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Semiochemicals released from logs infested by southern pine beetle (SPB), <i>Dendroctonus frontalis</i>, from a total of eight infestations located in Texas, South Carolina, and Virginia were collected four to eight days after initial attack. The quantities and chiralities of most semiochemicals, as analyzed by gas-liquid chromatography, showed geographic and temporal variations. Changes in the quantities of α-pinene (aP), frontalin (F), and <i>endo</i>-brevicomin (eB), are believed to result from responses of the host and the beetle to each other's activity at a given time and differences in their respective health. The chiralities of aP, F, and eB at all locations generally remained stable over time, yet variation across the insect's geographic range, particularly for aP and F, is believed to be due to genetic variation of individuals. Geographic and temporal variations in the quantities and chiralities of <i>cis</i>-verbenol (cV), <i>trans</i>-verbenol (tV), and verbenone (V) are presumed to be due to the multiple pathways of origin (SPB, autoxidation, and microorganisms). Analysis of the same semiochemicals isolated from hindguts of individual beetles from Texas, South Carolina, and North Carolina showed quantities of cV and tV to be substantially greater in females than in males; whereas, males contained much greater amounts of V. Geographic differences were found in quantities of tV and V in both sexes and in aP and F in males only. The chiralities of most semiochemicals present in SPB hindguts differed markedly from those released from infested logs. Males produced predominantly (+)-F and (-)-eB, (-)-cV, and (-)-V; however, the chirality of tV varied considerably among areas. In contrast, females produced predominantly (+)-cV and (+)-V and (-)-F, (-)-eB, and (-)-tV. The (+) enantiomer of aP predominated in both sexes, but the proportion of (+ )-aP was generally lower than that released from SPB-infested logs from the same areas. Geographic differences in chirality of tV and V were significant in males and for eB in females. In laboratory trials, aP autoxidized under ambient temperatures to form tV, myrtenol (M), V and to a lesser extent, cv. Both the quantities and chiralities of these compounds were dependent on the chirality of the aP precursor. Significantly greater amounts and proportions of the (+) enantiomer of each compound were produced when (+)-aP was predominant than when the antipode of the precursor was predominant. The extent to which autoxidation products playa role in bark beetle behavior is expected to be dependent on the proportion of aP in pine resin and its chirality present in a pine species. The information gained from this research was used to elaborate on previously proposed behavioral sequences occurring during the mass attack of host trees by SPB and to suggest new avenues to improve the use of semiochemicals in pest management efforts. / Ph. D.

Chapter 1 Hydrocarbon autoxidation, a free radical chain reaction, is believed to play a key role in the onset and developments of most degenerative diseases and disorders. The two propagating steps: 1) H-atom abstraction from the hydrocarbon by a hydrocarbon-derived peroxyl radical, and 2) addition of oxygen to the resultant alkyl radical to form a new peroxyl, play a role in determining the rate of hydrocarbon autoxidation, as well as the regio- and stereochemistry of the product hydroperoxides. In the current study, we carried out a set of calculations to provide a detailed framework for understanding the mechanism of the first two steps of autoxidation. Chapter 2 Radical-trapping chain-breaking antioxidants inhibit hydrocarbon autoxidation. Phenols are the prototypical radical-trapping antioxidants and are employed in nature, as well as in industry, to inhibit the autoxidation of hydrocarbons. The mechanism of inhibiting radical chain propagation has recently been suggested to be a PCET on the basis of theoretical calculations. It has been demonstrated that the antioxidant activitiy of phenols is increased in the presence of either protic acids or alcohols, but the basis of this acceleration is not well understood. In the current study, we used computational methods to investigate the effects of acids and alcohols on the PCET pathway for the reaction of phenol with a peroxyl radical. Chapter 3 The antibiotic pyrrolnitrin [3-chloro-4-(2’-nitro-3’-chlorophenyl) pyrrole] (PRN) is biosynthesized from L-tryptophan in four steps, catalyzed by the enzymes PrnA, B, C and D encoded by the prn operon. Two of the four gene products, PrnA and PrnC, are flavin-dependent halogenases, a recently discovered and highly interesting class of enzymatic halogenation catalysts. Their activities have never been unequivocally demonstrated by reconstitution of the activity from a recombinant protein. Herein, we report the results of our efforts to clone the genes encoding PrnA and PrnC, and overexpress, isolate and purify the proteins from E. coli. We were able to successfully reconsistute halogenation activity of both and have obtained the first kinetic data for PrnC, which shows kinetics similar to other flavin-dependent halogenases, along with substrate inhibition. / Thesis (Master, Chemistry) -- Queen's University, 2010-02-03 15:42:39.67

Orientador: Admar Costa de Oliveira / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-09T10:09:33Z (GMT). No. of bitstreams: 1 Santos_LiliaZagoFerreirados_D.pdf: 3274551 bytes, checksum: 903add15d9aa93e05454196d09939604 (MD5) Previous issue date: 2007 / Resumo: Ácido linoléico conjugado (CLA) é um conjunto de isômeros geométricos e posicionais do ácido linoléico, encontrado no leite, carnes e seus respectivos derivados. Desde a sua identificação como um agente anticarcinogênico, muitos outros efeitos lhe foram atribuídos; dentre eles, o efeito antioxidante, efeito um tanto quanto intrigante ao considerar que o CLA é um dieno conjugado, ou seja, um ácido graxo em sua fase inicial de autoxidação, mas com uma de suas ligas duplas conjugadas na forma trans. O objetivo desta Tese foi avaliar o efeito da suplementação com CLA, com e sem a presença de antioxidante, sobre o processo de autoxidação dos lípides biológicos, o conteúdo de lípides totais e a morfologia hepática de ratos Wistar saudáveis em crescimento. Foi realizado um ensaio biológico onde sessenta ratos foram divididos em seis grupos (n=10): grupos C (controle), CE (controle + vitamina E), AE (AdvantEdge® CLA), AEE (AdvantEdge® CLA + Vitamina E), CO (CLA One®) e COE (CLA One® + vitamina E). Os grupos controle C e CE receberam ácido linoléico e os grupos suplementados AE, AEE, CO e COE receberam misturas comerciais de CLA distintas cujo conteúdo médio de CLA era de 76,17 % com proporções semelhantes entre os isômeros trans-10, cis-12 e cis-9, trans-11. As condições de suplementação foram padronizadas em ensaio preliminar cujos resultados permitiram concluir que a melhor concentração de CLA a ser administrada, levando em consideração os aspectos operacionais e a resposta biológica, era de 2 % em relação ao consumo de dieta. Sendo assim, os ratos foram suplementados com 2 % de CLA por meio de entubação orogástrica durante 42 dias. Para os animais que receberam vitamina E em associação com o CLA, utilizou-se acetato de a-tocoferol na concentração de 30 mg / dia. Foram determinados índice de peróxido (IP), malondialdeído (MDA), 8-iso-PGF2a isoprostana e atividade da catalase como indicadores da autoxidação lipídica. O conteúdo total de lípides do fígado foi determinado e a morfologia do órgão foi analisada por meio de microscopia eletrônica de transmissão (MET). Os resultados demonstraram que a influência do CLA sobre o processo de oxidação dos lípides biológicos depende do tipo do suplemento e do indicador utilizado e seu respectivo local de determinação (tecido ou fluído corporal). Os valores de MDA sérico (AE: 1,80±0,67 mg MDA / kg; CO: 2,43±0,61 mg MDA / kg) e a atividade sérica da catalase (AE: 4734,23±1078,93 kU / L; CO: 5916,06±2490,71 kU / L) foram significativamente menores (P £ 0,05) em comparação com o controle (MDA: 3,85±0,24 mg MDA / kg; catalase: 10496,52±5121,84 kU / L), já os valores de 8-iso-PGF2a isoprostana foram maiores (P £ 0,05) para o grupo AE (urina: 95,13±20,26 pg / mL; plasma: 18,86±3,41 pg / mL) em relação ao controle (urina: 69,46±16,65 pg / mL; plasma: 13,84±3,55 pg / mL). Quanto ao IP, este foi maior (P £ 0,05) no grupo CO (84,38±10,97mEq / kg) em comparação com o grupo controle (54,75±9,70 mEq / kg). Em ralação à associação do acetato de a-tocoferol à suplementação com CLA, esta influenciou a ação do CLA sobre a oxidação dos lípides biológicos para os indicadores catalase, MDA hepático e 8-iso-PGF2a isoprostana urinária, de forma a diminuí-la. O conteúdo dos lípides hepáticos totais não aumentou nos ratos que receberam CLA (C: 23,93±3,64 %; AE: 21,19±2,05 %; CO: 21,16±0,90 %), embora as imagens obtidas por MET tenham demonstrado que houve aumento dos glóbulos de gordura em número e tamanho, aumento esse que não alterou a morfologia do órgão, visto que tanto o citoplasma quanto as organelas celulares estavam íntegras. Esses achados permitiram concluir que a suplementação com 2 % das misturas comerciais de CLA durante 42 dias influenciou o processo de oxidação dos lípides biológicos, no entanto, não foi possível estabelecer um consenso sobre seu efeito antioxidante/pró-oxidante visto a divergência dos resultados. Quanto às imagens hepáticas obtidas por MET, essas caracterizaram uma informação de natureza qualitativa, mas não menos importante, pois permitiu concluir que esse protocolo de suplementação com CLA não promeveu danos morfológicos ao órgão visto a integridade dos hepatócitos / Abstract: Conjugated linoleic acid (CLA) is a set of geometrical and positional isomers of the linoleic acid, found in milk, meats and their products. Since its identification as an anticarcinogenic agent, other effects have been attributed to it since, among them an antioxidant action -- a rather intriguing claim in view of the fact that CLA is a conjugated diene, i.e., a fatty acid in an early stage of autoxidation, but with one of its conjugated double bonds in the trans form. The objective of this Thesis was to assess the effect of CLA supplementation, both in the presence and in the absence of an antioxidant, on: (a) the process of biological lipid autoxidation, (b) the total lipid content, and (c) the hepatic morphology of healthy growing Wistar rats. A biological assay on sixty rats divided into six groups (n=10) was realized: C (control), CE (control + vitamin E), AE (AdvantEdge® CLA), AEE (AdvantEdge® CLA + Vitamin E), CO (CLA One®), and COE (CLA One®+ vitamin E). Control groups C and CE received linoleic acid, and supplemented groups AE, AEE, CO and COE received commercial CLA mixtures with a mean CLA content 76.17% and similar proportions of trans-10, cis-12 and cis-9, trans-11 isomers. A preliminary assay was conducted in order to standardize supplementation conditions; its results indicated that the best CLA concentration for administration, taking into account operational aspects and biological response, was 2% of diet intake. Rats were supplemented with that concentration of CLA by orogastric intubation for 42 days. For animals receiving vitamin E in combination with CLA, alpha-tocopherol acetate in the concentration of 30 mg/day was used. Peroxide index (IP), malondialdehyde (MDA), 8-iso-PGF2 alpha isoprostane, and catalase activity were determined as lipid autoxidation indicators. Total liver lipid content was determined, and organ morphology was examined by transmission electronic microscopy (TEM). Results demonstrated that the influence of CLA on the process of biological lipid oxidation depends on supplement type, on the chosen indicator, and on whether it is determined in a tissue or in a body fluid. Serum values of MDA (AE: 1.80±0.67 mg MDA / kg; CO: 2.43±0.61 mg MDA / kg) and catalase serum activity (AE: 4734.23±107893 kU / L; CO: 5916.06±2490.71 kU / L) were significantly lower (P <0,05) than in the controls (MDA: 3.85±0.24 mg MDA / kg; catalase: 10496.52±5121.84 kU / L), whereas 8-iso-PGF2 alpha isoprostane were higher (P <0.05) for AE (urina: 95.13±20.26 pg / mL; plasma: 18.86±3.41 pg / mL) than in the controls (urina: 69.46±16.65 pg / mL; plasma: 13.84±3.55 pg / mL). IP values were higher (P<0,05) for CO (84,.38±1097mEq / kg) than in the control (54.75±9.70 mEq / kg). Regarding the combination of alpha-tocopherol acetate and CLA supplementation, the presence of this antioxidant influenced the action of CLA on biological lipid oxidation as indicated by catalase, hepatic MDA and urinary 8-iso-PGF2 alpha isoprostane. Total hepatic lipid content did not increase in rats receiving CLA (C: 23.93±3,.64 %; AE: 21.19±2.05 %; CO: 21.16±0.90 %), although TEM images showed an increase in size and amount of fat globules; this, however, did not change organ morphology, as indicated by the fact that cell cytoplasm and organelles were undamaged. These findings allowed to conclude that supplementation with 2% of commercial CLA mixtures for 42 days influenced the process of biological lipid oxidation. However, no conclusion could be reached as to its anti-oxidant or prooxidant effect, because of inconsistencies in the results. Hepatic TEM images, even being a qualitative information, were nevertheless important, as they allowed to conclude that this CLA supplementation protocol did not cause any morphological damage to the organ, as indicated by the integrity of hepatocytes / Doutorado / Nutrição Experimental e Aplicada à Tecnologia de Alimentos / Doutor em Alimentos e Nutrição

Antioxidants are widely used to protect organic materials from damages caused by autoxidation, an oxidation process that occurs under normal aerobic conditions. In this thesis, novel multifunctional organoselenium and organotellurium antioxidants were designed, synthesized, and evaluated in search for compounds with better radical-trapping capacity, regenerability, and hydroperoxide-decomposing ability. Selenium was incorporated into ebselenols and hydroxy-2,3-dihydrobenzo[b]selenophenes and tellurium into diaryl disulfides and aryltellurophenols. All newly developed antioxidants were evaluated in a chlorobenzene/water two-phase lipid peroxidation system containing suitable co-antioxidants in the aqueous phase. Ebselenol carrying a hydroxyl group (OH) ortho to selenium showed a two-fold longer inhibition time than the reference α-tocopherol in the presence of aqueous-phase ascorbic acid. 2,3-Dihydrobenzo[b]selenophenes carrying a 5- or 7-OH outperformed α-tocopherol both when it comes to radical-trapping capacity and regenerability. Alkyltellurothiophenols, in situ formed from their corresponding disulfides by tris(2-carboxyethyl)phosphine, were also efficient regenerable radical-trapping antioxidants. The consumption of N-acetylcysteine in the water phase was followed and found to be limiting for the duration of the inhibition. The hydroperoxide-decomposing ability of all organoselenium antioxidants was evaluated. Ebselenols were often better glutathione peroxidase mimics than the parent. In an effort to find out more about antioxidant mechanisms, aryltellurophenols carrying electron donating and electron withdrawing groups in the phenolic or aryltelluro parts were synthesized and OH bond dissociation enthalpies, BDEO-Hs, were calculated. Compounds carrying electron donating groups in the phenolic or aryltelluro part of the molecule showed the best radical-trapping capacity. Deuterium labelling experiments suggested that hydrogen atom transfer could be the rate-limiting step in the antioxidant mechanism.

Autoxidation is a radical mediated chain-process that involves initiation, propagation, branching and termination reactions and is responsible for the spontaneous peroxidation of hydrocarbons, formally appearing as RH + O₂ → ROOH. Autoxidation is a consequentially damaging process in many domains, ranging from materials to automotive transportation to biology and medicine. One of the key intermediates in the propagation of autoxidation is the peroxyl radical (ROO•) which can be targeted by radical-trapping antioxidants (RTAs) that promote chain-termination, mitigating the damage of autoxidation. Chapter 1 lays out the fundamental chemistry of both autoxidation and RTAs as well as a history of the rational design of phenol and diarylamine-type RTAs. Lipid-peroxidation (i.e. autoxidation) is a key feature of ferroptosis which is a form of cell death that has been associated with many serious conditions such as ALS, Alzheimer's, Huntington's and Parkinson's disease, and lipid-soluble RTAs such as Vitamin E have been shown to acutely suppress ferroptosis. An aspect of RTA chemistry that has not been well studied/understood hitherto is their kinetic behaviour in phospholipid membranes, and we hypothesized that this would be a very relevant consideration for designing compounds that target lipid-peroxidation and ferroptosis. In Chapter 2 we systematically examine the kinetic behaviour for a series of hindered and unhindered phenolic RTAs in various mediums, particularly in phosphatidylcholine (PC) liposomes. The key chemical interaction in the PC membrane that fundamentally changed the observed kinetics of the phenolic RTAs is a very strong hydrogen-bonding interaction with the phosphate-diester headgroup that suppresses the phenols' ability to trap ROO•, an effect that was previously overlooked. In Chapter 3 we further expanded/validated the model by studying over 40 phenoxazine (PNX) and phenothiazine-based (PTZ) RTAs, which showed the quantitative/predictive capabilities of the H-bonding effect. By introducing a water-soluble co-antioxidant, Vitamin C (ascorbate), we were able to study many features of the PNX/PTZ radical intermediates with respect to their reactivity and dynamics. The PNX/PTZ were far more persistent than the Vitamin E analogue 2,2,5,7,8-pentamethyl-6-chromanol (PMC), meaning that they catalytically trapped lipid-peroxyls far more efficiently (i.e., higher turnover number). Additionally, there is strong evidence suggesting that the PNX/ascorbate synergism is a diffusion-controlled process. The study was further expanded to biological models. Ferroptosis in vitro was inhibited by every single one of these compounds, and there was a general positive correlation between RTA kinetics (kᵢₙₕ) and ferroptosis rescue potency (EC₅₀) as well as a positive correlation between lipophilicity (logP) and ferroptosis rescue potency. A lead PNX compound, 3-trifluoromethyl-8-tert-butylphenoxazine, was identified in this study on the basis of superior potency and metabolic stability. When used to treat mice with GPx4 deletion in kidneys, an in vivo model of ferroptosis, it was found to extend the life of the mice in a statistically significant fashion compared to the vehicle control. In Chapter 4 there is further elaboration on the dynamics of PNX/ascorbate synergy and a demonstration of the early works toward developing a drug-like-PNX ferroptosis inhibitor, based on the conclusions from the work in Chapter 3. In Chapters 5 and 6 the research is focused on the development novel RTAs for the application of inhibiting autoxidation in lubricants in high temperature environments. Heavy machinery and most transportation technologies require lubrication to aid safe and efficient movement, and these lubricants/greases are highly susceptible to autoxidation. Large quantities of RTA additives are expended to extend the service life of these materials and there is a constant appetite for innovation to find new and improved RTAs for improved economics and competitiveness. In Chapter 5 the behaviour of PNX and PTZ in a simulated high temperature lubricant autoxidations are analyzed, revealing that PNX is highly susceptible to direct O₂-mediated oxidation due to its rapid electron-transfer kinetics, while PTZ is far more resilient despite both compounds having nearly identical oxidation potentials. In Chapter 6, in this same context, previously unreported substituent effects are analyzed which significantly enhance the period of inhibition (tᵢₙₕ) for PTZ compounds. Particular alkyl substituents on the PTZ can increase the number of chains-trapped at high temperatures by fortuitous substituent oxidation that promotes termination, substantially improving their atom-economy. These findings prompt a broader critique of putative catalytic RTA mechanisms which have been taken for granted for nearly three decades.

The anti-inflammatory agent curcumin degrades rapidly, leading to speculations that curcumin’s reported effects stem from its degradation products. Curcumin can degrade via hydrolysis, and more recently it was discovered that curcumin can degrade via oxidation at physiological pH. Additionally, bicyclopentadione is the major degradation product from this oxidation reaction. Evidence from the literature suggests that curcumin degrades primarily through oxidation. However, the biology of the oxidation products is not well characterized, and there is debate on whether oxidation intermediates or curcumin itself is more biologically active. To further elucidate the biology of the oxidation products, their effects on inflammation were examined. RAW264.7 murine macrophage cells were stimulated with E. coli lipopolysaccharide (LPS) and treated with curcumin, curcumin’s total oxidative degradation products, and bicyclopentadione. Curcumin strongly decreased LPS-induced nitric oxide production and iNOS expression in a dose dependent manner; total degradation products slightly decreased nitric oxide production and iNOS expression, while bicyclopentadione failed to decrease either. Additionally, curcumin was significantly more effective than either bicyclopentadione or total degradation products in inhibiting COX-2 expression. iNOS and COX-2 arise from the activation of the NF-kB pathway, which curcumin is known to modulate; thus, the oxidation products’ effect on key proteins in this pathway was also examined. Neither total degradation products nor bicyclopentadione inhibited translocation of NF-kB into the nucleus, prevented degradation of IκBα, nor inhibited phosphorylation of IKK as effectively as curcumin. In conclusion, curcumin is significantly more effective at inhibiting inflammation than the oxidation degradation products.

Tilapia are freshwater fish that have become important in aquaculture and as a stable global source of seafood due to their ability to thrive in different environments. However, tilapia are sometimes considered nutritionally undesirable due to their high n-6 to n-3 fatty acid ratios. A market study was conducted first to determine fatty acid compositions in tilapia fillets in different US markets. Then a research was conducted to enhance nutritional value of tilapia by improving the n-3 and oleic acid contents in fish fillets without compromising fish growth or feed conversion ratios. Feeds were formulated with combinations of high and low n-6, n-3, and oleic acid levels using soybean oil, fish oil, algae oil, and high-oleic sunflower oil. Then 12 diets, including a commercial diet, were assigned to 24 tanks, each with 25 tilapia per tank. A Recirculating Aquaculture System (RAS) was used to grow the fish for 8 weeks. Fatty acid compositions of tilapia fillets were determined and samples were vacuum packed and stored at -10oC and -20oC to test oxidative degradation and fatty acid compositional changes. The market survey data showed that there were significant differences in fatty acid composition, lipid content, and n-6:n-3 fatty acid ratios depending on the country of origin. Samples from USA had ideal n-6:n-3 ratios (1.3 ±0.85) while samples from Southeast Asia had higher n-6:n-3 fatty acids ratio (6.6 ±0.54). Algae oil incorporation significantly increased DHA level while fish oil incorporation significantly increased both EPA and DPA. High-oleic sunflower oil based diets improved oleic acid levels and reduced linoleic acid compared to the soybean oil based diets. Sensory evaluation indicated that lipid source did not significantly impact preference or overall fillet quality, including texture. Interestingly, a survey showed people were interested in value-added tilapia, and would pay up to 30% more for nutritionally enhanced fish compared to the $5.00/lb fresh fillet price currently available in supermarkets. There was no observable oxidation during long term frozen storage. The oxidation study proved that value-addition would not be compromised during the long term storage conditions, even under temperature abuse. It is possible to improve tilapia nutritional quality through diet to provide consumers with value-added products that maintain quality during frozen storage. / Ph. D.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 2015. / Ovahimba people from Kunene region, northern Namibia, are known for covering their bodies with red ochre mixed with clarified butterfat, traditionally known as otjize to give them a distinct red appearance. Ochre refers to a clay-like earth pigment which contains some form of iron-containing mineral. A mixture of traditional herbs with clarified butterfat, otjizumba, is also applied around the necks as a perfume. This study was prompted by ethnographic interviews amongst the Ovahimba people which revealed functional uses of the traditional cosmetics, specifically the red ochre-derived cosmetic, as a mosquito repellent. Several analytical techniques were used to determine the presence of mosquito repellent compounds in the red ochre- derived cosmetic and the aromatic plant derived-cosmetic. GC-MS was used to identify the presence of compounds which have previously been found to have mosquito repellent capabilities. GC-MS analysis identified mostly oxygenated compounds which include ketones (2-dodecanone, 2-nanonone, 2-undecanone and 2-tridecanone), aldehydes (heptanal and nonanal) and carboxylic acids (hexanoic acid and heptanoic acid) in dichloromethane extracts of otjize and mostly hydrocarbons (o-cymene, α-pinene, limonene, and squalene) and less oxygenated compounds (terpinen-4-ol and α-campholenal) in plant derived cosmetic extracts. The chemical composition of the cosmetics was also analyzed using FTIR. FTIR analysis for organics in both cosmetics showed presence of vibrational motions including O-H, C=O, C-H, C=C and C-C which affirmed the presence of organic functional groups including aldehydes, ketones, esters, alkenes and alkanes. Peak patterns observed using GC-FID showed that the mixture of red ochre and clarified butterfat released higher quantities of volatiles than when individual samples were analyzed. Mineralogical composition of red ochre was determined by PXRD, supported by FTIR which revealed as significant amount of hematite (Fe2O3), the primary mineral responsible for the red hue of the ochre. Other major minerals including quartz (SiO2), kaolinite (Al2(Si2O5)(OH)4, calcites (CaCO3) and chalconatronite(Na2Cu(CO3)2.3H2O) were found to be present in the ochre powder. Elemental analysis of the ochre determined using EDXRF and ICP-OES supported mineralogical composition as iii Ovahimba red ochre exhibited high content of iron (Fe) and silicon (Si) and a significant amount of aluminum (Al), calcium (Ca) and copper (Cu). Based on % weight, presence of transition metals in red ochre powder identified using ICP-OES was observed in the descending order; Fe> V> Cu> Au> Ti> Zr. Based on the analysis carried out in this study, it is suggested that red ochre provides catalytic role, due to its diverse metal content especially the presence of transition metals including Fe and Cu, which might be influencing the production of secondary products during autoxidation of fatty acids present in otjize, specifically ketones and aldehydes. It was also concluded that the composition of clarified butterfat could be attributed to the release of mosquito repellent compounds in the red ochre derived cosmetic because when animal fat (kudufat) was used as an organic binder, the mixture did not release any of the identified possible mosquito repellent compounds. Keywords: Aldehydes, autoxidation, clarified butterfat, fatty acids, ketones, mosquito repellents, and red ochre

N,N,N\',N \'-tetrametil-p-fenilenodiamina (TMPD) catalisa a autoxidação de coenzimas piridínicos (NADH, NADPH) e modelos (ClBCH ,ClPCH ) ao cátion piridínico com rendimentos de 80-100%. A velocidade destas reações mostrou dependência de primeira ordem com respeito à concentração da 1,4-dihidronicotinamida e de meia ordem em relação às concentrações de O2 e TMPD. Estes dados cinéticos e testes com captadores de ion superóxido e superóxido dismutase indicam que os radicais HO&#8226;2 oriundos da autoxidação lenta do TMPD promovem a oxidação da dihidronicotinamida numa reação em cadeia; no término os radicais HO&#8226;2 se aniquilam por dismutação. O mecanismo proposto também é confirmado (1º) pela razão kC-H/kC-D=2,3 quando se substitui um dos hidrogênios do C4 de ClBCH por deutério, (2º) pelas idênticas velocidades iniciais em H2O e D2O, (3º) pelo valor da Ea = 10 kcal/mol na autoxidação do NADH e (4º) pelo aumento da velocidade de pH = 7,8 a pH 6,5. TMPD também promove a autoxidação do derivado 5, 6-hidratado (PHTN) da dihidronicotinamida ao cátion piridínico (ClPC+) apenas de fosfato ou arsenato estão presentes. O ClPC+ nã o se forma a partir do ClPCH em equilíbrio com o PHTN. Muito provavelmente se forma a partir do intermediário fosforilado no C6 por oxidação no C4 seguida de eliminação de fosfato. Quando PHTN e ClPCH foram oxidados pelo sistema O2/TMPD na presença de fosfato de piridínio ou de tetra-n-butilamônio em meio piridínico houve formação de pirofosfato, isolado por cromatografia de papel e por resina de troca aniônica. Adicionando-se ADP de tetra-n-butilamôneo ao sistema, constatou-se a formação de pirofosfato e de ATP com rendimentos mínimos de 5% e 3% , respectivamente. Por outro lado se a mistura de reação contém AMP de tetra-n-butilamôneo pôde-se verificar a formação de pirofosfato, ADP e ATP com rendimento total de 28% de \"ligações ricas\". A reação estudada foi proposta como modelo para síntese de ATP no sítio I da cadeia respiratória. / N,N,N\',N\'-tetramethyl-p-phenylenediamine (TMPD) catalyses the autoxidation of the pyridine coenzymes and of their models to the pyridinium form (80-100% yields). The first arder dependence of the rate upon the dihidronicotinamide concentration and half order upon both the O2 and TMPD concentrations, indicates that the relatively slow autoxidation of TMPD is the source of free radicals: dihydronicotinamide autoxidizes by the HO&#8226;2 chain mechanism and in the termination step the HO&#8226;2 radicals decay by dismutation. Such a mechanis is also supported by the inhibitory effects of cathecol, a scavenger of the HO&#8226;2 radical, and of superoxide dismutase, an enzyme which accelerates the dismutation of the O-2/ HO&#8226;2 species. The mecanism is further supported by (1) kC-H/kC-D=2,3 for substitution in 1-benzyl-1,4-dihydronicotinamide (ClBCH), (2) identical rates in H2O and D2O buffers, (3) Ea = 10 kcal/mole in the autoxidation of NADH and (4) the increase in rate from pH 7,8 to 6,5. TMPD promotes also the autoxidation of 1-n-propyl-6-hydroxy-1,4,5,6 - tetrahydronicotinamide (PHTN) to the 1-propyl-3-carboxamidopyridinium cation (ClPC+) provided phosphate ar arsenate are present. ClPC+ originates not from 1-n-propyl-1,4-dihydronicotinamide (ClPCH) in equilibrium with PHTN but most certainly from a C6 phosphorylated intermediate by oxidation at C4 and loss of phosphate. When PHTN an ClPCH were oxidated by the system O2/TMPD in the presence of pyridinium phosphate or tetra-n-butylammonium phosphate in pyridineas solvent, formation of pyrophosphate occurred. Pyrophosphate was isolated and identified by paper and ionic exchange resin chromatography. If tetra-n-butylammonium ADP is also present in the system, one can observe the formation of both pyrophosphate and ATP (5% and 3% minimum yields, respectively). In the presence of tetra-n-butylammonium AMP there, formation of pyrofosphate, ADP and ATP occurs. The total yield of energy rich bond is 28%. We suggest that the reaction is a model for the generation of the first ATP in the respiratory chain.