State of Science :: TOC Funded Programs
Proposal Preparation Award to Dr. Neal Davies, Department of Pharmaceutical Sciences, Washington State University
Dr. Davies and his laboratory have several projects underway analyzing the biologically active components in food that give rise to health promotion benefits. Information on Dr. Davies research program and team is posted on the Neal Davies lab Web Site.
With support from the Organic Center, preliminary assessments have been made of the flavonoid and antioxidant levels in conventional and organic foods. Significant differences have been found in some comparison studies. Dr. Davies and his team are developing a five-year, $200k/year, proposal to the National Institutes of Health program, for submission in 2006.
Funding from the Center is supporting additional pilot testing of conventional and organic blueberries, strawberries, rhubarb, lemon juice products, apples, and possibly other foods. Work partially supported by the Organic Center has been presented at scientific meetings. A number of journal articles have been submitted for publication that report the results of this preliminary work, as noted below.
"Preparative Enzymatic Synthesis and HPLC Analysis of Rhapontigenin: Applications to Metabolism, Pharmacokinetics and Anti-Cancer Studies," Kathryn Roupe, Greg Helms, Steven Halls, Jaimie Yanez, and Neal Davies.
Journal of Pharmacy and Pharmaceutical Science, Volume 8 Number 3, August 2005.
Purpose: A facile method was established to enzymatically synthesize rhapontigenin from the glycosylated parent compound rhaponticin. A novel and simple high-performance liquid chromatographic method was developed for the determination of rhapontigenin. The assay was successfully applied to both the in vitro and in vivo metabolic kinetic study of rhapontigenin.
Methods: Serum, or microsomes (0.1 mL) was precipitated with acetonitrile after addition of the internal standard, daidzein. Separation was achieved on an amylose tris 3,5 dimethylphenylcarbamate column (150 x 4.6mm, ID, 5?m) with UV detection at 324nm. Hep G2 hepatoma cells were treated with rhapontigenin or rhaponticin (0-250 ?g/mL) and cell viability was measured. Results: The calibration curves were linear ranging from 0.5 to 100 mg/mL. The mean extraction efficiency was > 99%. Precision of the assay (coefficient of variation) was <5%, including the limit of quantitation (0.5 ?g/mL). Bias of the assay was lower than 5%. The limit of detection was 100 ng/mL for a 0.1 mL sample. One glucuronidated metabolite of rhapontigenin has been identified. Preliminary pharmacokinetic data revealed the presence of a glucuronidated metabolite in the serum and a terminal elimination t1/2 of ~6h. Rhapontigenin demonstrated concentration-dependent anti-cancer activity with an IC50 115 ?g/mL in HEP G2 cells while rhaponticin showed no activity across the concentrations tested in vitro.
Conclusions: The preparative enzymatic synthesis method has demonstrated utility to provide sufficient rhapontigenin for pharmaceutical studies. Rhapontigenin is an active anti-cancer compound. The developed HPLC assay is sensitive, reproducible and accurate and can be applied to pharmacokinetic and metabolism studies.
"Pharmacometrics of Stilbenes: Seguing Towards the Clinic," Kathryn Roupe, Connie Remsberg, Jaimie Yanez, and Neal Davies
Current Clinical Pharmacology, Volume 1, Number 1. In Press. 2006
Stilbenes are small molecular weight (~200-300 g/mol), naturally occurring compounds and are found in a wide range of plant sources, aromatherapy products, and dietary supplements. These molecules are synthesized via the phenylpropanoid pathway and share some structural similarities to estrogen. Upon environmental threat, the plant host activates the phenylpropanoid pathway and stilbene structures are produced and subsequently secreted. Stilbenes act as natural protective agents to defend the plant against viral and microbial attack, excessive ultraviolet exposure, and disease. One stilbene, resveratrol, has been extensively studied and has been shown to possess potent anti-cancer, anti-inflammatory and anti-oxidant activities. Found primarily in the skins of grapes, resveratrol is synthesized by Vitis vinifera grapevines in response to fungal infection or other environmental stressors. Considerable research showing resveratrol to be an attractive candidate in combating a wide variety of cancers and diseases has fueled interest in determining the disease-fighting capabilities of other structurally similar stilbene compounds. The purpose of this review is to describe four such structurally similar stilbene compounds, piceatannol, pinosylvin, rhapontigenin, and pterostilbene and detail some current pharmaceutical research and highlight their potential clinical applications.
"Enzymatic Synthesis and HPLC Analysis of Rhapontigenin: Applications to Metabolism, Pharmacokinetics and Anti-Cancer Activity," Poster Presentation
"Anti-Cancer Activity, Pharmacokinetics, and Metabolism of the Blueberry Stilbene, Pterostilbene," Poster Presentation
"Stereospecific Disposition and Anti-Cancer Activity of the Chiral Flavonoids Eriocitrin and Eriodictyol in Rodents, Humans, and Fruit Juices," Poster Presentation