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. 2019 Sep 24;4(15):16471-16480.
doi: 10.1021/acsomega.9b02071. eCollection 2019 Oct 8.

Low-Cost Ru/C-Catalyzed Depolymerization of the Polymeric Proanthocyanidin-Rich Fraction from Bark To Produce Oligomeric Proanthocyanidins with Antioxidant Activity

Hongfei Zhu  1 , Peize Li  1 , Shixue Ren  1 , Wenying Tan  1 , Guizhen Fang  1
Affiliations

Low-Cost Ru/C-Catalyzed Depolymerization of the Polymeric Proanthocyanidin-Rich Fraction from Bark To Produce Oligomeric Proanthocyanidins with Antioxidant Activity

Hongfei Zhu et al. ACS Omega. .

Abstract

A new method has been developed for the high-value utilization of larch bark, which is regarded as a low-value byproduct of the logging industry. Polymeric proanthocyanidins (PPCs) were extracted from the Larix gmelinii bark and depolymerized by catalytic hydrogenolysis, using ruthenium/carbon (Ru/C) as the catalyst. The method has been found that although the molecular weight of the depolymerized product was significantly lower, the basic structural units were not destroyed, and the product retained a condensed flavanol polyphenol structure; the depolymerized product contains very little Ru metal and thus complies with food safety standards; the antioxidant properties of both the depolymerized products and PPCs were better than those of the commonly used antioxidant 2,6-di-tert-butyl-4-methylphenol. The relative molecular weight and steric hindrance of the depolymerized products were lower than those of the PPCs, leading to better antioxidant performance. A new technical route for the depolymerization of PPCs from the L. gmelinii bark is provided. The route offers practical and commercial advantages, and the product could have many applications as an antioxidant.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Molecular structure of PPCs from the L. gmelinii bark (a) PPCs; (b) (−)-epicatechin; (c) (+)-catechin.
Figure 2
Figure 2
Diagram showing proposed mechanism of Ru-catalyzed depolymerization of PPCs from the L. gmelinii bark.
Figure 3
Figure 3
Effect of temperature on the depolymerization rate of PPCs (3 MPa hydrogen, 500 rpm stirring, reaction time of 1 h, and 1.5% catalyst loading).
Figure 4
Figure 4
Effect of reaction time on depolymerization rate of PPCs (3 MPa hydrogen, 500 rpm stirring, 150 °C, and 1.5% catalyst loading).
Figure 5
Figure 5
Effect of catalyst loading on the depolymerization rate of PPCs (3 MPa hydrogen, 500 rpm stirring, 1 h, and 150 °C).,
Figure 6
Figure 6
UV–vis absorption spectra of PPCs, OPCs, and catechins.
Figure 7
Figure 7
FTIR spectra of PPCs and OPCs.
Figure 8
Figure 8
1H NMR spectra of OPCs (top) and PPCs (bottom).
Figure 9
Figure 9
Molecular weight distribution of OPCs and PPCs determined by GPC.
Figure 10
Figure 10
XPS spectrum of OPCs.
Figure 11
Figure 11
Reducing ability of OPCs, PPCs, and BHT at different mass concentrations.
Figure 12
Figure 12
DPPH• scavenging capacity of OPCs, PPCs, and BHT at different mass concentrations.
Figure 13
Figure 13
ABTS•+ scavenging capacity of OPCs, PPCs, and BHT at different mass concentrations.
Figure 14
Figure 14
ABTS•+ scavenging activity: IC50 values of OPCs, PPCs, and BHT.
See this image and copyright information in PMC

References

    1. An L.; Si C.; Wang G.; Sui W.; Tao Z. Enhancing the solubility and antioxidant activity of high-molecular-weight lignin by moderate depolymerization via in situ ethanol/acid catalysis. Ind. Crops Prod. 2019, 128, 177–185. 10.1016/j.indcrop.2018.11.009. - DOI
    1. Tudor E. M.; Barbu M. C.; Petutschnigg A.; Réh R. Added-value for wood bark as a coating layer for flooring tiles. J. Cleaner Prod. 2018, 170, 1354–1360. 10.1016/j.jclepro.2017.09.156. - DOI
    1. Ni L.; Zhao F.; Li B.; Wei T.; Guan H.; Ren S. Antioxidant and Fluorescence Properties of Hydrogenolyzised Polymeric Proanthocyanidins Prepared Using SO(4)(2-)/ZrO(2) Solid Superacids Catalyst. Molecules 2018, 23, 2445.10.3390/molecules23102445. - DOI - PMC - PubMed
    1. Denev P.; Číž M.; Kratchanova M.; Blazheva D. Black chokeberry (Aronia melanocarpa) polyphenols reveal different antioxidant, antimicrobial and neutrophil-modulating activities. Food Chem. 2019, 284, 108–117. 10.1016/j.foodchem.2019.01.108. - DOI - PubMed
    1. Fraser K.; Harrison S. J.; Lane G. A.; Otter D. E.; Hemar Y.; Quek S.-Y.; Rasmussen S. HPLC–MS/MS profiling of proanthocyanidins in teas: A comparative study. J. Food Compos. Anal. 2012, 26, 43–51. 10.1016/j.jfca.2012.01.004. - DOI

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