Characterization of Compounds with Tumor-Cell Proliferation Inhibition Activity from Mushroom (Phellinus baumii) Mycelia Produced by Solid-State Fermentation

Abstract

The inhibition of tumor-cell proliferationbyan organicsolvent extract from the solid-state fermentation of Phellinus baumii mycelia inoculated in rice medium was investigated in vitro. The active compounds inhibiting tumor-cell proliferation were characterized. Results revealed that all (petroleum ether, chloroform, ethyl acetate, and butanol) fractions inhibited tumor-cell proliferation in a dose-dependent fashion. The ethyl acetate extract had the highest inhibitory effecton tumor-cell proliferation, and the butanol fraction had the lowest. Six compounds were isolated and purified from the ethyl acetate extract of P. baumii mycelia by the tandem application of silica-gel column chromatography (SGCC), high-speed countercurrent chromatography (HSCCC), and preparative HPLC. These compounds were identified by NMR and electrospray ionization-mass spectrometry (ESI-MS) spectroscopic methods as ergosterol (RF1), ergosta-7,22-dien-3β-yl pentadecanoate (RF3), 3,4-dihydroxy benzaldehyde(RF6), inoscavinA (RF7), baicalein(RF10), and 24-ethylcholesta-5,22-dien-3β-ol (RF13). To further clarify the activity of these compounds, the cell-proliferation-inhibition tests of these compounds on various tumor cells were carried out and evaluatedin vitro. Results suggested that compounds RF6, RF7, and RF10 had potent inhibition effects on the proliferation of a series of tumor cell lines, including K562, L1210, SW620, HepG2, LNCaP, and MCF-7cells. These findings indicated that P. baumii mycelia produced by solid-state fermentation in rice canbe used to obtain active compounds with the ability to inhibittumor-cell proliferation.

Keywords: Extracts; Phellinus baumii; compound isolation; proliferation inhibition; solid-state.

Figure 1

The effect of extracts from P. baumii mycelia on the proliferation of HepG2 tumor cells. Each value is expressed as means ± SD (n = 3). 5-fluorouracil (5Fu) served as a positive control.

Figure 2

HPLC chromatograms (λ = 254 nm) of the fractions from P. baumii mycelium. 1: chloroform extract; 2: ethyl acetate extract; 3: butane extract; 4: petroleum ether extract.

Figure 3

Chemical structures of compounds RF1, RF3, RF6, RF7, RF10, and RF13 isolated from P. baumii mycelium produced by solid-state fermentation in rice.

Figure 4

Inhibitory effects of compounds at different concentrations on various tumor cell lines in vitro. (a) K562 cells; (b) L1210 cells; (c) HepG2 cells; (d) SW620 cells; (e) LNCaP cells; (f) MCF-7 cells. 5Fu served as a positive control.RF1 is ergosterol; RF3 is ergosta-7,22-dien-3β-yl pentadecanoate; RF6 is 3,4-dihydroxy benzaldehyde; RF7 is inoscavin A; RF10 is baicalein; RF13 is 24-ethylcholesta-5,22-dien-3β-ol.

Figure 5

Isolation flow schematic diagram of compounds from ethyl acetate fraction. RF1, ergosterol; RF3, ergosta-7,22-dien-3β-yl pentadecanoate; RF6, 3,4-dihydroxy benzaldehyde; RF7, inoscavin A; RF10, baicalein; RF13, 24-ethylcholesta-5,22-dien-3β-ol. HSCCC: high-speed countercurrent chromatography; SGCC: silica gel column chromatography.