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Furoquinolines of the Rutaceae and their role in plant-lepidopteran interactions

University of British Columbia

Two furoquinoline alkaloids, skimmianine and dictamnine, were purified from the dried leaves of Skimmia japonica (Rutaceae) and dried root of Dictamnus albus (Rutaceae), respectively. The furoquinolines were isolated through acid fractionation and silica gel column chromatography, and their identity was confirmed through HPLC and mass spectroscopic analysis. Skimmianine and dictamnine, as well as the furanocoumarins 8-methoxypsoralen (8-MOP) and 5-methoxypsoralen (5-MOP) were quantified in leaf tissue of S. japonica and Ruta graveolens (Rutaceae). Of these compounds, S. japonica contained skimmianine and 5-MOP, and quantities differed depending on the sex of the plant from which the leaves were taken. The compounds were not present on the surface of the leaves. R. graveolens was found to contain skimmianine, 5-MOP and 8-MOP, both on the surface and interior of the leaves. Neither plant contained detectable levels of dictamnine. Growth assays using Spodoptera litura (Lepidoptera: Noctuidae) and Trichoplusia ni (Lepidoptera: Noctuidae) demonstrated that both furoquinolines are potent antifeedants at concentrations below those found naturally. Skimmianine is twice as deterrent to S. litura as dictamnine on a weight to weight basis. 8-MOP was also deterrent to S. litura, but not as potent as either furoquinoline. Skimmianine was deterrent to T. ni, but 8-MOP had no effect on its growth. Simulated daylight conditions, with appropriate UV wavelengths, were found to have no effect on the antifeedant properties of either furoquinoline or 8-MOP in the S. litura trials. In addition, none of the compounds were physiologically toxic to larvae. It was found that a non-ratio-based method was more accurate than a ratiobased method for the analysis and interpretation of experimental data. In conclusion, the furoquinolines skimmianine and dictamnine, and the furanocoumarin 8-MOP, are deterrent to S. litura larvae. Skimmianine is deterrent to T. ni. The intensity of experimental light conditions may be essential for inducing toxicity in potentially phototoxic compounds.

Thesis/Dissertation

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2009-07-13

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http://hdl.handle.net/2429/10752

Botany

University of British Columbia

UBCV

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