Mutagens in feces have been suggested to be an indicator for risk of colon cancer. Groups consuming vegetarian diets are known to have lower mortality from colon cancer. The purpose of this study was to assess mutagenic activity in feces of persons habitually consuming vegetarian or non-vegetarian diets and to try to identify dietary factors or other health habits which contributed to fecal mutagenicity. Eleven strict vegetarians, six ovo-lacto vegetarians and twelve non-vegetarians, all from the Greater Vancouver area, participated in this study. Data on certain demographic variables and health habits, as well as dietary intake (food frequency and food records), were taken. One fecal sample was collected from each subject for the study. Aqueous extracts of the feces were prepared and analyzed for mutagens using the fluctuation test with Salmonella typhimurium TA100 and TA98. Levels of mutagenicity on each organism were then statistically correlated with frequency of consumption of food groups, nutrient intake, demographic data and health habits. Ovo-lacto vegetarians and strict vegetarians, as groups, had significantly lower levels of fecal mutagens than non-vegetarians in the TA100 assay. With TA98, only the strict vegetarians had lower levels of mutagens compared to the non-vegetarians. The presence of several different mutagenic compounds was indicated. Significant negative correlations were found with mutagenicity on TA98 for all subjects with the following dietary variables: fruits and juices, fiber and iron. Similar negative correlations were found for total carbohydrate and Southgate fiber intakes and mutagenicity on TA100. Within the group of non-vegetarians, there were negative correlations with mutagenicity on TA98 and total protein and with mutagenicity on TA100 and calcium. With the demographic variables and health habits, no clear pattern emerged to indicate factors which would predict lowered mutagenicity for all subjects. It is concluded that vegetarians have lower levels of fecal mutagenicity and that several dietary factors are likely to contribute to this phenomenon. / Land and Food Systems, Faculty of / Graduate

South Africa is home to a wide diversity of cultural groups, all of which utilize the flora for a variety of purposes. This is true with regard to traditional medicine systems which are similar to those of the rest of Africa south of the Sahara, with diviners (sangomas) and herbalists (inyangas) as the key health providers. In addition, the Country is rich in plant diversity with some 30 000 species of flowering plants - almost one tenth of the worlds recorded higher plants. This incorporates a large diversity of plants including trees, shrubs, herbs, bulbs and corms. The adverse effects of traditional medicinal plants and natural products are not well documented in the literature. Recently, many plants used as food or in traditional medicine have been shown to be potentially mutagenic using in vitro assays. Thus, the scientific evaluation of traditional medicine and medicinal plants is very important to validate claims made on safety and efficiency of such usages. After a survey of the available ethnobotanical literature, ten trees used in South African traditional medicine were selected. These species were: Acacia niolotica subspecies kraussiana, Acacia sieberiana, Albizia adianthifolia, Combretum kraussii, Faidherbia albida, Ficus sur, Prunus africana, Salix mucronata, Terminalia sericea and Trichilia dregeana. Plant parts including leaf, root and bark were collected from each of the selected trees (exceptions were Albizia adianthifolia, Faidherbia albida, Terminalia sericea and Prunus africana) and extracted using ethyl acetate, ethanol and water individually to ensure the extraction of compounds over a wide range of polarities. The extracts (in total, 78) were screened for antibacterial, anti-inflammatory (COX-1 and COX-2) and antiacetylcholinesterase activities and investigated for their potential mutagenic effects using the Ames test. Antibacterial activity was detected using the disc-diffusion and microdilution assays. The extracts were tested against Gram-positive bacteria: Bacillus subtilis, Staphylococcus aureus, Micrococcus luteus and Gram-negative bacteria: Escherichia coli and Klebsiella pneumoniae. Of the 78 different plant extracts 111 tested (final amount of plant material was 1 mg per disc), 84% showed activity against Gram-positive bacteria. From this percentage, 20% also showed activity against Gram-negative bacteria. The best inhibition was observed with ethyl acetate and ethanol root extracts of Terminalia sericea against both Gram-positive and Gram-negative bacteria. In the micro-dilution assay, 55% of the plant extracts showed minimum inhibitory concentration (MIC) values ~ 1.56 mg/ml against Gram-positive and/or Gram-negative bacteria. The ethyl acetate bark extract of Acacia sieberiana and the root and bark ethyl acetate extracts of Acacia nilotica inhibited bacterial growth of both Gram-positive and Gram-negative bacteria at concentrations ~ 0.8 mg/ml. The aqueous leaf extracts of Acacia sieberiana had a low MIC value (0.3 mg/ml) against Gram-negative Kleibsiella pneumoniae and the ethyl acetate extracts of the root inhibited growth of Escherichia coli with an MIC value of 0.1 mg/ml. However, these two extracts showed no activity in the disc-diffusion assay. The MIC values of the neomycin (control) were 0.8 I-Ig/ml and 3.1 I-Ig/ml against Kleibsiella pneumoniae and Escherichia coli respectively. In the anti-inflammatory test, 70% of the plant extracts from different plant parts (leaf, root, bark) of the tree investigated showed strong inhibition in both the CQX-1 and CQX-2 bioassays. The CQX-2 inhibitory effects of aqueous extracts were generally lower when compared to the organic solvent extracts. However, water extracts of Acacia nilotica was an exception (~ 90%). In the acetylcholinesterase inhibitory test, 21% of the plant extracts were active at concentrations ~ 1 mg/ml using the micro-plate assay. The lowest IC50 value was 0.04 mg/ml obtained with an ethanol bark extract of Combretum kraussii. The IC50 value of the galanthamine (positive control) was 2 I-IM. None of the investigated plants showed any potential mutagenic effects with Salmonella typhymurium strain TA 98 using the Ames test. Using bioassay-guided fractionation, anolignan B was isolated from the ethyl acetate root extract of Terminalia sericea. Antibacterial activity of anolignan B was determined using the microdilution assay. The compound possessed activity against both Gram-positive and Gram-negative bacteria. The lowest MIC value (3.8 IJg/ml) was observed with Staphylococcus aureus. MIC value of the neomycin was 1.5 IJg/ml. Anti-inflammatory activity of anolignan B was detected using the CQX-1 and CQX-2 bioasays. The compound showed strong inhibitory activity against CQX-1 and weaker activity against CQX-2. The ICso values were 1.5 mM and 7.5 mM with CQX-1 and CQX-2 respectively. The ICso values of indomethacin were 0.003 mM and 0.186 mM against CQX-1 and CQX-2 respectively. There were no potential mutagenic effects showen by anolignan B against Salmonella typhimurium strain TA 98 in the Ames test. Isolation of anolignan B from Terminalia species and the antibacterial and anti-inflammatory activities observed in this work have not been reported previously and could therefore be recorded as novel biological activities for this compound. These results also support the idea that the use of ethnobotanical data can provide a valuable short cut by indicating plants with specific uses which might likely be sources of biologically active chemicals. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Throughout the history of mankind, many infectious diseases have been treated with plant extracts. Venereal infections are one such group and are regarded as conditions that are highly responsive to traditional treatment. Aqueous, ethanol and ethyl acetate extracts of 13 plants used in South Africa for the treatment of venereal diseases were screened for in vitro antibacterial, antifungal, mutagenic and antimutagenic activities. Antibacterial activity was evaluated using the disc-diffusion and microdilution assays to determine the minimal inhibitory concentration (MIC) values of the extracts. The extracts were tested against the Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus, and the Gram-negative bacteria Escherichia coli and Klebsiella pneumoniae. Among the plants tested, Gunnera perpensa, Harpephyllum caffrum, Hypoxis latifolia and Ledebouria ovatifolia showed the best antibacterial activity. The aqueous rhizome extract of Gunnera perpensa displayed good activity against Gram-negative bacteria with an MIC value of 0.78 mg/ml, and against S. aureus (0.78 mg/ml). Aqueous and ethanol extracts of H. caffrum bark were active against both Gram-positive and Gram-negative bacteria. Hypoxis latifolia aqueous corm extracts exhibited very good MIC values against K. pneumoniae (0.78 mg/ml), E. coli and S. aureus (1.56 mg/ml). Ethanol and ethyl acetate bulb extracts of Ledebouria ovatifolia displayed good activity against Bacillus subtilis bacteria with MIC values of 0.78 mg/ml and 0.39 mg/ml respectively. Antifungal activity was evaluated using the microdilution bioassay. Good activity was shown by the ethanolic bark extracts of Bersama lucens and Harpephyllum caffrum against Candida albicans. Only in the case of Harpephyllum caffrum did aqueous extracts have activity against Candida albicans. In the Ames test, all plant extracts showed a negative genotoxic response except for ethanol and ethyl acetate bulb extracts of Cyrtanthus obliquus which induced mutations in TA98. Moderate antimutagenic activity was observed with the ethyl acetate extract of G. perpensa and the ethanolic extract of H. latifolia. High antibacterial and antifungal activity detected with Harpephyllum caffrum bark extracts resulted in an investigation on seasonal and geographical variation of this inhibitory activity. Seasonal variation in antibacterial and antifungal activities was investigated in order to determine the best collection time to ensure potential high medicinal activity in plant preparations. The highest inhibitory activity was detected with plant material collected in June and December 2003, with a decline in activity when collections were made in September 2004. The chemical profiles of TLC chromatograms were compared and little variation was found, particularly in the case of plant material obtained from the Botanic Garden of the University of KwaZulu-Natal and a 'Muthi' Shop in Pietermaritzburg. Identification of active compounds from G. perpensa and H. caffrum was not successful due to insufficient amounts of isolated fractions. / Thesis (Ph.D.)-University of KwaZulu-Natal, 2006.

Made available in DSpace on 2014-08-20T13:25:42Z (GMT). No. of bitstreams: 1 Dissertacao_ Gustavo_da_Silveira.pdf: 344081 bytes, checksum: 9df6d3d1e8eb064ac8609c019c8f7914 (MD5) Previous issue date: 2009-02-16 / Black oat (Avena strigosa Schreb.) is used as a forage or cover crop, green fertilizer, weed control (through competition or allelopatic effects) and soil pathogen reduction, playing an important role in crop rotation systems. Even with all these features, the high heterogeneity found in black oat fields indicates that very little progress has been made in breeding programs. Not much is known about yield potential, chemical composition of the forage and seed dormancy levels. Thus, the development of new genotypes with high forage yield performance as well as good seed quality and low dormancy will provide alternatives for the common black (preta comum) cultivar, currently predominating in the Southern Region of Brazil. Genetic variability widening can be achieved by artificial crosses and induced mutations, followed by selection. Therefore, black oat populations originating from artificial crosses and induced mutations (gamma rays) were compared in order to assess their efficiency in increasing the genetic variability. Agronomically important characters, i.e., associated to adaptation and farmer needs were measured. The results indicate that both techniques were efficient in increasing the genetic variability of forage characters, grain yield and seed dormancy levels. A high association was observed between plant stand and dry matter yield in early developmental stages. At later stages, the number of tillers was highly associated with biomass yield. In general, for both artificial hybridizations and gamma rays, differences in grain yield and seed dormancy levels were observed. Doses as well as parental combinations influenced the magnitude of the variability observed. The comparison of such techniques may help to accelerate the genetics gains in the black oat crop. / A importância da aveia preta (Avena strigosa Schreb.) esta relacionado à suas características para a produção de forragem, cobertura do solo, adubação verde, controle da infestação de plantas invasoras (através dos efeitos de competição e alelopáticos) e redução da população de patógenos do solo, especificando como espécie de grande aptidão para inclusão no sistema de rotação de culturas. Mesmo com todas estas características, a elevada heterogeneidade encontrada em pastagens de aveia preta é indicativa de que são poucos os trabalhos de pesquisa voltados para esta espécie, especialmente quanto a caracteres como potencial de produção, composição química da forragem e baixo nível de dormência nas sementes. Devido a isto, a obtenção de novas cultivares que apresentem bom comportamento forrageiro junto com a produção de sementes de qualidade e reduzido nível de dormência proverá alternativas para substituição da Preta Comum, variedade mais cultivada na região Sul. O incremento da variabilidade genética pode ser obtido através de cruzamentos artificiais e utilização de agentes mutagênicos, permitindo posteriormente a realização de seleção de constituições genéticas superiores. Neste sentido, foram avaliados caracteres de importância agronômica em populações de aveia preta originadas de cruzamentos artificiais e mutações induzidas (raios gama), de forma a analisar as técnicas de indução a variabilidade genética e a identificação de constituições genéticas adaptadas as necessidades do produtor agrícola. Os resultados evidenciaram que as duas técnicas foram eficientes na intensificação da variabilidade genética nos caracteres forrageiros, de rendimento de grãos e nível de dormência nas sementes. O caráter estande de plantas evidenciou elevada relação com a produtividade de matéria seca em estádios de desenvolvimento precoce das plantas; em fases mais adiantas o número de afilhos teve maior contribuição na produção de biomassa. De modo geral, tanto para as hibridações artificiais como para o agente mutagênico raios gama, as respostas para rendimento de grãos e nível de dormência foram diferenciadas, variando com a dose ou genitores utilizados na obtenção das populações. Consequentemente, o conhecimento de técnicas que incrementem a variabilidade genética pode auxiliar a seleção de constituições genéticas superiores, pela escolha de técnicas de melhoramento mais adequadas.

No / The use of biomarkers of early genetic effects, predictive for cancer, such as micronuclei (MN) in lymphocytes, may help to investigate the association between diet and cancer. We hypothesised that the presence of mutagens in the diet may increase MN formation. A 'pooled' standardised analysis was performed by applying the same experimental protocol for the cytokinesis block micronucleus assay in 625 young healthy women after delivery from five European study populations (Greece, Denmark, UK, Spain and Norway). We assessed MN frequencies in mono- and binucleated T-lymphocytes (MNMONO and MNBN) and the cytokinesis blocked proliferation index using a semi-automated image analysis system. Food frequency questionnaires (FFQs) were used to estimate intake of fatty acids and a broad range of immunotoxic and genotoxic/carcinogenic compounds through the diet. Pooled difference based on delivery type revealed higher MNMONO frequencies in caesarean than in vaginal delivery (P = 0.002). Statistical analysis showed a decrease in MNMONO frequencies with increasing calculated omega-6 PUFA concentrations and a decrease in MNBN frequencies with increasing calculated omega-3 PUFA concentrations. The expected toxic compounds estimated by FFQs were not associated with MN formation in mothers after delivery. In pregnant women, an omega-3 and -6 rich diet estimated by FFQ is associated with lower MN formation during pregnancy and delivery.