Bioactive chemical constituents, in vitro anti-proliferative activity and in vivo toxicity of the extract of Curcuma singularis Gagnep rhizomes

Curcuma singularis Gagnep is a Vietnamese medicinal plant which has been commonly used as a medicinal remedy in traditional and folk medicines for improving health as well as for treating some diseases, like rheumatoid arthritis, kidney failure. However, pharmacological effects, including anti-cancer activity and the safety of this plant has not been fully investigated.This study aimed to investigate the in vitro anti-growth activity of an extract derived from Curcuma singularis rhizome extract (CSE) against cell lines as well as determine its phytochemical composition. The other goal of our study was to assess the safety of CSE in rats.The main constituents in the extract were identified and quantitatively analyzed. The in vitro cytotoxicity of CSE was evaluated in several cancer and normal cell lines. The apoptotic activity of CSE and the expression of the apoptosis-related genes were investigated in AGS cells to clarify the underlying molecular mechanisms. The in vivo toxicity of CSE was assessed via acute and subacute oral studies on Sprague-Dawley rats, respectively according to the guidelines 425 and 407 of the Organization for Economic Cooperation and Development (OECD). The drug-related toxicity signs, mortality, body and organ weights were recoreded during the experimental period. In addition, the selected hematological and biochemical parameters, and histological alterations were determined at the end of the subacute toxicity test.Germacrone, ar-turmerone, and curcumol were three sesquiterpene components found in the extract. CSE showed cytotoxic effects in different cancer cells, but had minimal effects on normal cells. Apoptosis in AGS cells was caused by CSE in a concentration-dependent pattern through increase of Bax/Bcl-2 ratio, and release of cytochrome c, which leads to activation of caspase-3/-7, caspase-9, as well as cleavage of PARP. In the acute toxicity test, no signs of toxicity and no mortality were recorded in rats at both doses of 1000 and 5000 mg/kg. In the subacute toxicity study, CSE showed no drug-related adverse effects on water and food consumption, body and organ weights. CSE at a dose of 1000 mg/kg slightly increased WBC and platelet values in female rats, while it increased WBC values in male rats in all tested doses. The decrease of total cholesterol and triglyceride levels were found in female rats treated CSE at doses of 250 or 500 mg/kg. In addition, the increase of serum ALT and AST levels in rats treated at the dose of 1000 mg/kg were noted. No significant changes in histopathological structures of kidneys, spleen, heart and lungs, except liver tissue with minor modifications was found.Our findings indicated that CSE exhibited in vitro anti-proliferative effects on AGS cells by mainly activating the caspase-dependent mitochondrial apoptotic pathway. CSE also showed in vivo toxicity signals at the dose of 1000 mg/kg with proven minor hepatic injuries, which should be avoided the high dose for prolonged use. Curcuma singularis rhizomes may be used as a chemotherapeutic agent for the treatment of gastric cancer with in vitro anti-cancer investigation and in vivo biological safety evaluation.