| Abstrakt: |
The current study focuses on the isolation and in vitro characterization of bioactive metabolites produced by endophytic fungi isolated from the Himalayan yew (Taxus wallichianaZucc.). 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 T. wallichiana. Among the 16 isolates, the ethyl acetate (EA) fraction of isolate MUS1, showed antibacterial and antifungal activity against all test-pathogens used (Streptococcus faecalisATCC 19433, Staphylococcus aureusATCC 12600, Bacillus subtilisATCC 6633, Escherichia coliATCC 25922, Salmonella entericaATCC 13076, Pseudomonas aeruginosaATCC 27853, and Candida albicans). MUS1showed significant inhibition against Pseudomonas aeruginosaATCC 27853 (minimum inhibitory concentration (MIC): 250 µg/ml) and the pathogenic yeast, Candida albicans(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 MUS1. 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 MUS1, respectively. The DPPH-Half maximal inhibitory concentration (DPPH-IC50) 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 MUS1also produces Taxol (282.05 µg/l of fermentation broth). Isolate MUS1was identified as Annulohypoxylonsp. by internal transcribed spacer (ITS) sequencing. Having the ability to produce antimicrobial and antioxidant metabolites, as well as the anticancer compound Taxol, makes Annulohypoxylonsp. strain MUS1, a promising candidate for further study of naturally occurring bioactive metabolites. |
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