Antitumour effects of phyllanthus emblica L.: Induction of cancer cell apoptosis and Inhibition of in vivo tumour promotion and in vitro invasion of human cancer cells

Phyllanthus emblica Linn. (PE) is a medicinal fruit used in many Asian traditional medicine systems for the treatment of various diseases including cancer. The present study tested the potential anticancer effects of aqueous extract of PE in four ways: (1) against cancer cell lines, (2) in vitro apoptosis, (3) mouse skin tumourigenesis and (4) in vitro invasiveness. The PE extract at 50–100 µg/mL significantly inhibited cell growth of six human cancer cell lines, A549 (lung), HepG2 (liver), HeLa (cervical), MDA‐MB‐231 (breast), SK‐OV3 (ovarian) and SW620 (colorectal). However, the extract was not toxic against MRC5 (normal lung fibroblast). Apoptosis in HeLa cells was also observed as PE extract caused DNA fragmentation and increased activity of caspase‐3/7 and caspase‐8, but not caspase‐9, and up‐regulation of the Fas protein indicating a death receptor‐mediated mechanism of apoptosis. Treatment of PE extract on mouse skin resulted in over 50% reduction of tumour numbers and volumes in animals treated with DMBA/TPA. Lastly, 25 and 50 µg/mL of PE extract inhibited invasiveness of MDA‐MB‐231 cells in the in vitro Matrigel invasion assay. These results suggest P. emblica exhibits anticancer activity against selected cancer cells, and warrants further study as a possible chemopreventive and antiinvasive agent. Copyright © 2010 John Wiley & Sons, Ltd.     

Inhibition of Cancer Cell Proliferation and Antiradical Effects of Decoction,Hydroalcoholic Extract,and Principal Constituents of Hemidesmus indicus R. Br.

Indian Sarsaparilla (Hemidesmus indicus R. Br.) is widely used in Indian traditional medicine. In the present work, we explored the effects of decoction, traditional Ayurvedic preparation, and hydroalcoholic extract, a phytocomplex more traditionally studied and commercialized as food supplement in western medicine, from the roots as possible source of chemicals with new functional potential linked to their nutritional uses. The antiproliferative and antioxidant properties were assayed. To test antiproliferative affects, different cancer cell lines, growing both as monolayers (CaCo2, MCF‐7, A549, K562, MDA‐MB‐231, Jurkat, HepG2, and LoVo) and in suspension (K562 and Jurkat) were used. The decoction showed strong activity on HepG2 cells, while the hydroalcoholic extracts were active on HepG2, LoVo, MCF‐7, K562, and Jurkat cell lines. Weak inhibition of cancer cell proliferation was observed for the principal constituents of the preparations: 2‐hydroxy‐4‐methoxybenzaldehyde, 2‐hydroxy‐4‐methoxybenzoic acid, and 3‐hydroxy‐4‐methoxybenzaldehyde that were tested alone. The antiradical activity was tested with 2,2‐diphenyl‐1‐picrylhydrazyl and 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid)diammonium salt tests and inhibition of nitric oxide production in lipopolysaccharide‐stimulated RAW 264.7 macrophages. Interesting result has also been obtained for hydroalcoholic extract regarding genoprotective potential (58.79% of inhibition at 37.5 µg/mL). Copyright © 2015 John Wiley & Sons, Ltd.     

Norstictic Acid Inhibits Breast Cancer Cell Proliferation,Migration, Invasion,and In Vivo Invasive Growth Through Targeting C‐Met

Breast cancer is a major health problem affecting the female population worldwide. The triple‐negative breast cancers (TNBCs) are characterized by malignant phenotypes, worse patient outcomes, poorest prognosis, and highest mortality rates. The proto‐oncogenic receptor tyrosine kinase c‐Met is usually dysregulated in TNBCs, contributing to their oncogenesis, tumor progression, and aggressive cellular invasiveness that is strongly linked to tumor metastasis. Therefore, c‐Met is proposed as a promising candidate target for the control of TNBCs. Lichens‐derived metabolites are characterized by their structural diversity, complexity, and novelty. The chemical space of lichen‐derived metabolites has been extensively investigated, albeit their biological space is still not fully explored. The anticancer‐guided fractionation of Usnea strigosa (Ach.) lichen extract led to the identification of the depsidone‐derived norstictic acid as a novel bioactive hit against breast cancer cell lines. Norstictic acid significantly suppressed the TNBC MDA‐MB‐231 cell proliferation, migration, and invasion, with minimal toxicity to non‐tumorigenic MCF‐10A mammary epithelial cells. Molecular modeling, Z'‐LYTE biochemical kinase assay and Western blot analysis identified c‐Met as a potential macromolecular target. Norstictic acid treatment significantly suppressed MDA‐MB‐231/GFP tumor growth of a breast cancer xenograft model in athymic nude mice. Lichen‐derived natural products are promising resources to discover novel c‐Met inhibitors useful to control TNBCs. Copyright © 2016 John Wiley & Sons, Ltd.     

Cytotoxic Impact of Costunolide Isolated from Costus speciosus on Breast Cancer via Differential Regulation of Cell Cycle—An In‐vitro and In‐silico Approach

Costunolide, a sesquiterpene lactone, is a biologically active molecule found in most of the medicinally valuable plants. The present study aims to evaluate the anticancer property of costunolide isolated from Costus speciosus against breast cancer cell lines (MCF‐7 and MDA‐MB‐231). Costunolide effectively reduced the viability of both MCF‐7 and MDA‐MB‐231 cell lines at an IC₅₀ value of 40 μM. Flow cytometric analysis revealed costunolide mediated cell cycle arrest at G2/M phase in both the cell types. Western blotting results confirmed the alterations in the expression of cell cycle regulators (cyclin D1, D3, CDK‐4, CDK‐6, p18 INK4c, p21 CIP1/Waf‐1 and p27 KIP1) and apoptosis inducers (caspase‐3 and caspase‐9) upon costunolide treatment in comparison with their expressions in normal breast cell line (MCF‐10A). Costunolide mediated downregulation of positive cell cycle regulators and upregulation of negative cell cycle regulators were related to the induction of apoptosis in cancer cells. The above results were validated with in‐silico results that predicted stable interactions between costunolide and cancer targets. Thus costunolide effectively induced breast cancer cell apoptosis targeting cell cycle regulation, and the compound can be used as an effective herbal therapeutic molecule to treat breast cancer with further explorations. Copyright © 2015 John Wiley & Sons, Ltd.     

Zanthoxylum usambarense (Engl.) Kokwaro (Rutaceae) Extracts Inhibit the Growth of the Breast Cancer Cell Lines MDA‐MB‐231 and MCF‐7, But Not the Brain Tumour Cell Line U251 In Vitro

Zanthoxylum usambarense (Engl.) Kokwaro has traditionally been used for the treatment of malaria, upper respiratory tract infections, cough, rheumatism, tooth decay and sore gums in Kenya and other African countries. Dried ground parts of Z. usambarense were extracted by maceration using methanol (MeOH) at room temperature, extract was dried and reconstituted in 70% aq. MeOH and partitioned against n‐hexane and chloroform (CHCl₃) to obtain MeOH, n‐hexane and CHCl₃ extracts. All extracts were assessed for cytotoxicity against two breast cancer cell lines, MDA‐MB‐231 and MCF‐7, and the brain tumour cell line U251 by the MTT assay. The free‐radical scavenging activity of the extracts was also determined by the 2,2‐diphenyl‐1‐picryhydrazyl (DPPH) assay. In the DPPH assay, the MeOH extract was found to be the most active free‐radical scavenger with a RC₅₀ value of 41.1 × 10^?3 mg/mL. It also displayed significant cytotoxicity against the MCF‐7 cell line (IC₅₀ 42.9 µg/mL) and appeared to have induced cell death through apoptosis. None of the test extracts showed any activity against the U251 cell line at test concentrations. The present findings demonstrated that Z. usambarense could be a potential source for new cytotoxic compounds for possible anticancer drug development. Copyright © 2012 John Wiley & Sons, Ltd.     

Apoptotic effect of lambertianic acid through AMPK/FOXM1 signaling in MDA‐MB231 breast cancer cells

Though lambertianic acid (LA) was known to exert antitumor effect in liver and prostate cancers, its underlying anticancer mechanism is never reported in breast cancers so far. Thus, in this study, apoptotic mechanism of LA was elucidated in MDA‐MB‐231 breast cancer cells. Here, LA increased cytotoxicity in MCF‐7 and MDA‐MB‐231 cells; enhanced sub‐G1 population, G2/M arrest, and cleaved poly(ADP‐ribose) polymerase; activated phosphorylation of AMP‐activated protein kinase (AMPK)/acetyl‐CoA carboxylase pathway; and also suppressed phosphorylation of AKT and the expression of forkhead box M1 (FOXM1), X‐linked inhibitor of apoptosis protein, B‐cell lymphoma 2, and CyclinB1 in MDA‐MB‐231 cells. Furthermore, AMPK inhibitor compound C reversed the effect of LA on FOXM1, Cyclin B1, and cleaved poly(ADP‐ribose) polymerase in MDA‐MB‐231 cells. Notably, immunoprecipitation revealed that LA disturbed the direct binding of AKT and FOXM1 in MDA‐MB‐231 cells. Overall, these findings suggest that LA‐induced apoptosis is mediated via activation of AMPK and inhibition of AKT/FOXM1 signaling pathway.     

The Antioxidant and Anticancer Effects of Wild Carrot Oil Extract

Daucus carota L. ssp. carota (Apiacea) is used in traditional medicine in Lebanon and in different regions throughout the world. The present study investigates the in vitro anticancer activities of Daucus carota oil extract (DCOE) on four human cancer cell lines as well as its in vitro antioxidant activity. DCOE was extracted from the dried umbels with 50:50 acetone‐methanol. The oil extract was analyzed by gas chromatography–mass spectrometry and screened for its antioxidant properties in vitro using 1,1‐diphenyl‐2‐picryl hydrazyl free radical scavenging assay (DPPH), ferrous ion chelating assay (FIC) and the ferric reducing antioxidant power assay (FRAP). The anticancer activity of the oil extract against human colon (HT‐29, Caco‐2) and breast (MCF‐7, MDA‐MB‐231) cancer cell lines was evaluated using the trypan blue exclusion method and the WST‐1 cell proliferation assay. DCOE exhibited antioxidant activity in all assays used. The FRAP value was 164 ± 5.5 µmol FeSO₄/g, and the IC₅₀ values for DPPH and FIC assays were 2.1 ± 0.03 mg/ml and 0.43 ± 0.02 mg/ml, respectively. Also, DCOE demonstrated a significant increase in cell death and decrease in cell proliferation. The effect of DCOE on the cell lines exhibited time and dose‐dependent responses. The present study established that DCOE possesses both antioxidant and promising anticancer activities. Copyright © 2012 John Wiley & Sons, Ltd.     

Ramalin‐Mediated Apoptosis Is Enhanced by Autophagy Inhibition in Human Breast Cancer Cells

Breast cancer, the most commonly diagnosed cancer in women worldwide, is treated in various ways. Ramalin is a chemical compound derived from the Antarctic lichen Ramalina terebrata and is known to exhibit antioxidant and antiinflammatory activities. However, its effect on breast cancer cells remains unknown. We examined the ability of ramalin to induce apoptosis and its mechanisms in MCF‐7 and MDA‐MB‐231 human breast cancer cell lines. Ramalin inhibited cell growth and induced apoptosis in both cell lines in a concentration‐dependent manner. By upregulating Bax and downregulating Bcl‐2, ramalin caused cytochrome c and apoptosis‐inducing factor to be released from the mitochondria into the cytosol, thus activating the mitochondrial apoptotic pathway. In addition, activated caspase‐8 and caspase‐9 were detected in both types of cells exposed to ramalin, whereas ramalin activated caspase‐3 only in the MDA‐MB‐231 cells. Ramalin treatment also increased the levels of LC3‐II and p62. Moreover, the inhibition of autophagy by 3‐methyladenine or Atg5 siRNA significantly enhanced ramalin‐induced apoptosis, which was accompanied by a decrease in Bcl‐2 levels and an increase in Bax levels. Therefore, autophagy appears to be activated as a protective mechanism against apoptosis in cancer cells exposed to ramalin. These findings suggest that ramalin is a potential anticancer agent for the treatment of patients with non‐invasive or invasive breast cancer. Copyright © 2015 John Wiley & Sons, Ltd.     

Antitumor activities of dammarane triterpene saponins from Bacopa monniera

Bioassay‐guided methods were used to test the antitumor activity of methanol extract of the whole plant of Bacopa monniera (L.) Wettst. and four different fractions (petroleum ether, CHCl₃, EtOAc, and n‐BuOH fractions) of the methanol extract. Among the five crude samples, n‐BuOH fraction was noted to have the highest antitumor activity. The dammarane triterpene saponins isolated from n‐BuOH fraction, bacopaside É (1) and bacopaside VII (3), had potential antitumor effect. 1 and 3 showed cytotoxicity of all the tested human tumor cell lines MDA‐MB‐231, SHG‐44, HCT‐8, A‐549 and PC‐3M in MTT assay in vitro, and showed 90.52 % and 84.13 % inhibition in mouse implanted with sarcoma S180 in vivo at the concentration of 50 μmol/kg, respectively. The remaining two compounds, bacopaside II (2) and bacopasaponin C (4) were found to be much less potent compared with 1 and 3. 1 and 3 significantly inhibited human breast cancer cell line MDA‐MB‐231 adhesion, migration and Matrigel invasion in vitro at the concentration of 50 μmol/L. Since no antitumor activities about the monomers from Bacopa monniera (L.) Wettst. have been reported, these results indicate that the mechanism of action of 1 and 3 needs further study. Copyright © 2009 John Wiley & Sons, Ltd.     

Fangchinoline Induces G1 Arrest in Breast Cancer Cells Through Cell‐Cycle Regulation

Fangchinoline, an alkaloid derived from the dry roots of Stephaniae tetrandrine S. Moore (Menispermaceae), has been shown to possess cytotoxic, anti‐inflammatory, and antioxidant properties. In this study, we used Fangchinoline to inhibit breast cancer cell proliferation and to investigate its underlying molecular mechanisms. Human breast cancer cell lines, MCF‐7 and MDA‐MB‐231, were both used in this study. We found that Fangchinoline significantly decreased cell proliferation in a dose‐dependent manner and induced G1‐phase arrest in both cell lines. In addition, upon analysis of expression of cell cycle‐related proteins, we found that Fangchinoline reduced expression of cyclin D1, cyclin D3, and cyclin E, and increased expression of the cyclin‐dependent kinase (CDK) inhibitors, p21/WAF1, and p27/KIP1. Moreover, Fangchinoline also inhibited the kinase activities of CDK2, CDK4, and CDK6. These results suggest that Fangchinoline can inhibit human breast cancer cell proliferation and thus may have potential applications in cancer therapy. Copyright © 2013 John Wiley & Sons, Ltd.     

Rutin,a Quercetin Glycoside,Restores Chemosensitivity in Human Breast Cancer Cells

Several studies have documented the ability of flavonoids to sensitize cancer cells to chemotherapeutics and reverse multidrug resistance by inhibition of efflux pumps (adenosine triphosphate‐binding cassette transporters), apoptosis activation, and cell cycle arrest. In this study, the flavonoid rutin (quercetin 3‐O‐β‐d ‐rutinoside) was investigated as chemosensitizer towards two different human epithelial breast cancer cell lines: (i) MB‐MDA‐231, selected as representative for triple‐negative breast cancer and (ii) MCF‐7 used as a well‐characterized model of HER2‐negative breast cancer. To assess the cytocompatibility of rutin against non‐cancer cells, primary human mammary fibroblasts were used as control and non‐target cells. In MDA‐MB‐231 cells, 20 μM rutin enhanced cytotoxicity related to cyclophosphamide and methotrexate. Rutin significantly (p < 0.05) increased the anticancer activity of both chemotherapeutics, at 24–48–72 h, and decreased the activity of the adenosine triphosphate‐binding cassette transporters, namely, P‐glycoprotein (P‐gp) and breast cancer resistance protein (BCRP). Flow cytometry analysis showed 20 μM and 50 μM rutin arrested cell cycle at G2/M and G0/G1 phases, respectively, significantly promoting cell apoptosis. Rutin, via non‐selective inhibition of P‐gp and BCRP pumps, efficiently reverses multidrug resistance and restores chemosensitivity to cyclophosphamide and cyclophosphamide of human chemoresistant, triple‐negative breast cancer cells, successfully arresting cell cycle progression. Copyright © 2017 John Wiley & Sons, Ltd.     

Acylated Iridoids and Rhamnopyranoses from Premna odorata (Lamiaceae) as Novel Mesenchymal–Epithelial Transition Factor Receptor Inhibitors for the Control of Breast Cancer

Phytochemical investigation of Premna odorata Blanco, Lamiaceae, leaves afforded three new acylated iridoid glycosides 1–3 and two new acylated rhamnopyranoses 9 and 10, in addition to ten known compounds. The structures of the new compounds were confirmed using extensive 1D and 2D NMR analysis. Molecular modeling study suggested the potential of the acylated rhamnopyranoses to bind at the c‐Met kinase domain. Cell‐free Z′‐LYTE? assay testing revealed the good c‐Met phosphorylation inhibitory activity of 9, followed by 8, and 10, with IC₅₀ values of 2.5, 6.9, and 12.7 μM, respectively. The (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) cell proliferation assay testing against the human c‐Met expressing highly invasive MDA‐MB‐231 suggested compound 9 as the most active with IC₅₀ value of 13.3 μM. Testing of compound 9 against multiple phenotypic breast cancer cell lines including MCF‐7, BT‐474 cells, and MDA‐MB‐468 proved enhanced activity against the highly c‐Met expressing triple‐negative breast cancer cell lines. Acylated rhamnopyranoses are potential novel c‐Met inhibitors appropriate for future optimizations to control c‐Met‐dependent breast malignancies. Copyright © 2017 John Wiley & Sons, Ltd.     

Betanin‐Enriched Red Beetroot (Beta vulgaris L.) Extract Induces Apoptosis and Autophagic Cell Death in MCF‐7 Cells

Recent studies have pointed out the preventive role of beetroot extracts against cancers and their cytotoxic activity on cancer cells. Among many different natural compounds, these extracts contained betanin and its stereoisomer isobetanin, which belongs to the betalain group of highly bioavailable antioxidants. However, a precise identification of the molecules responsible for this tumor‐inhibitory effect was still required. We isolated a betanin/isobetanin concentrate from fresh beetroots, corresponding to the highest purified betanin extract used for studying anticancer activities of these molecules. The cytotoxicity of this betanin‐enriched extract was then characterized on cancer and normal cells and we highlighted the death signalling pathways involved. Betanin/isobetanin concentrate significantly decreased cancer cell proliferation and viability. Particularly in MCF‐7‐treated cells, the expressions of apoptosis‐related proteins (Bad, TRAILR4, FAS, p53) were strongly increased and the mitochondrial membrane potential was altered, demonstrating the involvement of both intrinsic and extrinsic apoptotic pathways. Autophagosome vesicles in MCF‐7‐treated cells were observed, also suggesting autophagic cell death upon betanin/isobetanin treatment. Importantly, the betanin‐enriched extract had no obvious effect towards normal cell lines. Our data bring new insight to consider the betanin/isobetanin mix as therapeutic anticancer compound, alone or in combination with classical chemotherapeutic drugs, especially in functional p53 tumors. Copyright © 2015 John Wiley & Sons, Ltd.     

In vitro antiproliferative and antioxidant activities and total phenolic contents of the extracts of Melastoma malabathricum leaves

The present study aims to determine the in vitro antiproliferative and antioxidant activities of various extracts from the leaves of Melastoma malabathricum using various established in vitro assays. The aqueous extract inhibited the proliferation of Caov-3 and HL-60 cell lines, while the chloroform extract exhibited antiproliferative activity against the Caov-3, HL-60, and CEM-SS cell lines. The methanol extract demonstrated antiproliferative activity against more cell lines, including the MCF-7, HeLa, Caov-3, HL-60, CEM-SS, and MDA-MB-231 cancer cell lines. Interestingly, all extracts did not inhibit the proliferation of 3T3 cells, thus indicating their noncytotoxic properties. Unlike the chloroform extracts, the aqueous and methanol extracts of M malabathricum (20, 100, and 500 μg/ml) produced high antioxidant activity for the superoxide scavenging assay with only the 500 μg/ml aqueous and methanol extracts exhibited high activity for the 2,2-diphenyl -1-picrylhydrazyl radical scavenging assay. The total phenolic content recorded for the aqueous, methanol, and chloroform extracts were 3344.2 ± 19.1, 3055.1 ± 8.7, and 92.5 ± 7.3 mg/100 g of gallic acid, respectively. The M malabathricum leaves possessed potential antiproliferative and antioxidant activities that could be attributed to its high content of phenolic compounds.     

Anticancer activity and molecular mechanisms of α‐conidendrin,a polyphenolic compound present in Taxus yunnanensis,on human breast cancer cell lines

α‐Conidendrin is a polyphenolic compound found mainly in Taxus yunnanensis, as the source of chemotherapy drug paclitaxel, which has been used in traditional medicine for treatment of cancer. This study aimed to investigate the anticancer activity and molecular mechanisms of α‐conidendrin on breast cancer cell lines. The results of the present study show that α‐conidendrin possesses potent antiproliferative effects on breast cancer cell lines MCF‐7 and MDA‐MB‐231. α‐Conidendrin significantly induced apoptosis in breast cancer cells via reactive oxygen species generation, upregulation of p53 and Bax, downregulation of Bcl‐2, depolarization of mitochondrial membrane potential (MMP), release of cytochrome c from mitochondria, and activation of caspases‐3 and ‐9. α‐Conidendrin remarkably inhibited the proliferation of breast cancer cells through induction of cell cycle arrest by upregulating p53 and p21 and downregulating cyclin D1 and CDK4. Unlike breast cancer cells, the antiproliferative effect of α‐conidendrin on human foreskin fibroblast cells (normal cells) was very small. In normal cells, reactive oxygen species levels, loss of MMP, release of cytochrome c, mRNA expression of p53, p21, cyclin D1, CDK4, Bax, and Bcl‐2 as well as mRNA expression and activity of caspases‐3 and ‐9 were significantly less affected by α‐conidendrin compared with cancer cells. These results suggest that α‐conidendrin can be a promising agent for treatment of breast cancer with little or no toxicity against normal cells.     

In Vitro and In Silico Evaluation of NF‐κB Targeted Costunolide Action on Estrogen Receptor‐Negative Breast Cancer Cells—A Comparison with Normal Breast Cells

Costunolide, a sesquiterpene lactone is a plant‐derived secondary metabolite found to be present in most of the pharmacologically active herbs, being the cause for their medicinal values. The present study aims to evaluate the cytotoxic effect of costunolide isolated from Costus speciosus rhizome extract on MDA‐MB‐231 cells and explore its targeted action in comparison with its action on the normal breast cells (MCF 10A). The effect of costunolide on cell viability of the cells was assessed by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide viability assay. The targeted action of the compound was analyzed comparing the effectiveness of the compound to alter the protein expression levels of NF‐κB subunits in the normal and the cancer cells using western blotting analysis. In silico studies were performed to predict the targeted interaction of costunolide with the NF‐κB subunit proteins. Costunolide inhibited the cell viability of MDA‐MB‐231 cells in a dose‐dependent manner leaving no significant change in the viability of the normal breast cells. The over expressed NF‐κB subunits – p65, 52 and 100 in the cancer cells were found to be downregulated when treated with costunolide at an effective dose of 20 and 40 μM costunolide. In silico results provided stable interactions between costunolide and the target proteins, supporting the in vitro results in addition. Thus, costunolide derived from C. speciosus plant source elevates a fresh conviction for its use in breast cancer therapy for its cytotoxic efficacy and non‐toxic nature. Copyright © 2014 John Wiley & Sons, Ltd.     

Improving anticancer activities of Oplopanax horridus root bark extract by removing water‐soluble components

O. horridus is used as a folk medicine by natives in the Northern Pacific coast of North America. This experiment studied the antiproliferative effects of the extract of O. horridus root bark and its fractions chromatographed from Dianion HP20 resin column with water, 30, 50, 70 and 100% ethanol on human breast cancer MCF‐7 cells and non‐small cell lung cancer (NSCLC) cells. The role of O. horridus in the cell cycle and apoptosis of MCF‐7 cells was also investigated. The results showed that the 70% and 100% ethanol fractions demonstrated more potent antiproliferative effects than the total extract on both cell lines. The antiproliferative effects may result from the enrichment of active constituents detected by high performance liquid chromatography (HPLC). The IC₅₀ of the total extract, 50, 70, and 100% ethanol fractions for antiproliferation on MCF‐7 cells were 248.4, 123.1, 44.0, and 31.5 μg/mL, respectively, and on NSCLC cells were 125.3, 271.1, 17.6, and 23.2 μg/mL, respectively. On the other hand, the water and 30% ethanol fractions significantly promoted cell proliferation on MCF‐7 cells at concentrations > 100 μg/mL, suggesting that the hydrophilic fractions should be removed from the extract when used for cancer chemoprevention in order to achieve desirable activities. The effects of the total extract on cell cycle and apoptosis were similar to that of the 100% ethanol fraction because of the similarity of their chemical composition. At higher concentrations, the apoptotic effects of the 70% ethanol fraction are more significant. Data from this study suggested that the 70% and 100% ethanol fractions are active antiproliferative fractions and that induction of apoptosis is the mechanism involved in the antiproliferative effect observed. Copyright © 2010 John Wiley & Sons, Ltd.     

Cytotoxic Properties of the Stem Bark of Citrus reticulata Blanco (Rutaceae)

The bioassay‐guided fractionation of the n‐hexane extract of Citrus reticulata Blanco (Rutaceae) stem bark yielded scoparone (1), xanthyletin (2), lupeol (3), β‐amyrin (4), stigmasterol (5), β‐sitosterol (6) and palmitic acid. The structures of these compounds were determined by comprehensive spectroscopic analyses, i.e., 1D and 2D NMR and EI‐MS, and by comparison with the reported data. Extracts, fractions and isolated compounds 1–6 were assessed for cytotoxicity by the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐dphenyltetrazolium bromide (MTT) assay against three human cancer cell lines, i.e., human lung adenocarcinoma cell line A549, human breast adenocarcinoma cell line MCF7 and human Caucasian prostate adenocarcinoma cell line PC3. Significant activity of the n‐hexane and the dichloromethane extracts was observed against the breast cancer cell line MCF7 with IC₅₀s of 45.6 and 54.7 μg/mL, respectively. Moreover, the 70% ethyl acetate in n‐hexane chromatographic fraction showed significant activity displaying IC₅₀ values of 53.0, 52.4 and 49.1 μg/mL against the cancer cell lines A549, MCF7 and PC3, respectively. Encouragingly, an IC₅₀ of 510.0 μg/mL against the human normal prostate cell line PNT2 indicated very low toxicity and hence favourable selectivity indices for the 70% ethyl acetate in n‐hexane fraction in the range of 9.6–10.4 towards cell lines A549, MCF7 and PC3. Because compounds isolated from the above fraction only delivered IC₅₀ values in the range of 18.2–96.3, 9.2–34.1 and 7.5–97.2 μg/mL against A549, MCF7 and PC3 cell lines, respectively, synergistic action between compounds is suggested. Bioassay results valorize the anticancer effectivity of the stem bark of this plant in Cameroonian pharmacopoeia. Copyright © 2017 John Wiley & Sons, Ltd.     

Trametenolic Acid B Reverses Multidrug Resistance in Breast Cancer Cells Through Regulating the Expression Level of P‐Glycoprotein

Trametenolic acid B (TAB) is the main active composition of Trametes lactinea (Berk.) Pat which possesses anti‐tumor activities. There was no report its antitumor effect through regulating P‐glycoprotein (P‐gp) so far, due to P‐gp over expression is one of the most important mechanisms contributing to the multiple drug resistance phenotype. The present aim was to investigate the effects of TAB on P‐gp in multidrug‐resistant cells; Paclitaxel‐resistant cell line MDA‐MB‐231/Taxol was established by stepwise exposure for 10 months. MDA‐MB‐231 cells and MDA‐MB‐231/Taxol cells were treated with TAB, and their growth was evaluated using MTT assays. Paclitaxel accumulation in the cells was analyzed by high performance liquid chromatogram (HPLC). The activity of P‐gp was detected by intracellular accumulation of rhodamine123 (Rho123), and the protein expression of P‐gp was evaluated using western blot. Results indicated that the IC₅₀ of MDA‐MB‐231/Taxol to paclitaxel (Taxol) was 33 times higher than that of nature MDA‐MB‐231. TAB increased the intracellular concentration of Taxol and inhibited the activity of P‐gp and suppressed the expression of P‐gp in MDA‐MB‐231/Taxol cells. Our present results showed that TAB could reverse Taxol resistance in MDA‐MB‐231/Taxol cells, mainly inhibiting the activity of P‐gp and down‐regulating the expression level of P‐gp, and then enhancing the accumulation of chemotherapy agents. © 2013 The Authors Phytotherapy Research Published by John Wiley & Sons Ltd.