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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Identification of compounds with cytotoxic activity from the leaf of the Nigerian medicinal plant, Anacardium occidentale L. (Anacardiaceae)

Taiwo, Bamigboye J., Fatokun, Amos A., Olubiyi, O.O., Bamigboye-Taiwo, O.T., van Heerden, F.R., Wright, Colin W. 2017 February 1922 (has links)
Yes / Cancer is now the second-leading cause of mortality and morbidity, behind only heart disease, necessitating urgent development of (chemo)therapeutic interventions to stem the growing burden of cancer cases and cancer death. Plants represent a credible source of promising drug leads in this regard, with a long history of proven use in the indigenous treatment of cancer. This study therefore investigated Anacardium occidentale, one of the plants in a Nigerian Traditional Medicine formulation commonly used to manage cancerous diseases, for cytotoxic activity. Bioassay-guided fractionation, spectroscopy, Alamar blue fluorescence-based viability assay in cultured HeLa cells and microscopy were used. Four compounds: zoapatanolide A (1), agathisflavone (2), 1, 2-bis (2,6-dimethoxy-4-methoxybenzoyl) ethane (Anacardicin, 3) and methyl gallate (4) were isolated, with the most potent being zoapatanolide A with an IC50 value of 36.2 ± 9.8 μM in the viability assay. To gain an insight into the likely molecular basis of their observed cytotoxic effects, Autodock Vina binding free energies of each of the isolated compounds with seven molecular targets implicated in cancer development (MAPK8, MAPK10, MAP3K12, MAPK3, MAPK1, MAPK7 and VEGF), were calculated. Pearson correlation coefficients were obtained with experimentally-determined IC50 in the Alamar blue viability assay. While these compounds were not as potent as a standard anti-cancer compound, doxorubicin, the results provide reasonable evidence that the plant species contains compounds with cytotoxic activity. This study provides some evidence of why this plant is used ethnobotanically in anti-cancer herbal formulations and justifies investigating Nigerian medicinal plants highlighted in recent ethno-botanical surveys. / This work was supported by a British Council Researcher Links Travel Grant 2013 to TBJ, a South Africa’s National Research Foundation (NRF) Grant No 98345, 2016 to FRVH and an academic staff funding provided to AAF by the School of Pharmacy, University of Bradford, UK.
2

Screening of natural products and Alkylating agents for Antineoplastic Activity

Kanyanda, Stonard Sofiel Elisa January 2007 (has links)
<p>Background and objectives: Apoptosis is a process in which a cell programmes its own death. It is a highly organized physiological mechanism in which injured or damaged cells are destroyed. Apart from physiological stimuli however, exogenous factors can induce apoptosis. Many anti-cancer drugs work by activating apoptosis in cancer cells. Natural substances have been found to have the ability to induce apoptosis in various tumour cells and these substances have been used as templates for the construction of&nbsp / novel lead compounds in anticancer treatment. On the other hand, alkylating agents such as cisplatin, cis- [PtCl2 (NH3) 2] have been widely used as antineoplastic agents for a&nbsp / wide variety of cancers including testicular, ovarian, neck and head cancers, amongst others. However, the use of cisplatin as an anticancer agent is limited due to toxicity and resistance problems. The aim of this present study was to screen the leaves of Rhus laevigata, a South African indigenous plant, for the presence of pro-apoptotic and&nbsp / anti-proliferative natural compounds and also to screen newly synthesised palladium based complexes (15 and 57) and a platinum based complex (58) for their antineoplastic&nbsp / activities tested against a panel of cell lines. Results. The results showed that crude methanol extracts from Rhus laevigata as well as the newly synthesised palladium based complexes (15 and 57) and a platinum based complex (58) induced apoptosis in the cell lines tested, as demonstrated by the externalization of phosphatidylserine, mitochondrial membrane permeabilization,caspase-3 activation, and DNA fragmentation. Caski (cervical cancer) and H157 (non small cell lung carcinoma) cell lines treated with the methanol extract from Rhus laevigata however, were more resistant to apoptosis induction. Among the metallocomplexes, complexes 15 and 57, palladium based complexes, were the most active. Conclusion: The methanol extract from the leaves of Rhus laevigata contain pro-apoptotic and antiproliferative natural compound(s), which need to be characterised and elucidated as they could provide the much-needed lead compounds in the fight against cancer. On the other hand the newly synthesized palladium complexes also need further evaluation to&nbsp / see if they can be used as anticancer agents that can overcome the problems associated with cisplatin.</p>
3

Screening of natural products and Alkylating agents for Antineoplastic Activity

Kanyanda, Stonard Sofiel Elisa January 2007 (has links)
<p>Background and objectives: Apoptosis is a process in which a cell programmes its own death. It is a highly organized physiological mechanism in which injured or damaged cells are destroyed. Apart from physiological stimuli however, exogenous factors can induce apoptosis. Many anti-cancer drugs work by activating apoptosis in cancer cells. Natural substances have been found to have the ability to induce apoptosis in various tumour cells and these substances have been used as templates for the construction of&nbsp / novel lead compounds in anticancer treatment. On the other hand, alkylating agents such as cisplatin, cis- [PtCl2 (NH3) 2] have been widely used as antineoplastic agents for a&nbsp / wide variety of cancers including testicular, ovarian, neck and head cancers, amongst others. However, the use of cisplatin as an anticancer agent is limited due to toxicity and resistance problems. The aim of this present study was to screen the leaves of Rhus laevigata, a South African indigenous plant, for the presence of pro-apoptotic and&nbsp / anti-proliferative natural compounds and also to screen newly synthesised palladium based complexes (15 and 57) and a platinum based complex (58) for their antineoplastic&nbsp / activities tested against a panel of cell lines. Results. The results showed that crude methanol extracts from Rhus laevigata as well as the newly synthesised palladium based complexes (15 and 57) and a platinum based complex (58) induced apoptosis in the cell lines tested, as demonstrated by the externalization of phosphatidylserine, mitochondrial membrane permeabilization,caspase-3 activation, and DNA fragmentation. Caski (cervical cancer) and H157 (non small cell lung carcinoma) cell lines treated with the methanol extract from Rhus laevigata however, were more resistant to apoptosis induction. Among the metallocomplexes, complexes 15 and 57, palladium based complexes, were the most active. Conclusion: The methanol extract from the leaves of Rhus laevigata contain pro-apoptotic and antiproliferative natural compound(s), which need to be characterised and elucidated as they could provide the much-needed lead compounds in the fight against cancer. On the other hand the newly synthesized palladium complexes also need further evaluation to&nbsp / see if they can be used as anticancer agents that can overcome the problems associated with cisplatin.</p>
4

Screening of natural products and alkylating agents for antineoplastic activity

Kanyanda, Stonard Sofiel Elisa January 2007 (has links)
Magister Scientiae - MSc / Apoptosis is a process in which a cell programmes its own death. It is a highly organized physiological mechanism in which injured or damaged cells are destroyed. Apart from physiological stimuli however, exogenous factors can induce apoptosis. Many anti-cancer drugs work by activating apoptosis in cancer cells. Natural substances have been found to have the ability to induce apoptosis in various tumour cells and these substances have been used as templates for the construction of novel lead compounds in anticancer treatment. On the other hand, alkylating agents such as cisplatin, cis- [PtCl2 (NH3) 2] have been widely used as antineoplastic agents for a wide variety of cancers including testicular, ovarian, neck and head cancers, amongst others. However, the use of cisplatin as an anticancer agent is limited due to toxicity and resistance problems. The aim of this present study was to screen the leaves of Rhus laevigata, a South African indigenous plant, for the presence of pro-apoptotic and anti-proliferative natural compounds and also to screen newly synthesised palladium based complexes (15 and 57) and a platinum based complex (58) for their antineoplastic activities tested against a panel of cell lines. Results. The results showed that crude methanol extracts from Rhus laevigata as well as the newly synthesised palladium based complexes (15 and 57) and a platinum based complex (58) induced apoptosis in the cell lines tested, as demonstrated by the externalization of phosphatidylserine, mitochondrial membrane permeabilization, caspase-3 activation, and DNA fragmentation. Caski (cervical cancer) and H157 (non small cell lung carcinoma) cell lines treated with the methanol extract from Rhus laevigata however, were more resistant to apoptosis induction. Among the metallocomplexes, complexes 15 and 57, palladium based complexes, were the most active. Conclusion The methanol extract from the leaves of Rhus laevigata contain pro-apoptotic and antiproliferative natural compound(s), which need to be characterised and elucidated as they could provide the much-needed lead compounds in the fight against cancer. On the other hand the newly synthesized palladium complexes also need further evaluation to see if they can be used as anticancer agents that can overcome the problems associated with cisplatin.
5

Screening of natural products and alkylating agents for antineoplastic activity

Kanyanda, Stonard Sofiel Elisa January 2007 (has links)
Magister Scientiae - MSc / Background and objectives: Apoptosis is a process in which a cell programmes its own death. It is a highly organized physiological mechanism in which injured or damaged cells are destroyed. Apart from physiological stimuli however, exogenous factors can induce apoptosis. Many anti-cancer drugs work by activating apoptosis in cancer cells. Natural substances have been found to have the ability to induce apoptosis in various tumour cells and these substances have been used as templates for the construction of novel lead compounds in anticancer treatment. On the other hand, alkylating agents such as cisplatin, cis- [PtCl2 (NH3) 2] have been widely used as antineoplastic agents for a wide variety of cancers including testicular, ovarian, neck and head cancers, amongst others. However, the use of cisplatin as an anticancer agent is limited due to toxicity and resistance problems. The aim of this present study was to screen the leaves of Rhus laevigata, a South African indigenous plant, for the presence of pro-apoptotic and anti-proliferative natural compounds and also to screen newly synthesised palladium based complexes (15 and 57) and a platinum based complex (58) for their antineoplastic activities tested against a panel of cell lines. Results. The results showed that crude methanol extracts from Rhus laevigata as well as the newly synthesised palladium based complexes (15 and 57) and a platinum based complex (58) induced apoptosis in the cell lines tested, as demonstrated by the externalization of phosphatidylserine, mitochondrial membrane permeabilization,caspase-3 activation, and DNA fragmentation. Caski (cervical cancer) and H157 (non small cell lung carcinoma) cell lines treated with the methanol extract from Rhus laevigata however, were more resistant to apoptosis induction. Among the metallocomplexes, complexes 15 and 57, palladium based complexes, were the most active. Conclusion: The methanol extract from the leaves of Rhus laevigata contain pro-apoptotic and antiproliferative natural compound(s), which need to be characterised and elucidated as they could provide the much-needed lead compounds in the fight against cancer. On the other hand the newly synthesized palladium complexes also need further evaluation to see if they can be used as anticancer agents that can overcome the problems associated with cisplatin. / South Africa
6

Discovery of cardioprotective isoxazole-amide compounds targeting the synergy of transcription factors GATA4 and NKX2-5

Välimäki, M. (Mika) 07 December 2018 (has links)
Abstract Acute myocardial infarction is a life-threatening condition that occurs as a result of reduced blood flow in the cardiac muscle, eventually leading to tissue damage. In infarcted areas, cardiomyocytes have insufficient ability to proliferate and replace the injured cells, which is associated with a deficient pumping capacity. A strictly regulated combinatorial interplay of transcription factors, e.g., GATA4, NKX2-5, TBX5, and MEF2C, orchestrates cardiac type gene expression during the cardiomyocyte differentiation and maturation processes. The aim of the present study was to (i) characterize the protein-protein interaction of the cardiac transcription factors GATA4-NKX2-5, (ii) evaluate the chemical agents that modify the synergy of GATA4-NKX2-5 in vitro, (iii) examine the capacity of the lead compound to promote myocardial repair in vivo after myocardial infarction and other cardiac injuries and (iv) study the structural features of the compound important for metabolism and cytotoxicity. Integration of the experimental mutagenic data with computational modeling suggests that the structural architecture of the GATA4-NKX2-5 interaction resembles the protein structure of the conserved DNA binding domain of nuclear receptors. Fragment-based screening, reporter gene-based optimization and pharmacophore searching were utilized to identify the most potent lead compound targeting the GATA4-NKX2-5 interaction: N-[4-(diethylamino)phenyl]-5-methyl-3-phenylisoxazole-4-carboxamide. This compound presented anti-hypertrophic effects in vitro and cardioprotective effects in vivo. In addition, structural analysis of the lead compound revealed the signature molecular features for metabolism and cytotoxicity. Current drug treatments are able to delay, but not prevent the progress of the heart failure; therefore, modulators of protein-protein interactions of key transcription factors may represent a novel class of pharmaceuticals for cardiac remodeling and repair. / Tiivistelmä Sydäninfarkti on henkeä uhkaava verenkierron häiriö, joka syntyy veren virtauksen äkillisen vähentymisen seurauksena sydänlihaksessa aiheuttaen kudosvaurion. Vaurioituneen sydänlihaskudoksen kyky uusiutua tai korvata kuolleet sydänlihassolut uusilla on puutteellinen, ja tämän seurauksena sydämen pumppauskyky heikkenee. Transkriptiotekijöiden GATA4, NKX2-5, TBX5 ja MEF2C muodostamat ja koordinoimat proteiinikompleksit säätelevät sydänsolujen geenien ilmenemistä solujen elinkaaren aikana. Väitöskirjatyön tavoitteena oli (i) karakterisoida geeninsäätelytekijöiden GATA4-NKX2-5 molekyylirakenteet ja niiden keskinäinen vuorovaikutus, (ii) seuloa kemiallisia yhdisteitä, jotka muokkaavat GATA4-NKX2-5 proteiinikompleksin aikaansaamaa geeniaktivaatiota, (iii) tutkia johtoyhdisteen vaikutuksia in vivo sydäninfarktia ja painekuormitusta kuvaavissa eläinmalleissa, ja (iv) tutkia johtoyhdisteen molekyylirakenteen yhteyttä yhdisteen metaboliaan ja sytotoksisuuteen. Väitöskirjatyö osoittaa molekyylimallinuksen ja kokeellisten tulosten perusteella, että geeninsäätelytekijöiden GATA4-NKX2-5 proteiinikompleksin orientaatio matkii tumareseptoriperheen DNA domeenin tertiäärirakennetta. Molekyylifragmenttien, lusiferaasi-reportterikokeen ja farmakoforimallin avulla seulottiin ja optimoitiin sitoutumisvoimakkuudeltaan lupaavin GATA4-NKX2-5 proteiinikompleksin toimintaan vaikuttava johtoyhdiste: N-[4-(dietyyliamino)fenyyli]-5-metyyli-3-fenyyli-isoksatsoli-4-karboksamidi. Johtoyhdisteellä havaittiin solu- ja eläinmalleissa hypertrofiaa estäviä vaikutuksia in vitro ja sydäntä suojaavia vaikutuksia in vivo. Väitöskirjatyö osoitti lisäksi aktiivisten molekyylien rakenneominaisuuksia, jotka keskeisesti vaikuttavat yhdisteiden metaboliaan ja sytotoksisuuteen. Nykyinen lääkehoito hidastaa, mutta ei pysäytä sydänlihasvaurioon liittyvän kroonisen sydämen vajaatoiminnan etenemistä. Lääkevaikutuksen kohdentaminen sydämen keskeisten transkriptiotekijöiden yhteisvaikutukseen avaa uuden mahdollisen tutkimuslinjan sydänlihasvaurion estossa ja korjauksessa.
7

論化學發明之非顯而易知性—美國聯邦巡迴上訴法院案例分析 / Non-obviousness in chemical invention - an analysis of CAFC case study

黃俊傑, Hwang, Jiunn-Jye Unknown Date (has links)
化學發明是專利申請領域別中另一個重要的領域,醫學藥品的龐大商機是重要的推手,因為大多數藥物的活性成份為有機小分子化合物,且研發一新藥,須費時10到15年,研發經費估計高達26億美金,各大專利藥廠當然積極申請專利,保護投資。另一方面,Hatch-Waxman Act鼓勵學名藥可以盡早上市,使一般民眾能以較便宜的價格取得所需藥品。在美國藥品市場數千億美元的商機吸引下,學名藥廠積極挑戰專利藥廠之專利權。其中非顯而易知性要件認定,為雙方訴訟爭點。 然,化學發明的非顯而易知性要件認定之所以異於機械、電子、電機等技術,在於我們無法準確預測在奈米尺度的化學反應與分子的物性與化性,因而產生化學反應結果的不可預期性。而藥物研發是先從資料庫中,篩選出具一定活性的化合物作為先導化合物,經由取代基的引入、改變,或官能基的置換,結合活性與化合物結構關係(SAR),達成先導化合物結構最佳化,以快速、準確的找出候選藥物分子,進入臨床實驗。 2007年,美國聯邦最高法院在KSR案,針對非顯而易知性,重申Graham 案建立的非顯而易知性判斷法則的重要性,與重新適用顯而易知的嘗試。KSR判決後,許多文章討論KSR判決將不只針對機械組合發明,同時也將會對醫藥化學發明非顯而易知性之認定標準,產生一定的影響。 本論文研究KSR判決後, CAFC使用顯而易知的嘗試、與先導化合物分析(lead compound analysis)判斷準則,於醫藥產業化學發明專利的非顯而易知性的判決。CAFC於涉及組合藥物或配方調配案件,使用顯而易知的嘗試審查基準;使用先導化合物分析,都涉及系爭藥物中「活性成份結構」的非顯而易知性認定,CAFC針對不同類型的化學發明案件,採用了不同的審查基準。 KSR判決雖然重新啟用「顯而易知的嘗試」判斷準則,且CAFC適用「顯而易知的嘗試」的案件,亦明顯的增加。唯,本論文研究發現,於醫藥產業化學發明專利的非顯而易知性的判決,仍明顯高於對非藥品相關案件。 / Chemical invention is one of key art in patent application driving from the huge market size of medicines, in which active ingredients are organic molecules. The average cost to research and develop each successful drug is estimated to be $2.6 billion US dollars, and took 10 to 15 years. In other word, whether pharmaceutical companies can recover their investment in drug development heavily depends on the patent protection of their drugs. On the other hand, the Hatch-Waxman Act introduced in 1984 created the generic drug pathway to the market, so general public can obtain the drugs at a affordable price. However, within this framework, the validity of drug patents are often challenged by generic manufactures, mainly the "non-obviousness" requirement in patent system. During this lengthy and expensive drug discovery, chemist often entails making small modifications to lead compounds to establish structure-activity relationship (SAR) to speed up the process. Those modifications might be deemed “obvious to try”—and then studying the largely unpredictable, yet critical, resulting biological effects. In 2007, the Supreme Court of the United States, in KSR decision, reasserted that a prima facie case of obviousness may be determined by the framework set forth in Graham and "obvious to try" test. Since then, there are predictions that KSR decision will have a substantial impact in pharmaceutical and life sciences arts. This study, we examine the CAFC ruling in pharmaceutical arts regarding to "non-obviousness" issue by "obvious to try" and "lead compound analysis" test after the KSR decision. And found that the "non-obviousness" judgment of the chemical invention patent in the pharmaceutical industry was still significantly higher than that of the non-drug-related cases.

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