4[beta]-Hydroxywithanolide E from Physalis peruviana inhibits growth of human lung cancer cells through DNA damage, apoptosis and G.sub.2 /M arrest

Background The crude extract of the fruit bearing plant, Physalis peruviana (golden berry), demonstrated anti-hepatoma and anti-inflammatory activities. However, the cellular mechanism involved in this process is still unknown. Methods Herein, we isolated the main pure compound, 4[beta]-Hydroxywithanolide (4[beta]HWE) derived from golden berries, and investigated its antiproliferative effect on a human lung cancer cell line (H1299) using survival, cell cycle, and apoptosis analyses. An alkaline comet-nuclear extract (NE) assay was used to evaluate the DNA damage due to the drug. Results It was shown that DNA damage was significantly induced by 1, 5, and 10 [mu]g/mL 4[beta]HWE for 2 h in a dose-dependent manner (p [less than] 0.005). A trypan blue exclusion assay showed that the proliferation of cells was inhibited by 4[beta]HWE in both dose- and time-dependent manners (p [less than] 0.05 and 0.001 for 24 and 48 h, respectively). The half maximal inhibitory concentrations (IC.sub.50 ) of 4[beta]HWE in H1299 cells for 24 and 48 h were 0.6 and 0.71 [mu]g/mL, respectively, suggesting it could be a potential therapeutic agent against lung cancer. In a flow cytometric analysis, 4[beta]HWE produced cell cycle perturbation in the form of sub-G.sub.1 accumulation and slight arrest at the G.sub.2 /M phase with 1 [mu]g/mL for 12 and 24 h, respectively. Using flow cytometric and annexin V/propidium iodide immunofluorescence double-staining techniques, these phenomena were proven to be apoptosis and complete G.sub.2 /M arrest for H1299 cells treated with 5 [mu]g/mL for 24 h. Conclusions In this study, we demonstrated that golden berry-derived 4[beta]HWE is a potential DNA-damaging and chemotherapeutic agent against lung cancer.