Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references.

Thesis (Ph.D.)(Microbiology and Plant Pathology)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

As folk medicines used in China for decades, Dioscorea nipponica Makino (DN, 穿龍薯蕷), D. panthaica Prain et Burkill (DP, 黃山藥), and D. zingiberensis C. H. Wright (DZ, 盾葉薯蕷) are regarded as having more or less similar traditional therapeutic actions, such as regulating qi, relieving pain, and dispersing swelling. It is noteworthy that, of the 49 species of the genus Dioscorea (薯蕷屬) distributed in China, only these three have been successfully developed as effective single-herb medicines for treating cardiovascular diseases by the modern pharmaceutical industry. Usually considered as the bioactive and major constituents, various steroidal saponins have been discovered from these herbs. In order to provide scientific data for the rational use of DN, DP and DZ, this present study focused on comparing these three herbs through the following four-pronged approach: morphology, chemistry, metabolism and anti-myocardial ischemia activity. The morphological study aimed to distinguish the rhizomes of DN, DP and DZ by macroscopic and microscopic observation. Comprehensive microscopic techniques, including common light microscopy, fluorescence microscopy and polarized light microscopy were successfully applied to fulfill this purpose. What’s more, it is the first research to observe characteristics of transections of crude drugs under polarized lighting for the purpose of authentication. Polarized light has been found to provide a number of unique characteristics. The results indicate that starch granules, vascular bundles and other significant tissue features can be used to authenticate these three herbs. The chemical study aimed to develop a reliable and effective protocol for comparing the chemical composition of DN, DP and DZ. The qualitative results by UPLC-QTOF-MS indicated that generally, DN and DP have similar chemical composition, but both are distinct from DZ. However, the aglycone, diosgenin, was the main component of all acid hydrolyzed DN, DP and DZ. As diosgenin has been reported for the anti-myocardial ischemia activity, we hypothesized that diosgenin could be one of the bioactive sapogenin related to the anti-myocardial ischemia (MI) activity of these three herbs. Then, to further validate the similarity of DN and DP, the major constituents, including six glycosides and one aglycone, contained in DN and DP were further quantified. The chemical composition of all DN and DP samples studied exhibited a high level of global similarity based on comparisons of chromatographic fingerprint profiles and the contents of determined components using fingerprint similarity evaluation, test of significance and principal component analysis. This chemical similarity validates the common application of DN and DP in the pharmaceutical industry as anti-MI herbal drugs. The metabolism study aimed to a) compare the metabolic profiles of total saponins (TS) from DN, DP and DZ (abbreviated as DNTS, DPTS and DZTS, respectively), which are considered to be their bioactive components, and b) to compare the changes in sustained levels of metabolites from rat biosamples. TS from each of the three species, and four individual saponins, namely protodioscin, pseudoprotodioscin, dioscin and diosgenin, were given to rats by oral administration. Chemical profiles of the rats’ plasma, urine and feces were monitored 1-36 h. A UPLC-QTOF-MS based method was performed to identify the absorbed constituents and their metabolic products in rat biosamples (i.e., blood, urine, and feces); the ratio of peak area of metabolites to that of internal standard was calculated and plotted versus time to characterize the sustained levels of metabolites in biosamples. The results indicated that formation of diosgenin by desugarization was the main pathway by which steroidal glycosides were metabolized. Generally, the metabolic profiles of DN and DP were shown to be quite similar, but different from that of DZ. However, some particular similarities were found among these three total saponins. Diosgenin, as one of the main metabolites commonly found in plasma and feces (excluding urine), from all groups receiving different total saponins, as well as individual saponins; this is likely to be one of the bioactive constituents playing an essential role in cardioprotective efficacy. In addition, these furostane-type saponins and spirostane-type saponin (including diosgenin) in these three total saponins showed two changing patterns, suggesting that the therapeutic effect of these Dioscorea saponins is achieved through a complex, multi-step process over time. Thus, these similarities described above constitute evidence supporting similarity in efficacy of these three herbs from the perspective of metabolism. The anti-myocardial ischemia activity study aimed to further investigate the underlying mechanisms with respect to anti-oxidative stress activity by which these Dioscorea spp. prevent MI, and to compare the therapeutic effect of total saponins from these three species on myocardial antioxidant levels and myocardium histology. The rats experienced myocardial ischemia induced by isoprenaline (ISO) injection; the test solutions (DNTS, DPTS, DZTS) were administered either after the ISO injection, or both before and after. Compared with the model group (ISO injection only), TS groups exhibited significantly reduced activities of serum CK, LDH and AST (P < 0.01), lowered level of MDA (P < 0.01 or P < 0.05), and increased activities of SOD, CAT, GPx and total antioxidant capacity (T-AOC) (P < 0.01 or P < 0.05). Heart tissues from TS groups (administered either after the ISO injection, or both before and after) revealed less severe histological damage than the model group. The findings of the present study provide evidence that DNTS, DPTS and DZTS can protect the myocardium against ischemic insult. Furthermore, the protective effect can be attributed to the increase of myocardial antioxidant levels and decrease of lipid peroxidation formation. Although the chemical compositions of DNTS and DPTS were similar, and distinct from DZTS, in general, the cardioprotective efficacy of these three Dioscorea TS for rat MI were closely comparable based on LDH, CK, AST, SOD, GPx, CAT, T-AOC and MDA levels, as well as on myocardial histology, thereby explaining the similarity in their clinical efficacy as anti-MI drugs. In conclusion, these findings in the present study constitute evidence that DN, DP and DZ all can be used as starting material for anti-MI drugs in the pharmaceutical industry.

published_or_final_version / Botany / Doctoral / Doctor of Philosophy

Menopause is the period during which the level of estrogen secreted by the ovaries gradually declines and patients of menopausal syndrome may experience osteoporosis, cognitive decline, hot flush, mood disorder, night sweat, depression, nervous tension and insomnia. The report published by the World Health Organization in 1990 stated that the total population of postmenopausal women in the world was 476 million. By 2030, the predicted population will reach 1200 million. The current way to relieve menopausal syndrome is hormone replacement therapy (HRT) which restores the endogenous estrogen level by administration of supplementary exogenous estrogen or estrogen plus progestin. However, various studies showed that HRT might increase the incidence of breast cancer and ovarian cancer. There is a potential risk of using HRT for menopausal syndrome. The novel protein DO isolated in this study could be a potential alternative of HRT for the treatment of menopausal syndrome. DO isolated from Chinese yam Dioscorea opposite Thunb. had adistinctive N-terminal sequence Gly-Ile-Gly-Lys-Ile-Thr-Thr- Tyr-Trp-Gly-Gln-Tyr-Ser-Asp-Glu-Pro-Ser-Leu-Thr-Glu-Ala, indicating that DO might be a novel protein.DO was an acid stable and thermal stable protein. As determined by electro-chemiluminescence immunoassay (ECLIA) detection, DO could stimulate estradiol biosynthesis in rat granulosa cells in vitro as well as inducing both estradiol and progesterone secretion in female aging Sprague Darley (SD)-rat model in vivo. From the results of real-time PCR and Western blot, the possible mechanism might be through up-regulating the expression of ovarian follicle stimulating hormone receptor(FSHR)and aromatase. DO also exerted a beneficial effect on the cognitive function through elevating the translational level of brain derived neurotrophic factor (BDNF)and TrkB gp 145 receptor in the prefrontal cortex of female aging SD-rat model. Though further pharmacological studies are required, the results in this study suggested that DO could be a safer potential alternative for HRT in the treatment of menopausal syndrome with beneficial effects on hormone levels and cognitive function. / published_or_final_version / Chinese Medicine / Master / Master of Philosophy

No description available.

Please read the abstract on Chapter 5. / Thesis (PhD (Microbiology and Plant Pathology))--University of Pretoria, 2007. / Microbiology and Plant Pathology / unrestricted

TOO MANY MOUTHS (TMM) is a gene which has been shown to regulate cell fate and control cell division in the plant leaf epidermis. TMM encodes a leucine rich repeat-receptor like protein (LRR-RLP) which has putative function as a signal transducing factor in the cell to cell signaling pathway involved in controlling proper spacing of stomata! initials throughout the leaf. This gene has been shown to be widely conserved across species of land plants ranging from bryophytes to angiosperms. Curiously, although this gene is highly conserved, stomata! installation pathways vary considerably across these species. Leaf development in both Arabidopsis and monocot grasses has been well characterized, and contrasting stomata! development pathways have been identified between them. Dioscorea bulbifera is a basal member of the monocot family, but this species forms broad leaves similar to many eudicot species. Stomata! development in this species retains some features characteristic of grass installation pathways such as few to no secondary asymmetric divisions of meristemoids. However, new epidermal cell formation occurs by fill-in between leaf veins, more closely resembling broad leaf eudicot development. A TMM ortholog has been isolated in this species and phylogenetic analysis of the sequence may help to place the signals controlling stomata! proliferation in Dioscorea bulbifera into evolutionary perspective.

Orientador: Lin Chau Ming / Coorientador: Angélica Cristina Fernandes Deus / Banca: Dirceu Maximino Fernandes / Banca: João Carlos Cury Saad / Banca: Gabriela Granghelli Gonçalves / Banca: Laís Lorena Queiroz Moreira / Resumo: A irrigação é uma prática agrícola importante para o cultivo do inhame, entretanto, há poucos resultados experimentais focados no Brasil, e não há informações sobre a necessidade de água para essa cultura sob diferentes texturas de solo no estado de São Paulo. Objetivou-se com o presente trabalho avaliar o desenvolvimento, biomassa e qualidade dos tubérculos do inhame sob diferentes lâminas de irrigação e texturas de solo. O experimento foi conduzido de 2016 a 2017 com duas colheitas em casa de vegetação na Universidade Estadual Paulista (FCA/UNESP), Botucatu. Estudou-se cinco lâminas de irrigação: 20%, 60%, 100% (controle), 140% e 180% da necessidade de água da cultura (ETc), e três texturas de solo: solo de textura argilosa (CS), solo de textura média (SCL) e solo de textura arenosa (SS). Os resultados mostraram que a altura da planta, diâmetro do pecíolo, número de folhas, área foliar, peso fresco/seco da parte aérea, da raiz e do tubérculo, número e diamêtro de tubérculo do inhame foram menores em 20% e 60% ETc e maiores em 140% and 180% ETc quando comparado com 100% ETc. SS apresentou maior número de folhas em todas as lâminas de irrigação, enquanto a área foliar para SS foi maior que SCL e CS em 20% ETc. Para a primeira colheita, SCL apresentou maior peso fresco/seco da raiz, e SS apresentou maior peso seco do tubérculo do que os outros dois solos. A maior eficiência no uso da água (WUE) e índice de colheita (HI) foram detectados em 20% ETc. Para a segunda safra, SS apr... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Irrigation is an important agricultural practice for the cultivation of taro, however, there are few experimental results focus on this practice in Brazil, and there is no information on water requirement for this crop under different soil textures in São Paulo State. Therefore, the objective of this work was to evaluate the development, biomass and corm quality of taro under varying water regimes and soil textures. The experiment was conducted from 2016 to 2017 with two harvests, in a greenhouse of Agronomical Sciences College, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil. The five irrigation levels were 20%, 60%, 100%, 140%, and 180% of crop water requirement (ETc), with 100% ETc as the control. And three soil textures: clay soil (CS), sandy clay loam soil (SCL) and sandy soil (SS) were used. Results showed that plant height, petiole diameter, leaf number and area, above-ground, root, and corm fresh/dry weight, corm number and diameter of taro were lower at 20% and 60% ETc, and higher at 140% ETc and 180% ETc when compared with 100% ETc. SS exhibited higher leaf number at all water regimes, whereas leaf area for SS was higher than SCL and CS at 20% ETc. For the first harvest, SCL showed higher root fresh/dry weight, and SS exhibited higher corm dry weight than the other two soils. The highest water-use efficiency (WUE) and index (HI) were detected at 20% ETc. For the second harvest, SS showed higher root and corm fresh weight, corm number and diameter. Th... (Complete abstract click electronic access below) / Doutor

Orientador: Lin Chau Ming / Banca: Maria Christina de Mello Amorozo / Banca: Moacir Haverroth / Resumo: As dioscoreáceas constituem uma importante fonte alimentar e estão distribuídas nas regiões tropicais, subtropicais e temperadas de todo mundo. O gênero Dioscorea, ao qual pertence a maioria das espécies cultivadas e silvestres da família, engloba espécies tropicais originárias da África, Ásia e América. O objetivo do trabalho foi realizar um levantamento das variedades de cará (Dioscorea spp.) cultivadas pelos agricultores com o intuito de verificar as espécies mantidas por eles e suas diversidades, nomes populares das variedades e sobre o sistema produtivo da cultura como: preparo das túberas sementes, manejo da cultura, preparo do solo, plantio, tratos culturais e comercialização. Para o início da pesquisa de campo, foi usada a técnica de amostragem do tipo "bola de neve", que consistiu em conversar com alguns agricultores e vendedores dos mercados de hortaliças da região para a localização dos principais agricultores que cultivam o cará e suas indicações subsequentes. Durante a pesquisa de campo, foram encontrados 48 agricultores que cultivam diversas culturas e também plantam o cará, com seu respectivos nomes populares para o gênero. Foram encontradas três espécies: Dioscorea alata, D. trifida e D. bulbifera. O preparo do solo é feito de forma rudimentar e o cultivo do cará é feito no sistema de "roça de toco". 14% dos agricultores utilizaram algum tipo de implemento agrícola para o preparo do solo. O preparo das "sementes" varia de acordo com cada espécie, sendo que 55% são plantadas partidas e 45% inteiras. A organização e destino da produção acontecem nas comunidades, onde grande parte é destinada à alimentação familiar, e o excedente é para a venda direta para consumidores ou via intermediários / Abstract: The dioscoreaceas constitute an important source of food and are distributed in tropical, subtropical and temperate all over the world. The genus Dioscorea, whose the most cultivated and wild species of the family belong to, encompassing tropical species originally from Africa, Asia and America. The objective was to survey the varieties of yams grown by farmers in order to verify the species kept by them and their diversity, popular names of the varieties and the crop production system as: preparation of tubers-seeds, crop management, soil preparation, planting, cultivation and marketing. In the field research the sampling "snowball", was used, which consisted of talking to some farmers and vegetable sellers in the region for the location of the main farmers who grow yams. During the fieldwork, there were 48 farmers growing different crops and also plant the yams, their respective common names for the genus. Three species were found: Dioscorea alata, D. trifida and D. bulbifera. Soil preparation is done rudimentary and the cultivation of yams is done on a "slash and burn" system. 14% of farmers used some type of agricultural implement for soil tillage. The "seed" preparation varies with each species, 55% are planted using divided portions of the tubers and 45% using entire tubers. The organization of production and destination are done in communities where a large part is devoted to the family diet, and the surplus is for sale delivered directly to consumers or by middle-men / Mestre