Publications by authors named "Sara Abdelfatah"

25 Publications

  • Page 1 of 1

The triterpenoid ursolic acid ameliorates stress in Caenorhabditis elegans by affecting the depression-associated genes skn-1 and prdx2.

Phytomedicine 2021 Jul 23;88:153598. Epub 2021 May 23.

Department of Pharmaceutical Biology, Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University, Staudinger Weg 5, 55128 Mainz, Germany. Electronic address:

Introduction: Depression is one of the leading causes of death worldwide. Lower antioxidant concentrations and increased oxidative stress levels contribute to the development of depression. Effective and tolerable medications are urgently needed. Nrf2 and PRDX2 are promising targets in the treatment of oxidative stress and, therefore, promising for the development of novel antidepressants. Ursolic acid (UA), a natural triterpenoid found in various plants is known to exert neuroprotective and antioxidant effects. Skn-1 (which corresponds to human Nrf2) and prdx2 deficient mutants of the nematode Caenorhabditis elegans are suitable models to study the effect of UA on these targets. Additionally, stress assays are used to mimic stress or depressed state.

Methods: We examined the antioxidant activity of UA in Caenorhabditis elegans wildtype and skn-1- and prdx2-deficient strains by HDCF-DA and juglone assays as well as osmotic and heat stress assays. Additionally, we analyzed the binding of UA to human PRDX2 and Skn-1 proteins by molecular docking and microscale thermophoresis.

Results: UA exerted strong antioxidant activities. Additionally, induction of stress resistance towards osmotic and heat stress was observed. qRT-PCR revealed that UA upregulated the gene expression of skn-1 and prdx2. Molecular docking studies supported these findings.

Conclusion: Our findings implicate that the strong antioxidant activity of UA may exert anti-depressive effects by its interaction with the Skn-1 transcription factor, which is part of a detoxification network, and the antioxidant PRDX2 protein, which protects the organism from the detrimental effects of radical oxygen species.
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http://dx.doi.org/10.1016/j.phymed.2021.153598DOI Listing
July 2021

Pyrrolizidine alkaloids cause cell cycle and DNA damage repair defects as analyzed by transcriptomics in cytochrome P450 3A4-overexpressing HepG2 clone 9 cells.

Cell Biol Toxicol 2021 Apr 21. Epub 2021 Apr 21.

Department of Pharmaceutical Biology, Institute of Pharmaceutical and Biomedical Science, Johannes Gutenberg University, Mainz, Germany.

Pyrrolizidine alkaloids (PAs) are a large group of highly toxic chemical compounds, which are found as cross-contaminants in numerous food products (e.g., honey), dietary supplements, herbal teas, and pharmaceutical herbal medicines. PA contaminations are responsible for serious hepatotoxicity and hepatocarcinogenesis. Health authorities have to set legal limit values to guarantee the safe consumption of plant-based nutritional and medical products without harmful health. Toxicological and chemical analytical methods are conventionally applied to determine legally permitted limit values for PAs. In the present investigation, we applied a highly sensitive transcriptomic approach to investigate the effect of low concentrations of five PAs (lasiocarpine, riddelliine, lycopsamine, echimidine, and monocrotaline) on human cytochrome P450 3A4-overexpressing HepG2 clone 9 hepatocytes. The transcriptomic profiling of deregulated gene expression indicated that the PAs disrupted important signaling pathways related to cell cycle regulation and DNA damage repair in the transfected hepatocytes, which may explain the carcinogenic PA effects. As PAs affected the expression of genes that involved in cell cycle regulation, we applied flow cytometric cell cycle analyses to verify the transcriptomic data. Interestingly, PA treatment led to an arrest in the S phase of the cell cycle, and this effect was more pronounced with more toxic PAs (i.e., lasiocarpine and riddelliine) than with the less toxic monocrotaline. Using immunofluorescence, high fractions of cells were detected with chromosome congression defects upon PA treatment, indicating mitotic failure. In conclusion, the tested PAs revealed threshold concentrations, above which crucial signaling pathways were deregulated resulting in cell damage and carcinogenesis. Cell cycle arrest and DNA damage repair point to the mutagenicity of PAs. The disturbance of chromosome congression is a novel mechanism of Pas, which may also contribute to PA-mediated carcinogenesis. Transcriptomic, cell cycle, and immunofluorescence analyses should supplement the standard techniques in toxicology to unravel the biological effects of PA exposure in liver cells as the primary target during metabolization of PAs.
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http://dx.doi.org/10.1007/s10565-021-09599-9DOI Listing
April 2021

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition).

Autophagy 2021 Jan 8;17(1):1-382. Epub 2021 Feb 8.

University of Crete, School of Medicine, Laboratory of Clinical Microbiology and Microbial Pathogenesis, Voutes, Heraklion, Crete, Greece; Foundation for Research and Technology, Institute of Molecular Biology and Biotechnology (IMBB), Heraklion, Crete, Greece.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.
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http://dx.doi.org/10.1080/15548627.2020.1797280DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7996087PMC
January 2021

Induction of stress resistance and extension of lifespan in Chaenorhabditis elegans serotonin-receptor knockout strains by withanolide A.

Phytomedicine 2021 Apr 28;84:153482. Epub 2021 Jan 28.

Department of Pharmaceutical Biology, Institute of Biochemistry and Pharmacy, Johannes Gutenberg University, Staudinger Weg 5, 55128 Mainz, Germany. Electronic address:

Introduction: Approximately 300 million people worldwide suffer from depression. The COVID-19 crisis may dramatically increase these numbers. Severe side effects and resistance development limit the use of standard antidepressants. The steroidal lactone withanolide A (WA) from Withania somnifera may be a promising alternative. Caenorhabditis elegans was used as model to explore WA's anti-depressive and anti-stress potential.

Methods: C. elegans wildtype (N2) and deficient strains (AQ866, DA1814, DA2100, DA2109 and MT9772) were used to assess oxidative, osmotic or heat stress as measured by generation of reactive oxygen species (ROS), determination of lifespan, and mRNA expression of serotonin receptor (ser-1, ser-4, ser-7) and serotonin transporter genes (mod-5). The protective effect of WA was compared to fluoxetine as clinically established antidepressant. Additionally, WA's effect on lifespan was determined. Furthermore, the binding affinities and pKi values of WA, fluoxetine and serotonin as natural ligand to Ser-1, Ser-4, Ser-7, Mod-5 and their human orthologues proteins were calculated by molecular docking.

Results: Baseline oxidative stress was higher in deficient than wildtype worms. WA and fluoxetine reduced ROS levels in all strains except MT9772. WA and fluoxetine prolonged survival times in wildtype and mutants under osmotic stress. WA but not fluoxetine increased lifespan of all heat-stressed C. elegans strains except DA2100. Furthermore, WA but not fluoxetine extended lifespan in all non-stressed C. elegans strains. WA also induced mRNA expression of serotonin receptors and transporters in wildtype and mutants. WA bound with higher affinity and lower pKi values to all C. elegans and human serotonin receptors and transporters than serotonin, indicating that WA may competitively displaced serotonin from the binding pockets of these proteins.

Conclusion: WA reduced stress and increased lifespan by ROS scavenging and interference with the serotonin system. Hence, WA may serve as promising candidate to treat depression.
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http://dx.doi.org/10.1016/j.phymed.2021.153482DOI Listing
April 2021

Ursolic acid enhances stress resistance, reduces ROS accumulation and prolongs life span in C. elegans serotonin-deficient mutants.

Food Funct 2021 Mar 17;12(5):2242-2256. Epub 2021 Feb 17.

Department of Pharmaceutical Biology, Institute of Biochemistry and Pharmacy, Johannes Gutenberg University, Staudinger Weg 5, 55128 Mainz, Germany.

Introduction: Depression and anxiety disorders contribute to the global disease burden. Ursolic acid (UA), a natural compound present in many vegetables, fruits and medicinal plants, was tested in vivo for its effect on (1) enhancing resistance to stress and (2) its effect on life span.

Methods: The compound was tested for its antioxidant activity in C. elegans. Stress resistance was tested in the heat and osmotic stress assay. Additionally, the influence on normal life span was examined. RT-PCR was used to assess possible serotonin targets.

Results: UA prolonged the life span of C. elegans. Additionally, UA significantly lowered reactive oxygen species (ROS). Molecular docking studies, PCR analysis and microscale thermophoresis (MST) supported the results that UA acts through serotonin receptors to enhance stress resistance.

Discussion: Considering the urgent need for new and safe medications in the treatment of depression and anxiety disorders, our results indicate that UA may be a promising new drug candidate.
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http://dx.doi.org/10.1039/d0fo02208jDOI Listing
March 2021

A novel ligand of the translationally controlled tumor protein (TCTP) identified by virtual drug screening for cancer differentiation therapy.

Invest New Drugs 2021 Jan 25. Epub 2021 Jan 25.

Department of Pharmaceutical Biology, Institute for Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University, Staudinger Weg 5, 55128, Mainz, Germany.

Introduction Differentiation therapy is a promising strategy for cancer treatment. The translationally controlled tumor protein (TCTP) is an encouraging target in this context. By now, this field of research is still at its infancy, which motivated us to perform a large-scale screening for the identification of novel ligands of TCTP. We studied the binding mode and the effect of TCTP blockade on the cell cycle in different cancer cell lines. Methods Based on the ZINC-database, we performed virtual screening of 2,556,750 compounds to analyze the binding of small molecules to TCTP. The in silico results were confirmed by microscale thermophoresis. The effect of the new ligand molecules was investigated on cancer cell survival, flow cytometric cell cycle analysis and protein expression by Western blotting and co-immunoprecipitation in MOLT-4, MDA-MB-231, SK-OV-3 and MCF-7 cells. Results Large-scale virtual screening by PyRx combined with molecular docking by AutoDock4 revealed five candidate compounds. By microscale thermophoresis, ZINC10157406 (6-(4-fluorophenyl)-2-[(8-methoxy-4-methyl-2-quinazolinyl)amino]-4(3H)-pyrimidinone) was identified as TCTP ligand with a K of 0.87 ± 0.38. ZINC10157406 revealed growth inhibitory effects and caused G0/G1 cell cycle arrest in MOLT-4, SK-OV-3 and MCF-7 cells. ZINC10157406 (2 × IC50) downregulated TCTP expression by 86.70 ± 0.44% and upregulated p53 expression by 177.60 ± 12.46%. We validated ZINC10157406 binding to the p53 interaction site of TCTP and replacing p53 by co-immunoprecipitation. Discussion ZINC10157406 was identified as potent ligand of TCTP by in silico and in vitro methods. The compound bound to TCTP with a considerably higher affinity compared to artesunate as known TCTP inhibitor. We were able to demonstrate the effect of TCTP blockade at the p53 binding site, i.e. expression of TCTP decreased, whereas p53 expression increased. This effect was accompanied by a dose-dependent decrease of CDK2, CDK4, CDK, cyclin D1 and cyclin D3 causing a G0/G1 cell cycle arrest in MOLT-4, SK-OV-3 and MCF-7 cells. Our findings are supposed to stimulate further research on TCTP-specific small molecules for differentiation therapy in oncology.
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http://dx.doi.org/10.1007/s10637-020-01042-wDOI Listing
January 2021

The alkaloid, soyauxinium chloride, displays remarkable cytotoxic effects towards a panel of cancer cells, inducing apoptosis, ferroptosis and necroptosis.

Chem Biol Interact 2021 Jan 24;333:109334. Epub 2020 Nov 24.

Department of Pharmaceutical Biology, Institute of Pharmaceutical and Biomedical Sciences, University of Mainz, Staudinger Weg 5, 55128, Mainz, Germany. Electronic address:

The cytotoxic potential of a naturally occurring indoloquinazoline alkaloid, soyauxinium chloride (SCHL), was determined on a broad panel of animal and human cancer cell lines, including various sensitive and drug-resistant phenotypes. The cytotoxicity, SCHL-induced autophagic, ferroptotic, and necroptotic cell death were evaluated by the resazurin reduction assay (RRA). Caspase-Glo assay was used to detect the activity of caspases using spectrophotometric analysis. Flow cytometry was applied for cell cycle analysis (PI staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP) (JC-1) and reactive oxygen species (ROS) (HDCFH-DA). SCHL and doxorubicin (reference molecule) exhibited cytotoxic effects towards the 18 cancer cell lines tested. The IC values obtained ranged from 3.64 μM (towards CCRF-CEM leukemia cells) to 16.86 μM (against the BRAF-wildtype SKMel-505 melanoma cells for SCHL). Collateral sensitivity of the resistant HCT116 p53 colon adenocarcinoma cells to SCHL was observed as well as the normal sensitivity of CEM/ADR5000 leukemia cells, MDA-MB-231-BCRP breast adenocarcinoma cells and U87. MGΔEGFR glioblastoma cells. SCHL induced apoptosis in CCRF-CEM cells via caspases 3/7-, 8- and 9-activation, MMP alteration and increased ROS production, and otherwise ferroptosis and necroptosis. SCHL is a prominent cytotoxic alkaloid that should be further studied to develop a novel drug to combat cancers including refractory phenotypes.
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http://dx.doi.org/10.1016/j.cbi.2020.109334DOI Listing
January 2021

Cytotoxicity of apigenin toward multiple myeloma cell lines and suppression of iNOS and COX-2 expression in STAT1-transfected HEK293 cells.

Phytomedicine 2021 Jan 8;80:153371. Epub 2020 Oct 8.

Department of Pharmaceutical Biology, Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University, Staudinger Weg 5, 55128 Mainz, Germany. Electronic address:

Background: Apigenin is one of the most abundant dietary flavonoids that possesses multiple bio-functions.

Purpose: This study was designed to determine the influence of apigenin on gene expressions, cancer cells, as well as STAT1/COX-2/iNOS pathway mediated inflammation and tumorigenesis in HEK293-STAT1 cells. Furthermore, the cytotoxic activity toward multiple myeloma (MM) cell lines was investigated.

Methods: Bioinformatic analyses were used to predict the sensitivity and resistance of tumor cells toward apigenin and to determine cellular pathways influenced by this compound. The cytotoxic and ferroptotic activity of apigenin was examined by the resazurin reduction assay. Additionally, we evaluated apoptosis, and cell cycle distribution, induction of reactive oxygen species (ROS) and loss of integrity of mitochondrial membrane (MMP) by using the flow cytometry analysis. DAPI staining was used to detect characteristic apoptotic features. Furthermore, we verified its anti-inflammatory and additional mechanism of cell death by western blotting.

Results: COMPARE and hierarchical cluster analyses exhibited that 29 of 55 tumor cell lines were sensitive against apigenin (p < 0.001). The Ingenuity Pathway Analysis data showed that important bio-functions affected by apigenin were: gene expression, cancer, hematological system development and function, inflammatory response, and cell cycle. The STAT1 transcription factor was chosen as target protein on the basis of gene promoter binding motif analyses. Apigenin blocked cell proliferation of wild-type HEK293 and STAT1 reporter cells (HEK293-STAT1), promoted STAT1 suppression and subsequent COX-2 and iNOS inhibition. Apigenin also exhibited synergistic activity in combination with doxorubicin toward HEK293-STAT1 cells. Apigenin exerted excellent growth-inhibitory activity against MM cells in a concentration-dependent manner with the greatest activity toward NCI-H929 (IC value: 10.73 ± 3.21 μM). Apigenin induced apoptosis, cell cycle arrest, ferroptosis and autophagy in NCI-H929 cells.

Conclusion: Apigenin may be a suitable candidate for MM treatment. The inhibition of the STAT1/COX-2/iNOS signaling pathway by apigenin is an important mechanism not only in the suppression of inflammation but also in induction of apoptosis.
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http://dx.doi.org/10.1016/j.phymed.2020.153371DOI Listing
January 2021

Identification and characterization of deschloro-chlorothricin obtained from a large natural product library targeting aurora A kinase in multiple myeloma.

Invest New Drugs 2021 Apr 25;39(2):348-361. Epub 2020 Sep 25.

Department of Pharmaceutical Biology, Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University, Staudinger Weg 5, 55128, Mainz, Germany.

Multiple myeloma (MM) is a devastating disease with low survival rates worldwide. The mean lifetime of patients may be extendable with new drug alternatives. Aurora A kinase (AURKA) is crucial in oncogenesis, because its overexpression or amplification may incline the development of various types of cancer, including MM. Therefore, inhibitors of AURKA are innovative and promising targets. Natural compounds always represented a valuable resource for anticancer drug development. In the present study, based on virtual drug screening of more than 48,000 natural compounds, the antibiotic deschloro-chlorotricin (DCCT) has been identified to bind to AURKA with even higher binding affinity (free bindung energy: -12.25 kcal/mol) than the known AURKA inhibitor, alisertib (free binding energy: -11.25 kcal/mol). The in silico studies have been verified in vitro by using microscale thermophoresis. DCCT inhibited MM cell lines (KMS-11, L-363, RPMI-8226, MOLP-8, OPM-2, NCI-H929) with IC values in a range from 0.01 to 0.12 μM. Furthermore, DCCT downregulated AURKA protein expression, induced G2/M cell cycle arrest and disturbed the cellular microtubule network as determined by Western blotting, flow cytometry, and fluorescence microscopy. Thus, DCCT may be a promising lead structure for further derivatization and the development of specific AURKA inhibitors in MM therapy.
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http://dx.doi.org/10.1007/s10637-020-01012-2DOI Listing
April 2021

N-acetylglycoside of oleanolic acid (aridanin) displays promising cytotoxicity towards human and animal cancer cells, inducing apoptotic, ferroptotic and necroptotic cell death.

Phytomedicine 2020 Jun 8;76:153261. Epub 2020 Jun 8.

Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, University of Mainz, Staudinger Weg 5, 55128 Mainz, Germany. Electronic address:

Background: The discovery of novel phytochemicals represents a reasonable approach to fight malignancies, especially those which are resistant to standard chemotherapy.

Purpose: We evaluated the cytotoxic potential of a naturally occurring N-acetylglycoside of oleanolic acid, aridanin, on 18 cancer cell lines, including sensitive and drug-resistant phenotypes mediated by P-glycoprotein, BCRP, p53 knockout, deletion-mutated EGFR, or BRAF mutations. Furthermore, metastasizing B16/F10 cells, HepG2 hepatocarcinoma and normal AML12 hepatocytes were investigated. The mechanisms of aridanin-induced cell death was further investigated.

Methods: The resazurin reduction assay (RRA) was applied to evaluate the cytotoxicity, autophagy, ferroptotic and necroptotic cell death. CCRF-CEM leukemia cells were used for all mechanistic studies. A caspase-Glo assay was applied to evaluate the caspase activities. Flow cytometry was applied for the analyses of cell cycle (PI staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP; JC-1) and reactive oxygen species (ROS; HDCFH-DA).

Results: Aridanin and doxorubicin (positive control) inhibited the proliferation of all cancer cell lines tested. The IC values for aridanin varied from 3.18 µM (CCRF-CEM cells) to 9.56 µM (HepG2 cells). Aridanin had considerably lower IC values than that of doxorubicin against multidrug-resistant CEM/ADR5000 cells and melanoma cell lines (MaMel-80a, Mel-2a, MV3, and SKMel-505). Aridanin induced apoptosis in CCRF-CEM cells through increase of ROS levels and MMP breakdown, and to a lesser extent via caspases activation. Aridanin also induced ferroptotic and necroptotic cell death.

Conclusion: The present study opens good perpectives for the use of this phytochemical as an anticancer drug to combat multi-facorial resistance to established chemotherapeutics.
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http://dx.doi.org/10.1016/j.phymed.2020.153261DOI Listing
June 2020

Cytotoxicity of a naturally occuring spirostanol saponin, progenin III, towards a broad range of cancer cell lines by induction of apoptosis, autophagy and necroptosis.

Chem Biol Interact 2020 Aug 23;326:109141. Epub 2020 May 23.

Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, University of Mainz, Staudinger Weg 5, 55128, Mainz, Germany. Electronic address:

This study was aimed to investigate the cytotoxic potential of a natural compound, progenin III on a broad range of cancer cell lines, including various sensitive and drug-resistant phenotypes. The cytotoxicity, progenin III-induced autophagic, ferroptotic and necroptotic cell death were evaluated by the resazurin reduction assay (RRA). Spectrophotometric analysis of caspases activity was performed using caspase-Glo assay. Flow cytometry was applied for cell cycle analysis (PI staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP) (JC-1) and reactive oxygen species (ROS) (HDCFH-DA). Progenin III and the reference molecule, doxorubicin exerted cytotoxic effects towards the 18 cancer cell lines tested including animal and human cell lines. The IC values obtained ranged from 1.59 μM (towards CCRF-CEM leukemia cells) to 31.61 μM (against the BRAF-V600E homozygous mutant SKMel-28 melanoma cells) for progenin III. Normal sensitivity was achieved with CEM/ADR5000 cells and HCT116p53 adenocarcinoma cells respectively compared to their sensitive congeners CCRF-CEM cells and HCT116 p53 cells. Progenin III induced apoptosis in CCRF-CEM cells mediated by caspases 3/7 activation, MMP alteration and increase ROS production, and otherwise autophagy and necroptosis. Progenin III is a potential anticancer molecule that deserves further investigations to develop a novel drug to combat malignant diseases including refractory cancers.
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http://dx.doi.org/10.1016/j.cbi.2020.109141DOI Listing
August 2020

8,8-bis-(Dihydroconiferyl)-diferulate displayed impressive cytotoxicity towards a panel of human and animal cancer cells.

Phytomedicine 2020 Apr 20;70:153215. Epub 2020 Apr 20.

Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, University of Mainz, Staudinger Weg 5, 55128 Mainz, Germany. Electronic address:

Background: Recalcitrant cancers appear as a major obstacle to chemotherapy, prompting scientists to intensify the search for novel drugs to tackle the cell lines expressing multi-drug resistant (MDR) phenotypes.

Purpose: The purpose of this study was to evaluate the antiproliferative potential of a ferrulic acid derivative, 8,8-bis-(dihydroconiferyl)-diferulate (DHCF2) on a panel of 18 cancer cell lines, including various sensitive and drug-resistant phenotypes, belonging to human and animals. The mode of induction of cell death by this compound was further studied.

Methods: The antiproliferative activity, autophagy, ferroptotic and necroptotic cell death were evaluated by the resazurin reduction assay (RRA). CCRF-CEM leukemia cells were used for all mechanistic studies. A caspase-Glo assay was applied to evaluate the activity of caspases. Cell cycle analysis (PI staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP) (JC-1) and reactive oxygen species (ROS) (HDCFH-DA) were assessed by flow cytometry.

Results: DHCF2 demonstrated impressive cytotoxic effects towards the 18 cancer cell lines tested, with IC values all below 6.5 µM. The obtained IC values were in the range of 1.17 µM (towards CCRF-CEM leukemia cells) to 6.34 µM (towards drug-resistant HCT116 p53 human colon adenocarcinoma cells) for DHCF2 and from 0.02 µM (against CCRF-CEM cells) to 122.96 µM (against multidrug-resistant CEM/ADR5000 leukemia cells) for the reference drug, doxorubicin. DHCF2 had IC values lower than those of doxorubicin, against CEM/ADR5000 cells and on some melanoma cell lines, such as MaMel-80a cells, Mel-2a cells, MV3 cells and SKMel-505 cells. DHCF2 induced autophagy as well as apoptosis in CCRF-CEM cells though caspases activation, MMP alteration and increase of ROS production.

Conclusion: The studied diferulic acid, DHCF2, is a promising antiproliferative compound. It deserves further indepth investigations with the ultimate aim to develop a novel drug to fight cancer drug resistance.
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http://dx.doi.org/10.1016/j.phymed.2020.153215DOI Listing
April 2020

Isopetasin and S-isopetasin as novel P-glycoprotein inhibitors against multidrug-resistant cancer cells.

Phytomedicine 2021 Jun 10;86:153196. Epub 2020 Mar 10.

Department of Pharmaceutical Biology, Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University, Mainz, Germany. Electronic address:

Background: A major problem of cancer treatment is the development of multidrug resistance (MDR) to chemotherapy. MDR is caused by different mechanisms such as the expression of the ABC-transporters P-glycoprotein (P-gp, MDR1, ABCB1) and breast cancer resistance protein (BCRP, ABCG2). These transporters efflux xenobiotic toxins, including chemotherapeutics, and they were found to be overexpressed in different cancer types.

Purpose: Identification of novel molecules that overcome MDR by targeting ABC-transporters.

Methods: Resazurin reduction assay was used for cytotoxicity test. AutoDock 4.2. was used for molecular docking. The function of P-gp and BCRP was tested using a doxorubicin uptake assay and an ATPase assay. ROS generation was detected using flow cytometry for the measurement of HDCFH-DA fluorescence. Annexin/PI staining was applied for the detection of apoptosis. Bioinformatic analyses were performed using LigandScout 3.12. software and DataWarrior software.

Results: In our search for new molecules that selectively act against resistant phenotypes, we identified isopetasin and S-isopetasin, which are bioactive natural products from Petasites formosanus. They exerted collateral sensitivity towards leukemia cells with high P-gp expression in CEM/ADR5000 cells, compared to sensitive wild-type CCRF-CEM leukemia cells. Also, they revealed considerable activity towards breast cancer cells overexpressing breast cancer resistance protein, MDA-MB-231-BCRP clone 23. This motivated us to investigate whether the function of P-gp was inhibited. In-silico results showed the compounds bound with high affinity and interacted with key amino acid residues in P-gp . Then, we found that the two compounds increased doxorubicin accumulation in P-gp overexpressing CEM/ADR5000 by three-fold compared to cells without inhibitor. P-gp-mediated drug efflux was ATP-dependent. Isopetasin and S-isopetasin increased the ATPase activity of human P-gp in a comparable fashion as verapamil used as control P-gp inhibitor. As isopetasin and S-isopetasin exerted dual roles, first as cytotoxic compounds and then as P-gp inhibitors, we suggested that their P-gp inhibition is part of a larger complex of mechanisms to induce cell death in cancer patients. P-gp dysfunction induces mitochondrial stress to generate ATP. Upon continuing stress by P-gp inhibition, the mitochondria generate reactive oxygen species (ROS). Initially established for verapamil, this theory was validated in the present study for isopetasin and S-isopetasin, as treatment with the two candidates increased ROS levels in CEM/ADR5000 cells followed by apoptosis.

Conclusion: Our study highlights the importance of isopetasin and S-isopetasin as novel ROS-generating and apoptosis-inducing P-gp inhibitors.
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http://dx.doi.org/10.1016/j.phymed.2020.153196DOI Listing
June 2021

The antioxidant 2,3-dichloro,5,8-dihydroxy,1,4-naphthoquinone inhibits acetyl-cholinesterase activity and amyloid β aggregation: A dual target therapeutic candidate compound for the treatment of Alzheimer's disease.

Biotechnol Appl Biochem 2020 Nov 17;67(6):983-990. Epub 2020 Feb 17.

Laboratory of Aromatic and Medicinal Plants, Biotechnology Center of Borj-Cedria, Hammam-Lif, Tunisia.

Alzheimer's disease is characterized by amyloid β aggregation and cholinergic neurodegeneration. In the present study, pure DDN (2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone) was examined, for the first time, for its dual potential as inhibitor of acetylcholinesterase (AChE) and Aβ aggregation. Such investigation was encouraged by the in vitro high antioxidant potential of DDN. Indeed, it revealed interesting antioxidant activity with IC values of 9.8 and 4.3 µM for ABTS and reducing power, respectively. The ability of DDN to counteract Aβ aggregation was evaluated by thioflavine-T assay. Strong inhibition of Aβ aggregation of more than 90% at 25 µM was measured. Moreover, results showed that DDN inhibited AChE (IC = 14.5 µM). To better understand the interactions between DDN and AChE, molecular docking was performed. Obtained data predicted a high interaction characterized by hydrogen bonding at TYR337 as for galanthamine (positive control). Several residues involved in AChE hydrophobic interactions were similarly implicated in binding of this domain to DDN (ASP74, THR83, and TYR124). All these data would be useless if DDN could not pass the blood-brain barrier. So, DDN was loaded into alginate microspheres to enhance its stability and bioavailability. Thereafter, drug release profiles were assessed using immersion cell apparatus.
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http://dx.doi.org/10.1002/bab.1870DOI Listing
November 2020

MCC1019, a selective inhibitor of the Polo-box domain of Polo-like kinase 1 as novel, potent anticancer candidate.

Acta Pharm Sin B 2019 Sep 10;9(5):1021-1034. Epub 2019 Feb 10.

Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg University, Mainz 55128, Germany.

Polo-like kinase (PLK1) has been identified as a potential target for cancer treatment. Although a number of small molecules have been investigated as PLK1 inhibitors, many of which showed limited selectivity. PLK1 harbors a regulatory domain, the Polo box domain (PBD), which has a key regulatory function for kinase activity and substrate recognition. We report on 3-bromomethyl-benzofuran-2-carboxylic acid ethyl ester (designated: MCC1019) as selective PLK1 inhibitor targeting PLK1 PBD. Cytotoxicity and fluorescence polarization-based screening were applied to a library of 1162 drug-like compounds to identify potential inhibitors of PLK1 PBD. The activity of compound MC1019 against the PLK1 PBD was confirmed using fluorescence polarization and microscale thermophoresis. This compound exerted specificity towards PLK1 over PLK2 and PLK3. MCC1019 showed cytotoxic activity in a panel of different cancer cell lines. Mechanistic investigations in A549 lung adenocarcinoma cells revealed that MCC1019 induced cell growth inhibition through inactivation of AKT signaling pathway, it also induced prolonged mitotic arrest-a phenomenon known as mitotic catastrophe, which is followed by immediate cell death apoptosis and necroptosis. MCC1019 significantly inhibited tumor growth in a murine lung cancer model without affecting body weight or vital organ size, and reduced the growth of metastatic lesions in the lung. We propose MCC1019 as promising anti-cancer drug candidate.
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http://dx.doi.org/10.1016/j.apsb.2019.02.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6804483PMC
September 2019

Cytotoxicity and antimitotic activity of Rhinella schneideri and Rhinella marina venoms.

J Ethnopharmacol 2019 Oct 29;242:112049. Epub 2019 Jun 29.

Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg University, Mainz, 55128, Germany. Electronic address:

Ethnopharmacological Relevance: Rhinella schneideri and Rhinella marina are toad venoms distributed in different parts of the world, including Brazil, Columbia and amazon. Venoms extracted from different species have many clinical applications such as antimicrobial cardiotonics and treatment of cancer. Aim of the study; In this study, we aim to investigate the effect of venoms extracted from R. schneideri and R. marina on cancer cells and verify possible mechanism of action.

Material And Method: Cytotoxicity analyses was performed using the resazurin reduction assay, where different concentrations of venoms were tested against sensitive CCRF-CEM and P-gp overexpressing ADR/CEM5000 leukemia cells. Programmed cell death was investigated using the flow cytometric annexin V/propidium iodide apoptosis assay. Furthermore, we analyzed flow cytometric cell cycle analyses of CCRF-CEM cells. Effect on tubulin formation was tested using molecular docking and fluorescence microscopy of U2OS-GFP-α-tubulin osteosarcoma cells treated for 24 h with venoms.

Results: Cytotoxicity assays revealed a strong activity towards wild-type CCRF-CEM cells (IC values of 0.202 ± 0.005 μg/ml and 0.18 ± 0.007 μg/ml for R. schneideri and R. marina, respectively) and multidrug-resistant CEM/ADR5000 cells (IC 0.403 ± 0.084 μg/ml and 0.32 ± 0.077 μg/ml for R. schneideri and R. marina, respectively). The venoms induced apoptosis as major mechanism of cell death. The venoms induced strong G2/M cell arrest in CCRF-CEM cells. We suggested tubulin as a major target for the venoms. In silico molecular docking of the major constituents of the venoms, i.e. bufalin, marinobufagin, telocinbufagin, hellebrigenin, showed strong binding affinities to tubulin. This result was verified in vitro. The venoms dysregulated microtubule arrangement of U2OS cells expressing GFP-labeled tubulin. Toxicity predictions by QSAR methodology highlighted the toxic features of bufadienolides.

Conclusion: Our study demonstrated the importance of toad venoms as source of cytotoxic compounds that may serve as lead compounds for the development of novel anticancer drugs.
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http://dx.doi.org/10.1016/j.jep.2019.112049DOI Listing
October 2019

Cytotoxicity of 40 Egyptian plant extracts targeting mechanisms of drug-resistant cancer cells.

Phytomedicine 2019 Jun 26;59:152771. Epub 2018 Nov 26.

Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg University, Staudinger Weg 5, Mainz 55128, Germany. Electronic address:

Background: The multidrug resistance (MDR) phenotype encounters a major challenge to the success of established chemotherapy in cancer patients. We hypothesized that cytotoxic medicinal plants with novel phytochemicals can overcome MDR and kill MDR-cells with similar efficacy as drug sensitive cells.

Purpose: We evaluated plant extracts from an unexplored ecosystem in Egypt with unusual climate and nutrient conditions for their activity against sensitive and multidrug-resistant cancer cell lines.

Material And Methods/study Design: Methylene chloride: methanol (1:1) and methanol: HO (7:3) extracts of 40 plants were prepared resulting in a sum of 76 fraction containing compounds with varying polarity. The resazurin reduction assay was employed to evaluate the cytotoxicity of these extracts on five matched pairs of drug-sensitive and their drug-resistant cell lines. Flow cytometry and Western blotting was used to determine cell cycle analyses, apoptosis, and autophagy. Reactive oxygen species (ROS) were measured spectrophotometrically.

Results: Extracts derived from Withania obtusifolia (WO), Jasonia candicans (JC), Centaurea lippii (CL), and Pulicaria undulata (PU) were the most active ones among 76 extracts from 40 Egyptian medicinal plants. They showed a significant reduction of cell viability on drug-sensitive CCRF-CEM leukemia cell line with IC values less than 7 µg/ml. Low cross-resistance degrees were observed in multidrug-resistant CEM/ADR5000 cells towards CL (1.82-fold) and JC (6.09-fold). All other drug-resistant cell lines did not reveal cross-resistance to the four extracts. Further mechanistic assessment have been studied for these four extracts.

Conclusion: The methylene chloride: methanol (1:1) fractions of WO, JC, CL, and PU are promising cytotoxic extracts that could be used to combat MDR cancer cells through different cell death pathways.
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http://dx.doi.org/10.1016/j.phymed.2018.11.031DOI Listing
June 2019

A selective inhibitor of the Polo-box domain of Polo-like kinase 1 identified by virtual screening.

J Adv Res 2019 Mar 31;16:145-156. Epub 2018 Oct 31.

Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg University, Mainz 55128, Germany.

Polo-like kinase 1 (PLK1), a member of the Polo-like kinase family, plays an important regulatory role in mitosis and cell cycle progression. PLK1 overexpression is correlated with tumourigenesis and poor prognosis in cancer patients. Therefore, the identification of novel compounds that inhibit PLK1 would provide attractive therapeutic approaches. Although some PLK1 kinase inhibitors have been developed, their application has been limited by off-target effects. PLK1 contains a regulatory domain named the Polo-box domain (PBD), which is characteristic only for the Polo-like kinase family. This domain represents an alternative therapeutic target with higher selectivity for PLK1. In this study, we applied virtual drug screening, fluorescence polarization and microscale thermophoresis to identify new scaffolds targeting the PBD of PLK1. One compound, 3-{[(1R,9S)-3-(naphthalen-2-yl)-6-oxo-7,11-diazatricyclo[7.3.1.0,]trideca-2,4-dien-11-yl]methyl}benzonitrile (designated compound ), out of a total of 30,793 natural product derivatives, inhibited the PLK1 PBD with high selectivity (IC50: 17.9 ± 0.5 µM). This compound inhibited the growth of cultured leukaemia cells (CCRF-CEM and CEM/ADR5000) and arrested the cell cycle in the G2/M phase, which is characteristic for PLK1 inhibitors. Immunofluorescence analyses showed that treatment with compound disrupted spindle formation due to the aberrant localization of PLK1 during the mitotic process, leading to G2/M arrest and ultimately cell death. In conclusion, compound is a selective PLK1 inhibitor that inhibits cancer cell growth. It represents a chemical scaffold for the future synthesis of new selective PLK1 inhibitors for cancer therapy.
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http://dx.doi.org/10.1016/j.jare.2018.10.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6412170PMC
March 2019

Identification of inhibitors of the polo-box domain of polo-like kinase 1 from natural and semisynthetic compounds.

Invest New Drugs 2020 02 15;38(1):1-9. Epub 2019 Mar 15.

Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg University, 55128, Mainz, Germany.

PLK1 has an important role in the regulation of cell cycle and represents an important target for cancer treatment. This enzyme belongs to the Polo-like kinases family, which is characterized by a regulatory domain named Polo-box domain (PBD). Rather than regular kinase inhibitors, this domain provides high selectivity to PLK1. Here, we report on four novel PLK1 PBD inhibitors identified by cytotoxicity screening and fluorescence polarization assay of a chemical library of natural and semisynthetic compounds. These compounds revealed two- to three-fold higher selectivity to the PDB of PLK1 than to those of the related family members, PLK2 and PLK3. These four substances inhibited tumor cell growth of sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 leukemia cells. The tested compounds increased the apoptotic cell fraction, which indicates apoptosis as a major mechanism of cell death. Cell cycle analysis showed compound (5) arrested the cell cycle of CCRF-CEM cells in the G2/M phase, while the other three molecules ((compound (3), compound (4), and compound (6)) exerted pronounced cytotoxicity with an increase of cells in the sub-G1 population. Molecular docking was performed for the understanding of ligand-protein interaction, the tested candidates showed strong binding affinity to PLK1 PBD. In conclusion, we identified four new chemical scaffolds that may serve as lead compounds for the development of selective PLK1 inhibitors in the future.
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http://dx.doi.org/10.1007/s10637-019-00752-0DOI Listing
February 2020

Biopiracy versus One-World Medicine-From colonial relicts to global collaborative concepts.

Phytomedicine 2019 Feb 11;53:319-331. Epub 2018 Jun 11.

Department of Chemistry, University of Nairobi, Nairobi, Kenya.

Background: Practices of biopiracy to use genetic resources and indigenous knowledge by Western companies without benefit-sharing of those, who generated the traditional knowledge, can be understood as form of neocolonialism.

Hypothesis: The One-World Medicine concept attempts to merge the best of traditional medicine from developing countries and conventional Western medicine for the sake of patients around the globe.

Study Design: Based on literature searches in several databases, a concept paper has been written. Legislative initiatives of the United Nations culminated in the Nagoya protocol aim to protect traditional knowledge and regulate benefit-sharing with indigenous communities. The European community adopted the Nagoya protocol, and the corresponding regulations will be implemented into national legislation among the member states. Despite pleasing progress, infrastructural problems of the health care systems in developing countries still remain. Current approaches to secure primary health care offer only fragmentary solutions at best. Conventional medicine from industrialized countries cannot be afforded by the impoverished population in the Third World. Confronted with exploding costs, even health systems in Western countries are endangered to burst. Complementary and alternative medicine (CAM) is popular among the general public in industrialized countries, although the efficacy is not sufficiently proven according to the standards of evidence-based medicine. CAM is often available without prescription as over-the-counter products with non-calculated risks concerning erroneous self-medication and safety/toxicity issues. The concept of integrative medicine attempts to combine holistic CAM approaches with evidence-based principles of conventional medicine.

Conclusion: To realize the concept of One-World Medicine, a number of standards have to be set to assure safety, efficacy and applicability of traditional medicine, e.g. sustainable production and quality control of herbal products, performance of placebo-controlled, double-blind, randomized clinical trials, phytovigilance, as well as education of health professionals and patients.
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http://dx.doi.org/10.1016/j.phymed.2018.06.007DOI Listing
February 2019

Cytotoxicity of abietane diterpenoids from Salvia multicaulis towards multidrug-resistant cancer cells.

Fitoterapia 2018 Oct 13;130:54-60. Epub 2018 Aug 13.

Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg University, Staudinger Weg 5, 55128 Mainz, Germany. Electronic address:

Diterpenoids salvimulticanol (1) and salvimulticaoic acid (2) together with known diterpenoid (3-6) were isolated from Salvia multicaulis. Structures were elucidated by spectroscopic techniques including HRESIMS as well as 1D-, and 2D-NMR. In-vitro cytotoxicity was assayed against human cancer cell lines. As several metabolites exhibited activity against drug-resistance lines, compounds were screened against a panel of human drug-sensitive and multidrug-resistant cancer lines. A proposed biosynthetic pathway for these new diterpenoids (1-2) as well as the cytotoxic structure-activity relationship of all identified compounds were discussed. Compound 1 and 6 showed the most potent cytotoxicity with IC 11.58 and 4.13 towards leukemia cell lines CCRF-CEM and CEM-ADR5000, respectively.
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http://dx.doi.org/10.1016/j.fitote.2018.08.002DOI Listing
October 2018

Treatment of Multidrug-Resistant Leukemia Cells by Novel Artemisinin-, Egonol-, and Thymoquinone-Derived Hybrid Compounds.

Molecules 2018 Apr 6;23(4). Epub 2018 Apr 6.

Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg University, 55128 Mainz, Germany.

Two major obstacles for successful cancer treatment are the toxicity of cytostatics and the development of drug resistance in cancer cells during chemotherapy. Acquired or intrinsic drug resistance is responsible for almost 90% of treatment failure. For this reason, there is an urgent need for new anticancer drugs with improved efficacy against cancer cells, and with less toxicity on normal cells. There are impressive examples demonstrating the success of natural plant compounds to fight cancer, such as alkaloids, taxanes, and anthracyclines. Artesunic acid (ARTA), a drug for malaria treatment, also exerts cytotoxic activity towards cancer cells. Multidrug resistance often results from drug efflux pumps (ABC-transporters) that reduce intracellular drug levels. Hence, it would be interesting to know, whether ARTA could overcome drug resistance of tumor cells, and in what way ABC-transporters are involved. Different derivatives showing improved features concerning cytotoxicity and pharmacokinetic behavior have been developed. Considering both drug sensitivity and resistance, we chose a sensitive and a doxorubicin-resistant leukemia cell line and determined the killing effect of ARTA on these cells. Molecular docking and doxorubicin efflux assays were performed to investigate the interaction of the derivatives with -glycoprotein. Using single-cell gel electrophoresis (alkaline comet assay), we showed that the derivatives of ARTA induce DNA breakage and accordingly programmed cell death, which represents a promising strategy in cancer treatment. ARTA activated apoptosis in cancer cells by the iron-mediated generation of reactive oxygen species (ROS). In conclusion, ARTA derivatives may bear the potential to be further developed as anticancer drugs.
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http://dx.doi.org/10.3390/molecules23040841DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6017613PMC
April 2018

Identification of Phlogacantholide C as a Novel ADAM10 Enhancer from Traditional Chinese Medicinal Plants.

Medicines (Basel) 2016 Dec 5;3(4). Epub 2016 Dec 5.

Clinic of Psychiatry and Psychotherapy, University Medical Center of the Johannes Gutenberg-University Mainz, 55131 Mainz, Germany.

Alzheimer's disease is one of the most prevalent dementias in the elderly population with increasing numbers of patients. One pivotal hallmark of this disorder is the deposition of protein aggregates stemming from neurotoxic amyloid-beta peptides. Synthesis of those peptides has been efficiently prevented in AD model mice by activation of an enzyme called alpha-secretase. Therefore, drugs with the capability to increase the expression of this enzyme, named ADAM10, have been suggested as a valuable therapeutic medication. We investigated 69 substances from a drug library derived from traditional Chinese medicine by luciferase reporter assay in human neuronal cells for their potential to selectively induce alpha-secretase expression. Western blot analysis was used to confirm results on the protein level. Ten of the 69 investigated compounds led to induction of ADAM10 transcriptional activity while BACE-1 (beta-site APP cleaving enzyme 1) and APP (amyloid precursor protein) expression were not induced. Two of them-Norkurarinol and Phlogacantholide C-showed substantial elevation of ADAM10 protein levels and Phlogacantholide C also increased secretion of the ADAM10-derived cleavage product APPs-alpha. Phlogacantholide C represents a novel ADAM10 gene expression enhancer from traditional Chinese medicinal herbs that may lay the groundwork for evolving potential novel therapeutics in Alzheimer's disease.
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http://dx.doi.org/10.3390/medicines3040030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5456242PMC
December 2016

Biopiracy of natural products and good bioprospecting practice.

Phytomedicine 2016 Feb 9;23(2):166-73. Epub 2016 Jan 9.

Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg University, Staudinger Weg 5, 55128 Mainz, Germany.

Background: Biopiracy mainly focuses on the use of biological resources and/or knowledge of indigenous tribes or communities without allowing them to share the revenues generated out of economic exploitation or other non-monetary incentives associated with the resource/knowledge.

Methods: Based on collaborations of scientists from five continents, we have created a communication platform to discuss not only scientific topics, but also more general issues with social relevance. This platform was termed 'PhytCancer -Phytotherapy to Fight Cancer' (www.phyt-cancer.uni-mainz.de). As a starting point, we have chosen the topic "biopiracy", since we feel this is of pragmatic significance for scientists working with medicinal plants.

Results: It was argued that the patenting of herbs or natural products by pharmaceutical corporations disregarded the ownership of the knowledge possessed by the indigenous communities on how these substances worked. Despite numerous court decisions in U.S.A. and Europe, several international treaties, (e.g. from United Nations, World Health Organization, World Trade Organization, the African Unity and others), sharing of a rational set of benefits amongst producers (mainly pharmaceutical companies) and indigenous communities is yet a distant reality. In this paper, we present an overview of the legal frameworks, discuss some exemplary cases of biopiracy and bioprospecting as excellent forms of utilization of natural resources.

Conclusions: We suggest certain perspectives, by which we as scientists, may contribute towards prevention of biopiracy and also to foster the fair utilization of natural resources. We discuss ways, in which the interests of indigenous people especially from developing countries can be secured.
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http://dx.doi.org/10.1016/j.phymed.2015.12.006DOI Listing
February 2016

Cytotoxicity of the indole alkaloid reserpine from Rauwolfia serpentina against drug-resistant tumor cells.

Phytomedicine 2015 Feb 19;22(2):308-18. Epub 2015 Jan 19.

Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg University of Mainz, Staudinger Weg 5, 55128 Mainz, Germany. Electronic address:

Background: The antihypertensive reserpine is an indole alkaloid from Rauwolfia serpentina and exerts also profound activity against cancer cells in vitro and in vivo. The present investigation was undertaken to investigate possible modes of action to explain its activity toward drug-resistant tumor cells.

Material And Methods: Sensitive and drug-resistant tumor cell lines overexpressing P-glycoprotein (ABCB1/MDR1), breast cancer resistance protein (ABCG2/BCRP), mutation-activated epidermal growth factor receptor (EGFR), wild-type and p53-knockout cells as well as the NCI panel of cell lines from different tumor origin were analyzed. Reserpine's cytotoxicity was investigated by resazurin and sulforhodamine assays, flow cytometry, and COMPARE and hierarchical cluster analyses of transcriptome-wide microarray-based RNA expressions.

Results: P-glycoprotein- or BCRP overexpressing tumor cells did not reveal cross-resistance to reserpine. EGFR-overexpressing cells were collateral sensitive and p53- Knockout cells cross-resistant to this drug compared to their wild-type parental cell lines. Reserpine increased the uptake of doxorubicin in P-glycoprotein-overexpressing cells, indicating that reserpine inhibited the efflux function of P-glycoprotein. Using molecular docking, we found that reserpine bound with even higher binding energy to P-glycoprotein and EGFR than the control drugs verapamil (P-glycoprotein inhibitor) and erlotinib (EGFR inhibitor). COMPARE and cluster analyses of microarray data showed that the mRNA expression of a panel of genes predicted the sensitivity or resistance of the NCI tumor cell line panel with statistical significance. The genes belonged to diverse pathways and biological functions, e.g. cell survival and apoptosis, EGFR activation, regulation of angiogenesis, cell mobility, cell adhesion, immunological functions, mTOR signaling, and Wnt signaling.

Conclusion: The lack of cross-resistance to most resistance mechanisms and the collateral sensitivity in EGFR-transfectants compared to wild-type cells speak for a promising role of reserpine in cancer chemotherapy. Reserpine deserves further consideration for cancer therapy in the clinical setting.
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http://dx.doi.org/10.1016/j.phymed.2015.01.002DOI Listing
February 2015