Elicitation of the Proline
Elicitation of the proline-linked pentose phosphate pathway metabolites and antioxidant enzymes in dark, germinated fava bean sprouts by aspirin.
Institute of Food Technologists Annual Meeting, New Orleans, Jun 29, 2008. Reena Randhir, UMass, Amherst, MA; Kalidas Shetty, UMass, Amherst, MA
The objective was to investigate the potential of Aspirin (Acetyl Salicylic Acid) as an elicitor of pentose phosphate pathway (PPP) and the link to proline biosynthesis in dark germinated fava bean sprouts. We hypothesize that Aspirin elicitation in fava bean sprouts can mimic a stress response leading to increased synthesis of phenolics, proline, levo-dihydroxy phenylalanine (LDOPA) and associated antioxidant activity. The parameters evaluated were total phenolics, antioxidant activity, LDOPA, proline, glucose-6-phosphate dehydrogenase (G6PDH), guaiacol peroxidase (GPX), superoxide dismutase (SOD) and catalase (CAT). Elicitation by Aspirin stimulated higher phenolic content during the late stages of dark germination in fava bean sprouts. High antioxidant activity observed during very early germination coincided with high LDOPA and the high activity during late germination coincided with total phenolics. A positive correlation between the stimulation of phenolic synthesis and G6PDH activity was observed indicating its role in carbohydrate mobilization. Improved GPX activity in response to elicitation indicated the polymerization of soluble phenolics. Higher GPX, SOD and CAT linked antioxidant enzyme response correlated to increase in proline and phenolics. The major implication from this research is that Aspirin is an elicitor of the PPP with increased synthesis of health relevant phenolics and L-DOPA associated with higher antioxidant activity. The stimulation of PPP was linked to increase in proline, suggesting a coupling of proline biosynthesis with PPP thereby supporting the proline-linked PPP hypothesis. The results also indicate the role of phenolic antioxidants during stress, by modulation of redox status of the cell by being effective free radical scavengers and also by inducing the antioxidant enzyme responses (SOD/CAT/GPX) in the cell through providing the reducing equivalents required for their activity.