The potential for Eucalyptus radiata leaf essential oil use as a commercial antimicrobial

The potential for Eucalyptus radiata leaf essential oil use as a commercial antimicrobial

186 Abstracts Tuberculosis (TB) is one of the major bacterial infectious diseases affecting people in South Africa. The problem of TB is worsened by...

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186

Abstracts

Tuberculosis (TB) is one of the major bacterial infectious diseases affecting people in South Africa. The problem of TB is worsened by the emergence of drug resistance and human immunodeficiency virus coinfection. Although drugs for treating TB have been available for many years, the long duration and side effects that they have result in patients failing to complete a treatment course. New treatments from various sources that take less time and are without side effects are required to alleviate the problems at hand. The idea that certain plants have healing potential was well accepted a long time ago before the existence of microbes was discovered by mankind. Thus, the aims of this study were to evaluate the antibacterial properties of plants that are used in South Africa in the traditional treatment of TB and related symptoms. Five plants were selected after scrutiny of available literature on medicinal plants used by various South African tribes in the treatment of TB and related symptoms. The petroleum ether, dichloromethane, 80% ethanol, and water extracts were evaluated for antibacterial activity against Klebsiella pneumoniae, Staphylococcus aureus, Mycobacterium tuberculosis H37Ra, and Mycobacterium aurum A + using the microdilution technique. A Salmonella microsome assay using two Salmonella typhimurium strains (TA98 and TA100) was used to test genotoxicity of extracts that showed minimum inhibitory concentration (MIC) values less than 1 mg/ml (good antimicrobial activity). Out of 36 extracts tested from different parts of the five plant species, 13 showed good antimicrobial activities against at least one or more of the bacterial strains tested, with MIC values ranging from 0.098 to 12.5 mg/ml. All the extracts tested were nongenotoxic against the tested Salmonella strains. The results observed in this study indicate that there is a need for further investigation of some of these plants against drug-resistant TB strains.

doi:10.1016/j.sajb.2015.03.069

Systematics of the Annesorhiza clade (Apiaceae) A.R. Mageea,b, A.N. Nicolasc, P.M. Tilneyb, B.-E. Van Wykb, G.M. Plunkettc a Compton Herbarium, South African National Biodiversity Institute, Private Bag X7, Claremont 7735, Cape Town, South Africa b Department of Botany and Plant Biotechnology, University of Johannesburg, PO Box 524, Auckland Park 2006, Johannesburg, South Africa c Cullman Program for Molecular Systematics, The New York Botanical Garden, 2900 Southern Boulevard, Bronx NY 10458-5126, USA The Annesorhiza clade comprises three genera (Annesorhiza, Chamarea and Itasina) largely endemic to the Greater Cape Floristic Region of South Africa and forms part of the protoapioid tribe Annesorhizeae. The three genera are herbaceous perennials with hysteranthous leaves and periodically-replaced, fleshy roots. The hysteranthous leaves, coupled with the poor collection record and the need to return to populations several times in order to obtain complete material, has resulted in the number of species being grossly underestimated. This is further exacerbated by the fact that the species flower in the dry summer or autumn months when little botanical exploration takes place. Extensive field excursions over the last few years have resulted in the number of species increasing by almost 100% in all three genera (from 12 to 23 species in Annesorhiza, 6 to 12 species in Chamarea and 1 to 2 species in Itasina). Several of the new species are restricted to seasonally moist, lowland vegetation which has been largely transformed, and as a result are now highly threatened. The species are distinguishable by characters of their leaves, flowers, fruit anatomy, and root morphology. Generic delimitations remain uncertain with previous authors proposing that Annesorhiza be expanded to include Chamarea. As a result, generic relationships were also explored

through phylogenetic analyses of nrETS and four chloroplast markers (trnK–rps16, ndhF–rpl32, psbA–trnH, rpl32–trnL). doi:10.1016/j.sajb.2015.03.070

A systematic study of Inulanthera (Asteraceae, Anthemideae) S.L. Magoswanaa,b, J.S. Boatwrighta, J.C. Manningb,c, A.R. Mageeb,d a Department of Biodiversity and Conservation Biology, Faculty of Natural Sciences, University of the Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa b Compton Herbarium, South African National Biodiversity Institute, Private Bag X7, Claremont 7735, Cape Town, South Africa c Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa d Department of Botany and Plant Biotechnology, University of Johannesburg, PO Box 524, Auckland Park 2006, Johannesburg, South Africa Inulanthera comprises ten woody perennial species, distributed largely in southern Africa but with a single species each endemic to Angola, Madagascar and Zimbabwe, respectively. The genus is readily distinguished in tribe Anthemideae by the tailed anthers (a generic synapomorphy for Inulanthera) and fruits lacking secretory cavities and elongated cells in the ribs. Inulanthera has never been taxonomically treated throughout its range and as a result there is no key to the species or accurate distribution data. A taxonomic revision of the genus is here presented in which we recognize only nine species, reducing Inulanthera calva into synonymy with Inulanthera dregeana. The species were found to differ in their leaf shape, division and vestiture as well as their life history and the structure of the pappus. The monophyly of the genus, particularly the placement of the Angolan and Madagascan species, as well as the subtribal position was also assessed using both nuclear and chloroplast sequence data, included in a broader phylogeny representing the early lineages of the tribe. doi:10.1016/j.sajb.2015.03.071

The potential for Eucalyptus radiata leaf essential oil use as a commercial antimicrobial G.D. Mahumanea, S.F. Van Vuurena, A.M. Viljoenb, G. Kamatoub a Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193, South Africa b Department of Pharmaceutical Sciences, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa Due to their bioactive components, essential oils are gaining momentum as effective antimicrobial agents for food and pharmaceutical applications. The essential oil of Eucalyptus radiata is one of the few understudied commercially produced medicinal Eucalyptus essential oils, with a broad-spectrum of anti-infective therapeutic applications. Young and mature leaves of the E. radiata species were sampled monthly, over a period of one year (January 2014 to December 2014); samples were evaluated for effects of seasonal variation on the essential oil yield, chemical composition and antimicrobial activity. Essential oils were obtained using the hydrodistillation method. Chemical composition was analysed by one and two dimensional gas chromatography coupled to mass spectrometry (GC-MS). The antimicrobial activity was analysed using the minimum inhibitory concentration (MIC) assay. The sum of the fractional inhibitory concentration (ΣFIC) was used to determine

Abstracts

the types of interactions observed from the 1:1 combinations of E. radiata leaf essential oils with other essential oils. Essential oil yield was largely influenced by the phenological growth stage of the leaf and seasonal variation. E. radiata essential oil showed similar antimicrobial activity in comparison to essential oils from other Eucalyptus species. Independent 1:1 combinations showed non-interactive effects. E. radiata essential oil showed broadspectrum antimicrobial activity against the 17 selected test microorganisms. Pseudomonas aeruginosa ATCC 27853, Streptococcus mutans NCTC 10919, Lactobacillus acidophilus ATCC 314, Streptococcus agalactiae ATCC 55618 and Streptococcus pyogenes NHLS 8668, showed the highest sensitivities (MIC values ≤ 1 mg/ml). The observed consistent noteworthy antimicrobial activity throughout the testing period (autumn, winter, spring, summer) provides credence to the reliable anti-infective properties of the E. radiata essential oil. Correlations from this study will contribute towards establishing a base of information to guide harvesting protocols towards the production of an ideal E. radiata essential oil quality and quantity as a commercial antimicrobial. doi:10.1016/j.sajb.2015.03.072

Ectopic expression of a phytocystatin leads to enhanced drought tolerance in soybean M.E. Makgopa Department of Plant Sciences, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa Legumes are one of the most important sources for vegetable protein, oil and secondary metabolites worldwide. Legumes are further used as a natural nitrogen source in agriculture (green fertilization) thus reducing the use of fertilizers. The ability of legumes to fix nitrogen is due to the symbiotic relationship between soybean and the soil bacteria rhizobia resulting in the formation of nodules. In legumes, drought causes early senescence due to loss of the symbiotic relationship between the plant and the rhizobacterium. Senescence is characterized by increases in proteolytic enzymes involved in various processes in the plant's responses to stress. Transgenic soybean plants over-expressing a cysteine protease inhibitor (OC-I) were successfully generated and characterized. Plants of transgenic lines had differential transgene expression. Transgenic plants had lower protease activity determined by both an in-gel assay and a fluorometric assay using SDS-PAGE and fluorogenic protease substrate, respectively. Seeds of different transgenic soybean lines had a lower germination rate and these transgenic lines had fewer leaves and shorter stems. Under drought stress, plants of transgenic lines performed better CO2 assimilation (photosynthesis) and instantaneous water-use efficiencies (IWUE) than wild-type non-transgenic plants. In particular, plants of one transgenic line (line 57) appeared to be more drought-tolerant when compared to plants of all other tested lines. These transgenic plants retained more soil water and also had fewer leaves when compared to wild-type non-transgenic plants. Results obtained in this study have provided evidence that preventing cysteine protease activity by over-expressing a protease inhibitor causes phenotypic changes of the plant demonstrating an important role of cysteine proteases in plant growth and development and plant stress. Future work will focus on identifying these OC-I sensitive proteases and investigating their individual function in plant growth and development and stress. doi:10.1016/j.sajb.2015.03.073

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The effect of various dosage rates of glyphosate on the growth and photosynthesis of Roundup Ready® maize hybrids C. Malana, J.M. Bernera, E. Hugob a Research Unit for Environmental Sciences and Development, North West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom 2520, South Africa b ARC-Grain Crops Institute, Private Bag X1251, Potchefstroom 2520, South Africa Glyphosate is the most widely used herbicide in the world. The success of this simple molecule is mainly attributed to the high specificity of glyphosate for 5-enolpyruvylshikimate-3-phosphate synthase, which is responsible for the biosynthesis of aromatic amino acids. Glyphosate's complex, dynamic behaviour and ability to control perennial weeds, assist its role as a fundamental tool in modern agriculture. However, reports are coming from farmers complaining that the use of glyphosate decreases their yields. The aim of this study was to investigate the effect of glyphosate on the growth and photosynthetic efficiency of maize plants treated with Roundup®. Five glyphosate tolerant maize cultivars were exposed to six different dosage rates at the four leaf stage. Chlorophyll a fluorescence was measured over a period of four weeks, along with the chlorophyll content and differences in plant height. No statistical difference in the photosynthetic efficiency between the six different Roundup® treatments could be observed. However, meaningful differences in terms of the cultivar reaction to the glyphosate application were found, therefore signifying that the five cultivars are not inevitably identical concerning their photosynthetic abilities. The decrease in yield as a result of Roundup® use is most likely not the result of a decrease in the plants' ability to convert light energy into chemical energy. doi:10.1016/j.sajb.2015.03.074

Rhizosphere soil phosphatase activity of intra-hole and sole planted cowpea, sorghum and maize varieties in Marapyane and Mbombela, South Africa M.P. Maredia, S.T. Masekoa, C. Mathewsa, F.D. Dakorab a Department of Crop Sciences, Tshwane University of Technology, 175 Nelson Mandela Drive, Private Bag X680, Pretoria 0001, South Africa b Department of Chemistry, Tshwane University of Technology, 175 Nelson Mandela Drive, Private Bag X680, Pretoria 0001, South Africa To assess acid and alkaline phosphatase production in rhizosphere of intra-hole planted cowpea–maize, cowpea–sorghum and sole–grown cowpea, maize and sorghum, field experiments were established at Marapyane and Mbombela. Cowpea cultivars, PAN 311 and TUV 546, a maize variety ZM 521 and sorghum M 48 were sown as intra-hole and as sole, with and without Bradyrhizobium inoculation. Acid phosphatase (APase) activity of un-inoculated TUV 546 was enhanced when intrahole planted with sorghum, followed by TUV 546 with maize, PAN 311 with sorghum and PAN 311 with maize at Marapyane. At Mbombela, APase activity was greater in un-inoculated PAN 311 with maize than PAN 311 with sorghum, TUV 546 with sorghum and TUV 546 with maize. Enhanced alkaline phosphatase (alkpase) activity was recorded in un-inoculated TUV 546 with maize and PAN 311 with sorghum, followed by PAN 311 with maize and TUV 546 with sorghum at Marapyane. Un-inoculated PAN 311 with sorghum increased AlPase activity than TUV 546 with maize, PAN 311 with maize and TUV 546 with maize at Mbombela. AlPase activity was however higher in Rhizobium-inoculated PAN 311 with sorghum, TUV 546 with maize, and least in TUV 546 with sorghum and PAN 311 with maize at Marapyane. At Mbombela, Rhizobium-inoculated TUV 546 with M48 elevated