Submitted to: Journal of Natural Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2015
Publication Date: 11/30/2015
Citation: Khrimian, A., Shirali, S., Guzman, F. 2015. Absolute configurations of zingiberenols isolated from ginger (Zingiber officinale) rhizomes. Journal of Natural Products. 78(1)3071-3074.
Interpretive Summary: Insect pests cause a significant damage to crops and forest, and monitoring their populations aids greatly to reducing the pesticide use and biological control. Pheromones, or chemicals that trigger a natural behavioral response in another member of the same species, are commonly used as baits for sampling inset populations. We isolated and determined detailed structures of two natural products (called zingiberenols) from ginger roots. One of these natural products was identical to a sex pheromone of the rice sting bug, one of the important rice pests in South America and a potentially invasive species. Thus, ginger could be a potential source of sex pheromone of this bug. The results of this study are of interest to other chemists and entomologist involved in the research of potential pest control compounds, and to state and federal agencies involved in monitoring and controlling insect pests of agriculture.
Technical Abstract: The sesquiterpene alcohol zingiberenol, or 1,10-bisaboladien-3-ol, was isolated some time ago from ginger, Zingiber officinale, rhizomes, but its absolute configuration had not been determined. With three chiral centers present in the molecule, zingiberenol can exist in eight stereoisomeric forms. We revisited the zingiberenol identification and, in fact, found two zingiberenols present in ginger, one cis and the other one trans, identified as (3R,6R,7S)-1,10-bisaboladien-3-ol (2), and (3S,6R,7S)-1,10-bisaboladien-3-ol (5). Assignments of absolute configurations were enabled by utilizing all available stereoisomers of 1,10-bisaboladiene-3-ol and two gas-chromatography columns: a 25 m Hydrodex -ß-6TBDM and 60 m DB-5MS. Thus, absolute configurations of carbons 6 and 7 in both isolated zingiberenols match those of zingiberene present abundantly in ginger rhizomes. Interestingly, (3R,6R,7S)-1,10-bisaboladiene-3-ol has recently been identified as a male-produced sex pheromone of rice stink bug, Oebalus poecilus, thus presenting ginger plants as a potential source of sex pheromone of this bug.