Changes of Phytochemical Components (Urushiols, Polyphenols, Gallotannins) and Antioxidant Capacity during Fomitella fraxinea⁻Mediated Fermentation of Toxicodendron vernicifluum Bark.

Da-Ham Kim,Young-Hoi Kim,Gi-Yoon Kim,Myung-Kon Kim,Min-Ji Kim,Yoseph Gebru,Dae-Woon Kim,Han-Seok Choi,Jong-Kuk Kim

doi:10.3390/molecules24040683

Abstract

The stem bark of Toxicodendron vernicifluum (TVSB) has been widely used as a traditional herbal medicine and food ingredients in Korea. However, its application has been restricted due to its potential to cause allergies. Moreover, there is limited data available on the qualitative and quantitative changes in the composition of its phytochemicals during fermentation. Although the Formitella fraxinea-mediated fermentation method has been reported as an effective detoxification tool, changes to its bioactive components and the antioxidant activity that takes place during its fermentation process have not yet been fully elucidated. This study aimed to investigate the dynamic changes of urushiols, bioactive compounds, and antioxidant properties during the fermentation of TVSB by mushroom F. fraxinea. The contents of urushiols, total polyphenols, and individual flavonoids (fisetin, fustin, sulfuretin, and butein) and 1,2,3,4,6-penta-O-galloyl-β-D-glucose (PGG) significantly decreased during the first 10 days of fermentation, with only a slight decrease thereafter until 22 days. Free radical scavenging activities using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6- sulfonic acid) (ABTS), and ferric reducing/antioxidant power (FRAP) as an antioxidant function also decreased significantly during the first six to nine days of fermentation followed by a gentle decrease up until 22 days. These findings can be helpful in optimizing the F. fraxinea–mediated fermentation process of TVSB and developing functional foods with reduced allergy using fermented TVSB.

Highlights

IntroductionThe xylem and bark of T. vernicifluum have been reported to possess strong antioxidant [6,7], antiplatelet [8,9], immune-enhancing [10], neuroprotective [11,12], anti-inflammatory [12,13], and anti-cancer activities [4,14,15]
It has been reported that fermentation with F. fraxinea is an effective way to remove toxic urushiols from Toxicodendron vernicifluum stem bark (TVSB), and that mushroom laccases play an important role in the detoxification [19]
The content of urushiol congeners noticeably decreased within 10 days of fermentation with a slow decrease thereafter until 22 days

Summary

Introduction

The xylem and bark of T. vernicifluum have been reported to possess strong antioxidant [6,7], antiplatelet [8,9], immune-enhancing [10], neuroprotective [11,12], anti-inflammatory [12,13], and anti-cancer activities [4,14,15]. Various methods have been attempted to remove or reduce urushiol congeners from the xylem and bark of T. vernicifluum, including physicochemical treatments such as solvent extraction, pyrolysis at high temperature, and enzymatic methods. Some of these methods are effective at removing urushiols, they have limitations such as the generation of harmful substances, high cost, process complexity, and low efficiency [19]

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Conclusion