Separation of catechins from green tea (Camellia sinensis L.) by microwave assisted acetylation, evaluation of antioxidant potential of individual components and spectroscopic analysis

Separation of catechins from green tea (Camellia sinensis L.) by microwave assisted acetylation,... Separation of individual green tea catechins has the limitation due to their structural resemblance and unequal distribution. Hence, the objective of this study was to develop separation methods based on 1.Preparative Thin Layer Chromatography (TLC) using oxalic acid impregnation and 2. Microwave (MW) mediated acetylation followed by classical silica gel column chromatography separation. The yield of total catechins by different extraction techniques was, conventional (7.3%), liquid-liquid (7.8%), Soxhlet (8.3%) and microwave (8.8%). Acetylation of total catechins under various MW conditions explored with acetic anhydride, triethylamine and standardized at 15 min at 1g scale and subjected to separation. Subsequently, the individual catechin acetates deacetylated under MW conditions and characterized by TLC, High-Resolution Mass Spectrometry (HRMS), Fourier Transform Infrared Spectroscopy (FT-IR), 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopic studies. The total polyphenol content of the extract was 931.17 ± 0.67 g GAE kg−1. The antioxidant activity of deacetylated catechins was evaluated by Ferric-Reducing Antioxidant Potential (FRAP) in terms of Trolox equivalence (TE) and % inhibition of 1, 1-diphenyl-2-picryl-hydrazyl (DPPH). Accordingly, the TE and DPPH % inhibition was epigallocatechingallate (12.3 and 71.9%), epicatechingallate (11.5 and 55.5%), epigallocatechin (9.10 and 46.0%), epicatechin (7.40 and 35.1%) respectively. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png LWT - Food Science and Technology Elsevier

Separation of catechins from green tea (Camellia sinensis L.) by microwave assisted acetylation, evaluation of antioxidant potential of individual components and spectroscopic analysis

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Publisher
Elsevier
Copyright
Copyright © 2018 Elsevier Ltd
ISSN
0023-6438
D.O.I.
10.1016/j.lwt.2018.01.042
Publisher site
See Article on Publisher Site

Abstract

Separation of individual green tea catechins has the limitation due to their structural resemblance and unequal distribution. Hence, the objective of this study was to develop separation methods based on 1.Preparative Thin Layer Chromatography (TLC) using oxalic acid impregnation and 2. Microwave (MW) mediated acetylation followed by classical silica gel column chromatography separation. The yield of total catechins by different extraction techniques was, conventional (7.3%), liquid-liquid (7.8%), Soxhlet (8.3%) and microwave (8.8%). Acetylation of total catechins under various MW conditions explored with acetic anhydride, triethylamine and standardized at 15 min at 1g scale and subjected to separation. Subsequently, the individual catechin acetates deacetylated under MW conditions and characterized by TLC, High-Resolution Mass Spectrometry (HRMS), Fourier Transform Infrared Spectroscopy (FT-IR), 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopic studies. The total polyphenol content of the extract was 931.17 ± 0.67 g GAE kg−1. The antioxidant activity of deacetylated catechins was evaluated by Ferric-Reducing Antioxidant Potential (FRAP) in terms of Trolox equivalence (TE) and % inhibition of 1, 1-diphenyl-2-picryl-hydrazyl (DPPH). Accordingly, the TE and DPPH % inhibition was epigallocatechingallate (12.3 and 71.9%), epicatechingallate (11.5 and 55.5%), epigallocatechin (9.10 and 46.0%), epicatechin (7.40 and 35.1%) respectively.

Journal

LWT - Food Science and TechnologyElsevier

Published: May 1, 2018

References

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