Identification of Odor-Active Compounds Released from a Damaged Plant of the Asian Skunk Cabbage Symplocarpus renifolius

Symplocarpus renifolius (Asian skunk cabbage) is a perennial herb of the Araceae family. As its common name implies, this plant produces a strong garliclike irritant odor with a rotten note when the plant parts are crushed. To elucidate the odor characteristics, the volatile compounds released from crushed plant parts (rhizome, petioles, and leaf blades) of S. renifolius were identified by a dynamic headspace method. Fifteen sulfur compounds were identified as odor-active compounds by gas chromatography–mass spectrometry–olfactometry (GC–MS–O). The sulfur compounds may be responsible for the strong odor emitted by crushed skunk cabbage. Many of the compounds lack a carbon–carbon bond, and all of the carbon atoms are connected to sulfur. This is regarded as the characteristic structure of the sulfur compounds released from the damaged plant parts of the skunk cabbage. Nine of the sulfur compounds were detected in all three of the plant parts analyzed in this study: hydrogen sulfide, methanethiol, 1-hexanethiol, methyl dithioformate, 2,4-dithiapentane, dimethyl trisulfide, methional, 2,3,5-trithiahexane, and tris­(methylthio)­methane. Methyl dithioformate and methylthiomethyl dithioformate were identified for the first time as natural products.