Volatiles from leaves of field‐grown plants and shoot cultures of Gynura bicolor DC

Systematic investigations of the volatiles of fi eld-grown plants and shoot cultures of Gynura bicolor have been conducted to obtain indispensable plant physiological information for propagating plants of consistent quality. Volatiles obtained by solvent-assisted fl avour evaporation (SAFE) of solvent extracts from leaves of commercial cultivars, shoot cultures and their regenerates were analysed using gas chromatography (GC), GC-mass spectrometry (GC-MS) and GC-olfactometry (GC-O). It was revealed for the fi rst time that this plant had the following chemical characteristics: fi eld-grown plants, i.e. those plants commercially cultivated in three diff erent regions of Japan and 7 month-old regenerates of shoot cultures had almost the same GC profi les; their major components were (E)-caryophyllene, α-humulene and bicyclogermacrene; in contrast, the major components of the shoot cultures were (Z,E)-α-farnesene, (E)-caryophyllene and α-copaene. The biosynthetic pathways for the sesquiterpenes found in these materials were presumed from the analytical results. Aroma evaluations using GC-O revealed that 1-octen-3-one, (Z)-1,5-octadien-3-one and trans-4,5-epoxy-(E)-2-decenal were aroma-impact compounds con- tributing to the characteristic metallic, green aroma, especially in the shoot cultures. In addition to these results, it was found that 2-isopropyl- and 2-isobutyl-3-methoxypyrazines were additional compounds related to the green, earthy aroma in the regenerates. These aroma-impact compounds were detected only because of the GC-O analysis. Copyright © 2009 John Wiley & Sons, Ltd.