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Background: Complementation of enzymatic and nonenzymatic antioxidative defense plays a decisive role in redox regulation of crops under drought. However, such type of study in Amaranth, particularly understanding the relationship between drought tolerance through tandem action of enzymatic and non-enzymatic bioactive antioxidants having phytonutrient promise is seldom studied and hence is the objective of the present investigation.Results: A comparative evaluation of dehydration stress-induced changes in reactive oxygen species-antioxidant interaction dynamics (assessed in terms of efficacy of ascorbate-glutathione pathway) among 10 promising accessions of Amaranthus hypochondriacus L. revealed significant accession-specific variation with accessions IC47434 and IC107144 bear out as better ecotypes for their redox regulation abilities (assessed in terms of redox biomarkers like DCFDA (2 0 ,7 0 -dichloroflorescindiacetate) oxidation, accumulation of O 2.À , H 2 O 2 , hydroperoxide, conjugated diene, free carbonyl content, membrane protein thiol level, total radical scavenging activity, and total thiol content).Further, RP-HPLC (reverse phase high performance liquid chromatography) coupled with potodiode assay revealed a significantly higher accumulation of redox-sensitive polyphenolic compounds like rutin, myricetin quercetin, gallic acid, p-hydroxy benzoic acid, vanillic acid, syringic acid, p-coumaric acid along with the pool of monophenol, diphenol, total phenol, flavonoids, anthocyanin, betacyanin for drought stress raised seedling of IC107144 and IC47434 as compared to one of the most susceptible cultivars IC94661. Conclusion:Taken as a whole, the work not only revealed the strong association between drought tolerance and bioavailability of pharmacologically important bioactive polyphenolic antioxidants but also unequivocally proposed the complementation of secondary polyphenolic compounds with Halliwell-Asada pathway for intensification of competent redox-regulation property necessary for drought stress acclimation in Amaranth germplasms.

Background Though vegetable amaranths harbor good pool of phenolic compounds, but till date, there is no systematic database on seasonal and genetic diversity based antioxidant‐dependent phytonutrient promise of amaranths of Gangetic plains of West Bengal particularly those derived from chalcone and cinnamic acids of phenyl propanoid metabolism and hence is the subject of present investigation. Results A comparative evaluation based on RP‐HPLC (Reverse Phase‐High Performance Liquid Chromatography) coupled photodiode assay of twenty one pharmacologically important bioactive polyphenolic compounds (flavonoids and phenolic acids) along with sensitive biomarkers of antioxidant properties (reducing property, metal chelating property, superoxide radical scavenging property, hydroxyl radical scavenging property, antilipid peroxidation, anti‐inflammatory property, and antidiabetic property) has been done for the assessment of genotype‐based seasonal variation of antioxidant‐based phytonutrient promise of vegetable amaranths of Indo‐Gangetic plains of West Bengal. The work exhibited genotype‐specific accumulation of bioactive polyphenolic compounds and associated antioxidant properties, with A. hypochondriacus L. exhibiting significantly greater abundance of majority of polyphenolic compounds tested, followed by A. viridis L. and A. hybridus L. The work also recorded the genotype‐specific seasonal elicitation of the synthesis of bioactive polyphenolic compounds. Conclusion Taken as a whole, the work suggests genotype‐specific seasonal variations in the accumulation of bioactive polyphenolic compounds and antioxidant‐based phytonutrient promise in diverse amaranth germplasms of Gangetic plain of West Bengal and identified lead germplasms as low‐cost antioxidant supplement for utilization in crop diversification program.