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Fulltext Antioxidant potential, cytotoxic activity and total phenolic content of Alpinia pahangensis rhizomes

Phang CW, Malek SN, Ibrahim H

BMC Complement Altern Med, 2013 Oct 01;13:243.
PMID: 24083445 DOI: 10.1186/1472-6882-13-243

BACKGROUND: Alpinia pahangensis, a wild ginger distributed in the lowlands of Pahang, Malaysia, is used by the locals to treat flatulence. In this study, the antioxidant and cytotoxic activities of the crude aqueous methanol and fractionated extracts of Alpinia pahangensis against five different cancer and one normal cell lines were investigated. The total phenolic content of each extract and its fractions were also quantified. This is the first report on the antioxidant and cytotoxic activities of Alpinia pahangensis extract.
METHODS: In the current study, the crude methanol and fractionated extract of the rhizomes of Alpinia pahangensis were investigated for their antioxidant activity using four different assays namely, the DPPH scavenging activity, superoxide anion scavenging, β-carotene bleaching and reducing power assays whilst their phenolic contents were measured by the Folin-Ciocalteu's method.In vitro neutral red cytotoxicity assay was employed to evaluate the cytotoxic activity against five different cancer cell lines, colon cancer (HCT 116 and HT-29), cervical cancer (Ca Ski), breast cancer (MCF7) and lung cancer (A549) cell lines, and one normal cell line (MRC-5). The extract that showed high cytotoxic activity was further investigated for its chemical constituents by GC-MS (gas chromatography-mass spectrometry) analysis.
RESULTS: The ethyl acetate fraction showed the strongest DPPH radical scavenging (0.35 ± 0.094 mg/ml) and SOD activities (51.77 ± 4.9%) whilst the methanol extract showed the highest reducing power and also the strongest antioxidant activity in the β-carotene bleaching assays in comparison to other fractions. The highest phenolic content was found in the ethyl acetate fraction, followed by the crude methanol extract, hexane and water fractions. The results showed a positive correlation between total phenolic content with DPPH radical scavenging capacities and SOD activities. The hexane fraction showed potent cytotoxic effect against KB, Ca Ski and HCT 116 cell lines with IC₅₀ of 5.8 ± 0.1 and 9.1 ± 2.0 ug/ml, respectively. The major components of hexane fraction analysed by GC-MS analysis were mostly methyl esters.
CONCLUSIONS: The current study suggests that the methanol extract and ethyl acetate fraction of A. pahangensis is a potential source of natural antioxidant for protective as well as prevention of life-threatening diseases. The hexane fraction of A. pahangensis may have the potential to be developed into therapeutic option for treating cancer.
Fulltext Flavokawain C Inhibits Cell Cycle and Promotes Apoptosis, Associated with Endoplasmic Reticulum Stress and Regulation of MAPKs and Akt Signaling Pathways in HCT 116 Human Colon Carcinoma Cells

Phang CW, Karsani SA, Sethi G, Abd Malek SN

PLoS One, 2016;11(2):e0148775.
PMID: 26859847 DOI: 10.1371/journal.pone.0148775

Flavokawain C (FKC) is a naturally occurring chalcone which can be found in Kava (Piper methysticum Forst) root. The present study evaluated the effect of FKC on the growth of various human cancer cell lines and the underlying associated mechanisms. FKC showed higher cytotoxic activity against HCT 116 cells in a time- and dose-dependent manner in comparison to other cell lines (MCF-7, HT-29, A549 and CaSki), with minimal toxicity on normal human colon cells. The apoptosis-inducing capability of FKC on HCT 116 cells was evidenced by cell shrinkage, chromatin condensation, DNA fragmentation and increased phosphatidylserine externalization. FKC was found to disrupt mitochondrial membrane potential, resulting in the release of Smac/DIABLO, AIF and cytochrome c into the cytoplasm. Our results also revealed that FKC induced intrinsic and extrinsic apoptosis via upregulation of the levels of pro-apoptotic proteins (Bak) and death receptors (DR5), while downregulation of the levels of anti-apoptotic proteins (XIAP, cIAP-1, c-FlipL, Bcl-xL and survivin), resulting in the activation of caspase-3, -8 and -9 and cleavage of poly(ADP-ribose) polymerase (PARP). FKC was also found to cause endoplasmic reticulum (ER) stress, as suggested by the elevation of GADD153 protein after FKC treatment. After the cells were exposed to FKC (60μM) over 18hrs, there was a substantial increase in the phosphorylation of ERK 1/2. The expression of phosphorylated Akt was also reduced. FKC also caused cell cycle arrest in the S phase in HCT 116 cells in a time- and dose-dependent manner and with accumulation of cells in the sub-G1 phase. This was accompanied by the downregulation of cyclin-dependent kinases (CDK2 and CDK4), consistent with the upregulation of CDK inhibitors (p21Cip1 and p27Kip1), and hypophosphorylation of Rb.
Proteomic analysis of flavokawain C-induced cell death in HCT 116 colon carcinoma cell line

Phang CW, Gandah NA, Abd Malek SN, Karsani SA

Eur J Pharmacol, 2019 Jun 15;853:388-399.
PMID: 31014923 DOI: 10.1016/j.ejphar.2019.04.032

Flavokawain C (FKC), a naturally occurring chalcone, has previously been shown to inhibit the growth of colon carcinoma HCT 116 cells through induction of apoptosis and cell cycle arrest. However, the possible underlying mechanisms of cell death as a response to FKC treatment remains unclear. In this study, we performed proteomic analysis of HCT 116 cells treated with FKC to identify proteins that change in abundance. This was followed by bioinformatic analysis to predict possible associated molecular targets or pathways involved in the observed effects of FKC. A total of 35 proteins that changed in abundance (17 increased and 18 decreased) were identified through two-dimensional gel electrophoresis followed by matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF/TOF MS). Using the Ingenuity Pathway Analysis (IPA), these proteins were predicted to be involved in cell death and survival, cell cycle, cellular growth and proliferation, protein synthesis, post-translational modification and amino acid metabolism by. Further analysis of the transcript levels of selected proteins using qPCR showed that some of the genes exhibited similar change of profile to that of the proteins'. Our results have provided novel insights into the potential molecular mechanisms underlying FKC-induced apoptosis or cell death in colon cancer cells.
Fulltext Flavokawain C exhibits anti-tumor effects on in vivo HCT 116 xenograft and identification of its apoptosis-linked serum biomarkers via proteomic analysis

Phang CW, Abd Malek SN, Karsani SA

Biomed Pharmacother, 2021 May;137:110846.
PMID: 33761587 DOI: 10.1016/j.biopha.2020.110846

Chalcones and their derivatives belong to the flavonoid family. They have been extensively studied for their anticancer properties and some have been approved for clinical use. In this study, the in vivo anti-tumor activity of flavokawain C (FKC), a naturally occurring chalcone found in Kava (Piper methysticum Forst) was evaluated in HCT 116 cells (colon carcinoma). We also attempted to identify potential biomarkers and/or molecular targets in serum with applicability in predicting treatment outcome. The anti-tumor effects and toxicity of FKC were assessed using the xenograft nude mice model. Cisplatin was used as positive control. The anti-proliferative and apoptotic activities were then evaluated in tumor tissues treated with FKC. Furthermore, two-dimensional electrophoresis (2-DE) followed by protein identification using MALDI-TOF/TOF-MS/MS was performed to compare the serum proteome profiles between healthy nude mice and nude mice bearing HCT 116 tumor treated with vehicle solution and FKC, respectively. Our results showed that FKC treatment significantly inhibited HCT 116 tumor growth. In vivo toxicity studies showed that administration of FKC did not cause damage to major organs and had no significant effect on body weight. FKC was found to induce apoptosis in tumor, and this was associated with increased expression of cleaved caspase-3 and decreased expression of Ki67 in tumor tissues. Our proteomic analysis identified five proteins that changed in abundance - Ig mu chain C region (secreted form), GRP78, hemopexin, kininogen-1 and apolipoprotein E. Overall, our findings demonstrated the potential of FKC as an anti-cancer agent for the treatment of colon carcinoma.
Induction of Apoptosis and Cell Cycle Arrest by Flavokawain C on HT-29 Human Colon Adenocarcinoma via Enhancement of Reactive Oxygen Species Generation, Upregulation of p21, p27, and GADD153, and Inactivation of Inhibitor of Apoptosis Proteins

Phang CW, Karsani SA, Abd Malek SN

Pharmacogn Mag, 2017 Jul;13(Suppl 2):S321-S328.
PMID: 28808400 DOI: 10.4103/0973-1296.210180

Chalcones have been shown to exhibit anti-cancer properties by targeting multiple molecular pathways. It was, therefore, of interest to investigate flavokawain C (FKC), a naturally occurring chalcone, which can be isolated from Kava (Piper methysticum Forst) root extract. The aim of this study was to investigate the inhibitory effect of FKC on the growth of HT-29 cells and its underlying mechanism of action. Cell viability of HT-29 cells was assessed by Sulforhodamine B assay after FKC treatment. Induction of apoptosis was examined by established morphological and biochemical assays. ROS generation was determined by dichlorofluorescein fluorescence staining, and superoxide dismutase activity was measured using the spectrophotometric method. Western blotting was used to examine the changes in the protein levels. FKC markedly decreased the cell viability of HT-29 cells and the cells showed dramatic changes in cellular and nuclear morphologies with typical apoptotic features. The induction of apoptosis correlated well with the externalization of phosphatidylserine, DNA fragmentation, decreased mitochondrial membrane potential, activation of caspases, and PARP cleavage. This was associated with an increase in reactive oxygen species and a decrease in SOD activity. The protein levels of XIAP, c-IAP1, and c-IAP2 were downregulated, whereas the GADD153 was upregulated after FKC treatment. FKC induced cell cycle arrest at the G1 and G2/M phases via upregulation of p21 and p27 in a p53-independent manner. Our results provide evidence that FKC has the potential to be developed into chemotherapeutic drug for the treatment of colon adenocarcinoma.
SUMMARY: Flavokawain C inhibited the growth of HT-29 human colon adenocarcinoma cellsFlavokawain C induced apoptosis in HT-29 cells, associated with an increase in reactive oxygen species and a decrease in SOD activityFlavokawain C induced cell cycle arrest at the G1 and G2/M phases via upregulation of p21 and p27 in HT-29 cellsHT-29 cells treated with flavokawain C caused downregulation of XIAP, c-IAP1, and c-IAP2, and upregulation of GADD153. Abbreviations used: FKC: Flavokawain C; SRB: Sulforhodamine B; ROS: Reactive oxygen species; SOD: Superoxide dismutase; PARP: Poly(ADP-ribose) polymerase; ER: Endoplasmic reticulum; IAPs: Inhibitor of apoptosis proteins; TUNEL: Transferase dUTP nick end labeling; Annexin V-FITC: Annexin V conjugated with fluorescein isothicyanate.
Fulltext Phytochemical and cytotoxic investigations of Alpinia mutica rhizomes

Malek SN, Phang CW, Ibrahim H, Norhanom AW, Sim KS

Molecules, 2011 Jan 14;16(1):583-9.
PMID: 21240148 DOI: 10.3390/molecules16010583

The methanol and fractionated extracts (hexane, ethyl acetate and water) of Alpinia mutica (Zingiberaceae) rhizomes were investigated for their cytotoxic effect against six human carcinoma cell lines, namely KB, MCF7, A549, Caski, HCT116, HT29 and non-human fibroblast cell line (MRC 5) using an in vitro cytotoxicity assay. The ethyl acetate extract possessed high inhibitory effect against KB, MCF7 and Caski cells (IC₅₀ values of 9.4, 19.7 and 19.8 µg/mL, respectively). Flavokawin B (1), 5,6-dehydrokawain (2), pinostrobin chalcone (3) and alpinetin (4), isolated from the active ethyl acetate extract were also evaluated for their cytotoxic activity. Of these, pinostrobin chalcone (3) and alpinetin (4) were isolated from this plant for the first time. Pinostrobin chalcone (3) displayed very remarkable cytotoxic activity against the tested human cancer cells, such as KB, MCF7 and Caski cells (IC₅₀ values of 6.2, 7.3 and 7.7 µg/mL, respectively). This is the first report of the cytotoxic activity of Alpinia mutica.