Chemical profile and antioxidant activity of bidirectional metabolites from Tremella fuciformis and Acanthopanax trifoliatus as assessed using response surface methodology

Abstract

This study aimed to establish a bidirectional fermentation system using Tremella fuciformis and Acanthopanax trifoliatus to promote the transformation and utilization of the synthesized antioxidant metabolites from fermentation supernatant. The effect of fermentation conditions on the total phenolic content was investigated using response surface methodology in terms of three factors, including temperature (22–28°C), pH (6–8), and inoculum size (2–8%, v/v). The optimized fermentation parameters were: 28°C, pH 8, and an inoculum size of 2%, which led to a maximum total phenolic content of 314.79 ± 6.89 μg/mL in the fermentation supernatant after 24 h culture. The content of total flavonoids and polysaccharides reached 78.65 ± 0.82 μg/mL and 9358.08 ± 122.96 μg/mL, respectively. In addition, ABTS+, DPPH⋅, and ⋅OH clearance rates reached 95.09, 88.85, and 85.36% at 24 h under optimized conditions, respectively. The content of total phenolics, flavonoids and polysaccharides in the optimized fermentation supernatant of T. fuciformis–Acanthopanax trifoliatus increased by 0.88 ± 0.04, 0.09 ± 0.02, and 33.84 ± 1.85 times that of aqueous extracts from A. trifoliatus, respectively. Simultaneously, 0.30 ± 0.00, 0.26 ± 0.01, and 1.19 ± 0.12 times increase of antioxidant activity against ABTS+, DPPH⋅, and ⋅OH clearance rates were observed, respectively. Additionally, the metabolite composition changes caused by fermentation were analyzed using ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) based on untargeted metabolomics and the phytochemical profile of fermentation supernatant differentiated significantly based on unsupervised principal component analysis (PCA) during fermentation from 24 to 96 h. Furthermore, a significant increase in antioxidant phenolic and flavonoid compounds, such as ellagic acid, vanillin, luteolin, kaempferol, myricetin, isorhamnetin, and (+)-gallocatechin, was observed after fermentation. Thus, these results indicated that the fermentation broth of T. fuciformis and A. trifoliatus had significant antioxidant activity, and may have potential application for health products such as functional beverages, cosmetics, and pharmaceutical raw materials.

Optimization of Antioxidant Activity of Compounds Generated during Ginseng Extract Fermentation Supplemented with Lactobacillus

“…As can be seen in Figure 3 A,C,E, in our case, the response surface curves changed sharply, indicating that they had a greater influence on the response value. When the contours of the interaction of the influencing factors are oval or saddle-shaped, the interaction of the two factors is significant; it is not significant when the contours are round [ 26 ]. As shown in Figure 3 B,D, the contour plot approached an oval shape, and the slope of the surface was steep, indicating that the interaction of the two groups of factors was significant; in other words, the interaction of the two factors had a significant effect on the O 2 ·− scavenging rate.…”

“…The liquid chromatography-mass spectrometry ion source operating parameters were as follows: Electrospray ion source (ESI) was used, the scanning mode was positive and negative ion switching, the multiple reaction monitoring mode was used for detection, the atomized gas flow was 3.0 L/min, the drying gas flow was 10.0 L/min, the heating gas flow was 10 L/min, the connection temperature was 300 • C, the desolvation line was at 250 • C, the heating block temperature was 400 • C, and the collision-induced dissociation pressure was 270 kPa. The following three factors were varied with the aim of increasing the antioxidant activity of the fermentation products: fermentation time (15,30,45,60, and 75 h), fermentation temperature (26,28,30,32, and 34 • C), and inoculum size (1.5, 2.0, 2.5, 3.0, and 3.5% v/v). The selection of time, temperature, and inoculum size as the main factors for process optimization was based on the method proposed by Tao et al [75].…”

“…and Radix Puerariae significantly increased the yield and antioxidant activity of produced exopolysaccharides [ 24 ], and these metabolites were found to prolong the life and improve the health of Caenorhabditis elegans [ 25 ]. In another study, we analyzed the active substances in the fermentation broth of Tremella albophyllum and found that they had antioxidant activity [ 26 ]. Additionally, Lactobacillus acidophilus was employed to ferment dandelion, and the capacity of the fermented extract to reduce uric acid and the underlying mechanism were validated [ 27 ].…”

“…Additionally, Lactobacillus acidophilus was employed to ferment dandelion, and the capacity of the fermented extract to reduce uric acid and the underlying mechanism were validated [ 27 ]. Our previous studies have included various attempts to realize the bidirectional fermentation of probiotics and medicinal plants [ 24 , 25 , 26 , 27 ]. Typically, a cosmetic ingredient named SPG (Schizophyllan), has been put into commercial production by MARUBI, a listed company based in Guangzhou, China.…”