Phenolic complexes are a major group of polyphenols in aged red wine. The objective of this work was to evaluate the in vitro antioxidant activity of the phenolic complexes. Thus, red wine polyphenols were fractionated into various fractions including monomers, oligomers, polymers, anthocyanins, and complexes. The in vitro antioxidant activities of these fractions and other phenolic standards (catechin, epicatechin, quercetin, and malvidin 3-glucoside) as well as ascorbic acid were verified by DPPH* test. On the other hand, the variation of antioxidant activities during the reaction between epicatechin and malvidin 3-glucoside mediated by acetaldehyde in a model wine solution was also monitored. The results showed that both the phenolic complex fraction and newly formed condensation products between epicatechin and malvidin 3-glucoside maintain antioxidant activities as strong as those of their compositional phenolics. This work provides, for the first time, direct evidence about the in vitro antioxidant activities of red wine phenolic complexes.

Background. Conyza blinii H. Lév is a medicinal plant that has a variety of pharmacological activities, but its study is at a standstill due to the shortage of resources. Method. This study utilized the surface sterilization method to isolate endophytic fungi, and they were preliminarily identified by morphology. Flavonoid-producing strains were screened by NaNO 2 -Al(NO) 3 colorimetry and further identified by the ITS sequence. Additionally, we used five antioxidant assays (DPPH, Hydroxyl radical, ABTS, FRAP and T-AOC assays) to systematically evaluate the antioxidant capacity of total flavonoids , and we also determined their antibacterial activity. Results. In this study, 21 endophytic fungi were isolated from wild Conyza blinii H. Lév for the first time. There were six flavonoid-producing strains, especially CBL11, whose total flavonoid content reached 50.78 ± 2.4 mg/L. CBL12, CBL12-2 and CBL1-1 all exhibited excellent antioxidant activity. The effect of CBL12 was similar to that of ascorbic acid at low concentrations, and its radical scavenging rates for DPPH and ABTS were 94.56 ± 0.29 % and 99.88 ± 0.27%, respectively, while its IC 50 values were only 0.11 ± 0.01 mg/mL and 0.2 ± 0.01 mg/mL. Through LC-MS, we found that CBL12 could produce many high-value flavonoids, such as 3-methoxyflavone, nobiletin, formononetin, scopoletin, and daidzein. Additionally, CBL9 had good antibacterial activity against both gram-positive and gram-negative bacteria. Notably, we obtained the high-yield strains CBL12 and CBL9, which not only had high yields (10.64 ± 1.01 mg/L and 10.17 ± 0.11 mg/L, respectively) but also had excellent biological activity. Hence, the results of this study provide new ideas for endophytic fungi that can be exploited as a source of flavonoids and other medicinal components from Conyza blinii H. Lév. Moreover, this study can serve as a reference for the development of rare medicinal materials. G. 2020. Isolation and identification of flavonoid-producing endophytic fungi from medicinal plant Conyza blinii H.Lév that exhibit higher antioxidant and antibacterial activities. PeerJ 8:e8978 http://doi.Patil MP, Patil RH, Maheshwari VL. 2015. Biological activities and identification of bioactive metabolite from endophytic aspergillus flavus L7 isolated from aegle marmelos. Current Microbiology 71:39-48 GN. 2006. The endophytic fungus Trametes hirsuta as a novel alternative source of podophyllotoxin and related aryl tetralin lignans.

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