Doutoramento em Ciências Farmacêuticas / PhD in Pharmaceutical Sciences

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Plant Biology." Includes bibliographical references (p. 131-142).

<p>The development of resistance by tumour cells to chemotherapeutic agents is a major problem in cancer treatments. One way to counter this is to find compounds with cytotoxic mechanisms other than those of drugs in clinical use today. The biological and chemical diversity encountered in Nature provide opportunities to discover completely new chemical classes of compounds. Some of these may represent previously unknown anticancer agents, and in some cases, novel, potentially relevant cytotoxic mechanisms. </p><p>The selection of plants for the cytotoxic investigation in this project was designed to cover large parts of the angiosperm system, providing a broad representation of species. Extracts of the plants were subjected to a polypeptide fractionation protocol, followed by bioassay-guided isolation, yielding series of fractions with increasing purity and cytotoxicity. The cytotoxicity assay included tumour cells from patients and a cell-line panel including ten different cell lines representing several types of resistant and non-resistant tumours. This screening strategy allowed fractions and compounds acting with novel mechanisms to be detected at an early stage. </p><p>The compounds isolated represent substantial chemical diversity and originate from diverse parts of the phylogenetic spectrum examined. They include the highly potent cytotoxic alkaloid, thiobinupharidine, the structure of which was determined by NMR techniques. Furthermore, two types of compound were shown to have previously unreported cytoxic activity: cyclotides (small macrocyclic polypeptides, in this case from violets) and polypeptides, possibly of thionine type, of loranthaceaeous mistletoes (collected in Panama). The well known cardiac glycosides from the foxglove, Digitalis, were identified as being responsible for the anti-tumour activity of this species.</p><p>In conclusion, the results obtained in this project show that selection based on phylogenetic information, together with a robust and reliable method to detect cytotoxicity, can be a useful approach for exploring the plant kingdom for cytotoxic substances.</p>

The development of resistance by tumour cells to chemotherapeutic agents is a major problem in cancer treatments. One way to counter this is to find compounds with cytotoxic mechanisms other than those of drugs in clinical use today. The biological and chemical diversity encountered in Nature provide opportunities to discover completely new chemical classes of compounds. Some of these may represent previously unknown anticancer agents, and in some cases, novel, potentially relevant cytotoxic mechanisms. The selection of plants for the cytotoxic investigation in this project was designed to cover large parts of the angiosperm system, providing a broad representation of species. Extracts of the plants were subjected to a polypeptide fractionation protocol, followed by bioassay-guided isolation, yielding series of fractions with increasing purity and cytotoxicity. The cytotoxicity assay included tumour cells from patients and a cell-line panel including ten different cell lines representing several types of resistant and non-resistant tumours. This screening strategy allowed fractions and compounds acting with novel mechanisms to be detected at an early stage. The compounds isolated represent substantial chemical diversity and originate from diverse parts of the phylogenetic spectrum examined. They include the highly potent cytotoxic alkaloid, thiobinupharidine, the structure of which was determined by NMR techniques. Furthermore, two types of compound were shown to have previously unreported cytoxic activity: cyclotides (small macrocyclic polypeptides, in this case from violets) and polypeptides, possibly of thionine type, of loranthaceaeous mistletoes (collected in Panama). The well known cardiac glycosides from the foxglove, Digitalis, were identified as being responsible for the anti-tumour activity of this species. In conclusion, the results obtained in this project show that selection based on phylogenetic information, together with a robust and reliable method to detect cytotoxicity, can be a useful approach for exploring the plant kingdom for cytotoxic substances.

Cancer is a human tragedy that strikes and kills the lives of our beloved people. With a limited number of effective anticancer drugs from natural resources currently in use, there is a real need for new, safe, cheap and effective anticancer drugs to combat this dreaded and formidable disease. Plants have a long history of use in the treatment of cancer. Several plant-derived anticancer agents including taxol, vinblastine, vincristine, the camptothecin derivatives, topotecan and irinotecan and etoposide derived from epi- podophyllotoxin are in clinical use all over the world. In this study, two endemic plant species from the Rubiaceae and Asteraceae families, namely Anthospermum hispidulum E.Mey. ex Sond. and Eriocephalus tenuifolius DC. were investigated for their anticancer properties. The organic (methanol/dichloromethane, 1:1 v/v) extracts of both plant species were found to have moderate anticancer activity against a panel of three human cancer cell lines namely, breast MCF7, renal TK10 and melanoma UACC62 at the CSIR anticancer screen. Bioassay-guided fractionation of the organic extracts of Anthospermum hispidulum led to the isolation of an active compound which was characterised as ursolic acid. Another compound, namely scopoletin was also isolated. The compounds isolated here are known compounds, but have not previously been reported as present in the genus Anthospermum. Bioassay-guided fractionation of the organic extracts of Eriocephalus tenuifolius resulted in the isolation of 8-O-isobutanoylcumambrin B as the active constituent. This compound is reported to have been isolated from related plant species; however its biological activity is not known. The compounds pectolinagenin, hispidulin, friedelinol and tetracosanoic acid were also isolated, but did not show any significant anticancer activity. The structures of all compounds isolated in this study were elucidated using nuclear magnetic resonance spectroscopy, mass spectroscopy and also by comparison with data reported in the literature. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Antibiotic resistance is a growing health issue that necessitates development of alternative drugs with antimicrobial properties. Antimicrobial peptides are a promising group of compounds in this respect and are used by all varieties of living organisms to defend against invading or competing organisms. Hairpinin is an antimicrobial peptide isolated from Echinochloa crus-galli that has previously been found to have antifungal activity. In this study, truncated variants of hairpinin were synthesized and their antifungal activity tested against Candida albicans, Aspergillus fumigatus, and Saccharomyces cerevisiae to identify the minimum structural element of hairpinin required for maintained activity. Hairpinin was active against all three fungi with a minimum inhibitory concentration ranging between 0.6 μM - 5 μM depending on strain and growth media. Two truncated versions were synthesized in this study by solid-phase peptide synthesis, also resulting in a dimer of one of the derivatives, and their antifungal activity was assessed together with four other truncated peptides previously synthesized. The findings indicated that hairpinins C-terminal end together with an inflexible central part stabilized by at least one disulfide bond was vital for activity. The mechanism of action in which hairpinin inhibits fungi was examined by liposome leakage assay of Escherichia coli and Saccharomyces cerevisiae model membranes. It was concluded that the mechanism of action did not involve membrane disruption, a common mechanism among similar antimicrobial peptides. Although hairpinin displayed potent antifungal activity, it was found to be proteolytically unstable in serum. To improve hairpinins value in pharmaceutical context stability has to be improved while preserving the important structural elements.

Caesalpinia férrea Martius, popularmente conhecida como pau-ferro e jucá, é utilizada na medicina tradicional para o tratamento de problemas hepáticos, respiratórios e, em especial, para distúrbios gastrintestinais e como cicatrizante. Deste modo, os objetivos do presente trabalho visaram avaliar os extratos brutos liofilizados de folha (EBLF) e caule (EBLC) quanto a caracterização botânica, o estudo químico e farmacológico, direcionando principalmente, às ações antiúlcera, antioxidante e cicatrizante, e toxicidade destes órgãos vegetais de C. ferrea. A triagem fitoquímica foi realizada com a droga vegetal constituída de folha (DF) e de caule (DC), bem como com os seus EBLF e EBLC. Os métodos empregados foram preconizados por Farnsworth (1966) e Matos (1988) onde foram pesquisados os seguintes compostos: flavonóides, glicósidos cardiotônicos, saponinas, antraderivados, alcalóides, cumarinas, taninos e óleo essencial. Além disso, foi realizada a quantificação de taninos e flavonóides segundo a metodologia proposta na Farmacopéia Européia (2001) e na Farmacopéia Brasileira (2003), respectivamente. Para a avaliação da Toxicidade de C. ferrea foram realizadas a Toxicidade Aguda de ambos os órgãos vegetais, a DL50 do EBLF e a Toxicidade subcrônica do EBLF e EBLC, todos os modelos seguiram a metodologia de Brito (1994). Para análise da atividade antiulcerogênica da espécie em estudo foi realizado o teste da indução de lesão gástrica aguda por etanol/HCI e lesão subcrônica por ácido acético. Grupos Tratados receberam EBLF ou EBLC ou frações ou extratos enriquecidos em flavonóides, Grupo Controle água ou tween 80 e Grupo de Referência Misoprostol ou Cimetidina. Três parâmetros foram avaliados neste modelo: Área Total de Lesão (ATL) , Área Relativa de Lesão (ARL) e índice de Lesão Ulcerativa (ILU). A atividade antioxidante \"in vitro\" foi medida através da inibição da autoxidação de homogenato de cérebro de Ratos (Stocks et aI., 1974). Os extratos foram solubilizados em etanol 70% e as diluições (0.05-0.003mg/mL) foram efetuadas em etanol 35%. O etanol 35% foi utilizado como controle. E na avaliação da Atividade Cicatrizante, os animais (ratos) sofreram uma incisão na região dorsal com auxílio de punch. Os Grupos Tratados receberam diariamente 1 mL de EBLF ou EBLC, solubilizados a 15% em água, e o Grupo Controle água destilada na mesma proporção por um período de 14 dias. Na triagem fitoquímica foram detectados para ambos os extratos, flavonóides, taninos, além de antraderivados e cumarinas nas Folhas. A porcentagem encontrada de Taninos na DF foi de 7.13% e no EBLF de 23.95% e na DC foi de 2.26% e no EBLC de 11.77%. Já a quantificação de flavonóides foi de 0.0095% na DF, 0.026% no EBLF, 0.00014% na DC e de 0.0017% no EBLC. No teste de toxicidade aguda, somente os animais que receberam EBLF apresentaram alterações comportamentais a partir dos primeiros tempos de observação e morte de 3 animais machos e 2 fêmeas (n=5/sexo). Dessa forma, a DL50 encontrada para este extrato vegetal foi de 5471.64 mg/Kg para as fêmeas e de 3112.94 mg/Kg para os machos. Na Toxicidade subcrônica, apenas os animais fêmeas que receberam EBLC (800 mg/Kg) apresentaram uma diferença significativa, em relação ao grupo controle, quanto ao peso do rim, porém não foi encontrada nenhuma alteração histológica neste órgão. EBLF e EBLC apresentaram significativa atividade antiulcerogênica no modelo de lesão gástrica aguda dentro dos parâmetros avaliados. O EBLC reduziu em 37% a ARL. Já o EBLF foi tão ativo como o Misoprostol reduzindo em 95%, 81% e 63% a ATL, a ARL e o ILU, respectivamente contra 92%, 70% e 59% do fármaco de referência. Porém, as frações e os extratos enriquecidos em flavonóides obtidos de ambos os extratos brutos liofilizados não apresentaram atividade antiulcerogênica em nenhum dos 3 parâmetros. Esses mesmos resultados foram obtidos no modelo de lesão gástrica subcrônica para ambos os extratos vegetais. Os EBLF e EBLC de C. ferrea promoveram uma atividade antioxidante de 94% e 84%, respectivamente, na concentração de 0.8196 &#181;g/mL, e um Q 1/2de 0.2331 (Folha) e 0.5061 (Caule) &#181;g/mL. Na avaliação da atividade cicatrizante de ambos os extratos vegetais, não foi encontrada diferença significativa entre os Grupos Tratados e Controle. No laudo histológico não se observou nenhum sinal de cicatrização tecidual. Apesar de C. ferrea ser utilizada pela população como cicatrizante, não foi possível confirmar tal atividade nas folhas e nos caules desta espécie. / Caesalpinia ferrea Martius , populary, known as iron-wood or juca, is utilized in traditional medicine in the treatment of both hepatic and respiratory problems and, in special, for gastrointestinals disturbances and eventual healing. The objective of the present work is to evaluate the leiophyllized brute extracts of the leaf (lBEl) and the stem (lBES), the botanic caracterization, the chemical and pharmacological studies, focuzing principally, the antiulcer and healing action, and also the toxicity of these vegetable organs of C. ferrea. The phytochemical was ma de with the drug of the leaf (DL) and of the stem (DS)- LaEL and lBES. The method was precognized by Famsworth (1966) e Matos (1988) where doing research of: flavonoids, cardiotonic glicosids, saponins, antraderivates, alkaloids, coumarins, tannins and essential oi!. Beyond that, the quantification of tannins and flavonoids according to the metodology proposed in European Pharmacopeia (2001) and Brazilian Pharmacopeia (2003) were also undertaken, respectively. For the evaluation of the C. ferrea toxicity, the acute toxicity of both vegetable organs, the DL50 of LBEL and the subcronical toxicity of LBEL and LBES, were analyzed following the metodology of Brito (1994).The test of induction of acute gastric lesion for ethanol/HCI was used for antiulcerogenic activity analysis of the species studied. Treated Groups received LBEL or LBES or fractions or extracts enrich in flavonoids, Controls Groups water or tween 80 and misoprostol Reference Group. Three parameters were evaluated considering: Total Area of Lesion (TAL), Relative Area of Lesion (RAL) and Rate of Ulcerative Lesion (RUL). And for evaluation of subcronic gastric lesion by acetic acid 30%, the Treated Group received LBEL or LBES, Control Group water and cimetidine Reference Group. The ulcerative lesions were evaluated only in 2 parameters: RAL and RUL. An antioxidant activity \"in vitro\" was measured through inibition of antioxidation of homogenate of rat brain (Stocks et aI., 1974). The extracts were solubilized in ethanol 70% and dilutions (0.05-0.003mg/mL) were performed in ethanol 35%. The ethanol 35% was utilized like control. And for evaluation of healing activity, the animals (rats) suffered na incision in the dorsal region with a punch aid. The Treated Groups received daily 1mL of LBEL or LBES, solubilized by 15% in water, and Control Group distilled in the same proportion during a 14 day period. In phytochemical were detected for both extacts, flavonoids, tannins., beyond antradderivate and coumarins in leaves. The percentages of tannins found were 7.13% in DL, 23.95% in LBEL, 2.26% in OS and 11.77% in LBES. The quantification of flavonoids was 0.0095% in DL, 0.026% in LBEL, 0.00014% in DS and 0.0017% in LBES. During the acute toxicity test, it was observed a behaviour alteration among animais that received LBEL up tp the first time of observation and death pof 3 males and 2 females. The DL50 found to this vegetable extract was 5471.64 mg/Kg for the females and 3112.94 mg/Kg for the males. In subronic toxicity, only the females receiving LBES (800mg/Kg) presented a significant difference, according to the Control Group, as much as the weight of a kidney. However, no histologic alteration in this organ was found. LBEL and LBES presented antiulcerogenic significant activity in acute gstric lesions, based on the parameters evaluated. The LBES was reduced to 37% in RAL. The LBEL was so active as the misoprostol, being reducid to 95%,81% and 63% TAL, RAL and the RUL, respectively against 92%, 70% and 59% of pharmaco of reference. Nevertheless, nor the fractions nor the flavonoids enriched extracts obtained from both leiophyllized brute extracts showed antiulcerogenic activity at the 3 studied parameters. Up to the present time, in model subcronic gastric lesion, none of both vegetable extracts in question has showed active similar to TAL, RAL and RUL in relation to the Control Group. The LBEL and LBES of C. ferrea promoved an antioxidant activity of 93,56% and 84,38%, respectively, in concentration of de 0.8196 &#181;g/mL, and a Q1/2 of 0.2331 (leaf) and 0.5061 (Stem) &#181;g/mL. Conceming the healing activity evaluation of both vegetable extracts, no significant differences between Treats and Control Groups were found. Also in histologic award, no sign of tecidual cicatrization was observed. In spite of the fact that C. ferrea has been utilized by the population as cicatrizant, no clear evidence of its leaves and stems healing activity has been confirmed.

Thesis (MTech. degree in Pharmaceutical Sciences)--Tshwane University of Technology, 2010. / Aims to assess the efficacy and adverse effects of Trichilia emetica in reducing post-inflammatory hyperpigmentation on black skin.

Copies of author's previously published articles inserted. / Bibliography: leaves 195-196. / xv, 196 leaves : ill., maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this research is to observe the evolutionary relationships within and between frog species, as well as to discover potentially useful medicinal peptides. The two main areas of research of this thesis are the characterisation of peptides from frogs belonging to the genus Litoria and the analysis of negative ion fragmentations from large peptides. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemistry, 1997?

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002. / Includes bibliographical references (leaves 72-82). Also available in electronic version. Access restricted to campus users.