Anti-cancer Effects of a Neutral Triterpene Fraction from Ganoderma lucidum and its Active Constituents on SW620 Human Colorectal Cancer Cells
Authors: Li Peng , Liu Lingxue , Huang Sheng , Zhang Yonghong , Xu Jianhua , Zhang Zhiqiang 
Published: October 2019

Background:

Ganoderma lucidum (Leyss. ex Fr.) Karst. (G. lucidum, GL) belongs to the family of
Ganodermataceae (Basidiomycetes), and possesses activities including antitumor, antimicrobial, antiviral, and
antiaging activities. Triterpenoids are typical chemical constituents in G. lucidum, and play an important role in
the anti-cancer effects. According to the substituent group at the carbon 26 position, GL total triterpenes fraction
can be divided into two types, Neutral Triterpene Fraction (NTF) and an Acidic Triterpene Fraction (ATF). The
anti-cancer effects of total triterpenes fraction and total acidic triterpene fraction extracted from G. lucidum have
been widely known in vivo and in vitro, whereas few have focused on total neutral triterpene fraction.

Objective:

The aim of this study was to evaluate the anti-cancer effects of NTF extracted from G. lucidum in
vitro and in vivo and explore its anti-cancer active constituents on SW620 human colorectal cancer cells.

Methods:

NTF and ATF were extracted from the dry fruiting body of G. lucidum by impregnation method with
90% ethanol, and further isolated by using alkaline extraction and acid precipitation method. The total triterpenoid
content of NTF and ATF was determined by using ultraviolet-visible spectrophotometry. The cytotoxic
effects on human colon cancer cells SW480, SW620, SW1116, and mouse embryonic fibroblast cell line
NIH3T3 were evaluated by using the MTT method. The anti-cancer activity of NTF in vivo was evaluated in
Athymic nude mice against SW620 cells. An activity-guided separation and purification process were used to
identify the anti-cancer active constituents of NTF by column and preparative high-performance liquid chromatography.
Structures of the constituents were confirmed by 1H-NMR, 13C-NMR and MS. Protein expression was
performed by Western blotting.

Results:

The percentage of total triterpenoids was 46.7% and 57.6% in ATF and NTF, respectively. Both fractions
could reduce the viability of SW480, SW620, and SW1116 cells in vitro, whereby NTF exhibited a
stronger effect than ATF. NTF markedly inhibited the growth of SW620 cell xenografts in mice at doses (250,
500mg/kg) during the treatment. Furthermore, a new garnoderic alcohol, named as ethyl ganoderate A and eight
known ganoderic alcohols were isolated and identified from NTF by a bioassay-guided separation process. All
of these compounds possessed anti-cancer activities against SW620 cells in vitro. As a representative ganoderma
alcohol, ganodermanondiol significantly reduced the viability of SW620 cells through the induction of
apoptosis, which was associated with the upregulated the levels of cleaved-poly (ADP-ribose) polymerase
(PARP), cleaved-caspase-3, and -9. In addition, ganodermanondiol showed low cytotoxic activity against normal
NIH3T3 cells.

Conclusion:

NTF are potential anti-cancer agents against colon cancer and the active constituents may be ganoderic
alcohols whose inhibitory mechanism of anti-cancer action may be related to the activation of a mitochondrial-
dependent pathway.