| Abstract
| - Cyclooxygenase and human tumor cell growth inhibitory extracts of horseradish (Armoracia rusticana)and wasabi (Wasabia japonica) rhizomes upon purification yielded active compounds 1−3 fromhorseradish and 4 and 5 from wasabi rhizomes. Spectroscopic analyses confirmed the identities ofthese active compounds as plastoquinone-9 (1), 6-O-acyl-β-d-glucosyl-β-sitosterol (2), 1,2-dilinolenoyl-3-galactosylglycerol (3), linolenoyloleoyl-3-β-galactosylglycerol (4), and 1,2-dipalmitoyl-3-β-galactosylglycerol (5). 3-Acyl-sitosterols, sinigrin, gluconasturtiin, and phosphatidylcholines isolated fromhorseradish and α-tocopherol and ubiquinone-10 from wasabi rhizomes isolated were inactive in ourassays. At a concentration of 60 μg/mL, compounds 1 and 2 selectively inhibited COX-1 enzyme by28 and 32%, respectively. Compounds 3, 4, and 5 gave 75, 42, and 47% inhibition of COX-1 enzyme,respectively, at a concentration of 250 μg/mL. In a dose response study, compound 3 inhibited theproliferation of colon cancer cells (HCT-116) by 21.9, 42.9, 51.2, and 68.4% and lung cancer cells(NCI−H460) by 30, 39, 44, and 71% at concentrations of 7.5, 15, 30, and 60 μg/mL, respectively. Ata concentration of 60 μg/mL, compound 4 inhibited the growth of colon, lung, and stomach cancercells by 28, 17, and 44%, respectively. This is the first report of the COX-1 enzyme and cancer cellgrowth inhibitory monogalactosyl diacylglycerides from wasabi and horseradish rhizomes. Keywords: Horseradish; wasabi; anticancer; galactosyl diacylglycerides; cyclooxygenase enzyme
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