Studies On Antitumor Activity Of Metarhizium Taii And Determination,Separation And Identification Of Its Secondary Metabolites

Objective:To evaluate the antitumor activity of Metarhizium taii, and to establish the HPLC fingerprint of active nucleosides of M. taii, as well as to separate secondary metabolites of M. taii.Methods:S180and B16solid tumor-bearing mice model were found by a subcutaneous transplant method. A series of routine methods were employed to evaluate the antitumor activity of M. taii, including mortality rate, inhibitory rate of tumor growth, thymus index, spleen index and survival rate of cancer-bearing mice. The fingerprint of nucleoside of M. taii was analyzed by high performance liquid chromatography (HPLC). Secondary metabolites of M. taii were isolated by various chromatographic techniques, and their chemical structures were identified using MS, NMR and other spectra. The activity of inhibiting tumour cell proliferation was measured by a sulforhodamine B (SRB) assay.Results:The active fraction from M. taii has obvious inhibitory effects against S180-bearing KM mouse at different doses of50mg/kg, and100mg/kg, and the tumor inhibitory rates are33.57%and57.88%, respectively. Also, there is a significant inhibitory action against melanoma B16-bearing C57BL/6mouse with the tumor inhibiting rate of31.49%at the dose of100mg/kg. Furthermore, the active fraction of M. taii could obviously affect the immune organs indices in tumor-bearing mice, inhibit the formation of blood vessels of tumor tissue in tumor-bearing mice, and decrease the lung metastasis in the melanoma B16-bearing mouse. Further, the fingerprint of active nucleoside compounds in M. taii was established by HPLC, in which11nucleoside compounds including uracil, cytidine, uridnine,2’-deoxyuridine, inosine, guanosine, adenine, thymine, adenosine, and2’-deoxyadenosine were detected and identified. Adenosine (2388±94μg/g), uracil1601±52μg/g), and undine (1295±57μg/g) were main nucleoside components. In this study, ergosterol was isolated and identified, and anti-cancer screen showed that ergosterol exhibited potent inhibition action against SGC-7901tumor cells with IC50value of5.99μM.Conclusions:The CHCl3extract fraction from M. taii is an active fraction with antitumor activity, and its antitumor actitivity is closely associated with the immunoregulatory and antiangiogenesis in tumor-bearing mice. The fingerprint of active nucleosides of M. taii was established. Ergosterol is one of the important antitumor components in active fraction of M. taii.