Thesis (Ph. D.)--University of Tennessee, Knoxville, 2004. / Includes bibliographical references (leaves 118-128). Also available via the World Wide Web.

M.Sc. / Please refer to full text for abstract

The revision of Metalasia by Karis (1989) made it clear that the rest of the Metalasia group, as defined by Anderberg (1991a), also needed to be investigated. Anderberg (1991a) identified the Relhania and Metalasia groups in the subtribe Relhaniinae of the tribe Gnaphalieae. The Metalasia group consists of 14 genera, of which seven are monotypic and four have recently been described. The monotypic genera Bryomorphe, Dolicothrix and Phaenocoma are well known, whereas the more recently described Atrichantha, Calotesta, Hydroidea and Planea (Hilliard & Burtt, 1981; Karis, 1990) are known from limited collections. In the broader context of the tribe it also became evident that Disparago (Koekemoer, 1993), Stoebe and Elytropappus (Levyns, 1937, 1935b) needed to be re-assessed to establish the rank of their formal and informal groupings. A number of genera in the group: Amphiglossa, Bryomorphe, Lachnospermum, Phaenocoma and Pterothrix, had not been studied since Flora Capensis (Harvey, 1865) and needed attention. The aims of this study were therefore, to clarify the taxonomy and nomenclature, to provide full taxonomic treatments for all the species in the Metalasia group, and to discuss their phylogenetic relationships. The fact that almost all taxa are endemic to southern Africa provided additional motivation to investigate the group. Furthermore the newly described genera and species have not been studied in the context of the whole group and the large number of specimens that are available today add a wealth of new information to the available knowledge. The need for further investigation was also emphasized by comments by Anderberg (1991a) that Elytropappus and Stoebe are probably paraphyletic or polyphyletic and that Amphiglossa is probably paraphyletic if Pterothrix is kept separate. Extensive fieldwork was undertaken to investigate species in their natural habitat. Spirit-preserved and dried specimens were collected and studied in the herbarium. Thorough morphological studies were undertaken, with extensive use of the SEM and light microscopes; photographs were produced to document the characters. Accurate records were kept of all specimens to assist in determining distribution ranges for each taxon as well as species densities for every genus. Anatomy of selected species was investigated. The results revealed that the leaves of Dolicothrix and Dicerothamnus were indeed glandular, that there are two small resin cavities in the leaf bases of some Seriphium species, and for the first time, provided information on leaf and cypsela anatomy for the group. During the course of this study several nomenclatural problems were solved: the correct name for Bryomorphe aretioides; Klenzea lycopodioides is a synonym of Dolicothrix ericoides, rather than of Bryomorphe; and the confusion around the names Elytropappus gnaphaloides and E. glandulosus was cleared. It was also found that Elytropappus hispidus and E. cyathiformis, and Stoebe cyathuloides and S. sphaerocephala are conspecific. On generic level it was found that Amphiglossa and Pterothrix are congeneric; and that Disparago, Elytropappus and Stoebe are paraphyletic. This resulted in Seriphium being re-surrected for a group of Stoebe species, and Disparago being divided into four genera and Elytropappus into three. Taxonomic treatments for 64 species, including nomenclature, synonymy, typification, full descriptions, geographical distribution, and keys to genera and species, are given. Fieldwork resulted in a large number of new distribution records, the discovery of six new species and also the re-collection of two species (Amphiglossa callunoides and A. corrudifolia) that were only known from type specimens and were thought to be extinct. Although attempts were made to investigate the group, both chemically and cytologically, I was not able to do this successfully. Chemical results indicated that the volatile oils and flavonoids are complex and would provide a wealth of information for future studies. Together with DNA investigations in the Gnaphalieae it could possibly assist to unravel existing uncertainties. A summary of the taxonomic implications of this study is given below: Genera New species No of species Taxonomic implications Amphiglossa A. celans, A. grisea A. rudolphii, A. susannae 11 • Pterothrix as synonym with several new combinations • Four new species • P. flaccida and P. spinescens as synonyms Atrichantha 1 Bryomorphe 1 • Nomenclature clarified Calotesta 1 Dicerothamnus 2 • New genus • New combinations Disparago 4 • Reverting to original concept of Gaertner for the genus • Three new genera created Dolicothrix 1 • Klenzea lycopodioides as new synonym Elytropappus E. aridus E. monticola 3 • E. cyathiformis as synonym • Genus split into three Gongyloglossa 1 • New genus • New combination Hydroidea 1 Lachnospermum 3 • Nomenclature clarified Laevicarpa 1 • New genus • New combination Metalasia 52 Monticapra 3 • New genus • New combinations Myrovernix 5 • New genus • New combinations • M. intricata transferred from Stoebe Phaenocoma 1 Planea 1 Seriphium 9 • Resurrect the genus • New combinations • Elytropappus ruscianus, Stoebe burchellii and S. vulgaris as synonyms Stoebe 16 • S. copholepis, S. ensori, S. sphaerocephala, S. humilis, S. salteri and S bruniades as synonyms. Total 117 Characters and character states were evaluated in terms of their taxonomic value and their contributions towards an improved understanding of phylogenetic relationships amongst the genera and species of the Metalasia group. The patterns of character state distributions were explored, using cladistic methods. This resulted in the discovery of several ‘new’ characters, as well as new ways of interpreting some of the ‘old’ characters. Examples include several very interesting observations made by means of SEM studies; e.g. the true identity of Elytropappus cyathuloides, the glands on the leaf surfaces of Dicerothamnus rhinocerotis, D. adpressus and Dolicothrix ericoides as well as resin cavities at the bases of leaves of some Seriphium species. All data gathered from the study were evaluated and analyzed cladistically to determine inter- and infraspecific relationships. New hypotheses regarding the relationships amongst the genera and species of the Metalasia group are presented. / Van Wyk, B.E., Prof.

No description available.

No description available.

A comprehensive phylogenetic hypothesis for the predominantly Neotropical American genus Baccharis is necessary to test its monophyly and clarify the infrageneric relationships within the genus. Given its great morphological diversity and wide geographic distribution, phylogenetic studies based on molecular data to test the monophyly of the genus and investigate the relationships of its infrageneric groups are here proposed, allowing the recognition and taxonomic revision of smaller and monophyletic taxa. Therefore, a phylogenetic hypothesis for Baccharis is provided based on 248 species sampled, four molecular regions (ETS, ITS, trnH-psbA, trnL-F) and Bayesian analyses. The results confirm subtribe Baccharidinae as a monogeneric group, and support a wide definition of Baccharis s.l., monophyletic and including all genera that were previously segregated from it. Comprehensive lists of infrageneric taxa and taxa accepted at species level were compiled to move towards a phylogeny-based infrageneric classification of Baccharis. Seven main lineages were recovered, treated here at subgeneric level, and in this process all subgenera recognized before had to be recircumscribed to constitute monophyletic taxa. Four subgenera roughly match previous subgeneric concepts, while two subgenera are synonyms. Two earlier segregated genera and two formerly existing sections are moved to the subgeneric rank. The survey of names published in the ranks of sections and series accounted 68 sections and 13 series; four new sections are described and three new statuses at the rank of section are proposed to accommodate taxa not corresponding to any previously described section, while 22 sections were considered synonyms. This procedure allowed the recognition of 47 sections, though this number is supposed to decrease after future studies are accomplished with a larger sampling. The names accepted at species level totalize 433 taxa that were here assigned to the most inclusive infrageneric category possible in the light of the data currently available. Baccharis subgen. Tarchonanthoides Heering, a group restricted to the southeastern South American grasslands and savannas, was chosen as a good target to first tackle for a taxonomic revision, due its small size, restricted area of occurrence when compared to the remaining subgenera, and morphological distinctiveness. This is the first attempt to provide a taxonomic revision of a subgenus of Baccharis according to a phylogenetic framework, and under no geographic constraint. The recircumscription of Baccharis subgen. Tarchonanthoides involves the synonymization of Lanugothamnus, and the exclusion of one section in order to keep the subgenus monophyletic. Other taxonomic and nomenclatural actions necessary are designation of lectotypes, a new status and new combinations, new synonymizations and clarification of the species concepts formerly misapplied to some names. Two recircumscribed sections and 13 species are accepted within the taxonomically revised B. subgen. Tarchonanthoides, which diversified mainly in open vegetations from southeastern South America in Brazil, Paraguay, Uruguay and Argentina. General morphological descriptions of the infrageneric taxa are provided, as well as a taxonomic key, descriptions, data on etymology, distribution and habitats, phenology, conservation status, etnobotany and vernacular names, and a list of specimens examined, line drawings, pictures and maps of distribution for all accepted species within this subgenus. Alongside the main goals, exploratory fieldwork and study of herbaria specimens allowed the description of eight new species: B. dichotoma, B. hemiptera, B. magnifica, B. napaea, B. nebularis, B. obdeltata, B. simplex and B. umbellata / Uma hipótese filogenética abrangente sobre Baccharis, um gênero Americano predominantemente Neotropical, é necessária para testar seu caráter monofilético e esclarecer suas relações infragenéricas. Devido a sua grande diversidade morfológica e ampla distribuição geográfica, estudos filogenéticos com base em dados moleculares para testar o monofiletismo do gênero e investigar as relações de seus grupos infragenéricos foram aqui conduzidos, permitindo o reconhecimento e a revisão taxonômica de táxons menores e monofiléticos. Desta forma, uma hipótese filogenética sobre Baccharis é aqui apresentada, com base em 248 espécies amostradas, quatro regiões do genoma (ETS, ITS, trnH-PSBA, trnL-F) e análises Bayesianas. Os resultados confirmam a subtribo Baccharidinae como um grupo monogenérico e sustentam uma definição ampla de Baccharis s.l. monofilético e incluindo todos os gêneros que foram previamente segregados dele. Listagens abrangentes de táxons infragenéricos e de táxons aceitos ao nível de espécie foram compiladas com o objetivo de direcionar uma classificação infragenérica baseada nas relações filogenéticas de Baccharis. Sete linhagens principais foram reconhecidas e são tratadas aqui no nível taxonômico de subgênero, e neste processo todos os subgêneros anteriormente reconhecidos tiveram que ser recircunscritos para constituírem táxons monofiléticos. Quatro subgêneros correspondem imprecisamente a conceitos subgenéricos aplicados anteriormente, enquanto que dois subgêneros são sinônimos. Dois gêneros segregados anteriormente de Baccharis e duas seções previamente existentes no gênero são realocadas em nível subgenérico. O levantamento de nomes publicados nas categorias taxonômicas de seção e série totalizaram 68 seções e 13 séries, quatro novas seções e três novos posicionamentos ao nível de seção são propostos para acomodar táxons que não correspondiam a qualquer das seções previamente descritas, enquanto que 22 seções foram sinonimizadas. Estes procedimentos permitiram reconhecer 47 seções, embora seja esperado que esse número diminua com a realização de futuros estudos baseados em maior amostragem. Os nomes aceitos ao nível de espécie totalizaram 433 táxons que foram posicionados na categoria infragenérica mais inclusiva possível à luz dos dados disponíveis atualmente. Baccharis subgen. Tarchonanthoides Heering, um grupo restrito aos campos e savanas do sudeste da América do Sul, foi definido como um alvo adequado para uma revisão taxonômica precursora devido ao número reduzido de espécies, área de ocorrência restrita quando comparado aos demais subgêneros e distinção morfológica. Esta é a primeira tentativa de proceder a revisão taxonômica de um subgênero de Baccharis em concordância com um sistema filogenético e livre de qualquer limitação geográfica. A recircunscrição de Baccharis subgen. Tarchonanthoides envolve a sinonimização de Lanugothamnus, e a exclusão de uma seção do subgênero, no sentido de torná-lo monofilético. Outras ações nomenclaturais e taxonômicas são necessárias como a designação de lectótipos, a proposição de um novo status, novas combinações, novas sinonimizações e o esclarecimento de conceitos de espécie previamente aplicados de forma equivocada para alguns nomes de espécies. Duas seções recircunscritas e 13 espécies são aceitas nesta revisão taxonômica de B. subgen. Tarchonanthoides, um grupo diversificado nas vegetações abertas do Sudeste da América do Sul, ocorrendo no Brasil, Uruguai, Argentina e Paraguai. Descrições morfológicas dos táxons infragenéricos são fornecidas, assim como uma chave taxonômica, descrições, dados sobre etimologia, distribuição e habitats, fenologia, estado de conservação, nomes em vernáculo e listas de espécies examinados, pranchas em nanquim, fotografias e mapas de distribuição para todas as espécies aceitas no subgênero. Paralelamente aos objetivos principais, expedições exploratórias a campo e o estudo de espécimes em herbários possibilitaram a descrição de oito novas espécies: B. dichotoma, B. hemiptera, B. magnifica, B. napaea, B. nebularis, B. obdeltata, B. simplex e B. umbellata

Em muitas espécies vegetais alguns órgãos desempenham mais do que uma função em certos estágios da vida. Raízes, caules ou folhas começam a acumular substâncias de reserva e, dependendo da sua origem, podem ser transformados em órgão de reserva, como tubérculos, bulbos, rizóforos e raízes tuberosas. Entre os compostos de reversa, os carboidratos são responsáveis por diversas funções, tais como fonte de energia, proteção contra a seca e temperaturas extremas. Os campos rupestres são caracterizados por um clima mesotérmico, com três a cinco meses de seca, correspondendo ao inverno, e seis a oito meses de chuvas, que corresponde ao verão. Os solos são rasos, salinos e com afloramentos rochosos. A flora possui um alto grau de endemismo, sugerindo a existência de estratégias adaptativas metabólicas para sobreviver aos estresses ambientais. O objetivo do presente trabalho foi realizar uma triagem dos carboidratos não estruturais em diferentes órgãos de espécies herbáceas predominantes destas regiões e a análise anatômica do sistema subterrâneo de quatro espécies de Asteraceae para visualização e localização dos cristais de inulina. Foram coletadas 26 espécies em três regiões distintas: 14 na Serra do Cipó e, cinco na Serra de Itacambira (estado de Minas Gerais), e sete na Serra Dourada (estado de Góias), representantes das famílias Amaranthaceae, Orchidaceae, Eriocaulaceae, Velloziaceae, Apiaceae, Apocynaceae e Asteraceae, sendo a última a mais representativa em números de espécies. Carboidratos solúveis foram quantificados colorimetricamente e analisados cromatograficamente por CCD e HPAEC/PAD. Amido foi quantificado por método enzimático e cristais de inulina foram visualizados sob luz polarizada. Frutanos foram detectados nos órgão subterrâneos de reserva de todas as espécies de Asteraceae e Amaranthaceae. A maior concentração de frutose total foi encontrada em Gomphrena marginata (Amaranthaceae), compreendendo 30% da massa seca de seus órgãos subterrâneos. Lessingianthus psilophyllus e Richterago polymorpha (Asteraceae) também contêm altas porcentagens de açúcares solúveis (34% e 33%, respectivamente), dos quais 26 e 27% correspondem aos frutanos. Todas as Asteraceae apresentaram frutanos da série homóloga da inulina com alto grau de polimerização. Gomphrena agrestis e Gomphrena marginata (Amaranthaceae) apresentaram frutanos da série dos levanos. Vellozia mínima e Barbacenia plantaginea (Velloziaceae) apresentaram os oligossacarídeos da série da rafinose. De todas as espécies estudadas, somente Habenaria caldensis, Oncidium hidrophylum (Orchidaceae), Mandevilla tenuifolia (Apocynaceae) and Klotzschia brasiliensis (Apiaceae) acumulam amido como principal polissacarídeo de reserva em seus órgãos subterrâneos, enquantoem Leiothrix curvifolia (Eriocaulaceae) o amido foi detectado nos caules. Cristais de inulina foram visualizados n as quatro Asteraceae analisadas e se e localizam principalmente no cilindro vascular. Foi observada também, a ocorrência de estruturas secretoras em Chresta curumbensis e Strophopappus glomeratus. Este trabalho fornece informações úteis para expandir o conhecimento de estratégias fisiológicas das plantas para sobreviverem a condições ambientais adversas, como ocorre nos campos rupestres, e contribuir para estabelecer estratégias de conservação para a biodiversidade tropical. / In many plant species some organs perform more than one function at certain stages of the life cycle. Roots, stems or leaves begin to accumulate reserve substances and depending on the origin may be transformed into storage organs like tubers, bulbs, rhizophores and tuberous roots. Among other storage compounds, carbohydrates are assigned several functions such as source of energy and protection against drought and extreme temperatures. Rocky fields are characterized by mesothermal climate, with three to five months of dry season in winter, and seven to eight months of humidity in summer. The soils are shallow, sandy and with rocky outcrops. The flora has a high degree of endemism suggesting the existence of metabolic adaptive strategies to overcome environmental stresses. The aim of this work was to carry out a screening of reserve compounds accumulated in different organs of predominant herbaceous species, and to analyze the localization of inulin crystals in the underground system in four Asteraceae species.Twenty-six species of the following families, Amaranthaceae, Orchidaceae, Eriocaulaceae, Velloziaceae, Apiaceae, Apocynaceae and Asteraceae were collected in three regions: 14 at \"Serra do Cipó\" and five at \"Serra de Itacambira\" (state of Minas Gerais), and seven at \"Serra Dourada\" (state of Goiás). The Asteraceae was the most significant in species number. Soluble carbohydrates were quantified colorimetrically and analyzed chromatographically by TLC and HPAEC/PAD, and starch was quantified by enzymatic assay. Inulin crystals were visualized under polarized light. Fructans were detected in underground reserve organs of all the Asteraceae and Amaranthaceae species. The highest concentration of total fructose was found in Gomphrena marginata (Amaranthaceae) comprising 30% of the underground organ dry mass. Lessingianthus psilophyllus and Richterago polymorpha (Asteraceae) also contained high percentages of soluble carbohydrates on a dry mass basis (34% and 33%, respectively), from which 26% and 27% corresponded to fructans. All the Asteraceae analyzed presented the inulin homologous series with a high degree of polymerization while Gomphrena agrestis and G. marginata (Amaranthaceae) presented the levan series. Vellozia minina and Barbacenia plantaginea presented the raffinose family oligosaccharides. Of all the analyzed species, only Habenaria caldensis, Oncidium hidrophylum (Orchidaceae), Mandevilla tenuifolia (Apocynaceae) and Klotzschia brasiliensis (Apiaceae) accumulate starch as the main reserve carbohydrate in the underground organs while in Leiothrix curvifolia (Eriocaulaceae) starch is accumulated in stems. Inulin crystals were visualized mainly in the vascular cilynder. in the four Asteraceae analyzed. Secretory structures were identified in Strophopappus glomerathus and Chresta curumbensis This work provides information to enhance the knowledge on physiological strategies used by plants to survive adverse environmental conditions such as those predominating in rocky fields, and may contribute for the establishment of conservation strategies of tropical biodiversity.

Em muitas espécies vegetais alguns órgãos desempenham mais do que uma função em certos estágios da vida. Raízes, caules ou folhas começam a acumular substâncias de reserva e, dependendo da sua origem, podem ser transformados em órgão de reserva, como tubérculos, bulbos, rizóforos e raízes tuberosas. Entre os compostos de reversa, os carboidratos são responsáveis por diversas funções, tais como fonte de energia, proteção contra a seca e temperaturas extremas. Os campos rupestres são caracterizados por um clima mesotérmico, com três a cinco meses de seca, correspondendo ao inverno, e seis a oito meses de chuvas, que corresponde ao verão. Os solos são rasos, salinos e com afloramentos rochosos. A flora possui um alto grau de endemismo, sugerindo a existência de estratégias adaptativas metabólicas para sobreviver aos estresses ambientais. O objetivo do presente trabalho foi realizar uma triagem dos carboidratos não estruturais em diferentes órgãos de espécies herbáceas predominantes destas regiões e a análise anatômica do sistema subterrâneo de quatro espécies de Asteraceae para visualização e localização dos cristais de inulina. Foram coletadas 26 espécies em três regiões distintas: 14 na Serra do Cipó e, cinco na Serra de Itacambira (estado de Minas Gerais), e sete na Serra Dourada (estado de Góias), representantes das famílias Amaranthaceae, Orchidaceae, Eriocaulaceae, Velloziaceae, Apiaceae, Apocynaceae e Asteraceae, sendo a última a mais representativa em números de espécies. Carboidratos solúveis foram quantificados colorimetricamente e analisados cromatograficamente por CCD e HPAEC/PAD. Amido foi quantificado por método enzimático e cristais de inulina foram visualizados sob luz polarizada. Frutanos foram detectados nos órgão subterrâneos de reserva de todas as espécies de Asteraceae e Amaranthaceae. A maior concentração de frutose total foi encontrada em Gomphrena marginata (Amaranthaceae), compreendendo 30% da massa seca de seus órgãos subterrâneos. Lessingianthus psilophyllus e Richterago polymorpha (Asteraceae) também contêm altas porcentagens de açúcares solúveis (34% e 33%, respectivamente), dos quais 26 e 27% correspondem aos frutanos. Todas as Asteraceae apresentaram frutanos da série homóloga da inulina com alto grau de polimerização. Gomphrena agrestis e Gomphrena marginata (Amaranthaceae) apresentaram frutanos da série dos levanos. Vellozia mínima e Barbacenia plantaginea (Velloziaceae) apresentaram os oligossacarídeos da série da rafinose. De todas as espécies estudadas, somente Habenaria caldensis, Oncidium hidrophylum (Orchidaceae), Mandevilla tenuifolia (Apocynaceae) and Klotzschia brasiliensis (Apiaceae) acumulam amido como principal polissacarídeo de reserva em seus órgãos subterrâneos, enquantoem Leiothrix curvifolia (Eriocaulaceae) o amido foi detectado nos caules. Cristais de inulina foram visualizados n as quatro Asteraceae analisadas e se e localizam principalmente no cilindro vascular. Foi observada também, a ocorrência de estruturas secretoras em Chresta curumbensis e Strophopappus glomeratus. Este trabalho fornece informações úteis para expandir o conhecimento de estratégias fisiológicas das plantas para sobreviverem a condições ambientais adversas, como ocorre nos campos rupestres, e contribuir para estabelecer estratégias de conservação para a biodiversidade tropical. / In many plant species some organs perform more than one function at certain stages of the life cycle. Roots, stems or leaves begin to accumulate reserve substances and depending on the origin may be transformed into storage organs like tubers, bulbs, rhizophores and tuberous roots. Among other storage compounds, carbohydrates are assigned several functions such as source of energy and protection against drought and extreme temperatures. Rocky fields are characterized by mesothermal climate, with three to five months of dry season in winter, and seven to eight months of humidity in summer. The soils are shallow, sandy and with rocky outcrops. The flora has a high degree of endemism suggesting the existence of metabolic adaptive strategies to overcome environmental stresses. The aim of this work was to carry out a screening of reserve compounds accumulated in different organs of predominant herbaceous species, and to analyze the localization of inulin crystals in the underground system in four Asteraceae species.Twenty-six species of the following families, Amaranthaceae, Orchidaceae, Eriocaulaceae, Velloziaceae, Apiaceae, Apocynaceae and Asteraceae were collected in three regions: 14 at \"Serra do Cipó\" and five at \"Serra de Itacambira\" (state of Minas Gerais), and seven at \"Serra Dourada\" (state of Goiás). The Asteraceae was the most significant in species number. Soluble carbohydrates were quantified colorimetrically and analyzed chromatographically by TLC and HPAEC/PAD, and starch was quantified by enzymatic assay. Inulin crystals were visualized under polarized light. Fructans were detected in underground reserve organs of all the Asteraceae and Amaranthaceae species. The highest concentration of total fructose was found in Gomphrena marginata (Amaranthaceae) comprising 30% of the underground organ dry mass. Lessingianthus psilophyllus and Richterago polymorpha (Asteraceae) also contained high percentages of soluble carbohydrates on a dry mass basis (34% and 33%, respectively), from which 26% and 27% corresponded to fructans. All the Asteraceae analyzed presented the inulin homologous series with a high degree of polymerization while Gomphrena agrestis and G. marginata (Amaranthaceae) presented the levan series. Vellozia minina and Barbacenia plantaginea presented the raffinose family oligosaccharides. Of all the analyzed species, only Habenaria caldensis, Oncidium hidrophylum (Orchidaceae), Mandevilla tenuifolia (Apocynaceae) and Klotzschia brasiliensis (Apiaceae) accumulate starch as the main reserve carbohydrate in the underground organs while in Leiothrix curvifolia (Eriocaulaceae) starch is accumulated in stems. Inulin crystals were visualized mainly in the vascular cilynder. in the four Asteraceae analyzed. Secretory structures were identified in Strophopappus glomerathus and Chresta curumbensis This work provides information to enhance the knowledge on physiological strategies used by plants to survive adverse environmental conditions such as those predominating in rocky fields, and may contribute for the establishment of conservation strategies of tropical biodiversity.

This dissertation deals with the phytochemical and biological investigations of Grindelia tarapacana Phil. (Asteraceae), a plant species native to the Desert of Atacama in Chile. Ten compounds were isolated by using various chromatographic techniques. Of these, seven are new and two are known diterpenoids of the manoyloxide type. One known steroid was also characterized during the course of this study. New diterpenoids included 14S,15-dihydroxy-13-epi-manoyloxide (tarapacol), 15-acetoxy-14S-hydroxy-13-epi-manoyloxide (tarapacol 15-acetate), 14S,15-diacetoxy-13-epi-manoyloxide (tarapacol diacetate), 11α,14S,15-trihydroxy-13-epi-manoyloxide (tarapacanol A), 14S,15-diacetoxy-11α-hydroxy-13-epi-manoyloxide (tarapacanol A 14, 15-diacetate), 12α,14S,15-trihydroxy-13-epi-manoyloxide (tarapacanol B) and 14S,15-dihydroxy-11-keto-13-epi-manoyloxide (tarapacanone). The chemical structures and stereochemistry were established on the basis of extensive spectral analyses including 2D NMR and NOE techniques. X-ray diffraction analysis of tarapacol 15-acetate supported its absolute configuration. The configurations of the other new remaining diterpenoids were assigned based on biogenetic considerations. The two known diterpenoids were 13-epi-manoyloxide and 12α-hydroxy-13-epi-manoyloxide. The steroid was identified as α-spinasterol. The characterization of the known compounds was based on the comparisons of their spectral and physical constants with those reported in the literature for standard samples. Ten known flavonoids were also identified. As part of screening studies for biological activity, anti-HIV and anti-Mycobacterium tuberculosis tests were carried out for the isolated compounds. Five diterpenoids were found to exhibit biological activities. In an anti-HIV test, 12α-hydroxy-13-epi-manoyloxide (at 31 μg/mL) strongly decreased the HIV antigen release to a 10% level and still kept the 84% cell survival, suggesting anti-HIV activity with high selectivity in vitro. The activity of several diterpenoids against Mycobacterium tuberculosis reference strain H₃₇ Ra in vitro was very positive. Three diterpenoids, tarapacol (MIC = 32 μg/mL), tarapacol 15-acetate (MIC = 32 μg/mL) and tarapacanol A 14,15-diacetate (MIC = 32 μg/mL) showed a potency similar to that obtained for the anti-tuberculosis agent pyrazinamide (MIC = 40 μg/mL). Tarapacol diacetate (MIC = 16 μg/mL) was found to be much more potent than pyrazinamide.

Not available / text