sp. strain , an endophytic fungus isolated from Zucc., produces taxol and other bioactive metabolites.

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The current study focuses on the isolation and in vitro characterization of bioactive metabolites produced by endophytic fungi isolated from the Himalayan yew ( Zucc.). The endophytic fungi were isolated on artificial media from inner tissues of bark and needles. Antimicrobial and antioxidant activity, along with total phenolic- and flavonoid-content assays were used in the evaluation of bioactivity of the fermented crude extracts. The ability of the endophytes to produce the anticancer compound Taxol was also analyzed using thin-layer chromatography (TLC) and reverse-phase high-performance liquid chromatography (RP-HPLC). A total of 16 fungal morphotypes were obtained from asymptomatic inner tissues of the bark and needles of . Among the 16 isolates, the ethyl acetate (EA) fraction of isolate , showed antibacterial and antifungal activity against all test-pathogens used ( ATCC 19433, ATCC 12600, ATCC 6633, ATCC 25922, ATCC 13076, ATCC 27853, and ). showed significant inhibition against ATCC 27853 (minimum inhibitory concentration (MIC): 250 µg/ml) and the pathogenic yeast, (MIC: 125 µg/ml). Antioxidant activity, total phenolic, and total flavonoid content as well as in vitro Taxol production were evaluated for EA fraction of isolate . Antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. At a concentration of 100 µg/ml, the % DPPH radical scavenging activity was 83.15 ± 0.40, 81.62 ± 0.11, and 62.36 ± 0.29, for ascorbic acid, butylated hydroxytoluene (BHT), and the EA fraction of , respectively. The DPPH-Half maximal inhibitory concentration (DPPH-IC) value for the EA fraction was 81.52 ± 0.23 µg/ml, compared to BHT (62.87 ± 0.08 µg/ml) and ascorbic acid (56.15 ± 0.19 µg/ml). The total phenolic and flavonoid content in the EA fraction were 16.90 ± 0.075 µg gallic acid equivalent (GAE) and 11.59 ± 0.148 µg rutin equivalent (RE), per mg of dry crude extract, respectively. TLC and RP-HPLC analysis showed that the isolate also produces Taxol (282.05 µg/l of fermentation broth). Isolate was identified as sp. by internal transcribed spacer (ITS) sequencing. Having the ability to produce antimicrobial and antioxidant metabolites, as well as the anticancer compound Taxol, makes sp. strain , a promising candidate for further study of naturally occurring bioactive metabolites.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02693-z.