Constituents of aromatic plants: teucrin A.

Teucrium chamaedrys L. (Labiatae), a herb used to combat obesity, can occasionally cause hepatitis. All mutagenicity tests done were negative. After 13 weeks of administration by oral route in Sprague Dawley rats T. chamaedrys proved to be well tolerated at 0.056 g kg(-1) day(-1) (i.e. 0.4 mg kg(-1) day(-1) of teucrin A). At this dose the compound induced minor effects on body weight of both males and females and slight, reversible liver changes, confined to females, which mainly consisted of hepatocellular hypertrophy. This modification, in absence of other morphological findings can be considered an adaptative metabolic, rather than toxic effect.

Constituents of aromatic plants: eucalyptol.

The subacute toxicity studies reported up to now in rats and mice suggested that mice were less susceptible than rats to the toxicity of eucalyptol. In fact, after gavage, it was found toxic in male rats at doses higher than 600 mg/kg while no effect was seen in mice up to 1200 mg/kg. However, the limitations and the quality of the study do not allow the extrapolation of a 'no effect level'. Several reports in rat and brushtail possum show the formation of hydroxylated bicycled products of eucalyptol as main metabolites. Moreover, metabolites which require ring opening have been also detected. Following the accidental exposure of human beings, death was reported in two cases after ingestion of 3.5-5 ml of essential eucalyptus oil, but a number of recoveries have also been described for much higher amounts of oil.

Constituents of aromatic plants: II. Estragole.

Estragole (ES) is a natural constituent of a number of plants (e.g. tarragon, sweet basil and sweet fennel) and their essential oils have been widely used in foodstuffs as flavouring agents. Several studies with oral, i.p. or s.c. administration to CD-1 and B6C3F1 mice have shown the carcinogenicity of ES. The 1-hydroxy metabolites are stronger hepatocarcinogens than the parent compound. Controversial results are reported for the mutagenicity of ES. However, the formation of hepatic DNA adducts in vivo and in vitro by metabolites of ES has been demonstrated.

Agglutinating activity of wheat gliadin peptide fractions in coeliac disease.

The K 562 (S) cell agglutinating activity of peptides obtained from in vitro digestion of bread wheat gliadins has been shown to be associated with a small fraction (coded as Fraction C), that can be easily separated by affinity chromatography of the whole digest on a sepharose 6-B-mannan or sepharose 6-B-oligomers of N-acetyl-glucosamine. Although the whole gliadin digests from 12 durum wheat varieties were unable to agglutinate K 562 (S) cells, all these digests were found to contain an active Fraction C. The lack of agglutinating activity of the whole durum wheat gliadin digests has been shown to be associated with the presence in these digests of another peptide fraction (coded as Fraction B) that is eluted much earlier from the sepharose 6-B-mannan column and is able to inhibit the cell agglutinating activity of Fraction C. Such an active Fraction B is not present in bread wheat gliadin peptides, although peptides with the same elution profile as Fraction B have been detected.

Effect of alpha-gliadin-derived peptides from bread and durum wheat on K562(S) cells.

Previous studies suggested that the proteins and peptides that are responsible for coeliac small intestinal lesions, are also able to agglutinate K562(S) cells. On the contrary, peptides from whole gliadins from durum (tetraploid) wheat do not agglutinate these cells. Bread wheat alpha-gliadins have been identified as a major toxic fraction in coeliac disease. In the present research, alpha-gliadins were purified from durum and bread wheat cultivars. alpha-gliadin peptides from bread wheat were active in agglutinating K562(S) cells, whereas alpha-gliadin from durum wheat failed to induce any agglutinating activity. These results suggest that the lack of toxicity of gliadin from durum wheat cultivars is not related to a low content of alpha-gliadins but is mainly due to intrinsic structural differences from bread wheat gliadins.