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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.
41

Alkaloidy čeledi Amaryllidaceae a jejich analoga jako potenciální léčiva / Alkaloids of family Amaryllidaceae and their analogues as potential drugs

Kavková, Zuzana January 2016 (has links)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Botany and Ecology Candidate: Zuzana Kavková Supervisor: doc. Ing. Lucie Cahlíková, Ph.D. Title of diploma thesis: Alkaloids of family Amaryllidaceae and their analogues as potential drugs The object of this diploma thesis was to prepare derivatives of alkaloids of Amaryllidaceae family and to deal with their biological activity. These alkaloids are famous for their antibacterial, antiinfectives, antifungal, antimalarial and inhibitory activity against AChE, BuChE and POP and also for cytotoxic effect against cell lines. In the current studies about anticancer activity it was found that the most active alkaloids are Amaryllidaceae alkaloids of these types: lycorine, crinane and pancratistatine. Their biological activity relates closely with their structure. The changes of different parts of the structure can explain the relationship between structure and activity, and also the importance of their organization which is necessary for starting the activity. Based on this finding were for the experiments chosen alkaloids like haemanthamine, haemanthidine and lycorine. An eleven derivatives were prepared and identified mostly by GC-MS and NMR. These derivatives were tested on a wide spectrum of tumor lines....
42

Studies on the physiological effect of a growth inhibitor isolated from the bulb of narcissus tazetta L.

January 1986 (has links)
by Hung-mee Poon. / Includes bibliographical references / Thesis (M.Ph.)--Chinese University of Hong Kong, 1986
43

Alkaloidy čeledi Amaryllidaceae: rod Hippeastrum / Alkaloids of family Amaryllidaceae: genus Hippeastrum

Öhlschlegelová, Jana January 2019 (has links)
Author: Jana Öhlschlegelová Title: Alkaloids of family Amaryllidaceae: genus Hippeastrum Diploma thesis Charles University, Faculty of Pharmacy in Hradec Králové, Department of Pharmaceutical Botany 2019, 74 p. Keywords: Hippeastrum, Amaryllidaceae, alkaloids, antiproliferative activity, Alzheimer's disease, cholinesterase inhibitors, galanthamine The aim of this diploma thesis was to unify current findings about alkaloids isolated from selected plants of the Hippeastrum genus in the Amaryllidaceae family. The fytochemical characteristics of the examined species was introduced, and a group of alkaloids which were isolated from these plant species was composed. Also, the biological activity was evaluated. Up to date, at least 13 plant species of the Hippeastrum genus were examined from the fytochemical perspective. Out of these species examined, 56 different alkaloids with defined structure were isolated. The isolated alkaloids are divided into several groups based on their structure. Namely, these are lycorine, homolycorine, crinine, galanthamine, narciclasine, tazettine, haemanthamine and montanine structural types. Also, alkaloids which differed structurally from these basic types were found in several plants studied. In the substances gained, the antiproliferative activity, inhibitory activity...
44

Deriváty Amaryllidaceae alkaloidu haemanthaminu jako potenciální léčiva / Derivatives of Amaryllidaceae alkaloid haemanthamine as potential drugs

Homolková, Ludmila January 2019 (has links)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Botany Candidate: Ludmila Homolková Supervisor: doc. Ing. Lucie Cahlíková, Ph.D. Title of diploma thesis: Derivatives of Amaryllidaceae alkaloid haemanthamine as potential drugs Modern research has shown that Amaryllidaceae alkaloids represent a rich reservoir of potential small molecules exhibiting several medicinal properties through various mechanisms. Among the many Amaryllidaceae alkaloids, galanthamine has been given a great amount of attention due the fact that it possesses potent acetylcholinesterase inhibition activity, and is distributed worldwide for the treatment of Alzheimer's disease. One of the interesting compounds is haemanthamine, β-crinine-type of Amaryllidaceae alkaloids, which displays significant in vitro cytotoxic activity against several different types of cancer cell lines. The object of this diploma thesis was to prepare several derivatives of alkaloid haemanthamine, and try to find relationship between structure and biological effect. The present work deals with the preparation of haemanthamine derivatives, and their biological activity connected to the treatment of cancer and Alzheimer's disease. Twelve aromatic ester of haemanthamine derivatives were prepared. The chemical structures...
45

The chemical investigation of the Amaryllidaceae and Hyacinthaceae.

Moodley, Nivan. January 2004 (has links)
This work is an account of investigations into the chemistry of members of the Amaryllidaceae and Hyacinthaceae families. The plants of the family Amaryllidaceae are a large group comprising over sixty genera and more than a thousand species. They are widely distributed, but are found more richly in the tropics, with a particularly high density in South Africa, with smaller centers of diversity in Andean South America and the Mediterranean. Amaryllidaceae plants have been extensively used by local traditional healers and have been reported to have numerous pharmacological uses. The alkaloids isolated from this family are a group of isoquinoline alkaloids found exclusively in this family. Plants belonging to two Amaryllidaceae genera were investigated phytochemically, one from each of the sub-tribes Crinineae and Amaryllidineae were investigated phytochemically. Brunsvigia natalensis is used in local traditional medicine to "straighten bones of children", treat barrenness in women and ease childbirth. This is the first phytochemical investigation of Brunsvigia natalensis, and yielded two new alkaloids, a new ceramide type compound and a known flavanoid. A comparative phytochemical investigation was carried out on the bulbs and seeds of Crinum stuhlmanni, which resulted in a number of different alkaloids being isolated from the seeds and bulbs of this plant. The southern African Hyacinthaceae is a large and chemically morphologically diverse group of plants. This family comprises approximately sixty-seven genera and nine hundred species worldwide, of which twenty-seven genera and three hundred and sixty - eight species are found locally. There are five sub-families of which three occur in southern Africa. The chemical constituents of this family can be divided into four classes, namely homoisoflavanones, steroidal compounds, bufadienolides and miscellaneous compounds. These plants are used in local traditional medicine for treating ailments such as hangovers, rheumatic fever, sprains and even cancer. The phytochemistry of three Hyacinthaceae plants was studied. The phytochemical investigation of Drimia macrocentra and Urginea riparia yielded a novel bufadienolide glycoside. These glycosides are quite unusual with the glycone attached to the aglycone at C-2 and C-3 and this has only been reported only once before in this family. The phytochemical investigation of Ledebouria revoluta yielded a number of homoisoflavanones. These homoisoflavanones have been shown to have anti-inflammatory activity and all of the compounds isolated in this work have been screened for this activity. Structural elucidation was carried out using spectroscopic methods such as NMR, MS, UV and IR. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2004.
46

Studies on factors influencing viability after cryopreservation of excised zygotic embryos from recalcitrant seeds of two amaryllid species.

Naidoo, Sershen. January 2010 (has links)
Recalcitrant unlike orthodox seeds do not show a sharp border between maturation and germination and remain highly hydrated and desiccation-sensitive at all developmental and post-harvest stages. In contrast with recalcitrant seeds, orthodox types retain viability for predictably long periods in the dry state and hence can be stored under low relative humidity and temperature conditions. Storage of recalcitrant seeds under conditions allowing little to no water loss, at moderate temperatures, allows for short- to medium-term storage but only facilitates viability retention for a matter of a few weeks to months, at best, because the seeds are metabolically active and initiate germination while stored. Cryopreservation, i.e. storage at ultra-low temperatures (usually in liquid nitrogen [LN] at -196°C), is a promising option for the long-term germplasm conservation of recalcitrant-seeded species but their seeds present some unavoidable difficulties in terms of the amenability of their germplasm to cryopreservation. Pre-conditioning treatments can reduce the amount of ‘free’ water available for freezing and may increase the chances of cells or tissues surviving exposure to cryogenic temperatures. Such conditioning may be imposed by physical dehydration or cryoprotection, i.e. exposure to compounds that depress the kinetic freezing point of water and so reduce the likelihood of lethal ice-crystal formation during cooling (i.e. exposure to LN at -196°C or sub-cooled LN at -210°C) and subsequent thawing. Partial dehydration is presently a standard pre-treatment for the cryopreservation of recalcitrant zygotic germplasm and explant cryoprotection has been shown to improve postthaw survival in some recalcitrant-seeded species. However, there is a paucity of information on the physiological and biochemical basis of post-thaw survival or death in recalcitrant seeds, and this is the major focus of the current contribution. Additionally, in light of the lack of understanding on how cryo-related stresses imposed at the embryonic stage are translated or manifested during subsequent seedling growth, this study also investigated the effects of partial dehydration and the combination of partial dehydration and cooling of recalcitrant zygotic embryos on subsequent in and ex vitro seedling vigour. All studies were undertaken on the zygotic embryos of two recalcitrant-seeded members of the Amaryllidaceae, viz. Amaryllis belladonna (L.) and Haemanthus montanus (Baker); both of which are indigenous to South Africa. Studies described in Chapter 2 aimed to interpret the interactive effects of partial dehydration (rapidly to water contents > and <0.4 g g-1), cryoprotection (with sucrose [Suc; nonpenetrative] or glycerol [Gly; penetrative]) and cooling rate (rapid and slow) on subsequent zygotic embryo vigour and viability, using three stress markers: electrolyte leakage (an indicator of membrane integrity); spectrophotometric assessment of tetrazolium chloride-reduction (an indicator of respiratory competence); and rate of protein synthesis (an indicator of biochemical competence). These studies showed that in recalcitrant A. belladonna and H. montanus zygotic embryos, stresses and lesions, metabolic and physical, induced at each stage of the cryopreservation protocol appear to be compounded, thus pre-disposing the tissues to further damage and/or viability loss with the progression of each step. Maximum post-thaw viability retention in both species appeared to be based on the balance between desiccation damage and freezing stress, and the mitigation of both of these via Gly cryoprotection. Post-thaw viabilities in both species were best when Gly cryoprotected + partially dried zygotic embryos were rapidly, as opposed to slowly, cooled. However, the rate at which water could be removed during rapid drying was higher in A. belladonna and this may explain why the optimum water content range for post-thaw survival was <0.40 g g-¹ for A. belladonna and >0.40 g g-¹ for H. montanus. These results suggest that to optimise cryopreservation protocols for recalcitrant zygotic germplasm, attention must be paid to pre-cooling dehydration stress, which appears to be the product of both the ‘intensity’ and ‘duration’ of the stress. Cryoprotection and dehydration increased the chances of post-thaw survival in A. belladonna and H. montanus zygotic embryos. However, transmission electron microscopy studies on the root meristematic cells from the radicals of these embryos (described in Chapter 3) suggest that their practical benefits appear to have been realised only when damage to the sub-cellular matrix was minimised: when (a) pre-conditioning involved the combination of cryoprotection and partial dehydration; (b) the cryoprotectant was penetrating (Gly) as opposed to non-penetrating (Suc); and (c) embryos were rapidly cooled at water contents that minimised both dehydration and freezing damage. The ability of A. belladonna and H. montanus embryos to tolerate the various components of cryopreservation in relation to changes in extracellular superoxide (.O2 -) production and lipid peroxidation (a popular ‘marker’ for oxidative stress) was investigated in studies featured in Chapter 4. Pre-conditioning and freeze-thawing led to an increase in oxidative stress and the accompanying decline in viability suggests that oxidative stress was a major component of cryoinjury in the embryos presently investigated. Post-thaw viability retention in Gly cryoprotected + partially dried embryos was significantly higher than noncryoprotected + partially dried embryos, possibly due to the relatively lower post-drying lipid peroxidation levels and relatively higher post-drying and post-thawing enzymic antioxidant activities in the former. Exposure of certain plant tissues to low levels of oxidative or osmotic stress can improve their tolerance to a wide range of stresses. In contrast, exposure of H. montanus zygotic embryos to low levels of oxidative stress provoked by exogenously applied hydrogen peroxide (H2O2) or exposure of A. belladonna embryos to low levels of osmotic stress provoked by low water potential mannitol and polyethylene glycol solutions (in studies featured in Chapter 5) increased their sensitivity to subsequent dehydration and freeze-thaw stresses. Exposure of Gly cryoprotected and non-cryoprotected amaryllid embryos to such stress acclimation treatments may pre-dispose A. belladonna and H. montanus embryos to greater post-drying and post-thaw total antioxidant and viability loss than untreated embryos. To assess the vigour of seedlings recovered from partially dried H. montanus embryos, seedlings recovered from fresh (F) and partially dried (D) embryos in vitro were hardened-off ex vitro, and subsequently subjected to either 42 days of watering or 42 days of water deficit (in studies described in Chapter 6). In a subsequent study (described in Chapter 7), seedlings recovered from fresh (F), partially dried (D) and cryopreserved (C) A. belladonna embryos were regenerated in vitro, hardened-off ex vitro and then exposed to 12 days of watering (W) or 8 days of water stress (S) followed by 3 days of re-watering. Results of these studies suggest that the metabolic and ultrastructural lesions inflicted on A. belladonna and H. montanus zygotic embryos during cryopreservation may compromise the vigour (e.g. development of persistent low leaf water and pressure potentials and reduced photosynthetic rates) and drought tolerance of recovered seedlings, compared with seedlings recovered from fresh embryos. While the adverse effects of freeze-thawing were carried through to the early ex vitro stage, certain adverse effects of partial drying were reversed during ex vitro growth (e.g. the increased relative growth rate of seedlings from partially dried embryos). The reduced vigour and drought tolerance of seedlings recovered from partially dried and cryopreserved embryos in the present work may therefore disappear with an extension in the period afforded to them for hardening-off under green-house conditions, and in the field. The results presented in this thesis reinforce the notion that each successive manipulation involved in the cryopreservation of recalcitrant zygotic germplasm has the potential to inflict damage on tissues and post-thaw survival in such germplasm relies on the minimisation of structural and metabolic damage at each of the procedural steps involved in their cryopreservation. The results also highlight the need to design research programmes aimed not only at developing protocols for cryopreservation of plant genetic resources, but also at elucidating and understanding the fundamental basis of both successes and failures. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2010.
47

Effects of some of the procedural steps of cyropreservation on cryo-recalcitrant zygotic embryos of three amaryllid species producing desiccation-sensitive seeds.

Ngobese, Nomali Ziphorah. 15 September 2014 (has links)
Cryopreservation is the most promising method for the long-term conservation of germplasm of plants producing desiccation-sensitive seeds. While such seeds are generally termed recalcitrant in the context of conventional storage practices, the term ‘cryo-recalcitrant’ is used for germplasm which is not readily amenable to cryopreservation. Cryo procedures usually involve a sequential combination of steps which must be optimised to limit the stresses experienced by specimens, thus promoting their survival. The present contribution reports on the effects of some of the steps involved in cryopreservation on the survival of the embryos of the amaryllids, Ammocharis coranica, Brunsvigia grandiflora and Haemanthus albiflos, with the ultimate aim of developing a protocol(s) for the successful cryopreservation of the germplasm of these species. The main foci of the investigations were the effects of rapid (flash) drying, the use of the cryoprotectant additives, glycerol (5 & 10%) and DMSO (0.1 & 0.25%), and employment of different cooling rates on the zygotic embryos of the selected species, which are known to be recalcitrant as well as being cryo-recalcitrant. Furthermore, this study reports on attempts at improving the rapidity of dehydration during flash drying by applying a vacuum, and also of providing cathodic protection (via highly reducing cathodic water and/or direct exposure to a static {negatively-charged} cathodic field during flash drying) to the explants at various stages in the protocol. These techniques were employed in attempts to ameliorate the adverse effects of reactive oxygen species associated with stresses imposed by the procedures during the cryopreservation process. The embryos of Ammocharis coranica, Brunsvigia grandiflora and Haemanthus albiflos were initially at water contents (WCs, dry mass basis) of 3.28±0.52, 2.55±0.22, 4.48±0.92 g g-1, respectively, after harvest. These embryos proved to be tolerant to moderately rapid water loss in the short term, with >60% retaining germinability at water contents ≥0.5 g g-1. The results from this study confirmed that dehydration to water contents below 0.5 g g-1 (dry mass basis) compromised survival, and that this effect was exacerbated if the embryos were cryoprotected prior to drying. Interestingly, the rate of water loss in embryos of these species differed, with A. coranica and H. albiflos drying at a (comparably) much slower rate than those of B. grandiflora. Subsequent rapid cooling yielded promising results when compared with slow cooling, as 30% of glycerol cryoprotected, rapidly cooled A. coranica embryos that had been flash-dried to 0.36±0.10 g g-1 generated normal seedlings. It was clear, however, that the effects of these procedures were exacerbated when all the steps of the cryo procedure were applied sequentially. However, the work also showed that these adverse effects may be ameliorated if each step of the cryopreservation protocol is optimised on a species-specific basis, thus promoting the chances of survival after cryopreservation and facilitating subsequent seedling establishment. This was evident in the 30% germination obtained when embryos of A. coranica, which had been cryoprotected with glycerol prior to flash drying before exposure to rapid cooling, while those that had not been cryoprotected or were cryoprotected with DMSO before drying did not survive. The incorporation of cathodic protection during flash drying appeared promising as it promoted the survival of 10% of H. albiflos embryos dehydrated to WCs between 0.37 and 0.26 g g-1 (whereas no survival was achieved without the inclusion of this step), and 70% of A. coranica embryos that were dehydrated to 0.35±0.21. In addition, the reduction of the explant size, from a whole 6 mm embryo to a 3-4 mm excised axis, promoted survival by up to 30% for A. coranica and H. albiflos, even at higher WCs. However, survival in these cases was based on observations of abnormal development, i.e. the development of roots or shoots, or calli. No surviving embryos were obtained from B. grandiflora after cooling, regardless of the preconditioning treatment or rate of cooling, and this was accredited to the greater degree of sensitivity of these embryos to the cryo procedures than those of the other two species. The use of cathodic water to re-hydrate explants after dehydration and of applying a vacuum during flash drying did not result in any observable benefits, and require further investigation for optimisation. The very limited success towards establishing a cryopreservation protocol for the species investigated in this study reinforces the difficulties associated with the cryopreservation of recalcitrant germplasm, which informs the cryo-recalcitrance of some explants. However, the results obtained have helped to identify a number of intervention points that could be used to minimise the damage incurred during the various procedural steps involved in cryopreservation. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2013.
48

Biologická aktivita sekundárních metabolitů rostlin II. Alkaloidy Narcissus jonquilla L. / Biological aktivity of secondary plants metabolites II. Alkaloids of Narcissus jonquilla L.

Jílek, Lukáš January 2015 (has links)
Jílek L.: The biological activity of secondary plants metabolites II. Alkaloids of Narcissus jonquilla L. Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Department of Pharmaceutical Botany and Ecology, Hradec Králové 2015, pp. 74. The aim of the diploma thesis was a preparation of alkaloid extracts to identification of alkaloid patterns and measure cholinesterase inhibitory activity. This activity is useful for treating Alzheimer's disease. Alkaloid extracts of seven Narcissus jonquilla L. (Amaryllidaceae) varieties (Bella Estrella, Bell Song, Fruit Cup, Hill Star, Chit Chat, Martinette, Dick Sickel) were studied with respect to their acetylcholinesterase (HuAChE) and butyrylcholinesterase (HuBuChE) inhibitory activity and alkaloid patterns. Thirteen different alkaloids were identified from their mass spectra and retention times. All samples exhibited content of tazettine, most samples contained lycoramine and galanthamine. Promising HuAChE inhibition activity was demonstrated by Narcissus jonquilla L. cv. Bell Song with IC50 values of 6,19 ± 0,85 μg/mL. The strongest inhibitory activity against HuBuChE was detected in extract from Narcissus jonquilla L. cv. Bella Estrella with IC50 value of 18,39 ± 1,51 μg/mL. Keywords: Alzheimer's disease, Amaryllidaceae, Narcissus, GC/MS,...
49

Alkaloidy čeledi Amaryllidaceae: rod Zephyranthes / Alkaloids of family Amaryllidaceae: genus Zephyranthes

Jánská, Lucie January 2018 (has links)
Author: Lucie Jánská Název: Alkaloids of family Amaryllidaceae: genus Zephyranthes Diploma thesis Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Department of Pharmacognosy 2018, 75 p. The aim of this diploma thesis was to summarize all knowledge about alkaloids izolated from Zephyranthes plants of Amaryllidaceae family. It contains a detail overview of botanical charactericts of phytochemically studied plants of the genus Zephyranthes. Also the overview of alkaloids with bilogical activity was described. Within the genus Zephyranthes 10 species were studied phytochemically and 89 alkaloids were isolated from this plants. This alkaloids are divided in several structural groups. The lycorine-, haemanthamine-, galanthamine- and pancratistatine-type alkaloids occure the most frequently. Acetylcholinesterase-inhibitory, anticancer and antimalarial activity of the alkaloids was described like the most important. The most significant acetylcholinesterase- inhibitory activity was observed in alkaloids from galanthamine sctructural type. Anticancer activity was found the most in lycorine-, pancratistatine- and haemanthamine- type alkaloids. The most notable antimalarial activity was observed in lycorine- and heamanthamine- type alkaloids. Keywords Zephyranthes, Amaryllidaceae,...
50

Alkaloidy čeledi Amaryllidacee: rod Nerine. / Alkaloids of family Amaryllidaceae: genus Nerine.

Hodulová, Adéla January 2018 (has links)
Author: Adéla Hodulová Title: Alkaloids of Amaryllidaceae family, genus Nerine Diploma thesis Charles University, Faculty of pharmacy in Hradec Králové, Department of Pharmaceutical botany 2018, 51 p. The aim of this diploma thesis was to summarize up the findings about alkaloids which where isolated from genus Nerine plants of Amaryllidaceae family. There was introduced a botanical characteristic of the phytochemical studied species of the genus Nerine. The most studied species was Nerine bowdenii. All the knowledges about mentioned alkaloids were sum up. Ten species have been phytochemical studied out of the genus Nerine until now. In total, 40 alkaloids were isolated from these plants. Alkaloids which where isolated from the Nerine are divided into several structural types. Anticancer, acetylcholinesterase-inhibitory of the alkaloids were described. The biological activity is connected with their stucture. The most significant anticancer activity was observed in alkaloids from crinine- and lycorine type . Acetylcholinesterase-inhibitory activity was pronounced the most in crinine-type alkaloids. Keywords: Nerine, Nerine bowdenii, Amaryllidaceae, alkaloids

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