Abstract: In order to study the antioxidant capacity of endophytic fungi,the total antioxidant capacity(FRAP method) and DPPH· assay were used to evaluate the antioxidant capacity of the 29 endophytic fungi metabolites and screen a high strain.The active strain LTS-6-6 was extracted to study the antioxidant capacity of the extractant of each phase.The results showed that the metabolites of 29 strains showed a certain antioxidant capacity,and 9 strains with strong DPPH· clearance rate(clearance rate≥50%) accounted for 31.03% of the tested strains.Among them,the strain LTS-6-6(Phrenochaeta) was a highly active strain.The ethyl acetate extract(EAE) of the fermentation broth showed strong antioxidant activity with the EC₅₀ of 7 μg/mL and a total antioxidant capacity of 527.59±10.66 mg Vc/g.The total phenolic and total flavonoid contents were respectively reached 641.14±7.50 mg gallic acid/g,100.30±8.44 mg rutin/g.The results indicated that the endophytic fungal metabolites of walnut had certain antioxidant capacity and were good resources for finding natural antioxidant active substances.

Key words: endophytic fungi of walnut, total reducing ability, DPPH·, antioxidant activity