellules en culture.

A dialysable and thermostable compound was partially purified from Cnestis glabra (Connaracea) seeds. It is insoluble in organic solvents. At a dose corresponding to 0.5 g of seeds it has a lethal effect on mice after convulsive attacks. Sodium dipropylacetate, an anticonvulsive agent prevents the convulsions but not the death of the animals. The toxic compound inhibits protein synthesis in a rabbit reticulocyte lysate and in hepatoma tissue culture; moreover in the cell culture, the incorporation of thymidine into DNA is inhibited.

Pleiotropic control mutations affecting the sporulation of Bacillus subtilis.

Mutations affecting quantitatively the production of the sporulation-associated extracellular alkaline protease were isolated and characterized. They fall into at least five genes, three of which, ScoA, B and C, were mapped in the argC-metC region. The pleiotropic effects of these mutations concern several or all of the following: rate and timing of protease production, synthesis of alkaline phosphatase, time-course of spore formation. Electron microscopic evidence indicates delayed switch from one morphological stage to another. The nature of the Sco mutations and the genetic regulation of sporulation are discussed.