posted on 2017-04-14, 15:22authored byTehane Ali, Masanori Inagaki, Hee-byung Chai, Thomas Wieboldt, Chad Rapplye, L. Harinantenaina Rakotondraibe
One new chlorinated xanthone, 6-chloro-3,8-dihydroxy-1-methylxanthone
(1), a new 2-bromo-gentisyl alcohol (2),
and a mixture of 6-epimers of 6-dehydroxy-6-bromogabosine C (3a and 3b), together with 19 previously identified
compounds, epoxydon (4), norlichexanthone (5), 2-chlorogentisyl alcohol (6), hydroxychlorogentisyl
quinone (7), 6-dehydroxy-6α-chlorogabosine C (8a), 6-dehydroxy-6β-chlorogabosine C (8b), gentisyl alcohol (9), gentisyl quinone (10), (R,S)-1-phenyl-1,2-ethanediol (11), dehydrodechlorogriseofulvin (12), dechlorogriseofulvin
(13), dehydrogriseofulvin (14), griseofulvin
(15), ethylene glycol benzoate (16), alternariol
(17), griseoxanthone C (18), drimiopsin
H (19), griseophenone C (20), and griseophenone
B (21), were isolated from cultures of Penicillium
concentricum, a fungal endophyte of the liverwort Trichocolea tomentella. The structures of the new compounds
(1, 2, 3a, and 3b) were elucidated by interpretation of spectroscopic data including
one- and two-dimensional NMR techniques. Among these, compounds 2–4 displayed modest cytotoxicity to the
MCF-7 hormone-dependent breast cancer cell line with IC50 values of 8.4, 9.7, and 5.7 μM, respectively, whereas compound 9 exhibited selective cytotoxicity against the HT-29 colon
cancer cell line with an IC50 value of 6.4 μM. During
this study we confirmed that the brominated gentisyl alcohol (2) was formed by chemical conversion of 4 during
bromide salt addition to culture media.