Antithyroid Activity of Onion Volatiles

In a previous communication (Saghir, Cowan, and Salji 1966) data were presented which showed that n-propyl disulphide, the major volatile constituent of common onion (Allium cepa) , inhibited thyroid activity in the rat. In the present paper, results are reported from further studies on the possible antithyroid activity of four other volatile compounds of Allium: methyl disulphide, allyl disulphide, allyl alcohol, and allyl monosulphide. Along with the n-propyl disulphide previously studied, these four compounds constitute the major volatile constituents of common onion; however, they are present also in other Allium species. Saghir, Mann, Bernhard, and Jacobsen (1964) found that methyl disulphide is the main component of rakkyo (A. chinense) and Chinese chives (A. tuberosum), both favourite food onions in China and Japan. In addition, the American wild Allium species emanate a preponderance of methyl sulphides when the tissues are injured (Saghir, Mann, Ownbey, and Berg 1966). Garlic (A. sativum) and great-headed garlic (A. ampeloprasum) have high proportions of allyl disulphide in their odour; furthermore, allyl monosulphide and allyl alcohol were reported recently as volatiles produced by Allium (Bernhard, Saghir, Jacobsen, and Mann 1964).