Xanthones and benzophenones isolated from the endophytic fungus Penicillium sp. ct-28 of Corydlis tomentella and their cytotoxic activity.

One new xanthone, griseophenexanthone A (1), one new benzophenone, digriseophene A (2), and 14 previously reported compounds were isolated from the culture of Penicillium sp. ct-28, an endophytic fungus of Corydlis tomentella. The structures of the isolated compounds were identified by an extensive analysis of HRESIMS, 1D and 2D NMR. MTT assay showed that six xanthones (1 and 3-7) significantly inhibited cell proliferation in four cancer cell lines, with IC50 values ranging from 18.12 ± 2.42 to 85.55 ± 7.66 µM. Our results showed that slight structural changes led to obvious activity differences among these compounds. We also investigated the effects of the six xanthones on cell cycle and apoptosis in human hepatoma HepG2 cells. Compound 7 caused cell cycle arrest at G1 phase, compounds 5 and 6 caused cell cycle arrest at S phase, whereas compounds 1, 3 and 4 had no effects on cell cycle distribution. All six xanthones induced apoptosis in dose-dependent manners in HepG2 cells accompanied by degradation of PARP and activation of caspase 3. The structure-activity relationship analysis revealed that the effects of these xanthones on cell cycle and apoptosis in HepG2 cells were closely related to the substituent groups on their skeleton. Our studies provide novel insights for the structural optimization of xanthones in the development of new anticancer drugs.

Characterization and identification of iridoid glucosides, flavonoids and anthraquinones in Hedyotis diffusa by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry.

The multiple bioactive constituents in Hedyotis diffusa Willd. (H. diffusa) were extracted and characterized by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC-ESI-MS(n)). The optimized separation condition was obtained using an Agilent ZorBax SB-C18 column (4.6×150 mm, 5 µm) and gradient elution with water (containing 0.1% formic acid) and acetonitrile (containing 0.1% formic acid), under which baseline separation for the majority of compounds was achieved. Among the compounds detected, 14 iridoid glucosides, 10 flavonoids, 7 anthraquinones, 1 coumarin and 1 triterpene were unambiguously identified or tentatively characterized based on their retention times and mass spectra in comparison with the data from standards or references. The fragmentation behavior for different types of constituents was also investigated, which could contribute to the elucidation of these constituents in H. diffusa. The present study reveals that even more iridoid glycosides were found in H. diffusa than hitherto assumed. The occurrence of two iridoid glucosides and five flavonoids in particular has not yet been described. This paper marks the first report on the structural characterization of chemical compounds in H. diffusa by a developed HPLC-ESI-MS(n) method.