Sesamolinol glucoside, disaminyl ether, and other lignans from sesame seeds.

The application of a procedure based on XAD-4 adsorption resin permitted the obtainment of an enriched polyphenolic extract from Sesamum indicum seeds. Chemical analysis of the obtained extract led to the identification of 12 lignans. Among them, 2 lignans, (+)-sesamolinol-4'-O-ß-D-glucoside and disaminyl ether, are reported for the first time as natural compounds. Their structure has been determined by spectroscopic methods, mainly by the application of one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) techniques [heteronuclear multiple-quantum coherence (HMQC), heteronuclear multiple-bond correlation (HMBC), and nuclear Overhauser effect spectrometry (NOESY)] and mass spectroscopy. The isolated compounds were evaluated for their antimutagenic activity. Among the tested lignans, the most active lignan was found to be sesamolin, followed by sesamolinol and samin, against H(2)O(2). Additionally, some of the tested lignans showed desmutagenic activity against benzo[a]pyrene (BaP).

Effect of the form of the sesame-based diet on the absorption of lignans.

The effect of different forms of sesame-based diets on the concentration of plasma lignans was assayed by estimating the levels of certain lignans (sesame lignans and enterolignans) in the plasma of experimental animals. In a series of experiments, male Wistar rats were fed either a raw sesame-enriched diet or a tahini-enriched diet. The plasma concentration of the lignans (sesame lignans and enterolignans) was determined at various time intervals over a 24 h period after a single administration. Enterodiol and enterolactone concentration in the tahini-treated group was significantly higher than in the raw sesame-treated group. In another series of experiments, male Wistar rats were fed, for 15 d, diets enriched in raw dehulled sesame, sesame perisperm, sesame oil, tahini and a polyphenolic extract derived from the seed perisperm. Enterodiol and enterolactone plasma concentration was high in the case of the sesame perisperm in spite of its low concentration in the assessed sesame lignans. Overall, the levels of the sesame lignans and enterolignans present in plasma seem to be influenced not only by the amount of lignan intake but also by other factors such as the form of the sesame-based diet.

Structural destabilization of the recombinant thermophilic TthL11 ribosomal protein by a single amino acid substitution.

Thermus thermophilus L11 protein has previously been reported to be resistant against tryptic and chymotryptic proteolysis under native conditions. With a single amino acid substitution, namely Trp101Arg, conformational changes were induced that resulted in the exhibition of specific amino acids that served as targets for tryptic and chymotryptic action and rendered the protein highly unstable even during purification. This unexpected process was evidenced by the isolation with size exclusion gel chromatography of the well-structured chymotryptic N-terminal domain in a high amount and its characterization both by Edman degradation and QTOF-EMS spectroscopy. On the other hand, the substitution of Val38Cys, which did not contribute to structural changes, indicates a very possible implication of this amino acid in the protein methylation process. The data reported in this work illustrate the distinctive amino acid dynamics in a thermophilic protein, which, while serving the function common to its counterparts from mesophilic organisms, has had to adapt to the extreme environmental conditions typical of thermophilic organisms.