Reena Randhir

Stimulation of phenolics, antioxidant and antimicrobial activities in dark germinated mung bean sprouts in response to peptide and phytochemical elicitors

The phenyl propanoid pathway (PPP) was stimulated in mung bean sprouts through the pentose phosphate and shikimate pathways, by natural elicitors such as fish protein hydrolysates (FPH), lactoferrin (LF) and oregano extract (OE). Elicitation significantly improved the phenolic, antioxidant and antimicrobial properties of mung bean sprouts. The optimal elicitor concentrations were 1 ml/l FPH, 250 ppm LF and 1 ml/l OE for the highest phenolic content that was approximately 20, 35 and 18% higher than control, respectively, on day 1 of dark germination. The antioxidant activity estimated by β-carotene assay in mung bean sprouts was highest on day 1 of germination for all treatments and control. In general, higher antioxidant activity was observed in the elicited sprouts compared with control. In the case of 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay the antioxidant activity for all treatments and control was highest on day 2. Among the different elicitor treatments, OE elicited mung bean sprouts showed the highest antioxidant activity of 49% DPPH inhibition on day 2. This increased activity correlates with high guaiacol peroxidase (GPX) activity indicating that the polymerizing phenolics required during lignification with growth have antioxidant function. For all elicitor treatments a higher glucose-6-phosphate dehydrogenase (G6PDH) activity was observed during early germination following the high phenolic content. This is due to the general mobilization of carbohydrates to the growing sprouts in response to elicitation. In general the GPX activity steadily increased with germination for treatments and control. The higher phenolics produced on day 1 was utilized for GPX-mediated polymerization to form polymeric phenolics and lignin required during germination. The late stage polymerization linked to GPX activity preceded stimulation of G6PDH. This indicated that as phenolics were polymerized by GPX in late stages, G6PDH linked precursors such as NADPH2 and sugar phosphates were being made available. Antimicrobial activity against Helicobacter pylori was observed in the mung bean sprout extract from control, LF and OE treatments from the day 1 stage. Both the LF and OE elicited extracts showed high antimicrobial activity, which correlated to high antioxidant activity on day 1. The higher antimicrobial activity was also observed with the higher stimulation of G6PDH and GPX activity during early stages of germination. This leads to the hypothesis that enhanced mobilization of carbohydrates (as indicated by G6PDH activity on days 2 and 4), enhanced polymerization of simple phenols (as indicated by GPX activity on day 3) contributed to high antioxidant activity producing intermediary metabolites (day 2).

l-DOPA and total phenolic stimulation in dark germinated fava bean in response to peptide and phytochemical elicitors

Abstract Fava bean sprouts are a rich source of levo dihydroxy phenylalanine ( l -DOPA) the precursor of dopamine and is used in the treatment of Parkinsons 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.

Light-mediated fava bean (Vicia faba) response to phytochemical and protein elicitors and consequences on nutraceutical enhancement and seed vigour

Abstract Fava bean seedlings are a rich source of levo dihydroxy phenylalanine ( l -DOPA), the precursor of the neurotransmitter dopamine. The nutraceutical value and seed vigour of light germinated fava bean seedlings were significantly improved by priming with natural elicitors like fish protein hydrolysates (FPH), lactoferrin (LF) and oregano extract (OE). These elicitors stimulate the phenylpropanoid pathway through the pentose phosphate and shikimate pathway enhancing the production of total phenolics and seed vigour. Previous research in our laboratory has shown that the best elicitor concentration for fava bean was 2 ml/l FPH, 50 ppm LF and 5 ml/l of OE. A 100% germination rate was observed in seeds primed with FPH, 97% with OE, and 92% in LF primed and control. Priming with FPH improved growth by 35 and 25.5% by OE when compared to control. The seeds primed with LF showed no significant increase compared to the control. A significant boost in total phenolics was seen in primed seedlings and this correlated with enhanced seedling height and weight. On day 16 the total phenolics was 25, 9 and 17% higher in FPH, LF and OE primed, respectively, when compared to control. On all days measured the G6PDH activity was higher in control than the elicited seedlings. Previous experiments have shown that for all elicitor treatments a high G6PDH activity was recorded during early germination (24 h) with a concurrent increase in total phenolics and was then reduced by day 20. In the case of control seedlings, phenolics and G6PDH activity was highest on day 20 corresponding to potential delayed developmental demand for metabolites. A steady increase in the GPX activity was observed as the germination progressed both in the case of control and primed seedlings reflecting the plants need for phenolics for lignification and structural development during growth. The antioxidant activity was maximal on day 20 for all treatments demonstrating that perhaps polymerization of phenolics has an antioxidant enhancing effect. The l -DOPA content in fava bean primed with FPH showed a 120% increase over that of the control, corresponding with the high phenolic production on day 16. The elicitors LH and OE showed a 97 and 30% increase respectively over that of the control. The present study demonstrates that elicited fava bean seedlings containing enhanced levels of l -DOPA has excellent potential for use as a functional food, nutraceutical and as an antioxidant. This research also holds agronomic importance suggesting the use of FPH and OE as elicitors to improve fava bean seed vigour and plant productivity.

Improved health-relevant functionality in dark germinated Mucuna pruriens sprouts by elicitation with peptide and phytochemical elicitors

The health-relevant functionality of Mucuna pruriens was improved by priming the seeds with elicitors of the pentose phosphate pathway (PPP) such as fish protein hydrolysates (FPHs), lactoferrin (LF) and oregano extract (OE) followed by dark germination. FPH elicited the highest phenolic content of 19 mg/g FW on day 1, which was 38% higher than control sprouts. OE enhanced Parkinsons disease-relevant L-DOPA content by 33% on day 1 compared to control sprouts. Anti-diabetes-relevant alpha-amylase inhibition percent (AIP) and alpha-glucosidase inhibition percent (GIP) were high in the cotyledons and decreased following elicitation and sprouting. For potential anti-diabetic applications, low AIP and high GIP with moderate L-DOPA content on day 4 of dark germination could be optimal. Improved L-DOPA concentrations in a soluble phenolic and antioxidant-rich M. pruriens background on day 1 sprouts have potential for Parkinsons disease management.

Low Microbial Load Sprouts with Enhanced Antioxidants for Astronaut Diet

• Novel methods to stimulate phenolic antioxidants from legume, mung bean (Vigna radiata) sprouts with low microbial count were developed to support a healthy diet for astronauts on the International Space Station (ISS) as well as lunar and Mars programs. INTRODUCTION • ANTIOXIDANTS AND NUTRITION • Plants are excellent sources of phenolic antioxidants • Phenolic phytochemicals – antioxidative action • scavengers of singlet oxygen and free radicals. • Donate hydrogen from hydroxyl groups positioned along the aromatic ring to terminate free radical oxidation of lipids and other biomolecules short-circuit a destructive chain reaction that ultimately degrades cellular membranes. • Implications for human health and in particular cancer. • Understanding Biosynthesis is essential for the development of functional foods, which refers to the improvement of conventional foods with added health benefits. Antioxidants for Protection from Radiation damage • Radiation exposure-linked oxidative stress and biological damage likely to be encountered by astronauts. • In addition to cell membrane damage can cause oxidative damage at the DNA level, having consequences for mutagenesis and cancer. • Preventive nutrient support through use of food-grade antioxidants, such as vitamin C, E and A, have the potential to reduce damage. • Phenolic antioxidants also have the potential to be used as diet-based support for managing radiation-linked antioxidant protection . • Sprout-based phenolic antioxidants can be designed as functional foods for diet-based protection. Phenolic Antioxidants from Plants • Secondary metabolites, which have diverse medicinal applications. – Curcumin from Curcuma longa – Rosmarinic acid from Rosmarinus officinalis . – Isoflavonoids from Glycine max and galanigin from Origanum vulgare – Ellagic acid via solid-state bioprocessing from fruits . – L-tyrosine and L-DOPA from fava bean and related legumes for stress adaptogenic and Parkinson’s diet therapy • Implications for stress-management in advanced life support systems beyond Earth. PHENOLIC ANTIOXIDANTS FROM LEGUME SPROUTS AND BIOCHEMICAL CONCEPTS • PEAS – a link between proline biosynthesis, oxidation, stimulation of glucose-6-phosphate dehydrogenase (G6PDH), and phenolic synthesis. • MUNG BEAN – microbial polysaccharide treatments stimulated phenolic content, proline, G6PDH and GPX. – In addition specific elicitors, xanthan gum, yeast extract and yeast glucan stimulated antioxidant activity. – oregano phenolic extracts as elicitors to stimulate phenolic content during dark germination of mung bean.