ABSTRACT
Salicylic acid (SA) is an effective elicitor to increase taxol production in Pestalotiopsis microspora. Addition of SA at the concentration of 300 µM yielded taxol 625.47 µg L-1, 45- fold higher than that of the control. Elicitation of the role of SA in the fungal taxol biosynthetic pathway revealed that SA enhanced reactive oxygen species and lipid peroxidation of unsaturated fatty acids of P. microspora mycelia. This oxidative process stimulates isoprene biosynthetic pathway by triggering expression of the geranylgeranyl pyrophosphate synthase gene leading to improved biosynthesis of taxol in P. microspora.
Subject(s)
Ascomycota/metabolism , Paclitaxel/metabolism , Salicylic Acid/pharmacology , Farnesyltranstransferase/biosynthesis , Fungal Proteins/biosynthesis , Gene Expression Regulation, Enzymologic/drug effects , Gene Expression Regulation, Fungal/drug effectsABSTRACT
BACKGROUND: Paclitaxel (taxol) is a potent anticancer drug that is used in the treatment of a wide variety of cancerous. In the present study, we identified a taxol derivative named 7-epi-10-deacetyltaxol (EDT) from the culture of an endophytic fungus Pestalotiopsis microspora isolated from the bark of Taxodium mucronatum. This study was carried out to investigate the effects of fungal EDT on cell proliferation, the induction of apoptosis and the molecular mechanisms of apoptosis in human hepatoma HepG2 cells in vitro. METHODS: The endophytic fungus was identified by traditional and molecular taxonomical characterization and the fungal EDT was purified using column chromatography and confirmed by various spectroscopic and chromatographic comparisons with authentic paclitaxel. We studied the in vitro effects of EDT on HepG2 cells for parameters such as cell cycle distribution, DNA fragmentation, reactive oxygen species (ROS) generation and nuclear morphology. Further, western blot analysis was used to evaluate Bcl-2-associated X protein (Bax), B-cell lymphoma 2 (Bcl-2), p38-mitogen activated protein kinase (MAPK) and poly [ADP-ribose] polymerase (PARP) expression. RESULTS: We demonstrate that the fungal EDT exhibited significant in vitro cytotoxicity in HepG2 cells. We investigated cytotoxicity mechanism of EDT in HepG2 cells. The results showed nuclear condensation and DNA fragmentation were observed in cells treated with fungal EDT. Besides, the fungal EDT arrested HepG2 cells at G2/M phase of cell cycle. Furthermore, fungal EDT induced apoptosis in HepG2 cells in a dose-dependent manner associated with ROS generation and increased Bax/Bcl-2 ratio, p38 MAPKs and PARP cleavage. CONCLUSIONS: Our data show that EDT induced apoptotic cell death in HepG2 cells occurs through intrinsic pathway by generation of ROS mediated and activation of MAPK pathway. This is the first report for 7-epi-10-deacetyltaxol (EDT) isolated from a microbial source.
Subject(s)
Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Endophytes/chemistry , Taxoids/pharmacology , Xylariales/chemistry , Antineoplastic Agents/chemistry , Carcinoma, Hepatocellular , Cell Cycle/drug effects , Cell Survival/drug effects , Hep G2 Cells , Humans , Liver Neoplasms , Reactive Oxygen Species/metabolism , Taxoids/chemistryABSTRACT
A novel phenolic compound, 4-(2,4,7-trioxa-bicyclo[4.1.0]heptan-3-yl) phenol (1), was isolated from Pestalotiopsis mangiferae, an endophytic fungus associated with Mangifera indica Linn. The structure of the compound was elucidated on the basis of comprehensive spectral analysis (UV, IR, ¹H-, ¹³C- and 2D-NMR, as well as HRESI-MS). Compound (1) shows potent antibacterial and antifungal activity against Bacillus subtilis, Klebsiella pneumoniae, Escherichia coli, Micrococcus luteus, Pseudomonas aeruginosa and Candida albicans. The transmission electron microscope study for the mode of inhibition of compound (1) on bacterial pathogens revealed the destruction of bacterial cells by cytoplasm agglutination with the formation of pores in cell wall membranes.
