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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

Phytochemical studies on some species of the Annonaceae

Etse, J. T. January 1986 (has links)
No description available.
2

A phytochemical-microbiological survey of the South American Bromeliaceae

Mills, Charles January 2000 (has links)
No description available.
3

The pharmacognosy of Diplotaenia cachrydifolia : Characterisation of the coumarins and volatile principles and the histology of D. cachrydifolia Boiss. (Apiaceae)

Salehy Surmaghy, M. H. January 1988 (has links)
No description available.
4

The phytochemistry and microbial activity of selected indigenous Helichrysum species

Reddy, Dakshina 10 June 2008 (has links)
ABSTRACT Helichrysum (Asteraceae) is a large genus consisting of approximately 500 species of which 245 taxa are indigenous to southern Africa. Many Helichrysum species are widely used by the indigenous population to treat various ailments, including coughs, colds, fever, infections, headache, menstrual pain and as a treatment for wounds. Medicinal uses are often not species-specific but often depend on the local availability. Guided by the traditional use and the lack of scientific information, nine species of Helichrysum were selected for this study. The essential oils were obtained through hydrodistillation and methanol and acetone extracts of the plant material were prepared. The essential oil composition was determined using GC-MS. The oil profiles were mostly dominated by the presence of monoterpenes such as a-pinene, 1,8-cineole and p-cymene. Monoterpenes were largely absent in the essential oil of H. felinum, but this oil was rich in sesquiterpenes with high yields of b-caryophyllene. The antimicrobial activity of the essential oils and plant extracts were of interest due to their traditional use as an antiseptic. The antimicrobial activity of the essential oils and extracts was determined by disc diffusion assays and, following this, the most active species were further investigated using the minimum inhibition concentration (MIC) assay. Helichrysum dasyanthum displayed the best activity against B. cereus (MIC = 16 mg/ml) and was the only extract that exhibited activity against all three fungal strains tested (C. neoformans, 1 mm; C. albicans, 3 mm; and A. alternata, 2 mm). The essential oil of H. petiolare and H. felinum exhibited the most pronounced activity against the fungal strains in the disc diffusion assay (C. albicans, 2mm).
5

Indigenous Salvia species : an investigation of their pharmacological activities and phytochemistry

Kamatou, Guy Paulin Poungoue 26 September 2008 (has links)
The genus Salvia belongs to the family Lamiaceae and encompasses 900 species worldwide of which 26 are found in southern Africa and many of them are used in local traditional medicine. However, the phytochemistry and pharmacological activities of the South African species have not been extensively investigated. The leaf trichome morphology that may be used to distinguish species was investigated with the scanning electron and light microscopy. Both glandular (capitate or peltate) and non-glandular trichomes were identified in all species. The essential oils were isolated by hydro-distillation and analysed by GC and GC-MS methods. The oil yield was relatively low and ranged from 0.004 (S. radula) to 0.50% (S. muirii) (w/w). Major components identified include α-pinene, 1,8-cineole, linalool, limonene, myrcene, β-caryophyllene, spathulenol, β-caryophyllene oxide, viridiflorol, δ-3- carene and α-bisabolol. High performance liquid chromatography analysis was used to identify phenolic compounds in 17 solvent extracts. Betulafolientriol oxide was detected in all species. Rosmarinic acid was only absent in S. verbenaca, while S. garipensis and S. radula were the only species which lacked oleanolic acid/ursolic acid. Various in vitro biological activities were investigated. Nearly all the solvent extracts displayed anti-oxidant activity with IC50 values ranging from 1.61 to 74.50 μg/ml using the DPPH· radical, while the IC50 values ranged from 11.88 to 69.26 μg/ml with the ABTS·+ radical. The solvent extract of S. schlechteri was three times more active than vitamin C. Total phenolic content based on gallic acid equivalents (GAE) revealed the presence of total soluble phenolics in the extract at 45 to 211 mg of GAE dry sample. Almost all the essential oils exhibited promising anti-inflammatory activity (5-lipoxygenase assay) with IC50 values ranging from 22.81 to 77.32 μg/ml. The antimalarial activity was determined using [3H]-hypoxanthine method on the Plasmodium falciparum (FCR-3) strain. The IC50 values of the essential oils ranged from 1.20 to 13.50 μg/ml and were low compared to the solvent extracts (IC50 values ranging from 3.91 to 26.01 μg/ml). Betulafolientriol oxide and salvigenin isolated from S. radula inhibited the growth of malaria parasites with IC50 values of 4.95 and 24.60 μg/ml, respectively. With the exception of S. radula, all the solvent extracts displayed moderate to good activity against Staphylococcus aureus, vii Bacillus cereus, Klebsiella pneumoniae, Escherichia coli and Mycobacterium tuberculosis with the MIC values ranging from 0.03 to 8.00 mg/ml. Four compounds, namely carnosol, 7-O-methylepirosmanol, oleanolic acid and its isomer ursolic acid were isolated from S. chamelaeagnea as the active principles against S. aureus. The solvent extracts of Salvia species were tested for in vitro anticancer activity against human breast adenocarcinoma (MCF-7), colon adenocarcinoma (HT-29) and glioblastoma (SF-268) using the sulforhodamine B assay. The extracts inhibited cell proliferation of all three cell lines to varying degrees, with the IC50 values ranging between 9.69 and 43.65 μg/ml and 8.72 and 59.12 μg/ml against the MCF-7 and SF-268 cell lines, respectively. The IC50 values against the HT-29 cell line ranged from 17.05 to 57.00 μg/ml. The in vitro toxicity profile of 28 samples (17 solvent extracts and 11 essential oils) was evaluated on human kidney epithelial cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5 dimethyl tetrazolium bromide method. The samples displayed some degree of toxicity with IC50 values ranging from 1.79 to 22.9 μg/ml for the essential oils and from 12.12 to 53.34 μg/ml for the solvent extracts. The essential oil composition of S. africana-caerulea, S. africana-lutea and S. lanceolata, collected at the same locality throughout the 2004/2005 growing season, was compared in terms of essential oil yields, chemical composition and biological activities. Mostly quantitative, rather than qualitative variation was observed. Major seasonal fluctuations of certain essential oil compounds were observed in all three species. Variations in biological activities of the solvent extracts over seasons were noted. The biological activities of the solvent extracts of three Salvia species (Salvia africanacaerulea, S. africana-lutea and S. lanceolata) were evaluated in the presence and absence of essential oils. The solvent extract of S. africana-caerulea without essential oil exhibited the best activity against Gram-positive bacteria (MIC value: 0.1 mg/ml), while the solvent extract containing essential oil of S. africana-lutea was the most active against Gramnegative bacteria. The toxicity profile of all three species was significantly higher (P < 0.05) with the solvent extracts containing essential oils. The in vitro biological activities add scientific support to the use of Salvia species in traditional medicine.
6

A Phytochemical and Antibacterial Analysis of Echinacea Purpurea (L.) Moench Throughout Seasonal Development

Daley, Elizabeth 07 February 2019 (has links)
Echinacea purpurea is consumed as a natural health product around the world. Due to the genus’ ethnobotanical relevance, the phytochemistry of Echinacea has been extensively studied, revealing a variety of bioactive metabolites including caffeic acid derivatives and alkylamides. Whereas seasonal trends in root chemistry have been established, trends in other plant parts are relatively understudied. Similarly, few studies have evaluated the effects of organic plant growth substances in field trials. With increased demand for organic products, industry is looking for alternative ways to optimize yields and medicinal properties. For this thesis, my first objective was to quantify the concentrations of E. purpurea’s secondary metabolites across organic treatments throughout the plant’s first growth year to determine optimal harvesting time and conditions in all parts of the plant. The second objective was to determine how seasonal variations affect its potential bioactivity through inhibition of Pseudomonas aeruginosa. Plants were grown in field plots treated with four different organic treatments: water (control), high cytokinin, low cytokinin, and fish oils; samples were collected biweekly from May-September. Dried plants were separated into major plant parts and were extracted exhaustively in 70% EtOH. Using high-pressure liquid chromatography (HPLC), concentrations of alkylamides and select caffeic acid derivatives were quantified in all samples and compared across plant part, developmental stage, and organic fertilizers. It was determined that while there were no major differences between treatments, phytochemical concentrations changed throughout the season in all plant parts; revealing that aerial parts of the plant also bioactive secondary metabolites and should not be excluded from future studies. Following this study, an MIC50 assay was used to test these extracts against P. aeruginosa PA14. It was noted that seasonality effects of phytochemistry were not consistent with bioactivity and that there were no significant differences between extract and carrier control. While the antibiotic activity of root extracts varied seasonally, the flower extract exhibited the most consistent antibiotic potential. The results presented in this thesis will not only aid in industry practices and yield optimization but, through filling knowledge gaps on seasonality and organic treatments in field trials, will increase the understanding of E. purpurea’s chemistry and related bioactivity, with implications on both the medicinal properties and eco-physiology of the species.
7

Phytochemistry of hydroxycoumarins from Manihot esculenta Euphorbiaceae (cassava)

Alhalaseh, Lidia January 2017 (has links)
This is an interdisciplinary research project on cassava (Manihot esculenta Crantz, Euphorbiaceae) ultimately working towards producing cassava roots which are long-lasting, free of post-harvest physiological deterioration (PPD). It aims to contribute to ensuring food security. In cassava, scopoletin and its -glycoside scopolin are considered phytoanticipants, not phytoalexins, due to their increasing accumulation during the PPD process compared to their barely detectable levels in fresh roots. Starting with a focussed literature review on the potential of cassava, contrasted with its limitations on harvesting due to PPD, and biosynthesis along the phenylpropanoid pathway of key hydroxycoumarins, e.g. scopoletin and esculetin, the associated gaps in our current knowledge have been set out. Whether scopoletin is biosynthesized de novo from L-phenylalanine in response to stress, or whether stress prompts its release from the corresponding glycoside is unknown. Therefore, assessing hydroxycoumarin biosynthesis and quantifying their accumulation patterns have been undertaken in wild-type and transgenic plants in order to elucidate the divergence in scopoletin biosynthetic pathways. The identification of key genes on each pathway leading to scopoletin in cassava, and then exploring their functional identities using the model plant A. thaliana and genetically engineered E. coli, where the genes were isolated, cloned, and expressed, were also undertaken. Transgenic A. thaliana lines with no activity of the key enzymes on the proposed pathway, namely F6ʹH1, CCoAOMT, and EOMT, were developed. Competition feeding experiments using stable isotopically labelled potential biosynthetic intermediates showed the incorporation of labelled ferulate into scopoletin in transgenic A.t-F6´H1 and M.e-F6´H. This confirmed the activity of other hydroxylase enzymes rather than F6´H1 in the ortho-hydroxylation steps. The hydroxycoumarins of interest were isolated, characterized, and quantified in the wild type and mutant lines using chromatographic and spectroscopic techniques, mainly NMR, HR-MS, and LC-MS. Taken together, a significant contribution to knowledge about hydroxycoumarin biosynthesis has been made.
8

The chemical investigation of the leaf exudates of a number of East African Aloe species

Conner, John Martin January 1988 (has links)
No description available.
9

Phytochemical studies on some species of the Simaroubaceae, Burseraceae and the Guttiferae

Ampofo, S. A. January 1985 (has links)
No description available.
10

Estudo fitoquímico, avaliação da atividade antimicrobiana, antioxidante e citotóxica de extrativos de Equisetum hyemale L. (Equisetaceae) /

Queiroz, Geisiany Maria de. January 2011 (has links)
Orientador: Rosimeire Cristina Linhari Rodrigues Pietro / Banca: Niege Araçari Jacometti Cardoso Furtado / Banca: Luis Vitor Silva do Sacramento / Resumo: São muitas as tentativas de se obter novas fontes de moléculas capazes de atuarem a favor da saúde humana combatendo problemas de saúde pública, especialmente a partir de espécies vegetais. Procurou se estabelecer neste trabalho parâmetros farmacognósticos relacionados à caracterização inicial da droga vegetal de Equisetum hyemale. O espécime de E. hyemale foi coletado no Horto de Plantas Medicinais e Tóxicas da Faculdade de Ciências Farmacêuticas de Araraquara. Estudos preliminares com a droga vegetal mostraram a presença de metabólitos secundários de maior polaridade. Os extratos etanólico 70% e metanólico foram obtidos por percolação e submetidos a estudos fitoquímicos realizados utilizando se reações gerais de identificação e métodos Cromatográficos em Camada Delgada (CCD). Os ensaios de atividade antimicrobiana foram realizados pelo método de difusão em ágar com "templates" e pelo método de determinação da Concentração Inibitória Mínima (CIM) por microdiluição em caldo, frente a cepas bacterianas e fúngicas. O potencial de atividade antioxidante dos extratos foi determinado baseando se na atividade sequestrante da solução de 2,2 difenil 1 picrilidrazila (DPPH). Os ensaios para atividade citotóxica foram realizados frente a linhagens de células eucarióticas in vitro. Os resultados obtidos no estudo fitoquímico mostraram a presença de compostos fenólicos e saponinas em ambos os extratos que apresentaram atividade antifúngica e frente à micro organismos bucais segundo a técnica de microdiluição em caldo. Os ensaios com DPPH demonstraram que os extratos tem capacidade sequestrante de radicais livres. Os testes de citotoxicidade revelaram que o extrato etanólico 70% apresentou baixa citotoxicidade na maior concentração testada (2000 µg/mL) frente a fibroblastos enquanto que frente a macrófagos causou 50% de morte celular nesta mesma... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: There are many attempts to obtain new sources of molecules that have the capacity of acting in favor of human health resolve public health problems, especially from plant species. This study aimed to establish pharmacognostic parameters to characterize the drug of Equisetum hyemale. E. hyemale were collected at "Horto de Plantas Medicinais e Tóxicas de Araraquara". The preliminary characterization reactions showed the presence of secondary metabolites of higher polarity in the drug and the extracts 70% ethanol and methanol were obtained by percolation, and submitted to phytochemical studies performed using methods for identification and Thin Layer Chromatography (TLC). The tests for antimicrobial activity were performed by agar diffusion with templates and broth microdilution methods, was used to determine the Minimum Inhibitory Concentration (MIC) values against bacterial and fungal strains. The extracts antioxidant potential was determined based on the activity of 2,2 diphenyl 1 picrylhydrazyl (DPPH) activity scavenging. The cytotoxicity assays were performed against eukaryotic cell lines in vitro. The results showed the presence of phenolic compounds and saponins in both extracts. The extracts showed antifungal activity and against oral micro organisms by microdilution method. The tests with DPPH showed that both extracts have an antioxidant activity compared with literature. Ethanolic extract showed low cytotoxicity at the highest evaluated concentration (2000 µg/mL) against fibroblastic while against macrophages caused 50% cell death at the same concentration, the methanolic extract caused 50% cell death at the concentration in between 1000 2000 µg/mL against both cells / Mestre

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