ANTICANCER AGENTS FROM ENDOPHYTES

The cytotoxic effect of fungal taxol isolated from the culture filtrate of M1D and PDB, was detected and quantified by using in vitro apoptotic method of assay23 on various cancer cells, at various concentrations. The human cancer cell lines (HLK210, H116, Int407, HL251 and BT220) were procured from the National Centre for Cell Sciences (NCCS), Pune, India. The morphological changes of the cancer cells which were treated with different concentrations of fungal taxol ranging between 0.005 μM and 5 μM were incubated for 48 h. The cells were then stained (DNA staining) with 0.5 mg/ml propidium iodide in phosphate buffered saline (PBS) for 15 min and de-stained in PBS solution. After ISSN 0975-6299 Vol.1/Issue-3/Jul-Sep.2010 www.ijpbs.net Microbiology 7 treatment with different concentrations of fungal taxol, the cell morphology was determined by light microscopy. In all, five different fields were randomly selected for counting at least 500 cells. The percentage of apoptotic cells was calculated for each experiment. Cells designated as apoptotic were those that displayed the characteristic morphological features of apoptosis, including cell volume shrinkage, chromatin condensation and the presence of membrane bound apoptotic bodies. The cells in the apoptosis were calculated by using the following formula. Percentage of apoptotic cells = Number of apoptotic cells/ Total number of cells × 100 Cytotoxicity effect of fungal taxol isolated from the endophytic fungus was detected and quantified using apoptotic assay23 on various cancer cells The taxol-producing endophytic fungi had previously tested for their cytotoxic activity via an apoptotic assay against different cancer cell lines. They showed strong cytotoxic activity in the presence of BT220, H116, Int407, HL251 and HLK210 human cancer cells in vitro. Previous report of the endophytic fungus showed the strong cytotoxic activity towards BT 220, H116, Int 407, HL 251 and HLK 210 human cancer cells in vitro, tested by Apoptotic assay13,30.

Recently,Taxol was tested using an in vitro cytotoxicity assay against human cancer cell lines (A-549 for lung cancer, HEP-2 for liver cancer, OVCAR-5 for ovarian cancer) in comparison with the standard authentic example, resulting in comparable activities20. Cytotoxicity effect of fungal taxol from medicinal plants were further tested using apoptotic assay on various cancer cells viz., human breast cell BT220, human colon H116, human intestine Int407, human lung HL251 and human leukemia HLK 210. It is indicated that with the increase of taxol concentration from 0.005 μM to 0.05 μM, taxol induced increased cell death through apoptosis. With further increase of taxol concentration from 0.05 μM to 0.5 μM, the taxolinduced cell death through apoptosis only increased slightly. When the taxol concentration was increased from 0.5 μM to 5 μM, the taxolinduced cell death through apoptosis decreased dramatically. It was observed at low to medium concentration (0.005–5 μM), the efficacy of fungal taxol was quite dependent on the specific cell type. It has been reported that taxol at low concentrations (nM) induces cell apoptosis and the efficacy of taxol is quite dependent on the specific cell type. This also supports the previous findings of other groups that at low concentration, taxol inhibits cell proliferation by blocking mitosis. 

CONCLUSION ：The aim of this review clearly mention about the isolation and characterization of taxol producing endophytic fungi from medicinal plants. In the review, it is confidently evident that the spectroscopic and chromatographic estimates are close to reality, given fact that the fungal taxol and standard taxol give identical results. It alsoindicates that the formation of taxol by endophytic fungus was found to be the highest and suggests that the fungus can serve as a potential species for genetic engineering to enhance the production of taxol. The significance in the discovery of fungi that produce taxol indicate that there are abundant resources of fungi that produce taxol. A background understanding that involves some specific examples and rationale of the presence of endophytic microorganisms in higher plants will aid in the development of a drug discovery program involving these organisms. A search for a rare and thus, expensive product such as Taxol may be facilitated by examining the endophytic microorganisms of certain plants for their ability to make this drug. To meet the urgent need of clinic and scientific research, besides Taxus supply, other approaches to obtain Taxol have also been discussed here.

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