Epothilone B from Aspergillus fumigatus with a strong antiproliferative and anti-tubulin polymerizing activities; apoptosis, and cell cycle analyses

Abstract

Abstract Epothilones were designated as one of the most recognized chemotherapeutic agents towards the drug-resistant tumors, for their higher potency to bind and stabilize the β-tubulin arrays, stopping the cell cycle. Epothilones were chemically resolved from Aspergillus fumigatus # MN744705.1, that being more affordable source than Sorangium cellulosum , for its rapid growth and unique biological behaviour. So, the aim of this work was to emphasize the chemical identity and efficacy of Aspergillus fumigatus Epothilone . The Epothilone structure of A. fumigatus was determined by HPLC, FT-IR, LC–MS analyses, with 507.7 m/z, compared to the authentic one of S. cellulosum . Aspergillus fumigatus epothilone B had the highest activity against HepG-2 (IC 50 value 6.3 μM), and HCT-116 and Pc3 (IC 50 value 7.4 μM), compared to Vero cells (18.7 μM) with selectivity index 2.9, 2.5, and 2.47, respectively. The anti-tubulin polymerizing potency of the purified Epothilone was about two folds more than Taxol, with an obvious resilient arrest to the cellular growth of the cells of HepG-2 at G2/M phase. The total, early and late apoptosis of the HepG2 cells were increased by 26.5%, 15.9% and 7.6%, respectively, with the epothilone of A. fumigatus, with an overall increase of apoptosis by 12 folds, compared to control. The caspase-9 and 3 activities were increased by 4 folds and 2.5 folds, with the Epothilone B, as revealed from the colorimetric activity and gene expression analyses. The level of released LDH of HepG-2 cells was increased exponentially with the Epothilone concentration, ensuring their negative effect on the plasma membrane permeability. From the docking results, the binding energy of Epothilone B with the tubulin-β was -9.96 kcal/mol, that was lower than Taxol (-7.87 kcal/mol), ensuring the higher affinity of Epothilone B to bind with the β-tubulin protein.