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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

Effect of nitrogen, location, and harvesting stage on peppermint (Mentha X piperita L.) productivity, oil content, and composition

Cerven, Vasile 02 May 2009 (has links)
Peppermint dry weight biomass was higher in Verona (8119 kg/ha) than in Stoneville (6115 kg/ha). Overall both, oil content and yield were higher in bud formation stage than flowering stage. The levels of major essential oil constitutes were (-)-menthol 26 – 30 %, (-)-menthone 14 – 21 %, (+)-menthofuran 5 – 11 %, and eucalyptol 3 – 4 % of total essential oil content at flowering stage. Menthone content and its yield were higher at first cut; however, (+)-menthofuran content and its yield were higher at the second cut at bud formation. Although N fertilizers at rate 80 kg/ha did not affect essential oil content and yield at cut 1, N rate at 80 + 80 kg/ha increased oil yield at cut 2.
2

The antimicrobial activity and essential oil composition of medicinal aromatic plants used in African traditional healing

Van Vuuren, Sandra Freda 29 February 2008 (has links)
Abstract A study on the essential oil chemistry and microbiological activity of South African indigenous medicinal plants with the aim of establishing a scientific rationale for their anti-infective properties was undertaken. For the purpose of this study, nine medicinal aromatic plants were selected. The hydrodistilled essential oil was analyzed by gas chromatography combined with mass spectrometry (GC-MS) and various techniques were used to document the antimicrobial activity. Disc diffusion studies on Myrothamnus flabellifolius indicated highest activities against the fungal test organisms Cryptococcus neoformans and Aspergillus niger with radial inhibition zones of 8 mm and 10 mm respectively. The highest antimicrobial activity noted in the minimum inhibitory concentration (MIC) assay was for C. neoformans (2 mg/mL). Time-kill studies demonstrated the death kinetic progression on M. flabellifolius essential oils where the killing rate was greatest for Candida albicans. Osmitopsis asteriscoides, a plant used traditionally for cuts and swellings showed highest disc diffusion antimicrobial efficacy against Staphylococcus aureus (3 mm) and C. neoformans (3 mm). The MIC study indicated highest susceptibilities (4 mg/mL) for Escherichia coli and Staphylococcus epidermidis. Death kinetics for the three organisms studied demonstrated that the killing rate was greatest for C. albicans. The role of the two major constituents (1,8-cineole and (-)-camphor) act synergistically to enhance antimicrobial activity. Disc diffusion assays undertaken on Artemisia afra showed highest activity against Candida tropicalis (5 mm). In the MIC assay the highest susceptibility was against Serratia odorifera (4 mg/mL). Time-kill assays on Artemisia afra showed a concentration dependent bactericidal activity, with evidence that the major constituents independently and in combination were not responsible for the overall activity of the plant. Lippia javanica, a plant used to treat coughs, colds and bronchitis, indicated highest susceptibility against the respiratory pathogen Klebsiella pneumoniae (5 mm) with the disc diffusion assay. The MIC assay indicated highest susceptibilities (4 mg/mL) against C. neoformans and E. coli. Death kinetic assays for three test organisms showed that the killing rate was the greatest for K. pneumoniae. The time-kill study for L. javanica in combination with A. afra demonstrated that the oils in combination act synergistically against K. pneumoniae. The antimicrobial activity of the essential oils and extracts were determined for Helichrysum cymosum subsp. cymosum where the extracts demonstrated at least a six times greater MIC efficacy than the essential oils. Using column chromatography, the antimicrobially active compound was isolated from H. cymosum subsp. cymosum and identified as helihumulone. The traditional use of plants as a treatment for infectious diseases is not always restricted to a single part of the plant as was noted in the study on Croton gratissimus var. subgratissimus, where the leaf, bark and root extracts were investigated singularly and combined in various ratios to establish possible interaction. The MIC and fractional inhibitory concentration (FIC) results indicated variable efficacies for the plant combinations. The greatest synergistic profile was noted for C. neoformans in the leaf and root combination (MIC 0.4 mg/mL and FIC of 0.4). Further isobologram combination studies were thereafter conducted on varying ratios of leaf and root extracts, indicating greatest synergy for Bacillus cereus, Enterococcus faecalis, C. albicans and C. neoformans. While seasonal variation had very little impact on the MIC results obtained from Heteropyxis natalensis, the ratio of the two major compounds (1,8-cineol and limonene) fluctuated on a monthly basis. Moderate antimicrobial activity (3.0-16.0 mg/mL) was found for most pathogens with higher sensitivities for C. neoformans. The geographical variation of H. natalensis essential oil indicated similar profiles for Gauteng, Nelspruit and Waterberg samples. The Lagalametse sample, however, showed distinct variation both chemically and microbiologically where efficacy was higher than in all other samples. The impact of the enantiomeric configuration was investigated for limonene in combination with 1,8- cineole with (+/-)-limonene in combination with 1,8-cineole having the most significant synergistic ratios against Pseudomonas aeruginosa. The antimicrobial activities of the non-volatile and volatile fractions of Tarchonanthus camphoratus and Plectranthus grandidentatus, singularly and in combination demonstrated that the volatile constituents contribute to the total efficacy of the plant. Isobologram representation of the combination of various ratios of T. camphoratus and P. grandidentatus essential oil and non-volatile extracts devoid of essential oils present a predominant synergistic profile for all pathogens studied. A comparative study on five indigenous oils (M. flabellifolius, O. asteriscoides, H. natalensis, A. afra and L. javanica) was undertaken with five popular commercial oils (Lavendula angustifolia, Thymus vulgaris, Melaleuca alternifolia, Mentha piperita and Rosmarinus officinalis). The highest antimicrobial activity was noted for Thymus vulgaris in the MIC assay, followed by M. flabellifolius, O. asteriscoides and M. alternifolia. With the time-kill assay, M. flabellifolius showed the most rapid cidal effect against all three pathogens tested. The comparative evaluation of commercial essential oils with indigenous oils validated the use of South African aromatic plants for their anti-infective properties.
3

Interaction between the non-volatile and volatile fractions on the antimicrobial activity of Tarchonanthus camphoratus

Van Vuuren, SF, Viljoen, A M 28 July 2009 (has links)
Abstract The contribution of the volatile constituents to the overall antimicrobial efficacy of the medicinal plant Tarchonanthus camphoratus was considered, where different extraction techniques were applied to yield four fractions. These comprised of the essential oil prepared by hydrodistillation, non-volatile constituents prepared by extraction of plant material remaining in the distilling apparatus (having no or negligible volatile constituents), and extracts prepared from fresh and dried plant material having both volatile and non-volatile constituents. The antimicrobial activities of the non-volatile and volatile fractions of T. camphoratus singularly (MIC method) and in combination (isobologram ratio method) demonstrated that the volatile constituents play an integral role in the total antimicrobial efficacy of the plant. The MIC values for the essential oils of T. camphoratus ranged from 1.5 to 16.0 mg/ml depending on the pathogen studied. With the exception of studies on Klebsiella pneumoniae, the non-volatile fraction devoid of volatile constituents displayed higher antimicrobial efficacies (2.0–4.0 mg/ml). When the volatile and non-volatile fractions were combined, increased efficacy was mostly noted with the dried plant material mostly showing a higher antimicrobially-active profile. Synergistic interactions were further validated by the isobologram studies on the combination of non-volatiles with essential oil.
4

Seasonal and geographical variation of Heteropyxis natalensis essential oil and the effect thereof on the antimicrobial activity

Van Vuuren, SF, Viljoen, AM, Őzek, T, Demirci, B, Başer, KHC 27 July 2007 (has links)
Heteropyxis natalensis (Heteropyxidaceae) is traditionally used to treat respiratory disorders, and as a decongestant and antimicrobial agent. The seasonal variation of the hydrodistilled essential oil was investigated. Three trees in the Johannesburg Botanical Garden (Gauteng) indicated similar chemical profiles with fluctuation in the levels of the two major constituents (1,8-cineole and limonene). Little variation between the antimicrobial activity of seasonally collected samples was documented, with standard deviations of ±0.3 to ±3.3 depending on the pathogen studied. Moderate antimicrobial activity (3.0–16.0 mg/ml) was noted for most pathogens tested with Cryptococcus neoformans exhibiting the highest sensitivity (2.0–3.0 mg/ml). The chemogeographical variation of the oil composition from five of the seven distinct localities studied all contains 1,8-cineole and limonene as major constituents. The antimicrobial study of these samples indicated little variability between localities (standard deviation of ±0.5 to ±3.8). As observed in the seasonal variation study, C. neoformans displayed the highest sensitivity (0.5–2.0 mg/ml). One oil sample (Lagalametse), was distinctly different both chemically and microbiologically.
5

Effect of Drought Stress on Total Protein, Essential Oil Content, and Physiological Traits of Levisticum Officinale Koch

Akhzari, Davoud, Pessarakli, Mohammad 13 November 2015 (has links)
Levisticum officinale Koch is one of the most important plants producing essential oil. An experiment was conducted to determine the effect of drought stress on growth, total protein and essential oil content of Levisticum officinale. The experiment was conducted in a greenhouse, in a completely randomized design using 5 replications. Aridity levels of field capacity irrigation (as control), −0.6 and −1.0 MPa were applied. There was significant effect of aridity on leaf area in Levisticum officinale. The highest leaf area values were found in the lowest aridity (FC) level. The root weight and root length in the −0.6 MPa aridity level were more than that of the control aridity level, but, shoot height and shoot weight were highest in the control treatment. Total soluble protein contents under −0.6 MPa drought stress was numerically lower than that in the control treatment, but statistically there was no significant difference between protein contents in the −0.6 MPa and the control treatment. Compared to the control treatment, total soluble protein contents of Levisticum officinale were significantly decreased in the −1.0 MPa drought treatment. Essential oil content of Levisticum officinale was significantly increased in the −0.6 MPa drought treatment compared to the control. Compared to control treatment, there was a significant reduction found in essential oil content of Levisticum officinale in the −1.0 MPa aridity treatment. The results suggest that in the drought levels between −0.6 to −1.0 MPa, Levisticum officinale could be used for arid and semi-arid lands economical use.
6

Effects of plant secondary metabolites on bacteria and fungi populations

Hassiotis, Christos N. January 1997 (has links)
No description available.
7

Studies of chemical constituents on the aerial parts of pelargoniumcapitatum

Mthembu, Zandile Lorraine January 2017 (has links)
>Magister Scientiae - MSc / Pelargonium capitatum is a plant that is popular in essential oils. The isolated essential oil constituents from the flowers and leaves of the plant were obtained by hydrodistillation followed by GC-MS analysis. The following essential constituents were obtained in abundance from flowers and leaves 8, 11-octadecadienoic acid and citronellol, caryophyllen, α-cubebene, copaene, azulene, pentacosane, 9, 12- octadecadienoic acid. Crude extracts from Pelargonium capitatum were fractionated through various chromatographic techniques in order to achieve satisfactory separations. Four compounds were characterized and the structural elucidation were unambiguously confirmed by spectroscopic methods including one and two-dimensional nuclear magnetic resonance and high resolution mass spectroscopy. The compounds were isolated from the ethyl acetate (2) and hexane (2) extracts, respectively. The four isolates were identified as quercetin, quercetin xylopyranoside, β-sitosterol and undecaprenol. The isolate and the different extracts were tested for cytotoxicity using brine shrimp lethality test. The results showed that quercetin and the extracts were active with hexane extract showed the highest cytotoxicity level of 1.5μg/ml. To the best of our knowledge quercetin xylopyranoside, β-sitesterol and undecaprenol compounds are reported for the first time from Pelargonium capitatum.
8

Seasonal variation in essential oil composition, oil toxicity and the biological activity of solvent extracts of three South African Salvia species

Kamatou, GPP, Van Zyl, RL, Van Vuuren, SF, Figueiredo, AC, Barroso, JG, Pedro, LG, Viljoen, AM 26 November 2007 (has links)
Aromatic plants contain both volatile and non-volatile fractions and the chemical composition of these two fractions may be influenced by seasonal changes. The essential oil and solvent extracts of S. africana-caerulea, S. africana-lutea and S. lanceolata, collected at the same locality throughout the 2005 growing season, were compared in terms of essential oil composition, yields and biological activities. Mostly quantitative, rather than qualitative variationwas observed in the oil composition of each species.Major fluctuations in the composition of S. africana-caerulea oil included limonene (2–33%) and viridiflorol (2–24%). Levels of α-pinene (1–12%), myrcene (2–12%) and α-eusdesmol (trace-13%) fluctuated seasonally in the S. africana-lutea oil. In S. lanceolata, considerable changeswere noted for β-caryophyllene (1–19%), β-caryophyllene oxide (1–21%) and ledol (3–12%). The extract prepared from S. lanceolata harvested inwinterwas more active against Gram-positive bacteria. The S. africana-caerulea extract exhibited the most favourable antiplasmodial activity when harvested in winter (IC50 value: 12 μgml−1), which contrasts with the lowest anti-plasmodial activity of S. lanceolata obtained at the same period (IC50 value: 43 μgml−1). The anti-oxidant activity of the solvent extracts also displayed variation over seasons with thewinter collection of S. africana-lutea yielding the most favourable anti-oxidant activity (IC50 value: 10 μg ml−1). All the solvent extracts prepared from the winter collection exhibited the lowest toxicity (20bIC50 valuesb60 μg ml−1), while the three essential oils obtained from autumn collection were more toxic (0.03bIC50 valuesb0.4 μg ml−1).
9

The Effect of Oregano Essential Oil on Microbial Load, Drying Kinetics and Sensory Atributes of Dried Meat

Hernandez Hernandez, Helga Johana January 2016 (has links)
Microbial load can be controlled using either synthetic or natural preservatives. Particular interest has been focused on the potential application of plant essential oils as safer additives for meat. However, there is no published research on the use of essential oils during the meat drying process. This study was focused on enhancing the meat drying process. At first a value-added dried meat product by using oregano essential oil (OEO) to inhibit the growth of bacteria, and the sensorial response from assessors is presented. It was found that the application of the OEO in meat is effective in inhibiting Salmonella enteritidis and Escherichia coli. After 6 hours of drying at 55°C, 2 ml (0.038 ml l-1 air) and 1.5 ml (0.028 ml l-1 air) of OEO were considered the minimal inhibitory concentrations (MICs) against S. enteritidis and E. coli, respectively. Samples treated with 0.75 ml of OEO were more attractive for consumption compared with the control; at a higher concentration of OEO, the sensory quality of the food was affected. Next, the effect of modified blanching treatments on the drying behaviour of beef meat was evaluated by determining moisture ratio versus time curves and the influence on sensory quality of the resulted product. The 3 treatments under investigation were (1) oil treatment (2) steam blanching and (3) hot air blanching with 3 doses of oregano essential oil (1) 1.5 ml (2) 3 ml and (3) 6 ml. Each treatment had an effect on the drying time of the beef samples, however, the dose of oregano essential oil applied did not affect the drying process. The results showed that steam blanching was very effective reducing the drying time. Meanwhile, 1.5 ml and 3 ml hot air blanching samples and 1.5 ml oil treatment samples were judged as better from sensory point of view and the respondents considered that adding oregano essential oil enriched the pleasantness of the smell. In conclusion, a value-added dried meat product obtained by using oregano essential oil to enhance food safety received an acceptable sensorial response from consumers. Additionally, each modified blanching treatment tested influences the drying kinetics process, but the dose of oregano applied did not affect the drying process. In this sense, hot air blanching and oil treatment with the lowest dose had an acceptable sensorial response from consumers.
10

Avaliação do potencial antimicrobiano in vitro de Coriandrum sativum L. em diferentes especies de Candida / Evaluation of the antimicrobial potential of Coriandrum sativum L. against different species of Candida

Begnami, Andreza Fabiana 03 March 2008 (has links)
Orientador: Vera Lucia Garcia Rehder / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-11T04:41:45Z (GMT). No. of bitstreams: 1 Begnami_AndrezaFabiana_M.pdf: 1069115 bytes, checksum: 6ccff8914d460d714a8f267c7192ecef (MD5) Previous issue date: 2008 / Resumo: O Coriandrum sativum L. conhecido popularmente como coentro é citado como antidiabético, antiinflamatório, hipoglicemiante e antibacteriano. O gênero Candida faz parte da microbiota da cavidade oral e sob circunstâncias especiais produzem candidíase e infecções sistêmicas. O objetivo desse trabalho foi avaliar a atividade do óleo essencial (OE), extratos hexânico (EHE) e hidroalcoólico (EHA) de folhas de C. sativum frente as diferentes espécies de Candida e identificar seus principais constituintes. Para obtenção dos EHE e EHA foram utilizadas 10g das folhas secas e moídas, originando-se 0,43 g do EHE e 2,34 g do EHA, com rendimentos de 4,3% e 24,3%, respectivamente. O OE (2,06 g - rendimento 0,03%) foi obtido por hidrodestilação em sistema do tipo Clevenger a partir de 7500 g de folhas frescas, sendo fracionado em coluna seca e originando sete frações (FOE) com diferentes polaridades, as quais foram analisadas por CCD e CG-EM. Os constituintes majoritários identificados do OE foram álcoois e aldeídos de cadeia linear: 1- decanol (24,17%), 2E-decenol (18,05%) e 2Z-dodecenol (17,55%). Os OE, EHE e EHA foram testados frente as diferentes espécies de Candida: C. albicans CBS 562; C.krusei CBS 573; C. parapsilosis CBS 604; C. dubliniensis CBS 7987 e C. tropicalis CBS 94. As amostras do OE e extratos foram solubilizadas em água destilada e tween 1% para concentração em solução de 4 mg/mL, testando-se concentrações de 1000 Yg/mL a 15,6Yg/mL. O OE apresentou forte inibição frente as diferentes espécies de Candida com MICs de 125 a 500 Yg/mL, enquanto os EHE e EHA inibiram apenas C. parapsilosis com MIC de 250 Yg/mL. As frações 4, 5 e 6 do OE enriquecidas em álcoois apresentaram forte inibição e amplo espectro antimicrobiano, com MICs de 7 a 250 Yg/mL, evidenciando que esses compostos são responsáveis pela atividade antimicrobiana frente as diferentes espécies de Candida , enquanto as frações FOE 1 a 3 ricas em aldeídos, com MICs de 31 a 1000 Yg/mL, apresentaram atividade antimicrobiana moderada. Esses resultados demonstram o potencial uso de Coriandrum sativum no combate a leveduras do gênero Candida / Abstract: Coriandrum sativum L. (Umbelliferae / Apiaceae), known as coriander, is a popular cooking condiment in Brazil; it has been reported as an anti-inflammatory, anti-diabetic and anti-bacterial agent. Different Candida spp., which might lead to complications such as skin candidosis or even systemic infections, are commonly found in the oral microbiota. The aim of this study was to evaluate the activity of the essential oil (EO) and hexanic and hydroalcoholic extracts of C. sativum against different species of Candida, as well as to identify their main constituents. To obtain the hexanic (HEE) and hydroalcoholic extracts (HAE), 10 g of dried leaves of C. sativum was used to attain 0.43 g of HEE and 2.34 g of HAE, with yields of 4.3% and 24.3%, respectively. Its essential oil (2.06 g ¿ yield 0.03 %) was obtained by hydrodistillation using the Clevenger system where 7500 g of its fresh leaves and dry-column chromatography was used to fraction the oil into seven fractions with different polarities. These fractions were then analyzed by TLC and GC-MS. The main constituents identified in the essential oil were long-chain alcohols: 1-decanol (24.17 %); 2E-decenol (18.05 %); and 2Z-dodecenol (17,55 %) and aldehydes. The HEE, HAE, and EO were tested against C. albicans CBS 562, C. krusei CBS 573, C. parapsilosis CBS 604, C. dubliniensis CBS 7987, and C. Tropicalis CBS 94. Samples of EO, HEE and HAE were dissolved in distilled water with 1% tween to obtain a solution concentration of 4 mg/mL and 1000 µg/mL to 15.6 µg/mL of which was tested against Candida spp. The EO showed antibacterial activity against most species of Candida, with MICs ranging from 125 µg/mL to 500 µg/mL, while the extracts inhibited only C. parapsilosis with a MIC of 250 µg/mL. Alcohol-enriched fractions 4, 5 and 6 of EO showed strong inhibition and broad antimicrobial spectrum, with MICs ranging from 7 to 250 µg/mL, suggesting that alcohol might be responsible for the antimicrobial activity against the various species of Candida tested. While the fractions 1 to 3 rich in aldehydes, with MICs ranging from 31 to 1000 µg/mL, showed moderate antimicrobial activity against the species of Candida tested. Results showed potential antimicrobial activity of Coriandrum sativum against Candida spp (yeast infections) / Mestrado / Farmacologia, Anestesiologia e Terapeutica / Mestre em Odontologia

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