44E-9 |
Antioxidant activities of selected Allium thiosufinates |
H. XIAO and K. L. Parkin. Dept. of Food Science, Univ. of Wisconsin, Madison, 1605 Linden Dr., Rm. A109A, Madison, WI 53706 A long list of health-promoting and bioactive effects have been ascribed to organosulfur components of tissue preparations from members of the Genus Allium. Antioxidant activities of Allium tissue extracts have been attributed to thiosulfinates (TS), such as allicin in garlic, even though many other endogenous components may have antioxidant potential. The objective of the study was to determine the capacity of three pure thiosulfinates (representative of Alliums) for scavenging the oxidative species: superoxide anion (O2-·), hydrogen peroxide (H2O2), hydroxyl radical (·OH), singlet oxygen (1O2) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. Pure methyl methaneTS (MMTS), propyl propaneTS (PPTS), and 2-propenyl 2-propeneTS (allicin) were prepared from the corresponding S-alk(en)yl-L-cysteine sulfoxide using a crude onion alliinase. The antioxidant properties of TS were investigated in systems containing or generating O2-·, ·OH, 1O2, H2O2 and DPPH radical, and compared to those of standard antioxidants (BHT, n-propyl-gallate, L-ascorbic acid, Trolox and reduced glutathione). All three TS species were similarly capable of scavenging ·OH and had antioxidant strengths slightly stronger than that of n-propyl-gallate, Trolox and glutathione. Allicin and PPTS were capable of scavenging 1O2. Allicin was up to 3-fold stronger than PPTS, while there was no scavenging activity of MMTS. All three TS could scavenge DPPH radical, with an order of effectiveness of: MMTS » PPTS < allicin. However, standard antioxidants were much better at scavenging DPPH radical (78-680-fold) than were the TS. Scavenging effects of all tested compounds and for all oxidative species behaved in a concentration-dependent manner. TS were not capable of scavenging either O2-· or H2O2. TS were effective agents for scavenging ·OH, and this may account for some of the bioactive properties observed for TS. However, since TS did not exhibit broad-spectrum antioxidant activities, other mechanisms may also be responsible for their action in biological systems.
Session 44E, Nutraceuticals & Functional Foods
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