M. Silano

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.

31-43 Amino Acid Sequence of the a-Gliadin Induces Anti-Endomysial Antibody Production during in Vitro Challenge

BACKGROUND Wheat gliadin is the culprit antigen of coeliac disease (CD). Two short sequences of NH2-terminal portion of gliadin seem to be responsible for CD. Antiendomysial antibodies (EMA), highly sensitive and specific for CD, are detectable in the culture media from treated CD patients, after in vitro challenge with peptic-tryptic (PT) digest of gliadin. In this study we detected EMA production after in vitro challenge with 31-43 peptide. We used 56-68 peptide, lacking toxic sequences, as a negative control. METHODS Duodenal samples from 11 treated CD patients and 9 control patients were cultured with 31-43 and 56-68 peptides and PT gliadin. Indirect immunofluorescence analysis was used for EMA detection. RESULTS EMA were detected in culture media of 10 of 11 specimens challenged with PT-gliadin and in the media of all specimens challenged with 31-43 peptide. No EMA were detectable in any treated patients cultured with 56-68 peptide or with medium alone. No EMA were observed in cultures of control specimens. DISCUSSION The ability of the 31-43 sequence of the alpha-gliadin to induce EMA production suggests its involvement in the pathogenesis of CD. Furthermore, it may be a more useful antigenic substance than PT gliadin for both in vitro and in vivo studies of CD.

Constituents of aromatic plants: I. Methyleugenol

Methyleugenol (ME) is a natural constituent of the essential oils of a number of plants widely used in foodstuffs as flavouring agents. Its occurrence, routes of intake, and available information on toxicity, kinetics and metabolism are reviewed. In view of the carcinogenic potential of ME, the need to check its presence in food products with effective analytical methods is pointed out.

In vitro screening of food peptides toxic for coeliac and other gluten-sensitive patients: a review

Experience gained through investigations on coeliac disease makes it possible to propose a screening method based on agglutination of isolated K562(S) cells to evaluate the occurrence in food protein of amino acid sequences that are able to adversely affect coeliac and related gluten-sensitive patients. The method consists of in vitro sequential peptic and tryptic digestion of food protein fractions under optimal pH, temperature and time conditions and in vitro incubation of the digest with K562(S) cells; the toxic potential is detected as an agglutination of K 562 (S) cells after a short incubation. Other in vitro test systems, including atrophic coeliac intestinal mucosa and rat fetal intestine, can be used to confirm the results obtained with the isolated cells. A fractionation step of the proteolytic digest on a sepharose-mannan column before exposure of the in vitro systems to the separated peptide fractions adds to the sensitivity of the method. This screening method is not only very useful to investigate action mechanisms in coeliac disease, but also to assess the safety of genetically-modified plant foods and novel foods for gluten-sensitive patients.

Agglutinating activity of alcohol-soluble proteins from quinoa seed flour in celiac disease

The edible seeds of the quinoa plant contain small quantities of alcohol-soluble protein which, after peptic-tryptic digestion, are unable to agglutinate K562(s) cells. When separated by affinity chromatography on sepharose-6B coupled with mannan, peptic-tryptic digest separated in two fractions. Fraction B peptides (about 1% of total protein) were shown to agglutinate K562(s) cells at a very low concentration, whereas peptides in fraction A and in the mixed fraction A+B were inactive, suggesting that fraction A contains protective peptides that interfere with the agglutinating activity of toxic peptides in fraction B.

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.