Production of phenolic compounds and antioxidant activity via bioconversion of wheat straw by Inonotus obliquus under submerged fermentation with the aid of a surfactant

Abstract

BACKGROUNDThis study investigated the effect of surfactants on wheat straw biodegradation and the growth‐associated generation of exo‐ and endo‐phenolic compounds (EPC and IPC) and antioxidant activity expression by liquid‐cultured Inonotus obliquus, an edible and medicinal mushroom, also known as a white rot fungus. Changes in the chemical composition and multiscale structure of wheat straw, in the production and activity of EPC and IPC and in individual flavonoids were analyzed.RESULTSFungal pretreatment decreased significantly the contents of all lignocellulose components, increased and enlarged substrate porosity and caused changes in the structure of wheat straw with the aid of Triton X‐100. A gradual increase in EPC and IPC production was observed up to 6.4‐ and 1.5‐fold for 9 days. The EPC obtained on day 9 showed the highest antioxidant activity (IC50 of 30.96 mg L−1) against 2,2‐diphenyl‐1‐picrylhydrazyl radicals. High‐performance liquid chromatographic results indicated the presence of high amounts of epicatechin‐3‐gallate (ECG; (374.9 mg g−1) and epigallocatechin‐3‐gallate (EGCG; 447.2 mg g−1) in the EPC; other polyphenols were also enhanced but to a lesser extent. Surfactant supplementation was effective in enhancing flavonoid production and in increasing antioxidant activity in EPC.CONCLUSIONSThe results indicated enhanced accumulation of phenolic compounds, particularly ECG and EGCG in Inonotus obliquus via biodegradation and bioconversion of lignocellulose residues. They also indicated enhancement in the production of several flavonoids and also an increase in antioxidant activity in the product by a surfactant‐treated process, which may be a useful way of exploiting underused lignocellulosic residues to various high‐added‐value functional ingredients. © 2020 Society of Chemical Industry

DPPH Radical Scavenging Activity of New Phenolics from the Fermentation Broth of Mushroom Morehella importuna

“…The experimental results indicated M. importuna could yield a wide variety of phenolics. Phenolics are the vital chemical ingredient of some culinary and medicinal mushroom, such as Phellinus pini [ 25 ], Flammulina velutipes [ 26 ], Inonotus obliquus [ 27 ], Ganoderma lucidum [ 28 ], Pleurotus citrinopileatus [ 29 ], Hypsizygus marmoreus [ 30 ], Porodaedalea chrysoloma [ 31 ], Antrodia cinnamomea [ 32 ], and Tuber indicum [ 33 ], etc. Phenolics exhibit antioxidant activity and provide health benefits.…”

Biologically active secondary metabolites from white-rot fungi

“… Zhao et al (2021) identified flavonoids, including gallic acid, ferulic acid, flavonoids epicatechin-3-gallate, epigallocatechin-3-gallate, naringin, rutin, naringenin, phelligridin G, inoscavin B, and davallialectone, from the ethanol extract of I. obliquus . Moreover, they showed that cultivating I. obliquus on wheat straw led to increased levels of inoscavin B and davallialectone.…”

Therapeutic properties of Inonotus obliquus (Chaga mushroom): A review

“…Therefore, attempts have been made to increase the production of phenolics and flavonoids by I. obliquus through different treatment processes to enhance its antioxidant activities. For example, Zhao et al ( 2021 ) reported that wheat straw culture increased the accumulation of inoscavin B ( 69 ) and davallialactone ( 71 ), while lignocellulose degradation enhanced the generation of flavonoids ECG ( 65 ), EGCG ( 66 ), rutin ( 73 ), and naringin ( 74 ), thereby augmenting I. obliquus’ antioxidative properties.…”