Antioxidant and growth inhibitory activities of Mesembryanthemum crystallinum L. in HCT116 human colon cancer cells

Seo, Jin A; Ju, Jihyeung

Abstract

PURPOSE
This study examined the antioxidant and cancer cell growth inhibitory activities of an ethanol extract and different solvent fractions of Mesembryanthemum crystallinum L. (ice plant).
METHODS
The ice plant was freeze-dried, extracted with 99.9% ethanol, and then fractionated with hexane, ethyl acetate, butanol, and water. The total polyphenol content (TPC), total carotenoid content (TCC), 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity (RSA), and ferric reducing antioxidant power (FRAP) were measured. Assays using 2"²,7"²-dichlorofluorescin-diacetate and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide were performed to measure the intracellular reactive oxygen species (ROS) and cell growth, respectively. Annexin V/propidium iodide staining and cell cycle analysis were performed for the detection of apoptosis and cell cycle arrest.
RESULTS
TPC, TCC, RSA, and FRAP of the ethanol extract (EE) were 3.7 mg gallic acid equivalent/g, 13.2 µg/g, 21.0% (at a concentration of 5 mg/mL), and 21.0% (at a concentration of 5 mg/mL), respectively. Among the different solvent fractions, the butanol fraction (BF) showed the highest TPC (5.4 mg gallic acid equivalent/g), TCC (86.6 µg/g), RSA (34.9% at 5 mg/mL), and FRAP (80.8% at 5 mg/mL). Treatment of HCT116 human colon cancer cells with EE and BF at concentrations of 250 and 500 µg/mL reduced the levels of intracellular ROS. Concomitantly, EE and BF resulted in the dose-dependent inhibition of cell growth (at the concentrations of 125, 250, and 500 µg/mL for 24 ~ 48 h) and the induction of apoptosis (at the concentrations of 250 and 500 µg/mL for 48 h) in HCT116 cells. An increased G2/M cell population was also found in the BF-treated cells.
CONCLUSION
These results suggest that ice plant possesses antioxidant and growth inhibitory activities in colon cancer cells.