Early Preclinical Studies of Ergosterol Peroxide and Biological Evaluation of Its Derivatives

<i>Ganoderma lucidum</i> is a medicinal mushroom that produces various pharmacological compounds, including triterpenoids. A major bioactive component of <i>G. lucidum</i> is ergosterol peroxide (EP), which is attributed to its anticancer effects. The current study focuses on the <i>in vitro</i> ADME (absorption, distribution, metabolism, and elimination), <i>in vivo</i> efficacy and toxicity of EP, and the synthesis of new EP derivatives to improve aqueous solubility. It was found that EP is metabolically stable in liver microsomes and plasma. <i>In vivo</i> studies showed that EP inhibits tumor growth in murine cancer models, and it is well tolerated by mice. The maximum tolerated dose was investigated in mice at escalating doses with a defined maximum amount of 500 mg/kg, which indicated no signs of toxicity, confirmed by plasma chemistry and analysis of harvested tissues. Complementary organ toxicity assays including cardio and hepatotoxicity assays of EP demonstrated no inhibitory effects. Next, a focused library of EP derivatives was developed to investigate the iterative addition of heteroatoms to improve the aqueous solubility properties of EP. Significant solubility improvement was observed by the introduction of hydrogen bonding promoting groups, particularly the sulfate group. Superior aqueous solubility properties are directly correlated with the biological activity of the compound against triple-negative breast cancer cellular (TNBC) models. The EP derivatives maintain ample therapeutic index at the tested concentrations, indicating they engage with the same biological target(s) as the parental compound (EP). The combined studies indicate that EP and its derivatives are selective TNBC cell death inducers, while sparing noncancerous tissue.