Cell experiment:

Jurkat cells (106 cells/mL) are cultured in the RPMI medium with or without different concentrations of ginkgolic acid for 48 hours to test the cytotoxicity of ginkgolic acid. The cytotoxicity of ginkgolic acid is determined using a tetrazolium compound (MTS) and an electron coupling reagent (PMS). MTS is chemically reduced by cells into formazan, which is soluble in the tissue culture medium. The measurement of the absorbance of the formazan can be carried out using 96 well microplates at 492 nm. Since the production of formazan is proportional to the number of living cells, the intensity of the produced color is a good indication of the viability of the cells.

Ginkgolic acid is an alkylphenol derivative that causes allergic skin inflammation. IC50 values of ginkgolic acid against the SUMOylation of RanGAP1-C2 are 3.0 μM. Ginkgolic Acid, a Major Component of Ginkgo biloba Extract, inhibited SUMOylation in vitro and in vivo [1].

The cytotoxicity of ginkgolic acid (15:1) in primary rat hepatocytes was lower than in HepG2 cells. Ginkgolic acid (15:1) was demonstrated less cytotoxicity in four-day-cultured primary rat hepatocytes than in 20-h cultured ones. Co-incubation with selective CYP inhibitors, α-naphthoflavone and ketoconazole, could decrease the cytotoxicity of ginkgolic acid (15:1) in primary rat hepatocytes. In agreement, pretreatment with selective CYP inducers, β-naphthoflavone and rifampin, could increase the cytotoxicity of ginkgolic acid (15:1) in HepG2 cells [2]. Ginkgolic acid inhibited the growth of tumorogenic cell lines in a dose- and time-dependent manner. Tumor cells were treated with GA for 72 h, 70.53 ± 4.54% Hep-2 and 63.5 ± 7.2% Tca8113 cells were retarded at GO/G1 phase, and the percentage of apoptosis was 40.4 ± 1.58 and 38.4 ± 1.7%, respectively [3]. In 293T cells expressing Flag-tagged SUMO, ginkgolic Acid Inhibited SUMOylation. Ginkgolic acid impaired SUMOylation by blocking the formation of an E1-SUMO thioester complex, by directly binding to E1 [1].

References:
[1] Fukuda I, Ito A, Hirai G, et al.  Ginkgolic acid inhibits protein SUMOylation by blocking formation of the E1-SUMO intermediate[J]. Chemistry & biology, 2009, 16(2): 133-140.
[2] Liu Z H, Zeng S.  Cytotoxicity of ginkgolic acid in HepG2 cells and primary rat hepatocytes[J]. Toxicology letters, 2009, 187(3): 131-136.
[3] Zhou C, Li X, Du W, et al.  Antitumor effects of ginkgolic acid in human cancer cell occur via cell cycle arrest and decrease the Bcl-2/Bax ratio to induce apoptosis[J]. Chemotherapy, 2010, 56(5): 393-402.