The marama bean is an underutilised legume growing wild in the arid and semi arid regions of Southern Africa. Sorghum is an important cereal crop in arid regions of the world. The seed coats of marama beans and bran of sorghum contain antioxidant phenolic compounds with potential health benefits. Aqueous extracts for possible use as antioxidant functional food ingredient were prepared from seed coats of marama beans and bran of condensed tannin sorghum by extracting with water (water extract) or with water acidified to pH 2 (acidified water extract). Aqueous extraction was used in order to obtain an extract free from organic solvents, safe for human consumption, and containing compounds representative of those that are available under aqueous conditions of the gastrointestinal tract. The extracts were analysed for total phenolic content, total flavonoid content, condensed tannin content and protein precipitation capacity using spectrophotometric methods and for individual phenolic compounds using HPLC-MS. Proanthocyanidins were characterised using thiolysis degradation in conjunction with HPLC-MS. The antioxidant activities of the extracts were measured using ABTS, DPPH and ORAC assays. Extracts were also evaluated for protective effect against free radical induced human erythrocytes haemolysis, oxidative DNA damage and human LDL oxidation. Extracts from marama bean seed coats had significantly higher total phenolic content, total flavonoid content, condensed tannin content, protein precipitation capacity and phenolic compound concentration than equivalent extracts from condensed tannin sorghum bran. Three phenolic acids and three flavonols esterified to gallic acid were identified in the extracts from marama bean seed coats. Extracts from condensed tannin sorghum bran had six major phenolic acids, two phenolic aldehydes and three flavanones. Proanthocyanidins in extracts from marama bean seed coats were predominantly highly galloylated prodelphinidins while those in extracts from condensed tannin sorghum bran were procyanidins. Extracts from marama bean seed coats had higher antioxidant activity and protective effects against free radical induced erythrocyte haemolysis and LDL oxidation compared to equivalent extracts from condensed sorghum bran. Extracts from condensed tannin sorghum bran showed some protective effect against oxidative DNA damage. However, extracts from marama bean seed coats gave inconclusive results probably due to prodelphinidins binding to DNA. Extraction of marama bean seed coats under acidic condition resulted in reduction in phenolic compound content, antioxidant activity and protective effect against erythrocyte haemolysis, possibly due to co-precipitation of phenolic compounds with interpolymer complex precipitate formed between highly galloylated condensed tannins and cell wall polysaccharides at pH 2. In contrast, extraction of condensed tannin sorghum bran under the acidic condition resulted in an extract with significantly higher phenolic content and protective effect against erythrocyte haemolysis than the water extract possibly due to enhanced extraction of free and esterified phenolics and release of bound phenolic compounds. Water extracts and acidified water extracts (from marama been seed coats or sorghum bran) did not show significant differences in their protective effect against oxidative DNA damage and LDL oxidation. Extraction under acidic condition may be the preferred method for sorghum bran because it increases recovery of phenolic compounds, but not for marama bean seed coats because it causes reduction in phenolic compound content. The findings of this study show that the extracts have a potential to reduce oxidative stress which is implicated in many chronic diseases such as neurodegenerative diseases, cancer and cardiovascular disease. The extracts can be used in the development of functional foods with potential health benefits. / Thesis (PhD)--University of Pretoria, 2012. / Food Science / unrestricted

Peptides represent a source of novel therapeutics for recalcitrant human diseases, but screening for bioactivity from natural or synthetic sources can be uneconomic. In contrast, in vivo expression of peptides from DNA libraries in a heterologous host such as Escherichia coli may combine production with screening. This dissertation aimed to use such an approach to discover novel bioactive peptides in a high throughput and cost-effective manner, with a focus on antimicrobials and antiaggregants as proof-of-principle. Antimicrobial peptides (AMPs) are innate defence effectors that may combat antibiotic-resistant pathogens. An inducible, autocleaving fusion tag was utilised to produce the model murine cathelicidin K2C18, along with a number of variants, which exhibited varying degrees of antimicrobial activity against a panel of microbes. Importantly, K2C18 also exhibited a bacteriostatic effect in vivo when secreted to the periplasm. This allowed for the implementation of an in vivo whole cell screen for novel AMPs, using genomic DNA libraries as an input. One putative hit, the peptide S-H4, showed similar in vivo behaviour to K2C18 and was active when added exogenously to microbial cultures. A second in vivo screen was constructed to search for inhibitors of Aβ42 aggregation, a process implicated in Alzheimer’s disease. The aggregation state of Aβ42 was coupled to the fluorescence of a chromophore fusion partner, and used to screen co-expressed peptides from a random DNA library for putative antiaggregants. Additionally, the system incorporated an internal fluorescent reference to allow ratiometric comparison between samples. Several hits were identified and further validated using flow cytometry, with work ongoing to assess their activity in vitro. Proof-of-principle of these two screens was achieved, indicating that such in vivo approaches to bioactive peptide discovery could lead to the development of new and useful therapeutics.

Orientador: Glaucia Maria Pastore / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-27T14:34:07Z (GMT). No. of bitstreams: 1 Santos_MichelleTeixeira_M.pdf: 1463009 bytes, checksum: 0c5abfd78d15e4538a9e205ff81e3046 (MD5) Previous issue date: 2015 / Resumo: Cresce o número de consumidores que optam por hábitos mais saudáveis e melhor qualidade de vida, incluindo em sua dieta alimentos que exerçam funções essenciais para a promoção da saúde e prevenção de doenças. O Brasil possui uma das maiores biodiversidades do planeta, com fontes inexploráveis de alimentos, como frutas exóticas ricas em compostos bioativos com funções diversas e complementares. Neste sentido, o presente trabalho buscou investigar o potencial prebiótico e a presença de compostos antioxidante em frutas exóticas da Mata Atlântica como o Cambuí Roxo (Eugenia candolleana), Araçá Una (Psidium eugeniaefolia) e Araçá Morango (Psidium guianensis). A extração etanólica apresentou melhor performance em relação à analise dos oligossacarídeos nas frutas. A concentração de oligossacarídeos totais nestes extratos foi em media de 44; 14 e 46 mg/100g de fruta para Cambuí roxo, Araçá una e Araçá morango, respectivamente, sendo verificada através de cromatografia de íons acoplada a detector amperiométrico pulsado. Os oligossacarídeos que se destacaram na composição das frutas foram os fruto-oligossacarídeos GF2, a estaquiose e a maltotriose. Foi observado ao microscópio a formação de aglomerados e formações celulares do tipo rede nos cultivos indicando a formação de exopolissacarídeo por Lactobacilos acidophilus em meio enriquecido com os extratos da frutas analisadas. A produção máxima de EPS foi verificada em 24h de cultivo sendo de 45,39; 41,90 e 17,16 mg/100g de meio para o Cambuí roxo, Araçá una e Araçá morango, respectivamente. A concentração de fenólicos para as extrações alcoólicas foi em média de 685; 395 e 361 mg de ácido gálico/100g de fruta, respectivamente para o Cambuí roxo, Araçá una e Araçá morango. Os extratos das frutas exóticas da Mata Atlântica foram avaliados, ainda quanto à capacidade antioxidante in vitro através do método Oxygen Radical Absorbance Capacity (ORAC) apresentando teores médios de 3.212; 2.065 e 2.641µM Trolox equivalente/100g de fruta para Cambuí roxo, Araçá una e Araçá morango, nesta ordem. A importância da pesquisa de compostos bioquímicos em frutas exóticas tem como objetivo, além de populariza-las, promover uma maior variedade de alimentos, novos sabores, aliado a componentes funcionais que exercem benefícios, tais como atividade prebiótica no intestino humano e atividade antioxidante, principal causa de envelhecimento celular. Os resultados desta pesquisa mostram a riqueza de componentes que podem ser explorados destas frutas / Abstract: A growing number of consumers who choose for good health and better quality of life, including in your diet foods that acts essential functions for health promotion and disease prevention. Brazil has one of the greatest biodiversity on the planet with unusable food sources, such as exotic fruits rich in bioactive compounds with different and complementary functions. In this sense, the present study investigated the prebiotic potential and the presence of antioxidant compounds in exotic fruits of the Atlantic Forest as Cambuí roxo (Eugenia candolleana), Araçá una (Psidium eugeniaefolia) and Araçá morango (Psidium guianensis). The ethanol extract showed better performance in relation to the analysis of oligosaccharides in fruits. The concentration of total oligosaccharides in these extracts was an average of 44; 14:46 mg/100g of fruit to Cambuí roxo, Araçá una and Araçá roxo, respectively, and verified by ion chromatography coupled with pulsed amperiométrico detector. Oligosaccharides that stood out in the composition of fruit were the fructo-oligosaccharides GF2, stachyose and maltotriose. It was observed under the microscope the formation of agglomerates and mobile network type formations on crops indicating the formation of exopolysaccharide by Lactobacillus acidophilus amid enriched with extracts of fruit analyzed. The maximum production of EPS was observed in 24 hours of cultivation being 45.39; 41.90 and 17.16 mg/100g medium for purple Cambuí roxo, Araçá una and Araçá morango respectively. The concentration of phenolic for alcoholic extractions averaged 685; 395 and 361 mg of AG/100 g of fruit, respectively for purple Cambuí roxo, Araçá una and Araçá morango. The extracts of exotic fruits of the Atlantic Forest were evaluated, even as the antioxidant capacity in vitro through the Oxygen Radical Absorbance Capacity method (ORAC) having average levels of 3,212; 2065 and 2.641?M Trolox equivalent/100 g of fruit to purple Cambuí roxo, Araçá una and Araçá morango, in that order. The importance of research biochemicals in exotic fruits, aims, and popularized them, promote greater variety of foods, new flavors, combined with functional components that exercise benefits such as prebiotic activity in the human gut and antioxidant activity, leading cause of cellular aging. The results of this research show the richness of components that can be exploited these fruits / Mestrado / Ciência de Alimentos / Mestra em Ciência de Alimentos

This dissertation is concerned with the metabolic bioactivation of several amines which are either known or suspected to be neurotoxic and with the exploration of bioactivation processes in order to generate metabolites with therapeutic potential. The following three programs were pursued in this work: (1) Theoretical considerations and recent experimental data have prompted an investigation of the neurotoxicological properties of the 6-hydroxydopamine analog 2-methylamino-1-(2,4,5-trihydroxyphenyl) propane and its possible precursor intermediate 1-(2-hydroxy-4,5-methylenedioxyphenyl)-2-methylaminopropane, potential metabolites of the serotonergic neurotoxin 2-methylamino- 1-(4,5-methylenedioxyphenyl)propane, (Methylenedioxymethamphetamine, MDMA). The syntheses and serotonergic neurotoxic properties of the potential metabolites are discussed. (2) The further biotransformation of the 1-(1-phenylcyclohexy!)- 3,4,5,6-tetrahydropyridinium metabolite derived from_ the psychosis inducing agent phencyclidine [1-(1-phenylcyclohexy]l)- piperidine, PCP] has been examined in rat liver and brain subcellular fractions. In the presence of brain mitochondria this tetrahydropyridinium compound was converted to 1-(phenylcyclohexyl)- 1,2,3,4-tetrahydropyridine-5-carboxaldehyde. The same product was identified in the corresponding liver mitochondrial and microsomal incubation mixtures and in liver microsomal incubations of phencyclidine. The chemical conversion of the synthetic tetra hydropyridinium perchlorate to this product by N⁵-formyltetrahydrofolic acid (folinic acid) suggests that the metabolic reaction is mediated by a transformylation process involving this or the corresponding N¹⁰-formyltetrahydrofolic acid. (3) Extensive substrate-activity studies have established that only those 1,2,3,6-tetrahydropyridine derivatives bearing a lipophilic C-4 substituent and an N-methyl group are likely to be good monoamine oxidase B substrates. The design and synthesis of potential prodrugs based on this enzyme-substrate selectivity has been pursued with model compounds. / Ph. D.

No / This study investigated and characterised transdermal permeation of bioactive agents from a topically applied Arnica montana tincture. Permeation experiments conducted over 48 h used polydimethylsiloxane (silastic) and human epidermal membranes mounted in Franz-type diffusion cells with a methanol-water (50:50 v/v) receptor fluid. A commercially available tincture of A. montana L. derived from dried Spanish flower heads was a donor solution. Further donor solutions prepared from this stock tincture concentrated the tincture constituents 1, 2 and 10 fold and its sesquiterpene lactones 10 fold. Permeants were assayed using a high-performance liquid chromatography method. Five components permeated through silastic membranes providing peaks with relative retention factors to an internal standard (santonin) of 0.28, 1.18, 1.45, 1.98 and 2.76, respectively. No permeant was detected within 12 h of applying the Arnica tincture onto human epidermal membranes. However, after 12 h, the first two of these components were detected. These were shown by Zimmermann reagent reaction to be sesquiterpene lactones and liquid chromatography/diode array detection/mass spectrometry indicated that these two permeants were 11,13-dihydrohelenalin (DH) analogues (methacrylate and tiglate esters). The same two components were also detected within 3 h of topical application of the 10-fold concentrated tincture and the concentrated sesquiterpene lactone extract.

Bioassay directed fractionation of the methyl ethyl ketone extract of Crescentia cujete resulted in the isolation of nine bioactive compounds, and detailed spectroscopic interpretation led to the assignment of their structures as (2S,3S)-3-hydroxy-5,6-dimethoxy dehydroiso-α-Iapachone [2.10], (2R)-5,6- dimethoxydehydroiso-α-Iapachone [2.11], (2R)-5-methoxy dehydroiso-alapachone [2.12], 5-hydroxy-2-(1'-hydroxyethyl)naphtho[2,3-b ]furan-4,9-dione [2.13], 2-(1 '-hydroxyethyl)naphtho[2,3-b ]furan-4,9-dione [2.14]' 2-isopropenylnaphtho[ 2,3-b ]furan-4,9-dione [2.15], 5-hydroxydehydro-iso-a-Iapachone [2.16], 3-hydroxymethylfuro[3,2-b ]naphtho[2,3-d]furan-5,10-dione [2.17], and 9- hydroxy-3-hydroxymethylfuro[3,2-b ]naphtho[2,3-d]furan-5,10-dione [2.18]. Compounds 2.10-2.12 are new, showing selective activity towards DNA repair-deficient yeast mutants. The selective DNA damaging activity of known compounds 2.13-2.16 is reported herein for the first time. Compounds 2.17 and 2.18 also show DNA damaging activity, and possess a novel fused ring system. The bioactive sterols ergosta-5-24(28)-diene-3β,7α-diol [3.1] and 24,28- epoxyergost-5-ene-3β,7α-diol [3.2], originally isolated from <i>Pseudobersama mossambicensis</i>, have been synthesized from stigmasterol. In addition to these sterols, some of their analogs were prepared, and the bioactivity of all compounds were assessed. / Ph. D.

Thesis (M.Phil.) - University of Queensland, 2006. / Includes bibliography.

Bioactive glasses are a class of synthetic inorganic material that have wide orthopedics, dentistry, tissue engineering and other biomedical applications. The origin of the bioactivity is closely related to the atomic structures of these novel glass materials, which otherwise lack long range order and defies any direct experimental measurements due to their amorphous nature. The structure of bioactive glasses is thus essential for the understanding of bioactive behaviors and eventually rational design of glass compositions. In this dissertation, molecular dynamics (MD) and reverse monte carlo (RMC) based computer simulations have been used to systematically study the atomic structure of three classes of new bioactive glasses: strontium doped 45S5 Bioglass®, ZnO-SrO containing bioactive glasses, and Cao-MgO-P2O5-SiO2 bioactive glasses. Properties such as ionic diffusion that are important to glass dissolution behaviors are also examined as a function of glass compositions. The accuracy of structure model generated by simulation was validated by comparing with various experimental measurements including X-ray/neutron diffraction, NMR and Raman spectroscopy. It is shown in this dissertation that atomistic computer simulations, when integrated with structural and property characterizations, is an effective tool in understanding the structural origin of bioactivity and other properties of amorphous bioactive materials that can lead to design of novel materials for biomedical applications.

published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy