Total Phenolic Stimulation

L-DOPA and Total Phenolic Stimulation in Dark Germinated Fava Bean in Response to Peptide and Phytochemical Elicitors

Process Biochemistry

Volume 37, Issue 11 , June 2002, Pages 1247-1256

Reena Randhir, Preethi Shetty and Kalidas Shetty

Department of Food Science, Chenoweth Laboratory, University of Massachusetts, Amherst, MA 01003, USA

 

Fava bean sprouts are a rich source of levo dihydroxy phenylalanine (L-DOPA) the precursor of dopamine and is used in the treatment of Parkinson's disease. Its phytopharmaceutical value was improved by priming the seeds with natural elicitors like fish protein hydrolysates (FPH), lactoferrin (LF) and oregano extract (OE). The elicitors in general stimulated the phenylpropanoid pathway through the pentose phosphate and shikimate pathway and enhanced the production of phenolics. Among the different FPH elicitor concentrations, 2 ml/l elicited the highest phenolic content of 3.4 mg/gFW on day 2, which is three times higher than that of control. LF proved to be a better elicitor at a low concentration of 50 ppm producing 5.2 mg of phenolics/gFW on day 3. The response of fava bean treated with 5 ml/l of OE showed the highest phenolic stimulation of 2.9 mg/gFW on day 3. Control, FPH and OE elicitors showed a higher antioxidant activity in germinating fava bean sprout on day 1 and 2 which correlated with higher phenolic content. In fava bean primed with FPH, the glucose-6-phosphate dehydrogenase (G6PDH) and guaiacol peroxidase (GPX) activity peaked on day 5 followed by a concurrent increase in phenolics on day 6 demonstrating the mobilization of carbohydrates from the cotyledons towards the phenylpropanoid pathway in response to the elicitors. In the case of both LF and OE the peak activity of G6PDH and GPX was seen just prior to the boost in phenolics on day 3 and drops to a minimal on day 4 suggesting that the products may allosterically regulate the enzyme. For all elicitors and control the L -DOPA content was high on day 1 and steadily declined with germination. The  L-DOPA content in fava bean elicited by LF showed a 40% increase, where as FPH and OE showed a 20% increase compared to that of the control. The maximal stimulation of L-DOPA content was seen on day 2 for fava bean treated with 2 ml/l of FPH, which was 100% higher than that of control.