Orientador: Silvia Rodrigues Machado / Banca: Elza Maria Guimarães dos Santos / Banca: Adriana Hissae Hayashi / Resumo: Uma característica da família Verbenaceae é a presença de tricomas secretores, geralmente produtores de óleos essenciais de grande valor medicinal. Muitas espécies de Lippia Houst. são utilizadas em programas fitoterápicos e de complementação alimentar no Brasil, sendo L. alba e L. sidoides as mais utilizadas e estudadas. O cerrado possui aproximadamente 33 espécies de Lippia cujo potencial farmacológico é desconhecido. Apesar da importância econômica como fonte de medicamentos e da representatividade de Lippia na flora aromática nativa, pouco se conhece sobre os aspectos estruturais e da secreção dos seus tricomas secretores. Neste trabalho foram estudados os tricomas secretores presentes em órgãos vegetativos e reprodutivos de L. stachyoides Cham. sob o ponto de vista morfológico, ontogenético, histoquímico e ultra-estrutural. Foram utilizadas técnicas convencionais em estudos anatômicos e ultra-estruturais; a identificação in situ da composição química das substâncias presentes nos tricomas foi realizada por meio de testes histoquímicos. Em L. stachyoides, os tricomas secretores são capitados e foram classificados em cinco tipos morfológicos, os quais são amplamente distribuídos no caule, folhas e inflorescências. A histoquímica revelou que nos tipos I e IV predominam substâncias hidrofílicas e nos tipos II e V, substâncias lipofílicas. De um modo geral, as características ultraestruturais observadas em cada tipo de tricoma corroboraram os resultados das análises histoquímicas. Os resultados do presente trabalho sugerem que as variações morfológicas dos tricomas secretores em L. stachyoides estão associadas com a composição química da secreção / Abstract: A feature of the family Verbenaceae is the presence of secretory trichomes, producers of essential oils with great medicinal value. Many species of Lippia Houst. are employed in phytotherapic and food complementation programs in Brazil, being L. alba and L. sidoides the most employed and studied species. The Brazilian cerrado has approximately 33 species of Lippia, whose pharmacological potential is unknown. Despite the economic importance of Lippia as a source of medicinal drugs and its representation in native aromatic flora, little is known about the structural and secretion features of its trichomes. In this work, the secretory trichomes, occurring in vegetative and reproductive organs of Lippia stachyoides Cham., were studied on the morphological, ontogenetic, histochemical and ultrastructural views. Usual techniques of vegetal anatomy and ultrastructure were employed; in situ identification of the chemical composition of the substances present in the trichomes was performed according to histochemical tests. In L. stachyoides, the secretory trichomes are capitate and classified according to five morphological types which are widely distributed in the shoot, leaves and inflorescences. The histochemistry revealed that in types I and IV, hydrophilic compounds are predominant and that lipophilic substances predominate in the types II and V. In general, the ultrastructural features observed in each trichome type corroborate the histochemical analysis. The results of this work suggest that morphological variations of secretory trichomes in L. stachyoides are associated to the chemical composition of the secretion / Mestre

Orientador: Vera Lucia Garcia Rehder / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-09T03:16:39Z (GMT). No. of bitstreams: 1 Araujo_JucemarySimplicio_M.pdf: 4127878 bytes, checksum: eb074da9b053d63e3abe078302afb0c6 (MD5) Previous issue date: 2007 / Resumo: Cordia verbenacea, (Boraginaceae), planta medicinal nativa do Brasil, apresenta em seu óleo essencial compostos com atividade antiinflamatória. Devido às suas propriedades terapêuticas, existe umgrande interesse na ampliação de estudos sobre a planta. O presente estudo investigou o efeito da nutrição mineral e do ácido jasmônico (AJ) no desenvolvimento da planta, na produção, composição química e teores de a-humuleno do OE. As plantas foram submetidas a tratamentos nutricionais com solução de Hoagland completa, omissão de N, K, P, B e suplemento de P e N. Durante o experimento foram observadas características de sintomas de deficiência nutricional. Após 90 dias de tratamento algumas características foram avaliadas como a altura das plantas e a área foliar, as plantas foram coletadas, o óleo essencial foi extraído por hidrodestilação e submetido à cromatografia a gás e espectrometria de massa. A deficiência em N foi mais limitante ao crescimento da planta. Sob esta deficiência a planta apresentou uma maior relação raiz/parte aérea, o que sugere uma maior alocação de recursos para a raiz numa situação de carência de N. A produção de folhas foi equivalente para a maioria dos tratamentos, com redução significativa no tratamento -P, suplemento de P (60 mg/L) e uma redução mais severa em -N. A omissão de B e K causou uma diminuição da absorção de P, provocando também um comprometimento nas estruturas de sustentação da planta. As plantas submetidas à omissão de P possivelmente apresentaram modulação dos sistemas de absorção deste nutriente, pois em um meio com maior escassez de P apresentaram maiores concentrações foliares deste elemento que nos tratamentos -B e -K. O suplemento de P (60 mg/g), foi o único tratamento nutricional em que se verificou um aumentou na produção de OE. Nos tratamentos com omissão no fornecimento de nutrientes esta produção foi menor. O percentual de a-humuleno foi equivalente entre a maioria dos tratamentos, contudo, o suplemento de P (60 mg/g), apesar do aumento do rendimento de OE, ocasionou uma queda no teor de a-humuleno. Duas horas após a aplicação de AJ foi verificado um aumento na produção de OE com a detecção de uma série de compostos ausentes no grupo controle, no entanto, os teores de a-humuleno não se alteraram. A escassez de estudos nutricionais sobre C. verbenacea não permite o estabelecimento de um estado nutricional adequado para a espécie, contudo, a planta aparentemente apresenta eficiência na absorção e utilização de nutrientes, pois mesmo em uma situação de omissão de nutrientes seu crescimento, produção de matéria seca, e taxa de crescimento relativo foram, em geral, pouco comprometidos / Abstract: The essential oil of Cordia verbenacea, a native Brazilian medicinal plant, presents anti-inflammatory properties. Due to its therapeutic properties, there is great interest in expanding research on it. The present study investigates the effect of mineral nutrition and jasmonic acid application on this plant's development, yield, chemical composition, and essential oil a-humulene concentration. The plants were submitted to nutritional treatments with Hoagland complete solution, N, K, P and B omission and P and N supplement. Nutritional deficiency symptoms were observed in the course of the experiment. After 90 days of treatment, some characteristics were evaluated, such as the plants' height and foliar area, plants were collected, and essential oil was extracted via hydrodestillation and submitted to gas chromatography and mass spectrometry. N deficiency was the most limiting factor in the plant growth. This deficiency presented a higher relation rate (root/shoot), suggesting that the lack of N affected shoot development. Lack of N showed a higher allocation of resources to the root rather than to the shoot. Leaf production was equivalent for most treatments, with significant reduction in -P treatment, P supplement (60 mg/L) and a more severe reduction in -N. B and K omission possibly caused a reduction in P absorption, also provoking alteration in the plant's sustaining structures. The plants submitted to P omission probably presented modulation in the nutrient absorption systems because in an environment with higher P scarcity, the nutrient presented higher foliar concentration levels of this element than in ¿B and -K treatments. The P supplement (60 mg/g) was the only nutritional treatment in which an essential oil yield increase was observed. The yield was lower in treatments with omission of nutrients. The percentage of a-humulene was equivalent among most treatments, yet the P supplement (60 mg/g), despite the increase in the essential oil yield, caused a decrease in the a-humulene content. Two hours after the AJ application, an increase in the production of essential oil was observed, with the detection of several compounds absent in the control group. Yet, the a-humulene percentage was not altered. The shortage of nutritional studies on C. verbenacea does not allow for the establishment of an adequate nutritional outline for this species. Nevertheless, the plant seems to present efficiency in the absorption and use of nutrients, for even in a situation of nutrients omission, its growth, dry mass production, and relative growth rate were not, in general, significantly compromised. / Mestrado / Biologia Vegetal / Mestre em Biologia Vegetal

The genus Lippia Houst. (family Verbenaceae Juss.) has been used medicinally for centuries in various cultures. Numerous traditional medicinal applications of the South African Lippias are known, and among these is Lippia scaberrima Sond., the "Beukesbossie". Products recovered from L. scaberrima include essential oils by means of batch microwave distillation and a herbal tea manufactured by various methods. Microwave heating occurs through direct absorbtion of input energy. The whole sample is heated simultaneously with a heating rate much faster than for water distillation. Microwave distillation times can be expected to be less than corresponding water distillation times. A large number of parameters influence essential oil composition and yield. Various geographical, climatic, botanical, production and other parameters were identified and listed. The natural distribution of airdried leaves and flower heads and water as solvent was used in a domestic type microwave oven. Microwave distillation production parameters were studied and optima determined with respect to maximum oil yield. The batch microwave distillation production parameters studied (irradiation time, ratio of water used to plant material used, plant material moisture content, solvent recycling, physical size of plant material, addition of a surface tension modifier, soaking as pretreatment, load size, distillation kinetics and alternative solution medium namely ethanol) lead to a better understanding of microwave essential oil production. It enabled design of prototype continuous microwave distillation apparatus. Mobile, continuous microwave distillation equipment enables extraction of essential oils in a rural environment. It allows rapid investigation of a large variety of plants, and retrieval of essential oils in an economical and uncomplicated manner. Water distillation represents a classical technique for essential oil retrieval whereas microwave distillation is probably the most modern method. Physical and chemical properties of microwave and water distilled oils were determined. This enabled comparison of the microwave technique to a standard, industrially accepted production method. Tea was manufactured from L. scaberrima by means of the green tea, Rooibos tea and black tea methods as a first iteration in the production of a commercial tea. Drying curves was developed as well as appropriate regions of production variables like withering- and fermentation temperatures and times. / Dissertation (PhD(Ing.Chem))--University of Pretoria, 2002. / Chemical Engineering / unrestricted

Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Sitophilus zeamais is a global important pest-insect, known for the losses that it causes during production and grain storage. One of the main problems caused by synthetic pesticides use is the development of resistant insect populations. Essential oils of plants have been considered a promising alternative to the conventional management of pests insects, however, its direct application has limitations due to the instability of its composition and high volatility. According to this, the technology of nanoformulations production can increase the potential of essential oil use, and its compounds, by increasing the efficiency, and stability of these compounds. The aim of this study was evaluate the lethal and sub lethal effects of Lippia sidoides essential oil, its majoritary compound (thymol), and nanoformulations of essential oil based prototypes, under S. zeamais populations (N = 5) from different regions of Brazil. The chemical composition of the essential oil, and nanoformulation was analyzed by GC/MS/DIC. The completely random design consisted in four replications for each combination of treatment x populations of S. zeamais. Bioassays of acute toxicity were conducted in Petri dishes (6 x 1,5 cm) with 10 unsexed adults. The lethal doses (LD50 and LD90), and the lethal time (LT50) were obtained through topic application bioassays. To the nanoformulation storage efficiency was used the LD95. On the population growth, and grain consume bioassays were used different concentrations of nanoformulations to mass grain treatment. The major compound present in the L. sidoides essential oil was thymol (68.5%). During nanoformulation storage, the concentration of these compound increased, getting to 82% of the essential oil composition. L. sidoides essential oil lethal doses, needed to kill 50% of S. zeamais populations, vary between 7.1 to 19.9 μg mg-1. Jacarezinho, and Maracaju populations were, respectively, the most tolerant and susceptible populations to L. sidoides essential oil. Intermediates susceptibilities were observed to Aracaju, Rio Branco, and Sete Lagoas populations. To thymol LD50 were observed variations between 17.1 to 25.7 μg mg-1. To nanoformulations prototypes (18%) containing L. sidoides essential oil, and thymol were observed LD50 variations between 26.4 to 36 e 20.8 a 27.7 μg mg-1, respectively. L. sidoides essential oil, thymol, and their nanoformulations had a fast action under S. zeamais populations. Lethal times needed to kill 50% of the population vary between 5.8 to 62 hours. In all of those cases, the nanoformulations took longer to cause the same mortality. The nanoformulations caused mortalities higher than 80% of S. zeamais populations of over 210 storage days. Nanoformulations increasing concentrations resulted on intrinsic tax (ri), and grain consume reduction of S. zeamais populations. This study prove that nanoformulations of L. sidoides oil essential based prototypes and its majoritary compound are promising alternatives to the management of S. zeamais once these demonstrated high efficacy, low liberation of the substances, and good storage stability. / Sitophilus zeamais é uma praga de importância mundial que ocasiona danos em grãos durante sua produção e estocagem. Um dos principais problemas da utilização de inseticidas organosintéticos, usados para o controle desta praga, consiste no desenvolvimento de populações de insetos resistentes. Óleos essenciais de plantas tem sido considerados uma boa alternativa ao manejo convencional, porém sua utilização direta apresenta limitações devido à instabilidade de sua composição e a alta volatilidade. Neste sentido, a tecnologia de produção de nanoformulações pode aumentar a potencialidade do uso dos óleos essenciais e seus compostos por aumentar a eficiência e a estabilidade destes compostos. No presente estudo analisamos os efeitos letais e subletais do óleo essencial de Lippia sidoides, de seu composto majoritário (timol) e de protótipos de nanoformulações a base destes compostos sobre populações de S. zeamais (N = 5) provenientes de diferentes regiões do Brasil. A composição química do óleo essencial e da nanoformulação foram analisadas por CG/EM/DIC. O delineamento experimental inteiramente casualizado, consistiu em quatro repetições para cada combinação de tratamento x população de S. zeamais. Bioensaios de toxicidade aguda foram conduzidos em placas de Petri (6 x 1,5 cm) contendo 10 adultos não sexados. As doses letais (DL50 e DL90) e o tempo letal (TL50) foram determinados em bioensaios de aplicação tópica. Para a eficiência do armazenamento das nanoformulações utilizou-se a DL95. Nos bioensaios de crescimento populacional e consumo de grãos foram utilizadas diferentes concentrações das nanoformulações para o tratamento da massa de grãos. O composto majoritário presente no óleo essencial de L. sidoides foi o timol (68,5%). Durante o armazenamento da nanoformulação esse composto aumentou, chegando a até 82% da composição do óleo. As doses letais do óleo essencial de L. sidoides necessárias para matar 50% das populações de S. zeamais variaram de 7,1 a 19,9 μg mg-1. As populações de Jacarezinho e Maracaju foram, respectivamente, a mais tolerante e susceptível ao óleo essencial de L. sidoides. Susceptibidades intermediárias foram observadas para as populações de Aracaju, Rio Branco e Sete Lagoas. O timol apresentou DL50 que variou de 17,1 a 25,7 μg mg-1. Os protótipos das nanoformulações (18%) contendo óleo essencial de L. sidoides e timol apresentaram DL50 que variaram de 26,4 a 36 e 20,8 a 27,7 μg mg-1, respectivamente. O óleo essencial de L. sidoides, o timol e suas nanoformulações atuaram rapidamente sobre as populações de S. zeamais. Os tempos letais necessários para matar 50% das populações variaram de 5,8 a 62 horas. Em todos os casos as nanoformulações demoram mais tempo para causar a mesma mortalidade. As nanoformulações causaram mortalidades superiores a 80% nas populações de S. zeamais até 210 dias de armazenamento. Concentrações crescentes das nanoformulações ocasiononaram redução da taxa intrínseca de crescimento (ri) e do consumo de grãos das populações de S. zeamais. Este trabalho comprova que os protótipos de nanoformulação a base do óleo essencial de L. sidoides e seu composto majoritário são promissores para o manejo de populações de S. zeamais uma vez que demonstraram alta eficácia, liberação lenta das substâncias e boa estabilidade no armazenamento.

The evolution of aerobic metabolic processes unavoidably led to the production of reactive oxygen species (ROS). ROS have the ability to cause harmful oxidative damage to biomolecules. Increased ROS generation and subsequent oxidative stress have been associated with aging and neurodegenerative disorders such as Parkinson’s and Alzheimer’s diseases as a result of the extreme sensitivity of the central nervous system to damage from ROS. Antioxidant defence systems have co–evolved with aerobic metabolic processes to counteract oxidative damage inflicted by ROS. The impact of neurodegenerative disorders on society is increasing rapidly as the life expectancy of the global population increases. In this day and age, a much younger group of the population is also experiencing neurodegenerative symptoms as a result of the harmful effect of the human immunodeficiency virus (HIV) on the central nervous system. Plants are an invaluable source of medicinal compounds. The use of plants for their healing properties is rooted in ancient times. The aim of this study was to select from twenty one plants, the plant with the most promising antioxidant activity and to determine whether extracts of this plant could act as free radical scavengers, comparing the results to Trolox, a known free radical scavenger. The next step was to isolate and characterize a compound from an extract exhibiting promising antioxidant activity. Bioassay–guided fractionation was followed to achieve this. During screening trials, twenty one plants, namely Berula erecta, Heteromorpha arborescens, Tarchonanthus camphoratus, Vernonia oligocephala, Gymnosporia buxifolia, Acacia karroo, Elephantorrhiza elephantina, Erythrina zeyheri, Leonotis leonurus, Plectranthus ecklonii, P. rehmanii, P. venteri, Salvia auretia, S. runcinata, Solenostemon latifolius, S. rotundifolius, Plumbago auriculata, Clematis brachiata, Vangueria infausta, Physalis peruviana and Lippia javanica were selected from literature, based on reported antioxidant activity within the plant families, for screening of their antioxidant activity. One hundred and ten extracts were prepared from the leaves, using Soxhlet extraction and the solvents petroleum ether (PE), dichloromethane (DCM), ethyl acetate (EtOAc) and ethanol (EtOH), consecutively. The focus during initial screening trials was on chemistry–based assays. The oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays were employed for the primary screening of the one hundred and ten leaf extracts. The ORAC assay was used to determine whether the plant extracts were able to scavenge peroxyl radicals and the FRAP assay was used to determine the reducing abilities of the extracts. Quantification of the peroxyl radical scavenging activity by the ORAC assay revealed that activity was observed for most of the extracts, with the ethyl acetate and ethanol extracts of L. javanica exhibiting the most promising activity. This pattern of activity was also found with the reducing capacity evaluated by the FRAP assay in which the EtOAc and EtOH extracts of L. javanica also exhibited the most promising activity. L. javanica was selected for further study by screening for biological activity, employing the nitro–blue tetrazolium (NBT) assay and thiobarbituric acid reactive substances (TBARS) assay. Using a cyanide model to induce neurotoxic effects in rat brain homogenate, the neuroprotective properties of the extracts of L. javanica leaves were examined using the NBT assay and compared to that of Trolox. The NBT assay determines the level of superoxide anions. All the extracts of L. javanica significantly reduced superoxide anion generation at all concentrations used. The petroleum ether and ethyl acetate extracts, at all concentrations, reduced superoxide anion generation to values lower than that of the control, suggesting that these extracts may be able to attenuate normal free radical processes in the brain. The petroleum ether extract exhibited the most promising activity at a concentration of 1.25 and 2.5 mg/ml and also exhibited similar results as the ethyl acetate extract at a lower concentration than the ethyl acetate extract (2.5 mg/ml compared to 5 mg/ml). A toxin–solution consisting of hydrogen peroxide (H2O2), iron(III)chloride (FeCl3) and ascorbic acid was used to induce lipid peroxidation and the ability of the extracts of the leaves of L. javanica to attenuate lipid peroxidation was investigated in rat brain homogenate and compared to that of Trolox. All of the extracts of L. javanica significantly attenuated toxininduced lipid peroxidation at all concentrations used. All of the extracts were also able to significantly attenuate toxin–induced lipid peroxidation to values lower than that of the control. These results suggest that all of the extracts of L. javanica possess the ability to attenuate not only toxin–induced lipid peroxidation, but also lipid peroxidation that occurs during normal processes in the brain. The petroleum ether extract was subjected to bioassay–guided fractionation using column and thin–layer chromatography and the NBT and TBARS assays. Fraction DD1 was investigated by means of nuclear magnetic resonance, infrared and mass spectrometry. The exact structure of fraction DD1 was not elucidated. Considering all the results, it is clear that L. javanica shows great potential as a medicinal plant with antioxidant activity and may therefore be beneficial in diminishing the destructive oxidative effects inflicted by free radicals. There are however still many compounds to be isolated from L. javanica. Key words: Verbenaceae, Lippia javanica, antioxidant, neurodegeneration, oxygen radical absorbance capacity (ORAC), ferric reducing antioxidant power (FRAP), nitro–blue tetrazolium assay (NBT), thiobarbituric acid reactive substances assay (TBARS). / Thesis (M.Sc. (Pharmaceutical Chemistry))--North-West University, Potchefstroom Campus, 2011.

The evolution of aerobic metabolic processes unavoidably led to the production of reactive oxygen species (ROS). ROS have the ability to cause harmful oxidative damage to biomolecules. Increased ROS generation and subsequent oxidative stress have been associated with aging and neurodegenerative disorders such as Parkinson’s and Alzheimer’s diseases as a result of the extreme sensitivity of the central nervous system to damage from ROS. Antioxidant defence systems have co–evolved with aerobic metabolic processes to counteract oxidative damage inflicted by ROS. The impact of neurodegenerative disorders on society is increasing rapidly as the life expectancy of the global population increases. In this day and age, a much younger group of the population is also experiencing neurodegenerative symptoms as a result of the harmful effect of the human immunodeficiency virus (HIV) on the central nervous system. Plants are an invaluable source of medicinal compounds. The use of plants for their healing properties is rooted in ancient times. The aim of this study was to select from twenty one plants, the plant with the most promising antioxidant activity and to determine whether extracts of this plant could act as free radical scavengers, comparing the results to Trolox, a known free radical scavenger. The next step was to isolate and characterize a compound from an extract exhibiting promising antioxidant activity. Bioassay–guided fractionation was followed to achieve this. During screening trials, twenty one plants, namely Berula erecta, Heteromorpha arborescens, Tarchonanthus camphoratus, Vernonia oligocephala, Gymnosporia buxifolia, Acacia karroo, Elephantorrhiza elephantina, Erythrina zeyheri, Leonotis leonurus, Plectranthus ecklonii, P. rehmanii, P. venteri, Salvia auretia, S. runcinata, Solenostemon latifolius, S. rotundifolius, Plumbago auriculata, Clematis brachiata, Vangueria infausta, Physalis peruviana and Lippia javanica were selected from literature, based on reported antioxidant activity within the plant families, for screening of their antioxidant activity. One hundred and ten extracts were prepared from the leaves, using Soxhlet extraction and the solvents petroleum ether (PE), dichloromethane (DCM), ethyl acetate (EtOAc) and ethanol (EtOH), consecutively. The focus during initial screening trials was on chemistry–based assays. The oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays were employed for the primary screening of the one hundred and ten leaf extracts. The ORAC assay was used to determine whether the plant extracts were able to scavenge peroxyl radicals and the FRAP assay was used to determine the reducing abilities of the extracts. Quantification of the peroxyl radical scavenging activity by the ORAC assay revealed that activity was observed for most of the extracts, with the ethyl acetate and ethanol extracts of L. javanica exhibiting the most promising activity. This pattern of activity was also found with the reducing capacity evaluated by the FRAP assay in which the EtOAc and EtOH extracts of L. javanica also exhibited the most promising activity. L. javanica was selected for further study by screening for biological activity, employing the nitro–blue tetrazolium (NBT) assay and thiobarbituric acid reactive substances (TBARS) assay. Using a cyanide model to induce neurotoxic effects in rat brain homogenate, the neuroprotective properties of the extracts of L. javanica leaves were examined using the NBT assay and compared to that of Trolox. The NBT assay determines the level of superoxide anions. All the extracts of L. javanica significantly reduced superoxide anion generation at all concentrations used. The petroleum ether and ethyl acetate extracts, at all concentrations, reduced superoxide anion generation to values lower than that of the control, suggesting that these extracts may be able to attenuate normal free radical processes in the brain. The petroleum ether extract exhibited the most promising activity at a concentration of 1.25 and 2.5 mg/ml and also exhibited similar results as the ethyl acetate extract at a lower concentration than the ethyl acetate extract (2.5 mg/ml compared to 5 mg/ml). A toxin–solution consisting of hydrogen peroxide (H2O2), iron(III)chloride (FeCl3) and ascorbic acid was used to induce lipid peroxidation and the ability of the extracts of the leaves of L. javanica to attenuate lipid peroxidation was investigated in rat brain homogenate and compared to that of Trolox. All of the extracts of L. javanica significantly attenuated toxininduced lipid peroxidation at all concentrations used. All of the extracts were also able to significantly attenuate toxin–induced lipid peroxidation to values lower than that of the control. These results suggest that all of the extracts of L. javanica possess the ability to attenuate not only toxin–induced lipid peroxidation, but also lipid peroxidation that occurs during normal processes in the brain. The petroleum ether extract was subjected to bioassay–guided fractionation using column and thin–layer chromatography and the NBT and TBARS assays. Fraction DD1 was investigated by means of nuclear magnetic resonance, infrared and mass spectrometry. The exact structure of fraction DD1 was not elucidated. Considering all the results, it is clear that L. javanica shows great potential as a medicinal plant with antioxidant activity and may therefore be beneficial in diminishing the destructive oxidative effects inflicted by free radicals. There are however still many compounds to be isolated from L. javanica. Key words: Verbenaceae, Lippia javanica, antioxidant, neurodegeneration, oxygen radical absorbance capacity (ORAC), ferric reducing antioxidant power (FRAP), nitro–blue tetrazolium assay (NBT), thiobarbituric acid reactive substances assay (TBARS). / Thesis (M.Sc. (Pharmaceutical Chemistry))--North-West University, Potchefstroom Campus, 2011.