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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

Exploring anti-tyrosinase bioactive compounds from the Cape flora

Sonka, Luveni January 2018 (has links)
>Magister Scientiae - MSc / Tyrosinase is an enzyme widely distributed in the biosphere and is found in many species of bacteria, fungi, animals, and plants; it is associated with melanin production. Even though it possesses many beneficial properties such as photoprotection, but overproduction causes undesirable effects such melasma, solar lentigines etc. Therefore, tyrosinase enzyme inhibitors are of far-ranging importance in cosmetics, medicinal products, and food industries. This study is aimed to test anti-tyrosinase activity in 37 plants from 20 families using mushroom tyrosinase inhibition method; each plant was extracted with methanol. The results showed that 17 plant extracts, exerted a considerable level of in vitro tyrosinase inhibition comparable to positive controls of kojic acid in the same solvent systems when evaluated spectrophotometrically. Among plant extracts, those that showed an inhibition rate >50 % at 50 μg/ml and ˃60 % at 200 μg/ml were A. karroo (Hayne.), A. afra Jacq. Ex Willd, C. geifolia (L.), E. racemosa (L.), H. petiolare Hilliard & B.L.Burt, M. quercifolia (L.), M. communis (L.), P. rigida (Wikstr.), P. ecklonii (Benth.), P. ericoides (L.), S. Africanacaerulea (L.), S. Africana-lutea (L.), S. antarcticus (Willd.), S. lucida (L.) F.A.Barkley, S. hamilifolius (L.), S. furcellata R.Br and T riparia which exhibited great anti-tyrosinase activity.
2

Detection of selective tyrosinase inhibitors from some South African plant extracts of lamiaceae family

Etsassala, Ninon Geornest Eudes Ronauld January 2016 (has links)
Magister Scientiae - MSc / Various dermatological disorders, such as formation of black pigmented patches on the surface of the skin arise from the over-activity of tyrosinase enzyme's degenerative action. This enzyme is further implicated in the involvement of melanin in malignant melanoma, the most lifethreatening skin tumors. Although, synthetic products were found effective to combat this menace, nevertheless, overtime detrimental effect on human skin is a challenge. Investigation of natural tyrosinase inhibitors from methanol extracts of medicinal plants of Lamiaceae family using L-tyrosine as substrate on three different complementary assays (TLC bio-autography, spectrophotometry and cyclic voltammetry) was carried out accordingly. The result indicated Salvia chamelaeagnea, Salvia dolomitica, Plectranthus ecklonii, Plectranthus namaensis, and Plectranthus zuluensis, with significant zone of inhibition against tyrosinase on TLC bio-autography, spectrophotometry result showed that extracts of Plectranthus ecklonii (IC50 = 21.58 μg/mL), Plectranthus zuluensis (IC50 = 23.99 μg/mL), Plectranthus madagascariensis (IC50 = 23.99 μg/mL) and Salvia lanceolata (IC50 = 28.83) demonstrated good anti-tyrosinase activity when compared with kojic acid (IC50 = 3.607 μg/mL). On the other hand, cyclic voltammetry are in consonant with above results thereby supported the nomination of some of the extracts as strong anti-tyrosinase agents. Salvia chamelaeagnea showed strong activity in cyclic voltammetry and clear zone of inhibition on TLC bioautography, these reasons gave us justification for further chemical study to isolate the bioactive constituents. Phytochemical investigation of the bioactive extract of Salvia chamelaeagnea using different chromatographic methods including column chromatographic and semi preparative HPLC afforded six (6) known compounds viz carsonol (C1), carnosic acid (C2), 7- ethoxylrosmanol (C3), ursolic acid (C4), rosmanol (C5) and ladanein (C6). Their chemical structures were elucidated by analyses of spectroscopic (1H and 13C NMR) data as well as correlations with existing literature. The methanolic extract of S. chamelaeagnea (SC) showed moderate antityrosinase (IC50 = 267.4 μg/mL) activity, total antioxidant capacities measured as: Oxygen radicals absorbance capacity (ORAC; 14970 ± 5.16 μM TE/g), ferric-ion reducing antioxidant power (FRAP; 9869.43 ± 7.87 μM AAE/g) and trolox equivalent absorbance capacity (TEAC; 13706.5 ± 0.95 μM TE/g). Excellent total antioxidant capacities were demonstrated by C1 and C5 respectively as FRAP (9338.92 ± 1.72; 8622.73 ± 1.92) μM AAE/g; TEAC (16505 ± 0.86; 10641.5 ± 0.52) μM TE/g; ORAC (14550.5 ± 3.65; 14633.90 ± 3.84) μM TE/g and including the inhibition of Fe2+ -induced lipid peroxidation (IC50 = 32.5; 30.25) μg/mL. All the compounds except C4 are electro-active with well-defined oxidation-reduction peaks while C1 demonstrated the highest tyrosinase inhibitory activity by strongly decreased the inhibition current with time using cyclic voltammetry method. The isolated compounds especially C1, C2 and C5 are well known to combat with ageing problems and documented for their powerful activity against oxidative stress and alzheimer's diseases, which are ageing related symptoms. The isolation of such bioactive compounds indicated the synergetic effect of the results of the three methods used in this thesis. This is the first report on the evaluation of both anti-tyrosinase and total antioxidant capacities of the isolated compounds from S. chamelaeagnea. The findings therefore can be used as background information for exploitation of skin depigmentation and antioxidant agents from natural source.
3

Potencial citotóxico e antimicrobiano de plantas da reserva florestal Adolpho Ducke, Manaus-AM

Carneiro, Ana Lúcia Basílio 15 June 2015 (has links)
Submitted by Alisson Mota (alisson.davidbeckam@gmail.com) on 2015-07-13T18:17:07Z No. of bitstreams: 1 Tese - Ana Lúcia Basílio Carneiro.pdf: 16610047 bytes, checksum: c4cd629d2777cd22001ca4ee47db8b8c (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-07-15T18:51:06Z (GMT) No. of bitstreams: 1 Tese - Ana Lúcia Basílio Carneiro.pdf: 16610047 bytes, checksum: c4cd629d2777cd22001ca4ee47db8b8c (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-07-15T18:57:21Z (GMT) No. of bitstreams: 1 Tese - Ana Lúcia Basílio Carneiro.pdf: 16610047 bytes, checksum: c4cd629d2777cd22001ca4ee47db8b8c (MD5) / Made available in DSpace on 2015-07-15T18:57:21Z (GMT). No. of bitstreams: 1 Tese - Ana Lúcia Basílio Carneiro.pdf: 16610047 bytes, checksum: c4cd629d2777cd22001ca4ee47db8b8c (MD5) Previous issue date: 2015-06-15 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / Tropical forests are species-rich reserves for the discovery and development of antimicrobial drugs. The aim of this work is to investigate the in vitro antimicrobial potential of Amazon plants found within the National Institute on Amazon Research’s Adolpho Ducke forest reserve, located in Manaus, state of Amazonas, Brazil. 75 methanol, chloroform and water extracts representing 12 plant species were tested for antimicrobial activity towards strains of Mycobacterium smegmatis, Escherichia coli, Streptococcus sanguis, Streptococcus oralis, Staphylococcus aureus and Candida albicans using the gel-diffusion method. Active extracts were further evaluated to establish minimum inhibitory concentrations (MIC) and antimicrobial profiles using bioautography on normal-phase thin-layer chromatography plates. Diclinanona calycina presented extracts with good antimicrobial activity and S. oralis and M. smegmatis were the most sensitive bacteria. D. calycina and Lacmellea gracilis presented extracts with the lowest MIC (48.8 μg/ml). D. calycina methanol and chloroform leaf extracts presented the best overall antimicrobial activity. All test organisms were sensitive to D. calycina branch chloroform extract in the bioautography assay. This is the first evaluation of the biological activity of these plant species and significant in vitro antimicrobial activity was detected in extracts and components from two species, D. calycina and L. gracilis. / O objetivo deste trabalho foi avaliar a atividade citotóxica, antitumoral e antimicrobiana de espécies vegetais amazônicas da Reserva Florestal Adolpho Ducke do Instituto Nacional de Pesquisas da Amazônia (INPA). As espécies vegetais sem estudos anteriores selecionadas e coletadas foram: Diclinanona calycina Benoist, (Annonaceae), Lacmellea gracilis (Mull. Arg.) Markgr. (Apocynaceae), Pleurisanthes parviflora (Ducke) Howard (Icacinaceae), Dilkea johannesii Berb. Rodr. (Passifloraceae), Sterigmapetalum obovatum Kuhlm. (Rhizophoraceae), Elaeoluma nuda (Baehni) Aubrév. (Sapotaceae). Após coleta e extração as amostras foram avaliadas quanto a citotoxicidade frente a Artemia franciscana e em linhagens de células tumorais. O potencial antimicrobiano foi determinado pelo método de difusão em ágar frente a Mycobacterium smegmatis, Escherichia coli, Streptococcus sanguis, S. oralis, Staphylococcus aureus e Candida albicans. Extratos ativos foram conduzidos a avaliação da concentração inibitórioa mínima (CIM) e bioautografia para identificar Rfs de componentes antimicrobianos. Prospecção fitoquímica das espécies promissoras foi realizada para detecção dos principais constituintes químicos. Dos 38 extratos avaliados para toxicidade em A. franciscana, dois apresentaram valores de CL50 inferiores a 100 μg/mL, portanto, tóxicos para essa espécie. A menor CL50 foi do extrato de D. calycina obtido em clorofórmio com valor de 22,9 ± 0,8 μg/mL. No screening para atividade antitumoral, nove extratos representando quatro espécies vegetais foram considerados muito ativos (MA) frente à célula tumoral de sistema nervoso (E. nuda e S. obovatum), cólon (S. obovatum), mama (E.nuda) e leucemia (L. gracilis, P. parviflora, S. obovatum). A maioria dos 75 extratos analisados inibiram o crescimento dos microrganismos teste com halos entre 8 e 40 mm de diâmetro. Extratos de D. calycina demonstraram atividade antimicrobiana com CIM de 48,8 μg/mL frente a S. aureus, S. oralis e S. sanguis e 97,7 μg/mL e 195 μg/mL frente a M. smegmatis. L. gracilis foi ativa apenas contra M. smegmatis (CIM 48,8 μg/mL). A bioautografia confirmou o potencial antimicrobiano de D. calycina e L. gracilis. Todos os microrganismos avaliados por bioautografia foram sensíveis ao extrato de galho de D. calycina obtido em clorofórmio. Na prospecção fitoquímica detectou-se a presença de fenóis, taninos, flavonóides, alcalóides e antraquinonas, em extratos de D. calycina e antraquinonas e cumarinas na espécie L. gracilis. Assim, a seleção permitiu identificar espécies vegetais amazônicas com atividade antimicrobiana e antitumoral in vitro e sugerir as espécies D. calycina, L. gracilis, E. nuda e S. obovatum para apreciação detalhada em outros estudos, pois poderão ter aplicação terapêutica no tratamento de doenças infecciosas e câncer.
4

Análise da atividade antimicrobiana de extratos e frações purificadas da planta arrabidaea chica verl

Mota, Milena Rodrigues Soares 25 March 2011 (has links)
Submitted by Alisson Mota (alisson.davidbeckam@gmail.com) on 2015-07-13T19:08:16Z No. of bitstreams: 1 Tese - Milena Rodrigues Soares Mota.pdf: 10830184 bytes, checksum: b6f2977c2b749cd675523693c33de0ff (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-07-15T17:58:31Z (GMT) No. of bitstreams: 1 Tese - Milena Rodrigues Soares Mota.pdf: 10830184 bytes, checksum: b6f2977c2b749cd675523693c33de0ff (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-07-15T18:07:20Z (GMT) No. of bitstreams: 1 Tese - Milena Rodrigues Soares Mota.pdf: 10830184 bytes, checksum: b6f2977c2b749cd675523693c33de0ff (MD5) / Made available in DSpace on 2015-07-15T18:07:20Z (GMT). No. of bitstreams: 1 Tese - Milena Rodrigues Soares Mota.pdf: 10830184 bytes, checksum: b6f2977c2b749cd675523693c33de0ff (MD5) Previous issue date: 2011-03-25 / Não Informada / This study describes the therapeutic potential of extracts and standardized fractions of Arrabidaea chica leaves. A. chica is a Bignoniaceae popularly known as “crajiru”. The genus Arrabidaea occurs in Tropical America, from the Southern Mexico to the Southern Brazil. The red color of its dried leaves is attributed to two flavonoidal pigments: carajurina (main pigment) and carajurona. Chemical studies described the isolation of saponins and flavonoids from the plant leaves; purified 3- desoxyanthocyanidins were reported as anti-inflammatory. The infusion or decoction of the plant leaves is used in the folk medicine to treat anemia, inflammation and in skin wound-healing. In this work, the antimicrobial activity of the standardized extracts and fractions of A. chica cultivated at Embrapa Amazônia Ocidental, Manaus, were evaluated against fungal and bacterial microorganisms grown either from local domestic dogs and cats, or from human samples supplied by the Microorganism Collection of FIOCRUZ, in Manaus, Brazil. The plant dried leaves were extracted with increasing polarity solvents and progressively purified in preparative thin layer chromatography (TLC) and silica-gel column; the semi-purified extracts were standardized in TLC. The agar diffusion method; bioautography; minimum inhibitory concentrations tested against Staphylococcus epidermidis (CBAM 293), Staphylococcus aureus (CBAM 324), Pseudomonas aeruginosa (CBAM 232), Escherichia coli (CBAM 002), Trichophyton mentagrophytes (CFAM 1288), Microsporum canis (CFAM 1289), Malassezia pachydermatis (CFAM 1290) e Candida albicans (CFAM 1285). The standardized fractions were effective against all these microorganisms, but more intensively against Microsporum canis and Staphylococcus epidermidis. The results might favour the use of the standardized sub-fractions of A. chica as topic phytotherapic agent to treat canine external otitis. So far oleanolic and ursolic acids were identified as the main compounds in the active semi-purified fraction but other compounds of the leaves extract were not discarded. Later studies will consider the veterinarian use of the standardized extract, of the active pure entities and the convenience of the natural active antibiotic mix. / Este estudo analisou o potencial terapêutico de extratos e frações purificadas da planta amazônica Arrabidaea chica visando seu uso tópico como medicamento e eficácia comprovada em doenças cutâneas. A. chica Verl., é uma Bignoniaceae conhecida popularmente como crajiru. O gênero Arrabidaea ocorre na América tropical, do sul do México ao sul do Brasil. A cor avermelhada da folha seca e sua propriedade tintorial são devidas a dois pigmentos flavonoídicos: a carajurina, que é o pigmento principal e a carajurona. Dela foram isolados saponinas e flavonóides; As 3-desoxiantocianidinas, descritas na planta parecem possuir atividade antiinflamatória. A medicina popular utiliza o decocto ou a infusão das folhas para tratar anemia, inflamações e na cicatrização da pele. Neste trabalho, a atividade antimicrobiana de extratos e frações padronizadas da A. chica cultivada na Embrapa Amazônia Ocidental, em Manaus/AM, foi avaliada contra fungos e bactérias de amostras clínicas coletadas de animais domésticos e contra amostras humanas depositadas na coleção de Microrganimos da FIOCRUZ, Manaus/AM. Para isso, as folhas secas da planta foram extraídas com solventes de polaridade crescente, as frações foram progressivamente purificadas em cromatografia de placa ou coluna de sílica-gel, os extratos semi-purificados foram padronizados em cromatografia líquida de alta eficiência acoplada à espectrometria de massas. Os testes de difusão em ágar, bioautografia e concentração inibitória mínima foram usados para avaliar a atividade antimicrobiana das subfrações padronizadas frente aos microrganismos Staphylococcus epidermidis (CBAM 293), Staphylococcus aureus (CBAM 324), Pseudomonas aeruginosa (CBAM 232), Escherichia coli (CBAM 002), Trichophyton mentagrophytes (CFAM 1288), Microsporum canis (CFAM 1289), Malassezia pachydermatis (CFAM 1290) e Candida albicans (CFAM 1285). As frações padronizadas foram ativas contra todos esses microrganismos, com melhores resultados contra M. pachydermatis e S. epidermidis. Os resultados foram favoráveis à utilização das subfrações padronizadas na formulação de um produto fitoterápico para uso tópico em otite canina. Nas frações ativas foram identificados os ácidos oleanólico e ursólico. Estudos posteriores deverão avaliar a possibilidade de uso humano das frações purificadas ou dos compostos identificados.

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