sinigrin and Autolysis

Aqueous Brussels sprouts extracts inhibit oxidation of isolated DNA in vitro, possibly through scavenging oxygen radicals. We have studied the effect of preincubating human lymphocytes with aqueous extracts of raw, cooked and autolysed Brussels sprouts and the glucosinolate, sinigrin, on hydrogen peroxide-induced DNA damage, strand breaks and base oxidation, in vitro by means of the Comet assay. DNA repair enzymes endonuclease III (EndoIII) and formamidopyrimidine-DNA glycosylase (FPG) were used to examine the levels of oxidised pyrimidines and purines in DNA, respectively. Aqueous extracts of cooked and autolysed Brussels sprouts and sinigrin decreased DNA strand breaks in human lymphocytes exposed to 100 microM H2O2 for 5 min on ice, although the level of EndoIII and FPG sensitive sites was not reduced. The maximum inhibition was by 38 and 39% at concentrations of cooked and autolysed extracts of 10 microg/ml and 5 microg/ml, respectively, whereas the inhibitory effect decreased with increasing concentrations up to 100 microg/ml. The maximum inhibition by sinigrin was by 54% at 2 microg/ml. Extracts of raw Brussels sprouts or green beans had no DNA-protective effect. The results indicate that compounds, including sinigrin, in cooked and autolysed Brussels sprouts can enhance lymphocyte resistance towards H2O2-induced DNA strand breaks in vitro.

Topics: Autolysis; Brassica; Comet Assay; Deoxyribonuclease (Pyrimidine Dimer); DNA Damage; DNA Repair; DNA-Formamidopyrimidine Glycosylase; Dose-Response Relationship, Drug; Endodeoxyribonucleases; Escherichia coli Proteins; Free Radical Scavengers; Glucosinolates; Humans; Hydrogen Peroxide; Lymphocytes; N-Glycosyl Hydrolases; Oxidation-Reduction; Plant Extracts; Quercetin

Meal prepared from unheated rapeseed (Brassica napus cv. Zephyr) showed the presence of t,iocyanate ion, while meal from heated seed of the same cultivar did not show detectable amounts. Unheated seed meal on autolysis, and heated seed meal on incubation with thioglucosidase, yielded increased amounts of thiocyanate ion. Various commercial rapeseed meals showed the presence of t,iocyanate ion only after enzyme incubation. Low glucosinolate, cv. Bronowski, and higher glucosinolate, cv. Zephyr on enzymic incubation yielded comparable amounts of thiocyanate ion, suggesting that the precursor responsible in the two varieties was the same and present in similar quantities. No formation of thiocyanate ion was observed on incubation of sinigrin with thioglucosidase. Rats dosed with heated meal, containing intact glucosinolate, showed a slight increase of thiocyanate ion in the urine as compared with control rats dosed with water, while a relatively large increase followed dosing with sinigrin. Rats dosed with meal containing free thiocyanate ion excreted the ingested thiocyanate ion almost quantitatively.

Topics: Animal Feed; Animals; Autolysis; Glucosinolates; Glycoside Hydrolases; Hot Temperature; Male; Rats; Seeds; Species Specificity; Thiocyanates; Thioglucosides; Thioglycosides