50 research outputs found

    Etude de l'activité antivirale d'extraits d'Euphorbia de Corse : recherche de nouveaux diterpènes d'intérêt biologique

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    Chikungunya fever is caused by an arthropod-borne virus that is associated with massive epidemics and severe morbidity (virus-induced arthralgia, fever, myalgia and rashes). Worldwide expansion of the mosquito vectors, such as Aedes albopictus ("Tiger moquito) is responsible for the spread of Chikungunya virus (CHIKV) throughout the world. A. albopictus has spread throughout Mediterranean areas, which could lead to epidemics outbreaks. Currently, no antiviral drugs or vaccines are available for the treatment or prevention of CHIKV infection. Since ten years, however, recent results showed that diterpene esters from Trignostemon (Euphorbiaceae) possess inhibiting activity of CHIKV replication.With the objective to discover new compounds with antiviral activities, 45 extracts from various plant parts of 11 Euphorbiaceae species native to Corsica were evaluated for selective inhibition of CHIKV replication. In collaboration with Dr. Leyssen (KU Leuven, Belgium), several extracts made from 10 Euphorbia species exhibited significant and selective anti-CHIKV activity in a virus-cell-based assay. The antiviral activities of 29 commercially available phorboïds were studied. Some phorboïds were potent inhibitors of CHIKV and human immunodeficiency virus (VIH) replication. Results allowed drawing new structure-activity relationships, which supported the hypothesis that PKC may be an important target in CHIKV replication. In order to confirm or infirm the presence of phorboïds with anti-CHIKV activity in Euphorbia extracts, a liquid chromatography (LC) coupled to linear ion trap mass spectrometry (MSn) method was developed using standard compounds. Application of this methodology indicated that none anti-CHIKV phorboïds was present in Euphorbia extracts. A second LC-MSn procedure was developed to profile untargeted phorboïdes. Results suggested that numerous other diterpene esters were present in the Euphorbia extracts. The species Euphorbia amygdaloides ssp. semiperfoliata was selected to perform a bioassay-guided purification procedure, which led to the isolation and identification of 14 jatrophane esters, including eight new components. Among them, antiviral evaluation indicated that one jatrophane ester was possessing anti-CHIKV and anti-HIV activities. Furthermore, the structure of an atypical jatrophane ester derivative, jatrohemiketal, was determined unambiguously through an original strategy combining NMR spectroscopy and molecular modeling. Finally, an original tandem mass spectrometry (MS/MS)-targeted supercritical fluid chromatography (SFC) method was developed and used to study bioactive fractions of E. amygdaloïdes ssp. semiperfoliata. The MS/MS data were analyzed by molecular networking. Thanks to this approach, four 4-deoxyphorbol esters and two new jatrophane esters were targeted, isolated and identified. Collaboration with the group of Pr. Alcami (CNM, Espagne) was started to explore the anti-HIV properties of the isolated diterpene esters. Thus, one compound derived from 4-deoxyphorbol esters proved to possess a potent inhibiting activity of HIV-1 replication (IC50 = 8 nM, and selectivity index > 6250). The investigation of the mechanism of this component indicated that it acted like prostratin, but with antiviral effect more than 28-fold. Furthermore, the evaluation of the anti-CHIKV activity indicated that another 4-deoxyphorbol derivative was one of the strongest inhibitor of CHIKV replication isolated up to date (EC50 = 0.34 ± 0.12 µM and selectivity index > 638).Le chikungunya est une maladie transmise par des moustiques du genre Aedes (dont A. albopictus, dit "moustique tigre"). Cette maladie provoque d'intenses fièvres et des douleurs articulaires chroniques fortement invalidantes. Les moustiques potentiellement vecteurs du virus du chikungunya (CHIKV) sont des espèces invasives qui, à la faveur du réchauffement climatique, se sont récemment implantés dans plusieurs régions du monde, dont la région méditerranéenne. Sa présence constitue un terreau favorable à la survenue d'épidémie. A l'heure actuelle, il n'existe ni vaccin, ni traitement médicamenteux efficace. Toutefois, des articles scientifiques ont récemment rapporté que des esters de diterpène isolés du genre Trigonostemon (Euphorbiaceae), avaient une activité inhibitrice de la réplication du CHIKV.Dans le cadre de ces travaux de thèse, des extraits de plantes du genre Euphorbia de Corse ont été étudiés dans le but d'isoler de nouvelles molécules douées d'activité antivirale sur la réplication du CHIKV. En collaboration avec le Dr. P. Leyssen (KU Leuven, Belgique), l'évaluation de l'activité anti-CHIKV de 45 extraits, obtenus à partir de 11 Euphorbiaceae de Corse, a permis de mettre en évidence la forte activité inhibitrice et sélective de des extraits d'espèces du genre Euphorbia in cellulo. L'activité antivirale d'une série de 27 diterpènes de type phorboïde, disponibles commercialement, a également été étudiée. Les résultats ont montré que certains dérivés avaient une forte activité inhibitrice de la réplication du CHIKV, mais aussi sur celle du virus de l'immunodéficience humaine (VIH). Ces études ont permis d'une part, de déduire des relations structure-activité inédites et d'autre part, de soutenir l'hypothèse d'un mécanisme d'action anti-CHIKV impliquant la modulation des protéines kinases C (PKCs) par les phorboïdes. Dans le but de confirmer ou d'infirmer la présence des phorboïdes dans les extraits d'Euphorbia, une première méthode utilisant la chromatographie liquide (LC) haute performance couplée à un spectromètre de masse à trappe d'ions (MSn), a été développée à partir des composés standards. L'application de cette méthodologie a révélé qu'aucun des phorboïdes ciblés n'était présent dans les extraits d'Euphorbia. Ainsi, une seconde procédure LC-MSn a été mise en œuvre afin de détecter - de manière non ciblée - différents types d’esters diterpéniques. L'utilisation de cette approche a révélé que de nombreux diterpènes, non-apparentés aux phorboïdes, étaient présents dans les extraits. Un extrait de l'espèce Euphorbia amygdaloides subsp. semiperfoliata a été sélectionné pour réaliser un fractionnement bio-guidé, aboutissant à l'isolement et l'identification de 14 esters de jatrophane, dont neuf nouveaux composés. Parmi eux, l'un s'est avéré inhiber la réplication du CHIKV et du VIH. Par ailleurs, la structure d'un ester de jatrophane atypique, le jatrohémicétal, a été élucidée grâce à une approche originale combinant modélisation moléculaire et spectroscopie par résonance magnétique nucléaire (RMN). Enfin, une nouvelle procédure de purification ciblée par spectrométrie de masse tandem (MS/MS) en chromatographie en phase fluide supercritique (SFC) a été développée et appliquée sur des fractions bioactives d'E. amygdaloïdes subsp. semiperfoliata. L’interprétation des données MS/MS s’est appuyée sur la génération de réseaux moléculaires. Par cette méthodologie, quatre nouvelles molécules ont pu être détectées, purifiées et identifiées ; il s’agit de deux nouveaux esters de jatrophane et de quatre esters dérivés du 4-déoxyphorbol. L'activité anti-VIH des constituants isolés a également pu être explorée dans le cadre d’une collaboration avec l'équipe du Pr. Alcami (CNM, Espagne). Ainsi, l’un des esters de 4-deoxyphorbol s’est révélé être doué d'un exceptionnel pouvoir inhibiteur de la réplication du VIH-1 (IC50 = 8 nM et index de sélectivité > 6250). Son mécanisme d'action semble s'apparenter à celui de la prostratine (molécule antivirale de référence) mais avec des propriétés antivirales environ 28 fois supérieur. Un deuxième ester de 4-déoxyphorbol s’est avéré être un des plus puissants inhibiteurs du CHIKV isolé à ce jour (EC50 = 0,34 ± 0,12 µM and SI > 638). Mots clés : Euphorbia, activité antivirale, chikungunya, diterpène, spectrométrie de mass

    Análise de sementes associado a aprendizagem de máquina para identificar espécies florestais nativas

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    Orientador: Prof. Dr. Antonio Carlos NogueiraCoorientadores: Profª. Drª. Dagma Kratz e Prof. Dr. Richardson RibeiroTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Agrárias, Programa de Pós-Graduação em Engenharia Florestal. Defesa : Curitiba, 31/07/2023Inclui referênciasResumo: A identificação e caracterização de sementes nativas representam um desafio para o setor florestal devido à variabilidade de características morfobiométricas. Atualmente, as metodologias para a análise biométrica de sementes florestais são realizadas por especialistas humanos utilizando métodos tradicionais de medições, como os paquímetros e variáveis baseadas em tamanho. Nesse contexto, concebeu-se uma nova metodologia empregando técnicas de processamento de imagens digitais e aprendizado de máquina com base em características externas das sementes para possibilitar a identificação de espécies florestais. A pesquisa foi dividida em três capítulos distintos. No primeiro capítulo foi realizada uma análise bibliométrica para quantificar e analisar os estudos científicos que abordam a análise de imagens e o aprendizado de máquina aplicados às sementes, e com isso apontar os principais tópicos e lacunas existentes para pesquisas com sementes florestais com esse enfoque. Os resultados indicam um aumento significativo de publicações a partir de 2017, com foco predominante em espécies de culturas agrícolas. Esses estudos estão direcionados principalmente para a classificação, identificação/detecção de cultivares e avaliação da qualidade das sementes, em que apenas 6,6% das publicações abordam espécies florestais, evidenciando a necessidade de mais pesquisas nesse campo com espécies nativas. No segundo capítulo foi proposta uma metodologia de captura e processamento de imagens para caracterização e diferenciação de espécies florestais nativas. Os resultados demonstraram que a análise de imagens de sementes, por meio dessa metodologia, contribuiu para a caracterização e diferenciação de espécies florestais nativas do Brasil, o que apresenta implicações diretas nos aspectos silviculturais, ecológicos e genéticos. No terceiro capítulo foram aplicados diferentes classificadores de aprendizado de máquina associados à análise de imagens para identificar espécies florestais nativas com base em características morfobiométricas das sementes. Os resultados revelaram que é possível identificar espécies florestais nativas com taxa satisfatória de acurácia usando imagens de sementes e aprendizado de máquina. Recomenda-se o classificador de árvores de decisão para a identificação de espécies. Os resultados fornecem subsídios importantes para aprimorar a caracterização e identificação de espécies, o que pode ser aplicado em diversos campos. Por fim, este trabalho contribui para identificar espécies florestais nativas, por meio do desenvolvimento de uma metodologia de análise e processamento de imagens e da aplicação de técnicas de aprendizado de máquina em sementes florestais.Abstract: The identification and characterization of native seeds represent a challenge for the forest sector due to the variability of morphobiometric characteristics. Currently, methodologies for the biometric analysis of forest seeds are carried out by human specialists using traditional measurement methods, such as calipers and variables based on size. In this context, a new methodology was conceived using techniques of digital image processing and machine learning based on external characteristics of the seeds to enable the identification of forest species. The research was divided into three distinct chapters. In the first chapter, a bibliometric analysis was carried out to quantify and analyze scientific studies that address image analysis and machine learning applied to seeds, and thereby point out the main topics and existing gaps for research with forest seeds with this focus. The results indicate a significant increase in publications from 2017 onwards, with a predominant focus on agricultural crop species. These studies are mainly focused on classification, identification/detection of cultivars and evaluation of seed quality, in which only 6.6% of publications address forest species, highlighting the need for further research in this field with native species. In the second chapter, a methodology for capturing and processing images for the characterization and differentiation of native forest species was proposed. The results showed that the analysis of seed images, using this methodology, contributed to the characterization and differentiation of forest species native to Brazil, which has direct implications for silvicultural, ecological, and genetic aspects. In the third chapter, different machine learning classifiers associated with image analysis were applied to identify native forest species based on morphobiometric characteristics of seeds. The results revealed that it is possible to identify native forest species with a satisfactory rate of accuracy using seed images and machine learning. The decision tree classifier is recommended for species identification. The results provide important subsidies to improve the characterization and identification of species, which can be applied in several fields. Finally, this work contributes to identify native forest species, through the development of an image analysis and processing methodology and the application of machine learning techniques in forest seeds

    Ethnobotany of Namaqualand : the Richtersveld

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    Bibliography: p. 145-152.The primary aim of this ethnobotanical dissertation was to provide a biobehavioural focus for indigenous plant use in the semi-arid areas of one of the six so-called Coloured Rural Reserves (Komaggas, Concordia, Richtersveld, Steinkopf, Leliefontein and Pella) in the north-western Cape (Namaqualand). Although much of the indigenous plant lore has been lost through westernization, the descendants of the Nama-speaking Khoi pastoralists, who are traditionally associated with Namaqualand, still partially rely on indigenous plants for subsistence. Firewood is used daily, medicinal plants are collected regularly and edible plants as well as plants used for household and other activities (such as dyeing of leather) are often used. This project can be seen as a rescue operation to obtain information on the use of indigenous plants before this fast-disappearing knowledge is lost. Richtersveld (and Leliefontein, for comparative and enrichment purposes only) were selected because literary sources confirm the observation that these are the areas where customary practises persist. A biobehavioural approach in terms of human-plant interactions has been applied. The main focus of the dissertation is on the diversity of useful plants and the range of activities associated with the use of the plants. The characteristics of the plants have been examined from an emic as well as etic perspective. The emic perspective was found to be particularly significant in assessing plant foods as well as medicinal plants. Etic perspectives were obtained through nutrient analyses of edible plants and discussions and literary research on medicinal compounds in plants used in health care. It seems that the emic and etic perspectives about plants are not as distinct as was initially thought. Peoples' perceptions about the plants guide them in their choice of plants but it is clear that some biological characteristics of the plants give rise to many of these choices. It may be possible to develop a system of criteria for different categories of plants which will enable archaeologists to make inferences about human-plant interactions. The dissertation ends by commenting on the archaeological significance of the way in which plants are used. The conclusion is that the archaeological record is a poor reflection of the range of activities associated with plant use; and a poor reflection of the diversity of plants which are used in subsistence strategies of the pastoralists of Namaqualand

    Renewing Ranobe for Tomorrow: An Integrated Approach to Sustainable Development in Madagascar

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    The Spiny Forest in southwest Madagascar is home to a 90% endemic array of species and the village of Ranobe. Climate change and deforestation through charcoal production, agricultural use, and development, have degraded 43% of land cover in the last decade. This project collaborated with Ho Avy, a local nonprofit, to design a sustainable development plan for the community. The plan is based on five key perspectives: 1) land use/land cover change management, 2) energy potential, 3) water and health, 4) food security, and 5) economic growth. The plan recommends increased education, shifting incentives, and investment in renewable technologies to be implemented in Ranobe to improve the health of the region’s population and unique environment.Master of ScienceNatural Resources and EnvironmentUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/83529/1/RenewingRanobeforTomorrow_SNRE_20110419.pd

    Special oils for halal and safe cosmetics

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    Three types of non conventional oils were extracted, analyzed and tested for toxicity. Date palm kernel oil (DPKO), mango kernel oil (MKO) and Ramputan seed oil (RSO). Oil content for tow cultivars of dates Deglect Noor and Moshkan was 9.67% and 7.30%, respectively. The three varieties of mango were found to contain about 10% oil in average. The red yellow types of Ramputan were found to have 11 and 14% oil, respectively. The phenolic compounds in DPKO, MKO and RSO were 0.98, 0.88 and 0.78 mg/ml Gallic acid equivalent, respectively. Oils were analyzed for their fatty acid composition and they are rich in oleic acid C18:1 and showed the presence of (dodecanoic acid) lauric acid C12:0, which reported to appear some antimicrobial activities. All extracted oils, DPKO, MKO and RSO showed no toxic effect using prime shrimp bioassay. Since these oils are stable, melt at skin temperature, have good lubricity and are great source of essential fatty acids; they could be used as highly moisturizing, cleansing and nourishing oils because of high oleic acid content. They are ideal for use in such halal cosmetics such as Science, Engineering and Technology 75 skin care and massage, hair-care, soap and shampoo products

    Structural and Functional Analysis of Extracts in Plants

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    Structural and Functional Analysis of Extracts in Plants collects 1 editorial, 3 reviews, and 26 research articles reporting recent research findings which cover several aspects of plant-derived bioactive compounds, to correlate extraction techniques with the chemical composition of extracts and their bioactivity for identifying molecules that might be used as active substances in a wide variety of areas.This book is a valuable resource for members of the scientific community wishing to further explore plants and the therapeutic applications of their bioactive compounds. It will appeal to scholars, teachers and scientists involved in plant product research, and facilitate the development of innovative new drugs

    Land cover and climate change threats to savanna and grassland habitats in KwaZulu-Natal

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    A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy The support of the Global Change and Sustainability Research Institute (GCSRI) towards this research is hereby acknowledged. Opinions expressed and conclusions arrived at, are those of the author and are not necessarily to be attributed to the GCSRI. February 2017 in Johannesburg, South AfricaGlobal change, specifically land cover change and climate change, are recognised as the leading drivers of biodiversity loss worldwide. Habitat loss has resulted in a loss of biodiversity and led to significant declines in species populations. Climate change is altering species distributions, ecosystem composition and phenology. Conservation planning is required to offset these dynamic threats to species persistence into the future. Plants form the basis of trophic structure and functioning and may not be able to track changing environmental conditions as well as mobile species. They thus represent an essential starting point for understanding climate change and habitat loss impacts. The patterns and processes which generate and maintain floristic diversity must be explored before global change impacts on these communities can be assessed and planned for at a landscape scale. This thesis investigates the environmental variables structuring indigenous plant community composition, pattern and turnover in grassland and savanna systems in KwaZulu-Natal. The threats posed by land cover change and climate change are explored and a coarse-grained landscape connectivity map developed to impart maximum resilience in order to maintain floristic diversity in the era of anthropogenically induced global change. The environmental variables correlated to floristic pattern and turnover were temperature, soil fertility and precipitation variables. The orientation of the temperature gradient conflicts with the soil fertility gradient, hence species with particular soil requirements will be hampered in their efforts to track the temperature gradient. The gradients were non-linear with turnover highest on dystrophic soils in warm and drier summer regions. The major drivers of land cover change were cropped agriculture, timber plantations (agroforestry), rural and urban development, dams and mines. The drivers of change differed according to land tenure type. The average rate of habitat loss in the province over an 18 year period was 1.2% per annum, levels which are considered unsustainable. A target level of 50% of natural habitat remaining is recommended. Environmental domains were identified using the environmental correlates of plant community composition. These were used to investigate climate change impacts using a collection of downscaled climate models. Conditions suiting savanna species are set to increase at the expense of conditions suiting grassland species raising significant challenges for the conservation of grasslands. Indices of habitat intactness and climatic stability were used to develop a vulnerability framework to guide conservation actions to mitigate global change impacts on floristic diversity. Building on the insights gained from the study, a connectivity map linking protected areas was developed, that if implemented, will maximise the opportunity to maintain floristic diversity into the future. The spatial location of the corridors was prioritised based on broad scale climatic refugia, high turnover areas and important plant areas for endemic and threatened species. The corridors were aligned along the major climatic gradients driving floristic pattern. The corridors represent the most natural and cost-effective way for species to adapt to climate change and persist in the landscape. This thesis provides new insights into two global threats facing plant communities in KwaZulu-Natal and provides a suite of products that inform dynamic conservation planning and directs appropriate conservation action. The results may be used to inform policy and legislation.MT201

    Factors influencing wetland distribution and structure, including ecosystem function of ephemeral wetlands, in Nelson Mandela Bay Municipality (NMBM), South Africa

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    The Nelson Mandela Bay Municipality (NMBM) is a semi-arid area along the southern coastline of South Africa (SA). Until recently, there was no systematic approach to research on wetland systems in the NMBM. The systematic identification of wetlands was made more difficult by the relatively large number of small, ephemeral systems that can be difficult to delineate. This has meant that fundamental knowledge on wetland distribution, structure and function has been limited and, consequently, management and conservation strategies have been based on knowledge on systems from other regions of the country. Environmental processes occur at different spatial and temporal scales. These processes have an effect on the abiotic factors and biotic structure of wetlands, resulting in inherently complex systems. The location of the NMBM provides a good study area to research some of these environmental and biological attributes at different spatial scales, due to the variability in the underlying geology, geomorphology, vegetation types and the spatial and temporal variability in rainfall, within a relatively small area of 1951 km2. Thus, the aim of this study was to determine the factors influencing wetland distribution, structure and ecosystem functioning within the NMBM. The first Research Objective of work presented here was to identify wetlands using visual interpretation of aerial photographs. A total of 1712 wetlands were identified within the NMBM using aerial photographs, covering an area of 17.88 km2 (Chapter 5). The majority of these wetlands were depressions, seeps and wetland flats. Valley bottom wetlands (channelled and unchannelled) and floodplain wetlands were also identified. A range of wetland sizes was recorded, with 86% of the wetlands being less than 1 ha in size and the largest natural wetland being a floodplain wetland of 57 ha, located south of the Swartkops River. The identified wetlands were used to create a wetland occurrence model using logistic regression (LR) techniques (Chapter 5), in accordance with Objective 2 of the study. An accuracy of 66% was obtained, which was considered acceptable for a semi-arid climate with a relatively high degree of spatial and temporal rainfall variability. The model also highlighted several key environmental variables that are associated with wetland occurrence and distribution at various spatial scales. Some of the important variables included precipitation, evapotranspiration, temperature, flow accumulation and groundwater occurrence. Wetland distribution patterns were described in Chapter 6. Spatial statistics were used to identify whether wetlands are clustered and, therefore, form mosaics within the surrounding landscape (Objective 3). Systems were found to be highly clustered, with 43% of wetlands located within 200 m of another system. Clustering and wetland presence was especially prominent in the southern portion of the Municipality, which is also associated with a higher mean annual precipitation. Smaller wetlands were also significantly more clustered than larger systems (Average Nearest Neighbour statistic, p-value < 0.0001). Average distances also significantly varied according to HGM type, with depressions being the most geographically isolated wetland type compared to the other HGM types. Overall, distances between wetlands indicated good proximal connectivity. Potentially vulnerable areas associated with wetland systems were identified successfully using landscape variables, in accordance with Objective 4. These variables were: land cover, slope gradient, flow accumulation, APAN evaporation, mean annual precipitation (MAP) and annual heat units. The existing Critical Biodiversity Network was also used in connection with these variables to further identify potentially vulnerable areas. The abiotic and biotic characteristics were decribed for three hydrogeomorphic (HGM) types at a total of 46 wetland sites (Chapter 7), as per Objective 5. Depressions, seeps and wetland flats were sampled across the different geological, vegetation and rainfall zones within the NMBM. The wetland sites were delineated up to Level 6 of the Classification System used in SA, and the various abiotic and biotic characteristics of these systems were defined. A total of 307 plant, 144 aquatic macroinvertebrate and 10 tadpole species were identified. Of these species, over 90 species were Eastern Cape and SA endemic species, as well as three threatened species on the IUCN Red List. Multivariate analyses (including Bray-Curtis similarity resemblance analyses, distance-based redundancy analyses, SIMPER analyses and BIOENV analysis in Primer), together with environmental data, were used to define community structure at an HGM level, in accordance with Objective 5. The importance of the spatial scale of the environmental data used to define plant and macroinvertebrate community structure was described in Chapter 7, to address Objective 6. The results showed that both broad-scale and site-level characteristics were important in distinguishing community structure within the HGM types that superseded general location, the sample timing or the stage of inundation. These results also indicated that a combination of both landscape and site-level data are important in defining the community structure in the various HGM types. Some of the important environmental variables that explained some of species assemblages were similar to those in the wetland occurrence model (Chapter 5), with some additional hydrological and soil physico-chemical parameters (e.g. soil electrical conductivity, soil pH, and surface and subsurface water nutrients). These significant variables indicate the complex, multi-scalar role of environmental attributes on wetland distribution, structure and function

    Special Issue in Honor of Professor James D. McChesney on the Occasion of his 80th Birthday

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    Plants have been the sources of important pharmaceuticals, flavoring agents, and agrochemicals. The antimalarial drugs artemisinin and quinine; the anticancer drugs taxol, etoposide, and vinca alkaloids; the sugar-free sweetening agents stevioside and rebaudiosides; and antifeedant azadiractin are good examples of important plant-based drugs, food additives, and agrochemicals currently on the market. Despite these and many other successes, there are significant challenges to discovering and developing commercially important natural products from plants, such as procuring plant materials in large quantities, separating active constituents from complex mixtures, and undesirable qualities, such as low solubility or poor chemical or metabolic stability of active constituents. Dr. James D. McChesney has contributed immensely to overcoming the inherent challenges associated with discovering and developing products modeled from plant-based natural product leads. His research on artemisinin, taxol, galanthamine, podophyllotoxin, and stevia sweet glycosides exemplifies the magnitude of these contributions. His extensive work on the structural modification of taxol led to the discovery and development of the anticancer agent TPI 287, a third-generation taxane analog that is currently undergoing clinical trials. Dr. McChesney has had a long, distinguished teaching and research career, has authored more than 225 research publications, and holds more than 60 patents. He is a past president and Fellow of the American Society of Pharmacognosy and a Fellow of the AAAS. He has mentored many graduate students, post-docs, and junior faculty members who hold prominent positions in natural products research establishments in the US and worldwide. We wish to dedicate this Special Issue Book Version to celebrate the eightieth birthday of Dr. McChesney, a prolific thinker with abundant inventiveness in the field of natural product chemistry and pharmacognosy
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