Allelochemicals Biologica... - Name

ALLEOPATHIC ORGANISMS AND
MOLECULES
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 Pcarotene
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-picrythydrazyl
(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 NADPH (2) 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).
5. WEED MANAGEMENT
Bhowmik and Inderjit (2003) examined some considerable efforts in designing
alternative weed management strategies due to increase in the number of herbicideresistant
weeds and environmental concerns in the use of synthetic herbicides. The
conventional synthetic herbicides are becoming less and less effective against the
resistant weed biotypes. These authors discussed the role of allelopathic cover crops/
crop residues, natural compounds, and allelopathic crop cultivars in natural weed
management, and gave numerous examples of employing crop residues, cover crops,
and allelopathic crop cultivars in weed management. They concluded that although
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