ABSTRACT
Epothilones are one of the common prescribed anticancer drugs for solid tumors, for their exceptional binding affinity with ß-tubulin microtubule, stabilizing their disassembly, causing an ultimate arrest to the cellular growth. Epothilones were initially isolated from Sornagium cellulosum, however, their extremely slow growth rate and low yield of epothilone is the challenge. So, screening for a novel fungal endophyte dwelling medicinal plants, with higher epothilone productivity and feasibility of growth manipulation was the objective. Aspergillus niger EFBL-SR OR342867, an endophyte of Latania loddegesii, has been recognized as the heady epothilone producer (140.2 µg/L). The chemical structural identity of the TLC-purified putative sample of A. niger was resolved from the HPLC, FTIR and LC-ESI-MS/MS analyses, with an identical molecular structure of the authentic epothilone B. The purified A. niger epothilone B showed a resilient activity against MCF-7 (0.022 µM), HepG-2 (0.037 µM), and HCT-116 (0.12 µM), with selectivity indices 21.8, 12.9 and 4, respectively. The purified epothilone B exhibited a potential anti-wound healing activity to HepG-2 and MCF-7 cells by ~ 54.07 and 60.0%, respectively, after 24 h, compared to the untreated cells. The purified epothilone has a significant antiproliferative effect by arresting the cellular growth of MCF-7 at G2/M phase by ~ 2.1 folds, inducing the total apoptosis by ~ 12.2 folds, normalized to the control cells. The epothilone B productivity by A. niger was optimized by the response surface methodology, with ~ 1.4 fold increments (266.9 µg/L), over the control. The epothilone productivity by A. niger was reduced by ~ 2.4 folds by 6 months storage as a slope culture at 4 °C, however, the epothilone productivity was slightly restored with ethylacetate extracts of L. loddegesii, confirming the plant-derived chemical signals that partially triggers the biosynthetic genes of A. niger epothilones. So, this is the first report emphasizing the metabolic potency of A. niger, an endophyte of L. loddegesii, to produce epothilone B, that could be a new platform for industrial production of this drug.