School Of Basic And Applied Sciences

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Author: search.filters.author.Yadav, Sudesh KumarSubject: search.filters.subject.Antioxidants

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    Pyramiding of tea Dihydroflavonol reductase and Anthocyanidin reductase increases flavan-3-ols and improves protective ability under stress conditions in tobacco
    (Springer Verlag, 2017) Kumar, Vinay; Yadav, Sudesh Kumar
    Tea (Camellia sinensis) is one of the richest sources of flavan-3-ols, an important class of flavonoids. The expression level of gene-encoded key regulatory enzymes of flavan-3-ol/anthocyanin biosynthetic pathway, dihydroflavonol 4-reductase (DFR) and anthocyanidin reductase (ANR), has been highly correlated with the flavan-3-ol contents and antioxidant activity in tea plant. In the present study, pyramiding of CsDFR and CsANR in tobacco was achieved. However, single transgenic tobacco overexpressing either CsDFR or CsANR was documented earlier. In continuation, pyramided transgenic lines were evaluated for the possible, either same or beyond, effect on flavan-3-ol accumulation and protective ability against biotic and abiotic stresses. The pyramided transgenic lines showed early flowering and improved seed yield. The transcript levels of flavan-3-ol/anthocyanin biosynthetic pathway and related genes in pyramided transgenic lines were upregulated as compared to control tobacco plants. The accumulations of flavan-3-ols were also found to be higher in pyramided transgenic lines than control tobacco plants. In contrast, anthocyanin content was observed to be decreased in pyramided transgenic lines, while DPPH activity was higher in pyramided transgenic lines. In pyramided transgenic lines, strong protective ability against feeding by Spodoptera litura was documented. The seeds of pyramided transgenic lines were also found to have better germination rate under aluminum toxicity as compared to control tobacco plants. Interestingly, the synergistic effect of these two selected genes are not beyond from transgenic lines expressing either CsDFR and CsANR alone as published earlier in terms of flavan-3-ols accumulation. However, the unique flower color and better seed germination rate are some interestingly comparable differences that were reported in pyramided lines in relation to individual transgenic plants. In conclusion, the present results reveal an interesting dynamic between CsDFR and CsANR in modulating flavan-3-ol/anthocyanin levels and functional analysis of stacked CsDFR and CsANR transgenic tobacco lines. ? 2017, Springer-Verlag GmbH Germany.
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    Anthocyanins enriched purple tea exhibits antioxidant, immunostimulatory and anticancer activities
    (Springer India, 2017) Joshi, Robin; Rana, Ajay; Kumar, Vinay; Kumar, Dharmesh; Padwad, Yogendra S.; Yadav, Sudesh Kumar; Gulati, Ashu
    Purple coloured tea shoot clones have gained interest due to high content of anthocyanins in addition to catechins. Transcript expression of genes encoding anthocyanidin reductase (ANR), dihydroflavonol-4-reductase (DFR), anthocyanidin synthase (ANS), flavonol synthase (FLS) and leucoantho cyanidin reductase (LAR) enzymes in three new purple shoot tea clones compared with normal tea clone showed higher expression of CsDFR, CsANR, CsANS and lower expression of CsFLS and CsLAR in purple shoot clones compared to normal clone. Expression pattern supported high content of anthocyanins in purple tea. Four anthocyanins (AN1?4) were isolated and characterized by UPLC-ESI-QToF-MS/MS from IHBT 269 clone which recorded highest total anthocyanins content. Cyanidin-3-O-?-d-(6-(E)-coumaroyl) glucopyranoside (AN2) showed highest in vitro antioxidant activity (IC50?DPPH?=?25.27???0.02??g/mL and IC50?ABTS?=?10.71???0.01??g/mL). Anticancer and immunostimulatory activities of cyanidin-3-glucoside (AN1), cyanidin-3-O-?-d-(6-(E)-coumaroyl) glucopyranoside (AN2), delphinidin-3-O-?-d-(6-(E)-coumaroyl) glucopyranoside (AN3), cyanidin-3-O-(2-O-?-xylopyranosyl-6-O-acetyl)-?-glucopyranoside (AN4) and crude anthocyanin extract (AN5) showed high therapeutic perspective. Anthocyanins AN1?4 and crude extract AN5 showed cytotoxicity on C-6 cancer cells and high relative fluorescence units (RFU) at 200??g/mL suggesting promising apoptosis induction activity as well as influential immunostimulatory potential. Observations demonstrate potential of purple anthocyanins enriched tea clone for exploitation as a nutraceutical product. ? 2017, Association of Food Scientists & Technologists (India).