In vitro toxicity of Ganoderma lucidum

Simerpal Kaur Gill2, Ricky Man5, Michael Rieder1,2,3,4. Departments of Paediatrics1 Physiology & Pharmacology2 and Schulich School of Medicine3, University of Western Ontario and Robarts Research Institute4, Department of Pharmacology5, University of Hong Kong.

Ganoderma lucidum (Ling-zhi, Reishi mushroom) has been used in Traditional Chinese Medicine for over 5000 years for a wide array of ailments (Chen et al. 2004). Recently, it has been suggested that the polysaccharide extract of Ganoderma lucidum (PS-GL) possesses anti-tumor properties due to immunostimulation (Shiao, 2003). It has been suggested that PS-GL can be used as an adjunctive to chemotherapy in paediatric patients undergoing chemotherapy to enhance the immune system and decrease the risk of infections (Silva, 2003). However, the toxicity of both PS-GL and the crude extract of GL for this condition remain unknown.

The objective of these experiments was to determine the toxicity of PS-GL and GL in cells of the lymphoreticular lineage (Jurkat E6.1 cells and LG2 cells).

Two different cell types were used: Jurkat E6.1 cells, T cell lymphoblasts, and LG2 cells, B cell lymphoblasts. A thiazolyl blue tetrazolium bromide (MTT) toxicity assay was used to measure percent cell viability as compared to control. Cells were incubated with concentrations of PS-GL or GL ranging from 50µg/mL to 350 µg/mL for 24 hours and 48 hours. Plates were incubated overnight, and cell viability was assessed the next day using a spectrophotometer at 590 nm. A lymphocyte proliferation assay was used to determine proliferation of Jurkat E6.1 cells and LG2 cells with and without the induction of mitogens. Cells were incubated with concentrations of GL ranging from 25µg/mL to 350µg/mL for 24 hours and 48 hours. After incubation, cells were harvested, and proliferation was determined using a microbeta counter. All cells were plated in quadruplicate, and statistical significance was assessed using Dunnett Multiple Comparison test with p<0.05.

There were significant time (24hr, 48hr) and concentration dependent decreases in cell viability in both Jurkat E6.1 cells (IC50= >350µg/mL, 350 µg/mL) and LG2 cells (IC50= 350µg/mL, 150µg/mL) treated with PS-GL (n=7, n=5, respectively), and significant decreases in cell viability in Jurkat E6.1 cells (IC50= 200µg/mL, 250µg/mL) and LG2 (IC50= >350µg/mL, 325µg/mL) treated with GL (n=10, n=10, respectively). Similarly, decreases in proliferation were seen in both mitogen-stimulated and nonmitogen-stimulated Jurkat E6.1 cells (IC50= 250µg/mL, 225µg/mL; IC50= >350µg/mL, 275µg/mL) and LG2 cells (IC50= 300µg/mL, 250µg/mL; IC50= 325µg/mL, 275µg/mL) treated with GL (n=3, n=4, respectively).

PS-GL and GL both produce time and concentration dependent toxicity in both Jurkat E6.1 cells and LG2 cells in low micromolar concentrations. The extent to which toxicity is seen in primary cells such as peripheral mononuclear cells needs to be determined.

Chen J et al. (2004) Chinese Medical Herbology and Pharmacology; 770-771.
Shiao M (2003) The Chemical Record 3; 172-180.
Silva D (2003) Integrative Cancer Therapies 2; 358-364.