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| Author(s): |
Elma Regina Silva de Andrade
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2002-08-12 |
| Examining board members: |
Ursula Maria Lanfer Marquez;
Maria da Pureza Spínola Miranda;
Fernando Salvador Moreno
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| Advisor: | Ursula Maria Lanfer Marquez |
| Abstract | |
The biological effects of S-methyl-cysteine (SMC) and the peptide γ-glutamyl-cysteine (γ-Glu-SMC), distributed in some edible legume seeds, mainly in common bean (Phaseolus vulgaris L.), are controversial when these compounds are ingested by laboratory animals and humans. In the present study it was investigated the rate of intestinal absorption of SMC and γ-Glu-SMC employing isolated segments of rat intestines and analyzing comparatively the absorption of protein amino acids. The everted segments of duodenum and jejunum were incubated in a nutritive solution and the aminoacids SMC, Phe and Met and the peptide γ-Glu-SMC were added individually in order to measure their absorption rates in intervals of 10 min until reaching 60 minutes of incubation. The absorption rate of each compound was measured by ion exchange chromatography (amino acid analyzer). The absorption rates observed for SMC were higher than those observed for Met and Phe. The same samples were also analyzed by reversed phase-HPLC after derivatization with o-phthalaldehyde (Gustine,.1985). Results did not succeed because the chromatographic column lost efficiency probably due to adsorption of byproducts of the derivatization reaction. We suggest that modifications on the analytical protocol should be developed. Results showed that the peptide γ-Glu-SMC seem to be hydrolyzed supported by the appearance of small amounts of free SMC on the serosal side of the intestines. The hydrolysis was probably catalyzed by the enzyme γ-glutamyltranspeptidase (γ-GT). The appearance of only small amounts of free SMC could be explained by an eventual loss of the activity of γ-GT during preparation and incubation of the intestinal segments. However, in additional assays, the enzyme did not show any loss of activity during incubation of the segments for 40 min. We observed also that the activity of the enzyme γ-GT was 3 times higher in duodenum than in jejunum. This observation could be relevant for absorption studies employing intestinal segments. Further studies are necessary for a better understanding of the absorption process of the peptide γ-Glu-SMC. (AU) | |