Fiscalin A

Compounds isolated from the marine sea fan-derived fungus Neosartorya siamensis (KUFA 0017), namely, 2,4-dihydroxy-3-methylacetophenon (1), chevalone C (2), nortryptoquivaline (4), tryptoquivaline H (6), tryptoquivaline F (7), fiscalin A (8), epi-fiscalin A (9), epi-neofiscalin A (11) and epi-fiscalin C (13) were tested for anti-proliferative activity by MTT assay, DNA damage induction by comet assay, and induction of cell death by nuclear condensation assay on colon HCT116, liver HepG2 and melanoma A375 cancer cell lines. Compounds 2, 4, 8, 9, 11 and 13 presented IC50 values ranging from 24 to 153 μM in the selected cell lines. Cell death was induced in HCT116 by compounds 2, 4 and 8. In HepG2, compounds 4, 8, 9 and 11 were able to induce significant cell death. This induction of cell death is possibly not related to genotoxicity because none of the compounds induced significant DNA damage. These results suggest that selected compounds present an interesting anti-proliferative activity and cell death induction, consequently showing potential (specifically epi-fiscalin C) as future leads for chemotherapeutic agents. Further studies on mechanisms of action should ensue. Copyright © 2016 John Wiley & Sons, Ltd.

Samples of Xylaria humosa, a rare species of Xylariaceae, were collected during an investigation into the diversity of the fungus in the Phu Khieo Wildlife Sanctuary, Thailand. Nine compounds were isolated from the species and their structures elucidated by spectroscopic methods. The compounds were ergosterol (1), ergosterol peroxide (2), two meroterpenoids, chevalone B and C (3-4), together with five indole alkaloids, tryptoquivaline L (5), tryptoquivaline M (6), fiscalin A (7), epi-fiscalin A (8) and epi-fiscalin C (9). Compounds 2-9 exhibited variable cytotoxic activity against KB, NCI-H187 and MCF-7 cell lines.

Doxorubicin (Dox) is one of the most successful anticancer drugs in use. However, chemoresistance is one of the main limitations that patients face. Therefore, development of new strategies to improve the efficacy of Dox is needed. Marine-derived fungi are especially promising sources of new anticancer compounds. In this work, antitumor activity of crude ethyl extract of the cultures of the marine-derived fungus Neosartorya siamensis KUFA 0017 (NS), combined with Dox, was evaluated in six cancer cell lines. To evaluate possible mechanisms involved in the eventual improvement of Dox's cytotoxicity by NS extract, effects on DNA damage, cell death, ultrastructural modifications, and intracellular accumulation of Dox were assessed. The NS extract demonstrated a significant enhancement of Dox's cytotoxic activity in A549 cells, inducing DNA damage, cell death, and intracellular accumulation of Dox. Additionally, the cytotoxic effect of eight compounds, isolated from this extract, that is, 2,4-dihydroxy-3-methylacetophenone-(C1), nortryptoquivaline-(C2), chevalone C-(C3), tryptoquivaline H-(C4), fiscalin A-(C5), epi-fiscalin-C (C6), epi-neofiscalin A-(C7), and epi-fiscalin A-(C8), alone and combined with Dox was also evaluated in lung cancer cells. The cytotoxic effect of Dox was potentiated by all the isolated compounds (except C1) in A549 cells. Therefore, we concluded that NS extract potentiated cytotoxicity by inhibiting cell proliferation, increasing intracellular accumulation of Dox, and inducing cell death (possibly by an autophagic process). The isolated compounds also enhanced the activity of Dox, supporting the potential of this sort of combination. These data call for further studies to characterize drug interactions and underlying mechanisms.