Anticancer Active Secondary Metabolites Of Three Endophytic Fungi

Secondary metabolites of endophytic fungi have the characteristics of excellent biological activity and novel structure.They are significant natural sources of lead compounds in drug development.Ajuga decumbens Thumb.and Pseudostellaria heterophylla(Miq.)Pax ex Pax et Hoffm.are two authentic medicinal materials of Fujian Province,which contain a large amount of active substances.However,there are very few studies of endophytic fungi on these two plants in the literature.So we choose the endophytic fungi of these two plants as one of our research objects.Firstly,the strains were screened by the tumor cell model.In the preliminary work of the laboratory,strain A-S-6 with good cytotoxic activity was screened by MTT assays from 12 strains of endophytic fungi of Ajuga decumbens.Strains ?-f-33' and ?-L-13 were screened by PML/RARa fusion proteins degradation activity experiments from 104 stralins of endophytic fungi of Pseudostellaria heterophylla.In this study,the three active strains A-S-6,?-f-33' and ?-L-13 were our research objects.The secondary metabolites of the three active strains were separated and purified by normal phase silica gel column chromatography and reversed phase,gel column chromatography sephadex LH-20,high performance liquid chromatography and recrystallization.The structures of the isolated compounds were identified by high resolution mass spectrometry,nuclear magnetic resonance spectroscopy,circular dichroism,ultraviolet spectroscopy,infrared spectroscopy and other methods.12 compounds were isolated from strain A-S-6,in which compound 4,5 and 10 were new compounds.4 compounds were isolated from strain ?-f-33'.From strain ?-L-13,5 compounds were isolated and compound 19 was a new compound.Finally,a total of 21 compounds were isolated from active strains,including 8 indole alkaloids,5 trichothecenes,2 benzodiazepines,2 pyrone derivatives,1 xanthone dimer,1 porphyrin compound,1 dihydroisocoumarin compound and 1 benzene derivative.The cytotoxic activity evaluation and the degradation activity of PML/RARa fusion proteins were evaluated for the isolated compounds.Compounds 11 and 16 were found to have strong cytotoxic activity.Compound 10 has selective cytotoxic activity against human epidermal cancer cell line A431 with IC50=40.2 7?M.Compound 12 has weak selective cytotoxic activity against human osteosarcoma cell U-20S cells.Compounds 14,16 and 21 can degrade PML/RARa fusion proteins,induce apoptosis in APL cells,and may act through the casepase pathway.This study found the anti-cancer active ingredients from the endophytic fungi of Ajuga decumbens and Pseudostellaria heterophylla.We provide lead compounds for further study on looking for anti-cancer mechanisms of these compounds,looking for targets of the compounds in the cells,discussing the structure-activity relationship of the compounds and the development of new anti-cancer drugs.