Cytotoxicity of naturally occurring phenolics and terpenoids from Kenyan flora towards human carcinoma cells.

BACKGROUND: Cancer constitutes a major hurdle worldwide and its treatment mainly relies on chemotherapy. OBJECTIVES: The present study was designed to evaluate the cytotoxicity of eleven naturally occurring compounds including six phenolics amongst them were 4 chalcones and 2 flavanones as well as 5 terpenoids (3 clerodane and 2 trachylobane diterpenoids) against 6 human carcinoma cell lines and normal CRL2120 fibroblasts. MATERIALS AND METHODS: The neutral red uptake (NR) assay was used to evaluate the cytotoxicity of the compounds, whilst caspase-Glo assay was used to detect caspase activation. Cell cycle and mitochondrial membrane potential (MMP) were all analyzed via flow cytometry meanwhile levels of reactive oxygen species (ROS) was measured by spectrophotometry. RESULTS: Chalcones: 2',4'-dihydroxy-6'-methoxychalcone (1); 4',6'-dihydroxy-2',5'-dimethoxychalcone (2); 2',4',6'-trihydroxy-5'-methoxychalcone (3); 2',6'-diacetate-4'-methoxychalcone (4), trachylobane diterpenoids: 2,6,19-trachylobanetriol; (ent-2α,6α)-form (10) and 2,18,19-trachylobanetriol; (ent-2α)-form (11) as well as doxorubicin displayed IC50 values below 110 µM in the six tested cancer cell lines. The IC50 values of the most active compounds were between 6.30 µM and 46.23 µM for compound 1 respectively towards breast adenocarcinoma MCF-7 cells and small lung cancer A549 cells and between 0.07 µM and 1.01 µM for doxorubicin respectively against SPC212 cells and A549 cells. Compounds 1 induced apoptosis in MCF-7 cells mediated by increasing ROS production and MMP loss. CONCLUSION: Chalcones 1-3 are potential cytotoxic phytochemicals that deserve more investigations to develop novel anticancer drugs against human carcinoma.

Identification of biomarkers associated with partial epithelial to mesenchymal transition in the secretome of slug over-expressing hepatocellular carcinoma cells.

BACKGROUND: Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths worldwide. Complete epithelial to mesenchymal transition (EMT) has long been considered as a crucial step for metastasis initiation. It has, however, become apparent that many carcinoma cells can metastasize without complete loss of epithelial traits or with incomplete gain of mesenchymal traits, i.e., partial EMT. Here, we aimed to determine the similarities and differences between complete and partial EMT through over-expression of the EMT-associated transcription factor Slug in different HCC-derived cell lines. METHODS: Slug over-expressing HCC-derived HepG2 and Huh7 cells were assessed for their EMT, chemo-resistance and stemness features using Western blotting, qRT-PCR, neutral red uptake, doxorubicin accumulation and scratch wound healing assays. We also collected conditioned media from Slug over-expressing HCC cells and analyzed its exosomal protein content for the presence of chemo-resistance and partial EMT markers using MALDI-TOF/TOF and ELISA assays, respectively. RESULTS: We found that Slug over-expression resulted in the induction of both complete and partial EMT in the different HCC-derived cell lines tested. Complete EMT was characterized by downregulation of E-cadherin and upregulation of ZEB2. Partial EMT was characterized by upregulation of E-cadherin and downregulation of vimentin and ZEB2. Interestingly, we found that Slug induced chemo-resistance through downregulation of the ATP binding cassette (ABC) transporter ABCB1 and upregulation of the ABC transporter ABCG2, as well as through expression of CD133, a stemness marker that exhibited a similar expression pattern in cells with either a complete or a partial EMT phenotype. In addition, we found that Slug-mediated partial EMT was associated with enhanced exosomal secretion of post-translationally modified fibronectin 1 (FN1), collagen type II alpha 1 (COL2A1) and native fibrinogen gamma chain (FGG). CONCLUSIONS: From our data we conclude that the exosomal proteins identified may be considered as potential non-invasive biomarkers for chemo-resistance and partial EMT in HCC.

Cytotoxicity of seputhecarpan D, thonningiol and 12 other phytochemicals from African flora towards human carcinoma cells.

BACKGROUND: Despite the remarkable progress in cancer therapy in recent years, this disease still remains a serious public health concern. The use of natural products has been and continues to be one of the most effective ways to fight malignancies. The cytotoxicity of 14 compounds from African medicinal plants was evaluated in four human carcinoma cell lines and normal fibroblasts. The tested samples included: ß-spinasterol (1), friedelanone (2), 16ß-hydroxylupeol (3), ß-amyrin acetate (4), lupeol acetate (5), sequoyitol (6), rhamnitrin (7), europetin 3-O-rhamnoside (8), thonningiol (9), glyasperin F (10), seputhecarpan B (11), seputhecarpan C (12), seputhecarpan D (13) and rheediaxanthone A (14). METHODS: The neutral red uptake (NR) assay was used to evaluate the cytotoxicity of samples; caspase-Glo assay, flow cytometry for cell cycle analysis and mitochondrial membrane potential (MMP) as well as spectrophotometry to measure levels of reactive oxygen species (ROS) were performed to detect the mode of action of compounds 9 and 13 in MCF-7 breast adenocarcinoma cells. RESULTS: Compounds 3, 9-13 displayed cytotoxic effects against the four tested cancer cell lines with IC50 values below 85 µM. Compounds 9 and 13 had IC50 values below 10 µM in 4/4 and 3/4 tested cell lines respectively. The IC50 values varied from 0.36 µM (against MCF7 cells) to 5.65 µM (towards colon carcinoma DLD-1 cells) for 9, from 9.78 µM (against MCF7 cells) to 67.68 µM (against HepG2 cells) for 13 and 0.18 µM (towards HepG2 cells) to 72 µM (towards Caco-2 cells) for the reference drug, doxorubicin. Compounds 9 and 13 induced cell cycle arrest in Go/G1 whilst doxorubicin induced arrest in G2/M. The two molecules (9 and 13) also induced apoptosis in MCF-7 cells through activation of caspases 3/7 and 9 as well as enhanced ROS production. CONCLUSION: Compounds 9 and 13 are good cytotoxic phytochemicals that should be explored more in future to develop a cytotoxic drug to fight human carcinoma.

Cytotoxicity of the methanol extracts of Elephantopus mollis, Kalanchoe crenata and 4 other Cameroonian medicinal plants towards human carcinoma cells.

BACKGROUND: Cancer still constitutes one of the major health concerns globally, causing serious threats on patients, their families, and the healthcare system. METHODS: In this study, the cytotoxicity of the methanol extract of Elephantopus mollis whole plant (EMW), Enantia chlorantha bark (ECB), Kalanchoe crenata leaves (KCL), Lophira alata bark (LAB), Millettia macrophylla leaves (MML) and Phragmanthera capitata leaves (PCL) towards five human solid cancer cell lines and normal CRL2120 fibroblasts, was evaluated. Extracts were subjected to qualitative chemical screening of their secondary metabolite contents using standard methods. The cytotoxicity of samples was evaluated using neutral red uptake (NR) assay meanwhile caspase activation was detected by caspase-Glo assay. Flow cytometry was used to analyze the cell cycle distribution and the mitochondrial membrane potential (MMP) whilst spectrophotometry was used to measure the levels of reactive oxygen species (ROS). RESULTS: Phytochemical analysis revealed the presence of polyphenols, triterpenes and sterols in all extracts. The IC50 values of the best samples ranged from 3.29 µg/mL (towards DLD-1 colorectal adenocarcinoma cells) to 24.38 µg/mL (against small lung cancer A549 cells) for EMW, from 2.33 µg/mL (mesothelioma SPC212 cells) to 28.96 µg/mL (HepG2 hepatocarcinoma) for KCL, and from 0.04 µg/mL (towards SPC212 cells) to 0.55 µg/mL (towards A549 cells) for doxorubicin. EMW induced apoptosis in MCF-7 cells mediated by MMP loss and increased ROS production whilst KCL induced apoptosis via ROS production. CONCLUSION: This study provides evidences of the cytotoxicity of the tested plant extract and highlights the good activity of Elephantopus mollis and Kalanchoe crenata. They deserve more exploration to develop novel cytotoxic drugs.

Cytotoxicity of Plumbagin, Rapanone and 12 other naturally occurring Quinones from Kenyan Flora towards human carcinoma cells.

BACKGROUND: Cancer is a major public health concern globally and chemotherapy remains the principal mode of the treatment of various malignant diseases. METHODS: This study was designed to investigate the cytotoxicity of 14 naturally occurring quinones including; 3 anthraquinones, 1 naphthoquinone and 10 benzoquinones against 6 human carcinoma cell lines and normal CRL2120 fibroblasts. The neutral red uptake (NR) assay was used to evaluate the cytotoxicity of the compounds, whilst caspase-Glo assay was used to detect caspases activation. Cell cycle and mitochondrial membrane potential (MMP) were all analyzed via flow cytometry meanwhile levels of reactive oxygen species (ROS) were measured by spectrophotometry. RESULTS: Anthraquinone: emodin (2), naphthoquinone: plumbagin (4), and benzoquinones: rapanone (9), 2,5-dihydroxy-3-pentadecyl-2,5-cyclohexadiene-1,4-dione (10), 5-O-methylembelin (11), 1,2,4,5-tetraacetate-3-methyl-6-(14-nonadecenyl)-cyclohexadi-2,5-diene (13), as well as doxorubicin displayed interesting activities with IC50 values below 100 µM in the six tested cancer cell lines. The IC50 values ranged from 37.57 µM (towards breast adenocarcinoma MCF-7 cells) to 99.31 µM (towards small cell lung cancer A549 cells) for 2, from 0.06 µM (MCF-7 cells) to 1.14 µM (A549 cells) for 4, from 2.27 µM (mesothelioma SPC212 cells) to 46.62 µM (colorectal adenocarcinoma DLD-1 cells) for 9, from 8.39 µM (SPC212 cells) to 48.35 µM (hepatocarinoma HepG2 cells) for 10, from 22.57 µM (MCF-7 cells) to 61.28 µM (HepG2 cells) for 11, from 9.25 µM (MCF-7 cells) to 47.53 µM (A549 cells) for 13, and from 0.07 µM (SPC212 cells) to 1.01 µM (A549 cells) for doxorubicin. Compounds 4 and 9 induced apoptosis in MCF-7 cells mediated by increased ROS production and MMP loss, respectively. CONCLUSION: The tested natural products and mostly 2, 4, 9, 10, 11 and 13 are potential cytotoxic compounds that deserve more investigations towards developing novel antiproliferative drugs against human carcinoma.

Two new pterocarpans and a new pyrone derivative with cytotoxic activities from Ptycholobium contortum (N.E.Br.) Brummitt (Leguminosae): revised NMR assignment of mundulea lactone.

BACKGROUND: Ptycholobium is a genus related to Tephrosia which comprises only three species. Compared to Tephrosia, which has been phytochemically and pharmacologically studied, Ptycholobium species have only few or no reports on their chemical constituents. Moreover, no studies on the cytotoxic activities of its secondary metabolites have been previously documented. RESULTS: From the non polar fractions of the roots bark of Ptycholobium contortum (syn Tephrosia contorta), two new pterocarpans: seputhecarpan C 1 and seputhecarpan D 2 and a new pyrone derivative, ptycholopyrone A 3 were isolated. Alongside, five known compounds identified as 3-α,α-dimethylallyl-4-methoxy-6-styryl-α-pyrone or mundulea lactone 4, glyasperin F 5, seputhecarpan A 6, seputheisoflavone 7 and 5-O-methyl-myo-inositol or sequoyitol 8 were also obtained. Their structures were established by the mean means of spectroscopic data in conjunction to those reported in literature. The NMR assignment of the major compound mundulea lactone 4 is revised in this paper. In addition, the cytotoxicity of the isolated metabolites was evaluated on two lung cancer cell lines A549 and SPC212. 8 was not active while compounds 1, 2, 4-7 displayed antiproliferative effects against the two carcinoma cell lines with IC50 values below 75 µM. IC50 values below 10 µM were obtained for 4, 6 and 7 on SPC212 cells. CONCLUSION: Based on the obtained results, Ptycholobium contortum turns to be a rich source of phenolic metabolites among them some bearing prenyl moieties. This study reports for the first time the isolation of pyrone derivatives 3 and 4 from Ptycholobium genus. The cytotoxicity observed for the isolate is also reported for the first time and shows that 4, 6 and 7 could be chemically explored in order to develop a hit candidate against lung cancer. Graphical abstractTwo new pterocarpans and a new pyrone derivative with cytotoxic activities from ptycholobium contortum (N.E.Br.) Brummitt (Leguminosae): revised NMR assignment of mundulea lactone.