T11 AM Aquatic Plants: Methods, Mechanisms and Markers
Tuesday, 15 November 2005: 8:00 AM - 11:40 AM in 343-344

(BRA-1117-850085) Characterizing the herbicidal effects of statin pharmaceuticals in Lemna gibba.

Brain, R¹, Reitsma, T¹, Bestari, K¹, Solomon, K¹, ¹ University of Guelph, Guelph, Ontario, Canada

ABSTRACT- Statins are synthetic lipid-lowering agents which competitively inhibit 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) in the treatment of high cholesterol. HMG-CoA is one of the most highly regulated enzymes in mammals as well as plants. In plant systems HMG-CoA is the rate determining step in the cytosolic mevalonic acid pathway where isopentenyl diphosphate (IPP) is synthesized. IPP provides the basic building blocks of the terpenoid biosynthetic pathway. An autonomous pathway in the chloroplast has also been characterized which synthesizes IPP, however, although there is some crosstalk between pathways, the anabolic products are considered largely distinct. The mevalonic acid pathway is responsible for the synthesis of sterols and the side-chain of ubiquinone, which are critical for membrane fluidity and electron transport, respectively. The plastidic pathway is responsible for the synthesis of carotenoids, chlorophylls, and plastoquinone, which are critical components of the photosynthetic pathway. Statin pharmaceuticals have previously been considered not to have significant impacts on anabolic plant processes through the inhibition of HMG-CoA, however our laboratory studies with Lemna gibba indicate that statins do cause concentration-dependent toxicity via reduction of mevalonate (HMG-CoA mediated) derived products. This presentation will discuss the concentration-dependent effects of atorvastatin and lovastatin on the levels of plastoquinone, ubiquinone, -sitosterol, and stigmasterol in L. gibba, quantified using HPLC-UV/Vis. Extraction and quantification protocols developed for quinones and sterols as well as atorvastatin and lovastatin will be detailed.

Key words: Statins, Sterols, Quinones, Lemna gibba