Colossolactones were isolated previously from the Vietnamese mushroom ganoderma colossum, such triterpenoids. The different colossolactone compounds (schisanalactonoe a, colossolactone I, ergosterol, colossolactone III, colossolactone II, colossolactone IV, colossolactone E) characterized by the presence of a six-membered lactone ring (ring D) with or without a seven-membered lactone rings (ring A) were isolated. In the current study, using DPPH free radical scavenging assay, all colossolactone compounds showed weak antioxidant activity with EC50’s of 99.46, 220.32, 219.65, 100.81, 238.54, 116.57 and 131.94 µM, respectively. Isolated compounds were examined for their potential anticancer activity against breast (MCF-7), cervix (HeLa), colorectal (HCT-116) and liver (HepG2) cancer cells. Cytotoxicity of the isolated compounds was assessed in the aforementioned cell lines using SRB assay after 72 h of exposure and fitted using Emax model. Amongst colossolactones, schisanalactonoe-A and colossolactone-IV showed the best cytotoxic profile in all cell lines under investigation with IC50’s ranged from 4.9 to 64.2 µM; and R-fraction less than 47.5%. Further mechanistic studies for the detailed mechanism of cytotoxicity of schisanalactonoe-A and colossolactone-IV are currently carried out.

Citation Format: Mohammed A. Baghdadi, Fahad A. Al-Abbasi, Ali M. El-Halawany, Ahmed M. Al-Abd. Chemotherapeutic effects of naturally occurring colossolactones against solid tumor cells in-vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 131. doi:10.1158/1538-7445.AM2017-131