Most prawns are prepared as frozen or canned meat and the remaining waste is used as a feed supplement or directly disposed on to the land, which affects the environment. Fresh prawn bio-waste contains protein, astaxanthin, flavor compounds and chitin. The use of chitin in various applications is limited due to its water insolubility. In this research, a new method is developed to prepare water-soluble colloidal chitin (WSCC) from prawn waste. WSCC having the percentage of degree of deacetylation same with that of chitin follows non-newtonian shear thinning behaviour. The characteristic study showed that the breakage of polymer chains during processing thus reduced the molecular weight and bulk density of WSCC. Therefore, functional properties of WSCC can be controlled by optimizing the processing conditions. Astaxanthin complex has attracted considerable interest in relation to its health benefits because of its powerful antioxidant activity. Traditional extraction of astaxanthin complex from prawn waste using organic solvents requires post-purification steps, creates solvent disposal problem and degrades the pigment. This research develops an efficient way of recovering astaxanthin complex from prawn waste that eliminates the problems associated with solvent extraction methods and offers possible recyclability of the solvents used. Post-harvest blackening in prawns adversely affects both quality and consumer acceptability. However, consumer safety over the chemicals, especially sulphites used in inhibiting prawn blackening is of a major concern. This study shows that the antioxidant, astaxanthin complex can inhibit the poly phenol oxidase (PPO) catalyzed blackening reaction in prawns. Although prawns have astaxanthin complex present in their natural state, its concentration in vivo may not be sufficient to act against PPO. Therefore, astaxanthin complex-enriched feed in prawn culture may prevent prawn melanosis and may eliminate the post-harvest handling methods.

Most prawns are prepared as frozen or canned meat and the remaining waste is used as a feed supplement or directly disposed on to the land, which affects the environment. Fresh prawn bio-waste contains protein, astaxanthin, flavor compounds and chitin. The use of chitin in various applications is limited due to its water insolubility. In this research, a new method is developed to prepare water-soluble colloidal chitin (WSCC) from prawn waste. WSCC having the percentage of degree of deacetylation same with that of chitin follows non-newtonian shear thinning behaviour. The characteristic study showed that the breakage of polymer chains during processing thus reduced the molecular weight and bulk density of WSCC. Therefore, functional properties of WSCC can be controlled by optimizing the processing conditions. Astaxanthin complex has attracted considerable interest in relation to its health benefits because of its powerful antioxidant activity. Traditional extraction of astaxanthin complex from prawn waste using organic solvents requires post-purification steps, creates solvent disposal problem and degrades the pigment. This research develops an efficient way of recovering astaxanthin complex from prawn waste that eliminates the problems associated with solvent extraction methods and offers possible recyclability of the solvents used. Post-harvest blackening in prawns adversely affects both quality and consumer acceptability. However, consumer safety over the chemicals, especially sulphites used in inhibiting prawn blackening is of a major concern. This study shows that the antioxidant, astaxanthin complex can inhibit the poly phenol oxidase (PPO) catalyzed blackening reaction in prawns. Although prawns have astaxanthin complex present in their natural state, its concentration in vivo may not be sufficient to act against PPO. Therefore, astaxanthin complex-enriched feed in prawn culture may prevent prawn melanosis and may eliminate the post-harvest handling methods.

Konstanz, Univ., Diss., 2006.

Astaxanthin is a strong antioxidant with the ability of reducing the markers of inflammation. To explore the protective effect of astaxanthin on maternal ethanol induced embryonic deficiency, and to investigate the underlying mechanisms, we detected the morphology, expression of neural marker genes, oxidative stress indexes, and inflammatory factors in mice model of fetal alcohol spectrum disorder with or without astaxanthin pretreatment. Our results showed that astaxanthin blocked maternal ethanol induced retardation of embryonic growth, and the down-regulation of neural marker genes, Otx1 and Sox2. Moreover, astaxanthin also reversed the increases of malondialdehyde (MDA), hydrogen peroxide (H2O2), and the decrease of glutathione peroxidase (GPx) in fetal alcohol spectrum disorder. In addition, maternal ethanol induced up-regulation of toll-like receptor 4 (TLR4), and the down-streaming myeloid differentiation factor 88 (MyD88), NF-κB, TNF-α, and IL-1β in embryos, and this was inhibited by astaxanthin pretreatment. These results demonstrated a protective effect of astaxanthin on fetal alcohol spectrum disorder, and suggested that oxidative stress and TLR4 signaling associated inflammatory reaction are involved in this process.

Carotenoid utilization in rainbow trout (Oncorhynchus mykiss Walbaum) and Atlantic salmon (Salmo salar L.) has been investigated with respect to tissue distribution of carotenoids and the role of the liver on the bioavailability of the lipid soluble carotenoids, astaxanthin and canthaxanthin. Species-specific and tissue-specific accumulations were noted for astaxanthin and canthaxanthin in the rainbow trout and Atlantic salmon, possibly indicating fundamental differences in their utilization in these species. The liver and the kidney were revealed to be the major tissues involved in carotenoid metabolism in both rainbow trout and Atlantic salmon. Apparent digestibilities (-96% and -30% for rainbow trout and Atlantic salmon, respectively) and flesh carotenoid retentions (-12% and -5.4% for rainbow trout and Atlantic salmon, respectively) differed significantly between species, suggesting that rainbow trout are more efficient depositors of carotenoids within the flesh. Isolated rainbow trout liver perfusion experiments revealed small differences in the uptake of astaxanthin and canthaxanthin. Uptake of astaxanthin in both synthetically-derived and serum-derived models showed saturable uptake mechanism that occurred earlier than for canthaxanthin. These results can potentially offer an explanation for the better utilization of astaxanthin in rainbow trout, where the liver reduces the bioavailability of canthaxanthin through continued uptake. Results show a low hepatic extraction ratio (0.03-0.07), in line with published post-prandial elimination rates. Neither astaxanthin nor canthaxanthin significantly induced hepatic or renal xenobiotic-metabolizing enzymes in the rainbow trout, contrary to published reports in rats and mice. This may imply fundamental species-specific differences in the metabolic pathways for these carotenoids. Histochemical investigations revealed that both carotenoids significantly impacted liver structure, resulting in higher levels of total lipids and mucopolysaccharides. This is thought to be due to their antioxidant functions and their provitamin A activity. Carotenoid-treated fish also had higher levels of glycogen phosphorylase in liver sections, providing the first evidence in fish for the possibility of glucuronidation of their metabolites. The present investigations demonstrate the liver to be a major organ in carotenoid metabolism, and consequently affects carotenoid distribution and availability. In addition, carotenoid supplementation significantly affects liver structure and may potentially enhance its function. Furthermore, these investigations have provided new avenues of investigation into the use of isolated organ perfusions for biochemical nutrition research, and expanded the knowledge of liver physiology and biochemistry.

Tierärztl. Hochsch., Diss., 2004--Hannover.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The ocean’s fish resources are declining mainly because of irresponsible exploitation. Fish is a vital source of protein for humans and growing world populations are threatening the sustainability of commercial fisheries. This has led to the rapid growth of aquaculture worldwide. In South Africa, aquaculture of both fresh and marine species is expanding and is now practised in all nine provinces of the country. One of the major problems in aquaculture is the economic losses as a result of diseases. Viruses, bacteria, fungi and parasites are well known to infect fish, with bacteria causing the majority of diseases. Antibiotics were commonly used to control diseases, however, due to their negative impact on the environment, the use of these agents is questioned. This has led to the search for probiotics as an alternative way to control bacterial diseases in aquaculture. Probiotics used in aquatic environments can be defined as live microbial supplements which have beneficial effects on the host by altering the microbial communities associated with the host and the immediate environment. Probiotics have a variety of different mechanisms of action, including competition with pathogens, production of beneficial compounds, enhancement of host immune response and antiviral effects. This study aimed to isolate potential probiotic bacteria from the gastrointestinal tract (GIT) of the South African abalone (Haliotis midae). Nine different bacterial species were isolated and identified as Corynebacterium variabilei, Staphylococcus carnosus, Staphylococcus equorum, Staphylococcus cohniii, Vibrio aestuarianus, Vibrio nigripulchritudo, Vibrio cyclitrophicus, Photobacterium leiognathi, and Paracoccus marcusii (Chapter 2). One of these isolates, P. marcusii (isolate 6.15), showed promising probiotic properties together with the potential to be used as a pigmentation source due to its production of the carotenoid astaxanthin. Aquatic animals are not able to synthesize astaxanthin and under aquaculture conditions do not come into contact with natural pigment sources. This results in dark grey meat which is unappealing for consumers. Therefore, astaxanthin is included in the feed of a variety of aquaculture species such as salmon, trout, red see bream and shrimp to give the meat a pink/orange colour. Astaxanthin also plays an important role in other essential biological functions of fish such as increasing the defence potential against oxidative stress and enhancing sexual maturity, embryo development, and egg survival. Mozambique tilapia (Oreochromis mossambicus) and rainbow trout (Oncorhynchus mykiss), two important aquaculture species in South Africa, were used to evaluate the probiotic and pigmentation effect of P. marcusii (isolate 6.15). Fish feed was coated with freeze dried bacterial cells (107 CFU/kg feed) and administrated to tilapia and trout. Because tilapia cannot incorporate astaxanthin into their meat, no pigmentation effect of P. marcusii (isolate 6.15) was evaluated for this species. However, tilapia showed significant improvement in growth and immune parameters. Fish supplemented with P. marcusii (isolate 6.15) had a higher percentage increase in body weight and a better feed conversion ratio for the duration of the trial. Enhanced lysozyme activity in the blood serum of the fish was also seen (Chapter 3). In contrast, P. marcusii (isolate 6.15) did not have any probiotic or pigmentation effect on rainbow trout. A possible reason for this may be that the concentration of P. marcusii (isolate 6.15) added to the feed was too low. More probably, it is suspected that no pigmentation was observed due to the destruction of the astaxanthin before being ingested by the trout, because astaxanthin is a very unstable molecule. Furthermore, the GIT microbial communities of trout were investigated over the duration of the trial for the different treatments. No similarities in community structures were observed betwee the different treatments, however, bacterial communities in the GIT of fish sampled at the same time were very similar (Chapter 4). / AFRIKAANSE OPSOMMING: Die oseaan se vis hulpbronne is besig om af te neem as gevolg van die onverantwoordelike gebruik daarvan. Vis is ‘n belangrike bron van proteïene vir mense en die toenemende wêreld populasie bedreig die volhoubaarheid van kommersiële visserye. As gevolg hiervan is daar ‘n drastiese toename in die akwakultuur industrie wêreldwyd. Ook in Suid Afrika brei die akwakultuur van beide vars water en mariene vis spesies uit. Een van die grootste probleme in akwakultuur is ekonomiese verliese as gevolg van siektes wat veroorsaak word deur virusse, bakterieë, fungi en parasiete. Bakterieë veroorsaak die meerderheid van die siektes en antibiotika word algemeen gebruik vir die beheer van bakteriële siektes. Die gebruik van antibiotika word egter bevraagteken omdat dit verskeie negatiewe implikasies vir die omgewing inhou Daarom word probiotika oorweeg as ‘n alternatief tot antibiotika om bakteriële siektes te voorkom en te behandel. Probiotika wat in akwatiese omgewings toegedien word kan gedefinieer word as a lewende mikrobiese aanvulling wat ‘n positiewe effek op die gasheer het, deur die mikrobiese gemeenskappe geassosieer met die gasheer en die ommidellike omgewing te verander. Hierdie mikrobiese aanvulling verbeter die gesondheid van die visse deur verskeie meganismes wat insluit kompetisie met patogene, produksie van voordelige chemiese verbindings, verhoging van die gasheer se immuniteit en antivirale effekte. Die doel van hierdie studie was om potensiële probiotika te isoleer uit die spysverterings kanaal (SVK) van die Suid Afrikaanse perlemoen spesie, Haliotis midae. Tydens die studie is daar nege verskillende bakteriële spesies geïsoleer en geidentifiseer as stamme verteenwoordegend van Corynebacterium variabilei, Staphylococcus carnosus, Staphylococcus equorum, Staphylococcus cohniii, Vibrio aestuarianus, Vibrio nigripulchritudo, Vibrio cyclitrophicus, Photobacterium leiognathi en Paracoccus marcusii (Hoofstuk 2). Een van die isolate, P. marcusii, het belowende probiotika en potensiële pigmentering eienskappe getoon a.g.v. die produksie van die karotenoïed astazantien. Akwatiese diere is nie daartoe instaat om hierdie pigment te produseer nie en onder akwakultuur toestande kom die visse ook nie in kontak met natuurlike bronne van hierdie pigment nie. Dit lei daartoe dat die vleis van visspesies soos forel en salm grys word wat dit onaantreklik vir verbruikers maak. Daarom word astazantien bygevoeg by visvoer om sodoende ‘n pienk/oranje kleur te verseker.Daar benewens speel astazantien ook ‘n rol in belangrike biologiese funksies van visse. Dit sluit in die verhoging in beskerming teen oksidatiewe stres, bevordering van seksuele volwassenheid, embrio ontwikkeling en eier oorlewing. Twee belangrike akwakultuur spesies in Suid Afrika, Mosambiek tilapia (Oreochromis mossambicus) en reënboog forel (Oncorhynchus mykiss), was in hierdie studie gebruik. Die probiotiese en pigmentasie effek van P. marcusii op reënboog forel was gëevalueer terwyl slegs die probiotiese effek op tilapia geëvalueer weens die onvermoeë van tilapia om die pigment in hul vleis te inkorpereer. Visvoer korrels was omhul met gevriesdroogde bakteriële selle (107 CFU/kg kos) en vir die visse gevoer. Daar was ‘n duidelike verbetering in groei en immuun parameters van tilapia. Visse toegedien met P. marcusii het ‘n hoër persentasie vermeerdering in liggaamsgewig en ‘n beter voedsel omsettings verhouding gehad tydens die verloop van die proef in vergelyking met die kontroles (Hoofstuk 3). In kontras hiermee kon daar geen probiotiese of pigmenterings effekte waargeneem word by die reënboog forel nie. ‘n Moontlike rede hiervoor kon wees dat die konsentrasie van P. marcusii wat by die kos gevoeg is te laag was. Dit is egter ook moontlik dat die astazantien vernietig was voordat dit deur die forel opgeneem is aangesien astazantien ‘n baie onstabiele molekuul is. Verder het ons die impak van verskillende visvoer behandelings op die mikrobiese gemeenskappe in die spysverteringskanaal (SVK) van forel tydens die verloop van die proef bestudeer. Geen ooreenkomste in mikrobiese gemeenskap strukture in die forel SVK is waargeneem tussen die verskillende voer behandelings nie, maar daar is wel ooreenkomste gevind tussen die mikrobiese gemeenskappe van visse by spesifieke tyd intervalle (Hoofstuk 4).

Une présence en excès d'espèces réactives oxygénées induit un déséquilibre redox cellulaire pouvant conduire à des pathologies liées au stress oxydatif, notamment les pathologies cardiovasculaires. Connue et étudiée pour ses propriétés antioxydantes, l’astaxanthine, molécule de la famille des caroténoïdes, présente un intérêt thérapeutique potentiel. Cependant, sa structure chimique lui confère un caractère hydrophobe ainsi qu’une sensibilité à l’air, à la lumière et à la chaleur. Dans cette thèse, tout d’abord, un système de complexation de l’astaxanthine avec l’hydroxypropyl-b-cyclodextrine a été élaboré (CD-A). Nous démontrons que cette complexation améliore la stabilité de l’astaxanthine en solution aqueuse tout en préservant ses activités antioxydantes, mesurées par des méthodes chimiques et biologiques. L’action du CD-A semble être médiée par les voies de signalisation PTEN/AKT, Nrf2/OH1/NQO1 dans des cellules endothéliales soumises au stress oxydatif. Puis, afin de libérer l’astaxanthine in situ sur le site du stress, nous avons élaboré deux systèmes de type matriciel en PVA/dextrane ou en pullulane/dextrane chargés en CD-A. Nous avons évalué, comme preuve de concept, la faisabilité de ces dispositifs pour le traitement local de la pathologie d’ischémie/reperfusion. Les patchs de PVA/dextrane/CD-A ont montré une bonne compatibilité in vitro, ainsi qu’une grande stabilité et tenue mécanique sans modification des propriétés antioxydantes. Leur biocompatibilité in vivo et suturabilité au muscle cardiaque ont aussi été étudiées. Le deuxième système à base de pullulane/dextrane/CD-A a été évalué in vitro et in vivo dans un modèle d’ischémie/reperfusion du membre inférieur à différentes périodes d'implantation. Les résultats ont montré l’activation d’un mécanisme de défense normal lié à la présence d’un matériel étranger et une diminution de la translocation du Nrf2 pouvant indiquer un effet protecteur dans les tissus traités par le CD-A. Ce manuscrit présente des arguments en faveur du potentiel thérapeutique de systèmes de libération d’astaxanthine agissant au niveau du stress oxydatif lié aux pathologies cardiovasculaires. / An over concentration of reactive oxygen species induces a redox imbalance within the cell inducing oxidative tissue damage and leading to oxidative stress related diseases, particularly cardiovascular pathologies. Astaxanthin, a well-known and studied antioxidant molecule, member of the xanthophyll carotenoid family, presents an important therapeutic potential. However, the chemical structure confers to astaxanthin a hydrophobic character and renders it susceptible to air, light and temperate degradation. During this thesis, a carrier system based on astaxanthin inclusion within hydroxypropyl-β-cyclodextrin(CD-A) was developed. We demonstrate that after astaxanthin inclusion, not only its stability was enhanced by also the antioxidant scavenging capabilities were preserved, confirmed by chemical and biological tests. The action of CD-A seems to be mediated by PTEN/AKT, Nrf2/OH1/NQO1 signaling pathways of endothelial cells submitted to oxidative stress. Then, two systems based on PVA/dextran and Pullulan/Dextran loaded within CD-A were evaluated for astaxanthin in situ delivery in the stressed environment. The feasibility of using these systems in the local treatment of ischemia/reperfusion injury was evaluated as a proof of concept. PVA/Dextran patches showed good in vitro compatibility, high mechanical and stability properties, while preserving CD-A antioxidant capabilities, also the path suturability to the cardiac muscle and the in vivo biocompatibility were studied. The second system based on pullulan/dextran scaffolds were evaluated in vitro and in vivo in an ischemic/reperfusion model at different implantation periods. Results showed an inner body defense mechanism to foreign materials. Additionally, the Nrf2 translocation could indicate a protective effect of CD-A in treated tissues. This manuscript provides a support evidence of the therapeutic potential of CD astaxanthin delivery system, to act against oxidative stress linked to cardiovascular conditions.

Parkinson’s disease is the second common neurodegenerative disease and is most frequently diagnosed in individuals over 60. There are no available medications that can prevent or restore the loss of neurons that correspond to motor impairments in patients. Identifying novel therapeutic compounds that are capable of slowing and reversing the extensive neurodegeneration that occurs in PD remains an important goal of the field. While basic research has identified potential therapeutic agents, studies often use young model organisms to demonstrate efficacy of the target compound. This approach ignores the impact of the aged CNS on the disease process, and likely contributes to high failure rates of translation in clinical trials. Here we investigate the capacity for astaxanthin (AXT), a xanthophyll carotenoid, to attenuate the neurotoxicity to MPTP, a toxin routinely used to establish parkinsonian symptoms in mice. We show that AXT reduces MPTP induced neurotoxicity in young, but less effective in the aged animals. While AXT is an interesting neuroprotective capacity, there are also multiple reports that indicate AXT may preserve cognitive function in the context of neurodegeneration and neural injury, the impact of AXT under physiological conditions and in the aged CNS has been largely uninvestigated. We also evaluate the effect of AXT on cognitive function in young and aged mice. Here, we show that AXT supplementation can modulate neural plasticity is associated with improved performance in cognitive behavioral tasks. This diet effect was observed in both young and aged mice, suggesting a novel and direct mechanism of action in synaptic function.

Corn gluten meal (CGM) is a high protein (60% crude protein), highly digestible feed ingredient widely used in diets for salmonids, however its use has been related to reduction in muscle pigmentation possibly due to pigment interaction. Therefore, laboratory scale and in vivo trials were conducted to reduce pigment level in CGM and to assess its effect on fish muscle pigmentation, respectively. In the first chapter, a bench-scale study was carried out to investigate factors that affect bleaching of carotenoids in CGM, using white soy flake flour (WSFF) as a lipoxygenase (LOX) source. Plackett-Burman and Box-Behnken designs were used to screen and optimize factors, respectively. Furthermore, a 12-week growth trial was conducted in order to assess the effects of dietary regular and pigment bleached CGM on growth and muscle pigmentation of rainbow. In the second chapter, a 24-week growth trial was carried out in order to assess the effects of increasing levels of CGM on growth and muscle pigment deposition in rainbow trout. In the third chapter, a bench-scale (10 g) corn wet milling procedure was used to assess the bleaching of carotenoids from CGM during steeping. Studies from this thesis confirmed the negative effects of CGM on fillet pigmentation and highlighted the need for evaluation of muscle quality traits such as colour in response to inclusion of new feed ingredients. Furthermore, this thesis gives insight on how to reduce pigments from corn gluten meal using cost-effective and practical bleaching approaches.