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| 2. |
- Burman, Robert, 1979-, et al.
(författare)
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Evaluation of toxicity and anti-tumour activity of cycloviolacin O2 in mice.
- 2010
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Ingår i: Biopolymers. - : Wiley. - 0006-3525 .- 1097-0282. ; 94:5, s. 626-634
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Tidskriftsartikel (refereegranskat)abstract
- Cycloviolacin O2 is a small cyclic cysteine-rich protein belonging to the group of plant proteins called cyclotides. This cyclotide has been previously shown to exert cytotoxic activity against a variety of human tumor cell lines as well as primary cultures of human tumor cells in vitro. This study is the first evaluation of its tolerability and antitumor activity in vivo. Maximal-tolerated doses were estimated to 1.5 mg/kg for single intravenous (i.v.) dosing and 0.5 mg/kg for daily repeated dosing, respectively. Two different in vivo methods were used: the hollow fiber method with single dosing (i.v. 1.0 mg/kg) and traditional xenografts with repeated dosing over 2 weeks (i.v. 0.5 mg/kg daily, 5 days a week). The human tumor cell lines used displayed dose-dependent in vitro sensitivity (including growth in hollow fibers to confirm passage of cycloviolacin O2 through the polyvinylidene fluoride fibers), with IC50 values in the micromolar range. Despite this sensitivity in vitro, no significant antitumor effects were detected in vivo, neither with single dosing in the hollow fiber method nor with repeated dosing in xenografts. In summary, the results indicate that antitumor effects are minor or absent at tolerable (sublethal) doses, and cycloviolacin O2 has a very abrupt in vivo toxicity profile, with lethality after single injection at 2 mg/kg, but no signs of discomfort to the animals at 1.5 mg/kg. Repeated dosing of 1 mg/kg gave a local-inflammatory reaction at the site of injection after 2–3 days; lower doses were without complications.
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| 3. |
- Felth, Jenny, 1979-, et al.
(författare)
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Gambogic acid is cytotoxic to cancer cells through inhibition of the ubiquitin-proteasome system
- 2013
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Ingår i: Investigational new drugs. - : Springer Science and Business Media LLC. - 0167-6997 .- 1573-0646. ; 31:3, s. 587-598
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Gambogic acid (GA), displays cytotoxicity towards a wide variety of tumor cells and has been shown to affect many important cell-signaling pathways. In the present work, we investigated the mechanism of action of GA by analysis of drug-induced changes in gene expression profiles and identified GA and the derivative dihydro GA as possible inhibitors of the ubiquitin-proteasome system (UPS). Both GA and dihydro GA inhibited proteasome function in cells resulting in the accumulation of polyubiquitin complexes. In vitro experiments showed that both GA and dihydro GA inhibited 20S chymotrypsin activity and the inhibitory effects of GA and dihydro GA on proteasome function corresponded with apoptosis induction and cell death. In conclusion, our results show that GA and dihydro GA exert their cytotoxic activity through inhibition of the UPS, specifically by acting as inhibitors of the chymotrypsin activity of the 20S proteasome.
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| 4. |
- Felth, Jenny, 1979-
(författare)
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Studies of Cytotoxic Compounds of Natural Origin and their Mechanisms of Action
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cancer incidence is increasing and novel anticancer drugs with new mechanisms of action are essential for future chemotherapeutic treatment. Natural products have historically played an important role in the development of anti-cancer drugs and have potential to do so also in the future. In this thesis two classes of natural products are identified as possible drug lead candidates, and the mechanisms of their action are elucidated. Initially, in a screening of a compound library for cytotoxic effects in colon cancer cells, natural products with potent activity were identified. Based on their potency, and on previously reported activities in cancer cells, two main groups of compounds, cardiac glycosides (CGs) and gambogic acid (GA) analogues, were selected for further in-depth studies. The concentration-dependent cytotoxicity was confirmed in cell lines of different origin. Cardiac glycosides were mainly evaluated for their activity in colon cancer cells and in leukemic cells, whereas the GA analogues were studied using a resistance-based panel of ten human cancer cell lines. Using activity profiles and the ChemGPS-NP model, the compounds were compared, structurally and mechanistically, to standard chemotherapeutic drugs. The results from these analyses suggested that the CGs and the GA analogues act by mechanisms different from those of antimetabolites, alkylating agents, topoisomerase I and II inhibitors, or tubulin-active agents. By analysis of drug-induced gene expression, one GA analogue, dihydro GA, was identified as a possible inhibitor of the ubiquitin-proteasome system (UPS), and the CGs showed similarities to protein synthesis inhibitors. Starting from these hypotheses, we further investigated the mechanisms of actions on a molecular level. The results showed that GA and dihydro GA act as inhibitors of the 20S proteasome chymotrypsin activity, leading to accumulation of ubiquitinated proteins. The CGs were confirmed to inhibit protein synthesis in colon cancer cell lines. However, interestingly, in leukemia cell lines, it seemed that the CGs act through a different, yet unexplored, mechanism of action. The leukemic cells (pre-B and T-ALL) were particularly susceptible to the cytotoxic effects of CGs, including at concentrations that may be achievable in the clinic.
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| 5. |
- Hallböök, Helene, et al.
(författare)
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Ex Vivo Activity of Cardiac Glycosides in Acute Leukaemia
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:1, s. e15718-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Despite years of interest in the anti-cancerous effects of cardiac glycosides (CGs), and numerous studies in vitro and in animals, it has not yet been possible to utilize this potential clinically. Reports have demonstrated promising in vitro effects on different targets as well as a possible therapeutic index/selectivity in vitro and in experimental animals. Recently, however, general inhibition of protein synthesis was suggested as the main mechanism of the anti-cancerous effects of CGs. In addition, evidence of species differences of a magnitude sufficient to explain the results of many studies called for reconsideration of earlier results. Principal Findings: In this report we identified primary B-precursor and T-ALL cells as being particularly susceptible to the cytotoxic effects of CGs. Digitoxin appeared most potent and IC50 values for several patient samples were at concentrations that may be achieved in the clinic. Significant protein synthesis inhibition at concentrations corresponding to IC50 was demonstrated in colorectal tumour cell lines moderately resistant to the cytotoxic effects of digoxin and digitoxin, but not in highly sensitive leukaemia cell lines. Conclusion: It is suggested that further investigation regarding CGs may be focused on diagnoses like T-and B-precursor ALL.
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| 6. |
- Hassan, Saadia, et al.
(författare)
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Novel activity of acriflavine against colorectal cancer tumor cells
- 2011
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Ingår i: Cancer Science. - : Wiley. - 1347-9032 .- 1349-7006. ; 102:12, s. 2206-2213
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Tidskriftsartikel (refereegranskat)abstract
- A high-throughput screen of the cytotoxic activity of 2000 molecules from a commercial library in three human colon cancer cell lines and two normal cell types identified the acridine acriflavin to be a colorectal cancer (CRC) active drug. Acriflavine was active in cell spheroids, indicating good drug penetration and activity against hypoxic cells. In a validation step based on primary cultures of patient tumor cells, acriflavine was found to be more active against CRC than ovarian cancer and chronic lymphocytic leukemia. This contrasted to the activity pattern of the CRC active standard drugs 5-fluorouracil, irinotecan and oxaliplatin. Mechanistic studies indicated acriflavine to be a dual topoisomerase I and II inhibitor. In conclusion, the strategy used seems promising for identification of new diagnosis-specific cancer drugs.
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| 7. |
- Roggen, Heidi, et al.
(författare)
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2-Substituted agelasine analogs : Synthesis and biological activity, and structure and reactivity of synthetic intermediates
- 2011
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Ingår i: Pure and Applied Chemistry. - 0033-4545 .- 1365-3075. ; 83:3, s. 645-653
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Tidskriftsartikel (refereegranskat)abstract
- 2-Substituted N-methoxy-9-methyl-9H-purin-6-amines were synthesized either from their corresponding 6-chloro-9-methyl-9H-purines or 2-chloro-N-methoxy-9-methyl-9H-purin-6-amine. Great diversity in the amino/imino tautomeric ratios was observed and calculated based on H-1 NMR. The tautomers were identified by 1D and 2D H-1, C-13, and N-15 NMR techniques, and showed significant variation both in C-13 and N-15 shift values. Comparison of the tautomeric ratios with Hammett F values revealed that as the field/inductive withdrawing abilities of the 2-substituent increased, the ratio of amino: imino tautomers was shifted toward the amino tautomer. Computational chemistry exposed the significance of hydrogen bonding between solvent and the compound in question to reach accurate predictions for tautomeric ratios. B3LYP/def2-TZVP density functional theory (DFT) calculations resulted in quantitatively more accurate predictions than when employing the less expensive BP86 functional. N-7-Alkylation of the 2-substituted N-methoxy-9-methyl-9H-purin-6-amines showed that when the field/inductive withdrawing ability of the 2-substituent reached a certain point the reactivity drastically dropped. This correlated with the atomic charges on N-7 calculated using a natural bond orbital (NBO) analysis. Biological screening of the final 2-substituted agelasine analogs indicated that the introduction of a methyl group in the 2-position is advantageous for antimycobacterial and antiprotozoal activity, and that an amino function may improve activity against several cancer cell lines.
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| 8. |
- Roggen, Heidi, et al.
(författare)
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Antimicrobial and antineoplastic activities of Agelasine analogs modified in the purine 2-position
- 2011
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Ingår i: Archiv der Pharmazie. - : Wiley. - 0365-6233 .- 1521-4184. ; 344:1, s. 50-55
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Tidskriftsartikel (refereegranskat)abstract
- Agelasines are 7,9-dialkylpurinium salts found in marine sponges (Agelas sp.), which display a variety of antimicrobial and cytotoxic effects. We have synthesized simplified agelasine analogs modified in the purine 2-position and examined their antimicrobial and anticancer activities. The compounds were screened against Staphylococcus aureus, Escherichia coli, Mycobacterium tuberculosis, Candida krusei, and Candida albicans, protozoa causing tropical diseases (Plasmodium falciparum, Leishmania infantum, Trypanosoma cruzi, and Trypanosoma brucei), a panel of human cancer cell lines (U-937 GTB, RPMI 8226/s, CEM/s, and ACHN) as well as VERO and/or MRC-5 cells. The results indicate that the introduction of a methyl group in the purine 2-position is beneficial for antimycobacterial and antiprotozoal activity, and that amino groups may enhance activity against several cancer cell lines.
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| 9. |
- Ruhaak, Lucia Renee, et al.
(författare)
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Evaluation of the Cyclooxygenase Inhibiting Effects of Six Major Cannabinoids Isolated from Cannabis sativa
- 2011
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Ingår i: Biological and Pharmaceutical Bulletin. - : Pharmaceutical Society of Japan. - 0918-6158 .- 1347-5215. ; 34:5, s. 774-778
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Tidskriftsartikel (refereegranskat)abstract
- Cyclooxygenase enzymes (COX-1 and COX-2) catalyse the production of prostaglandins from arachidonic acid. Prostaglandins are important mediators in the inflammatory process and their production can be reduced by COX-inhibitors. Endocannabinoids, endogenous analogues of the plant derived cannabinoids, occur normally in the human body. The Endocannabinoids are structurally similar to arachidonic acid and have been suggested to interfere with the inflammatory process. They have also been shown to inhibit cancer cell proliferation. Anti-inflammatory effects of cannabinoids and endocannabinoids have been observed, however the mode of action is not yet clarified. Anti-inflammatory activity (i.e., inhibition of COX-2) is proposed to play an important role in the development of colon cancer, which makes this subject interesting to study further. In the present work, the six cannabinoids tetrahydrocannabinol (Delta(9)-THC), tetrahydrocannabinolic acid (Delta(9)-THC-A), cannabidiol (CBD), cannabidiolic acid (CBDA), cannabigerol (CBG) and cannabigerolic acid (CBGA), isolated from Cannabis sativa, were evaluated for their effects on prostaglandin production. For this purpose an in vitro enzyme based COX-1/COX-2 inhibition assay and a cell based prostaglandin production radioimmunoassay were used. Cannabinoids inhibited cyclooxygenase enzyme activity with IC50 values ranging from 1.7.10(-3) to 2.0.10(-4) M.
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| 10. |
- Strömstedt, Adam A., et al.
(författare)
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Bioassays in Natural Product Research : Strategies and Methods in the Search for Anti-inflammatory and Antimicrobial Activity
- 2014
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Ingår i: Phytochemical Analysis. - : Wiley. - 0958-0344 .- 1099-1565. ; 25:1, s. 13-28
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Forskningsöversikt (refereegranskat)abstract
- Introduction: Identifying bioactive molecules from complex biomasses requires careful selection and execution of relevant bioassays in the various stages of the discovery process of potential leads and targets.Objective: The aim of this review is to share our long-term experience in bioassay-guided isolation, and mechanistic studies, of bioactive compounds from different organisms in nature with emphasis on anti-inflammatory and antimicrobial activity.Methods: In the search for anti-inflammatory activity, in vivo and in vitro model combinations with enzymes and cells involved in the inflammatory process have been used, such as cyclooxygenases, human neutrophils and human cancer cell lines. Methods concerning adsorption and perforation of bacteria, fungi, human cells and model membranes, have been developed and optimised, with emphasis on antimicrobial peptides and their interaction with the membrane target, in particular their ability to distinguish host from pathogen.Results: A long-term research has provided experience of selection and combination of bioassay models, which has led to an increased understanding of ethnopharmacological and ecological observations, together with in-depth knowledge of mode of action of isolated compounds.Conclusion: A more multidisciplinary approach and a higher degree of fundamental research in development of bioassays are often necessary to identify and to fully understand the mode of action of bioactive molecules with novel structure-activity relationships from natural sources. Selection and execution of relevant bioassays are critical in the various stages of the discovery process of potential drug leads and targets from natural sources. The aim of this review is to share our long-term experience in bioassay-guided isolation of bioactive compounds from different organisms in nature with emphasis on anti-inflammatory and antimicrobial activity. We conclude that an increased multidisciplinary approach and a higher degree of fundamental research in development of bioassays are essential to discover complex structure-activity relationships.
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