Abstract
BackgroundCurcuma purpurascens BI. (Zingiberaceae) commonly known as ‘Koneng Tinggang’ and ‘Temu Tis’ is a Javanese medicinal plant which has been used for numerous ailments and diseases in rural Javanese communities. In the present study, the apoptogenic activity of dichloromethane extract of Curcuma purpurascens BI. rhizome (DECPR) was investigated against HT-29 human colon cancer cells.MethodsAcute toxicity study of DECPR was performed in Sprague–Dawley rats. Compounds of DECPR were analyzed by the gas chromatography–mass spectrometry–time of flight (GC-MS-TOF) analysis. Cytotoxic effect of DECPR on HT-29 cells was analyzed by MTT and lactate dehydrogenase (LDH) assays. Effects of DECPR on reactive oxygen species (ROS) formation and mitochondrial-initiated events were investigated using a high content screening system. The activities of the caspases were also measured using a fluorometric assay. The quantitative PCR analysis was carried out to examine the gene expression of Bax, Bcl-2 and Bcl-xl proteins.ResultsThe in vivo acute toxicity study of DECPR on rats showed the safety of this extract at the highest dose of 5 g/kg. The GC-MS-TOF analysis of DECPR detected turmerone as the major compound in dichloromethane extract. IC50 value of DECPR towards HT-29 cells after 24 h treatment was found to be 7.79 ± 0.54 μg/mL. In addition, DECPR induced LDH release and ROS generation in HT-29 cells through a mechanism involving nuclear fragmentation and cytoskeletal rearrangement. The mitochondrial-initiated events, including collapse in mitochondrial membrane potential and cytochrome c leakage was also triggered by DECPR treatment. Initiator caspase-9 and executioner caspase-3 was dose-dependently activated by DECPR. The quantitative PCR analysis on the mRNA expression of Bcl-2 family of proteins showed a significant up-regulation of Bax associated with down-regulation in Bcl-2 and Bcl-xl mRNA expression.ConclusionsThe findings presented in the current study showed that DECP suppressed the proliferation of HT-29 colon cancer cells and triggered the induction of apoptosis through mitochondrial-dependent pathway.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-015-0534-6) contains supplementary material, which is available to authorized users.
Highlights
Curcuma purpurascens BI. (Zingiberaceae) commonly known as ‘Koneng Tinggang’ and ‘Temu Tis’ is a Javanese medicinal plant which has been used for numerous ailments and diseases in rural Javanese communities
Since DECPR showed the strongest suppressive effect towards HT-29 cells, we carried out the further experiments only on the respective colon cancer cell
Induction of mitochondrial-initiated events by DECPR To determine the possible mechanism of action in which DECPR suppressed the proliferation of HT-29 cells, we investigated the changes in the three critical apoptosisrelated factors, namely cell membrane permeability, membrane potential (MMP) and cytochrome c
Summary
Curcuma purpurascens BI. (Zingiberaceae) commonly known as ‘Koneng Tinggang’ and ‘Temu Tis’ is a Javanese medicinal plant which has been used for numerous ailments and diseases in rural Javanese communities. The apoptogenic activity of dichloromethane extract of Curcuma purpurascens BI. Rhizome (DECPR) was investigated against HT-29 human colon cancer cells. 10 billion cells die through apoptosis daily in the adult human body indicating the importance of this process for maintaining homeostasis of the body [6]. Extensive production of ROS by natural products is an important stimulus, which causes perturbation in the inner mitochondrial membrane leading to an opening of the mitochondrial permeability transition pores (MPTP) [10], collapse in mitochondrial membrane potential (MMP) [11] and leakage of several apoptogenic factors [12]. The activation of executioner caspases induces the irreversible programmed cell death of apoptosis, which provides an effective approach to cancer therapy [5,13]
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