15A-7 |
Effect of UV treatment on the proline-linked pentose phosphate pathway for phenolics antioxidant and L-DOPA synthesis in dark germinated Vicia faba. |
P. J. SHETTY1, M. T. Atallah1, and K. Shetty2. (1) Dept. of Nutrition, Univ. of Massachusetts, Amherst, Chenoweth Lab., Amherst, MA 01003, (2) Dept. of Food Science, Univ. of Massachusetts, Amherst Fava beans (Vicia faba) have potentially high amounts of phenolic antioxidants. Antioxidant properties of the polyphenols are extensively studied for their ability to curb the lipid oxidation in food and in health. This legume is also the best natural dietary source of L-DOPA, the neuromodulator and the treatment for Parkinson’s disease. The rationale behind this study was to observe the stimulation of nutraceutical metabolites when germinating fava beans are exposed to ultra violet (UV) light through Proline-linked Pentose Phosphate Pathway. Studies have shown some phenolic phytochemicals can be stimulated with UV light. Our objective was to overexpress the pathway through the regulation of the key enzyme, glucose – 6 – phosphate dehydrogenase (G6PDH), for enhanced phenolics and L-DOPA production and investigate the link to proline metabolism. Enzyme guaiacol peroxidase (GPX) was monitored to understand the extent to which the phenolics will be converted to polymeric phenols. Seeds were pretreated in water, exposed to 5, 10 and 15 hr UV light and germinated for 8 days in dark. Total phenolics, proline levels and enzyme activities were measured spectrophotometrically. L-DOPA was measured by HPLC. Antioxidant activity of the phenolics was determined by inhibition of the b - carotene oxidation. Total phenolic content increased 10 fold after 15hr UV light exposure on day 6 along with the highest activity of G6PDH. All the treatments showed higher antioxidant activity and proline levels compared to the control. Results indicate an increase in nutraceutically relevant phenolic metabolites along with enhanced antioxidant activity in response to UV stress. This novel approach provides a mechanism to understand and enhance biosynthesis important and relevant compounds in plant and legume systems for use in nutraceutical applications.
Session 15A, Biotechnology
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