Several novel sulfides from acetone extracts of bulbs of garlic (Allium sativum L.), were identified and investigated. These were named garlicnins B 1 (1), C 1 (2), and D (3), and they were found to have the ability to control macrophage activation. Garlicnins B 1 (1) and C 1 (2) possess a new skeleton of cyclic sulfoxide and their structures of garlicnins B 1 (1) and C 1 (2) were characterized as 3,4-dimethyltetrahydrothiophene-Soxide derivatives carrying the substitutions of a propenyl and a sulfenic acid, and an allyldithiine and a 1-propene-sulfenic acid (a), respectively. The mechanism of the proposed production of these compounds is discussed. Garlicnin D (3), dithiine-type, was estimated to be derived by addition of (a) allyl thiosulfenic acid (b) derived from allicin. The identification of these novel sufoxides from onion and garlic accumulates a great deal of new chemistry to the Allium sulfide field, and future pharmacological investigations aid the development of natural, healthy foods and anti-cancer agents that could potentially prevent or combat disease.Key words Allium sativum; sulfoxide; garlicnin B 1 ; garlicnin C 1 ; garlicnin D; macrophage activation Garlic, Allium sativum L. (Liliaceae) is at the top of the National Cancer Institute's list of designer foods that prevent cancer. The various biological activities of garlic are generally classified into two cases, cardiovascular disease prevention and cancer prevention. For the former, activities include the inhibition of cholesterol synthesis, platelet aggregation, and arterial smooth muscle cell proliferation inhibition as well as having anti-inflammatory, anti-oxidant, and hydrogen sulfide-mediated vasodilatory effects. Effects on carcinogen metabolism (enhanced cellular glutathione synthesis induced cell cycle arrest and apoptosis) and prevention of Helicobacter pylori infection, gastric cancer, and colorectal cancer make up the latter category.1-3) The chemistry of garlic sulfides is summarized in a text book editted by Block. 3,4) In previous work, we isolated a novel, stable sulfide, 3,4-dimethyl-5-(1-propenyl)-tetrahydrothiophene-2-sulfoxide-S-oxide, from the acetone extract of Allium cepa L. which was found to inhibit macrophage activation. We named this onionin A. 5)Here, sulfur-containing substances from an acetone-soluble extract of A. sativum L. have been isolated and characterized to aid the development of natural, healthy foods that potentially prevent and combat disease, in particular tumors.Chinese garlic (1061 g) was roughly chopped and blended in a mixer along with acetone. Subsequently, the mixture was soaked in acetone for 3 d at room temperature. The filtrate was evaporated at 40°C in vacuo to obtain a residue (26.1 g), which was then subjected to polystyrene gel column chromatography (Diaion HP-20). It was first eluted with water, then with methanol (residue after evaporation: 5.90 g), and finally with acetone (the residue after evaporation: 0.32 g). Part of the methanolic eluate (3.0 g) was partitioned between ethyl ace...