Identification of potential anti-tumor compounds from the stipe of Ganoderma sinense using liquid chromatography-mass spectrometry-based chemometrics

Ganoderma (Lingzhi) has been used in Traditional Chinese Medicines for the prevention or treatment of cancer. Among the various species, Ganoderma lucidium had been studied extensively and was shown to possess antitumor activities. In contrast, there is little known about the bioactivity and chemical composition of Ganoderma sinense. We have previously studied the antitumor activity of different parts of G. sinense and found that the stipe exhibited more potent antitumor activity than the pileus [1]. Hence, in this study, we aimed to identify marker compounds from the stipe of G. sinense with potential anti-tumor activity using liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS) with multivariate statistical tools. This chemometric technique could facilitate analysis of bioactive compounds from plants with less time, solvent and raw materials as compared to traditional bioactivity-guided isolation method [2]. The stipe of G. sinense was firstly extracted with water, and then separated using silica gel column eluted with dichloromethane followed by ethyl acetate – methanol (10:0 to 9:1) to give five fractions (GS-E-1 to GS-E-5). The cytotoxic activities of these fractions were then assessed using MTT assay in murine breast tumor 4T1 cells. Among all fractions tested, sub-fraction GS-E-1 was found to possess the strongest cytotoxic activity. The chemical composition of this sub-fraction GS-E-1 was further studied using LC-TOF-MS and analysed with multivariate statistical tools. The chemometric analysis indicated that significant amount of 9- and 13-oxo-octadecadienoic acids were present uniquely in sub-fraction GS-E-1. The cytotoxic activities of 9- and 13-oxo-octadecadienoic acids have been reported previously, which may account for the cytotoxic activities of the sub-fraction GS-E-1 in breast tumor cells. In conclusion, this is the first report of the presence of 9- and 13-oxo-octadecadienoic acids in the stipe of G. sinense and they might be responsible for the anti-tumor activities. Further studies will be needed to confirm their activities.

Keywords: Ganoderma sinense, stipe, LC-TOF-MS, anti-tumor, 9-oxo-octadecadienoic acid, 13-oxo-octadecadienoic acid.

References:

[1] Yue GGL, Fung KP, Tse GMK, Leung PC, Lau CBS. Comparative studies of various Ganoderma species and their different parts with regard to their antitumor and immunomodulating activities in vitro. J Altern Complement Med 2006, 12: 777 – 789

[2] Kulakowski DM, Wu SB, Balick MJ, Kennelly EJ. Merging bioactivity with liquid chromatography-mass spectrometry-based chemometrics to identify minor immunomodulatory compounds from a Micronesian adaptogen, Phaleria nisidai. J Chromatogr A 2014, 1364: 74 – 82

No conflict of interest has been declared by the author(s).