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Item Nanodelivery systems of thymoquinone for improving its bioavailability and efficiency in the food and biomedical applications(Elsevier B V, 2025-10-15) Shaddel R; Rashidinejad A; Karimkhani MM; Tarhan O; Jafari SMThymoquinone (TQ), a hydrophobic bioactive constituent of Nigella sativa seeds, has garnered attention for its potential in treating various ailments due to its antioxidative and anti-inflammatory properties. However, TQ's hydrophobicity, instability in varying pH environments, photosensitivity, rapid hepatic metabolism, and low bioavailability present major challenges for its application in pharmaceutical and nutraceutical formulations. Nanotechnology offers innovative nanocarriers that can overcome these limitations. Notable among these are lipid-based nanocarriers (e.g., nano-liposomes, nano-emulsions, niosomes, solid lipid nanoparticles, and nanostructured lipid carriers), biopolymeric systems (e.g., nano-hydrogels, nanofibers, nanotubes, and cyclodextrin inclusion complexes), and inorganic nanocarriers. These delivery systems are designed to enhance TQ's solubility, protect it from degradation, and improve its bioavailability and therapeutic performance. Despite numerous advances, the clinical and industrial translation of these nano-delivery systems remains limited, primarily due to scalability issues, regulatory constraints, and a lack of standardized evaluation protocols for food and biomedical use. This review provides a comprehensive analysis of these nanocarriers, emphasizing their mechanisms for TQ encapsulation, controlled release, and bioaccessibility enhancement. It also highlights current limitations and outlines future directions for their development. Unlike previous reviews, this work offers a comparative evaluation of nanocarrier systems for both food and biomedical applications, addressing their effectiveness, limitations, and readiness for real-world translation. The key takeaway is that among the various approaches, lipid-based and biopolymeric nanocarriers have demonstrated the greatest potential for enhancing TQ delivery, particularly in oral and functional food formulations, as well as targeted cancer therapy, due to their biocompatibility, scalability, and effective release profiles.Item Bioaccessibility and associated concepts: Terminology in the context of in vitro food digestion studies(Elsevier Ltd, 2025-09-01) Grundy MM-L; Deglaire A; Le Feunteun S; Reboul E; Moughan PJ; Wilde PJ; McClements DJ; Marze SIn vitro gastrointestinal models are widely used to study food digestion, in combination with analytical methods to determine the physicochemical and biochemical fate of food compounds. The in vitro bioaccessibility determined with these models is often used as an indicator of the in vivo bioavailability. However, the bioaccessibility concept is not used consistently within the scientific literature, leading to confusion and making it difficult to compare the results from different studies. The aim of this article is to provide standardized definitions of in vitro digestibility and bioaccessibility, detailing the main processes involved, including physical release, solubilization, and biochemical/metabolic reactions. The terminology of complementary cellular, ex vivo, and animal/human in vivo experiments is also given. Application of the in vitro terminology to different nutrients is discussed, including lipids, proteins, carbohydrates, vitamins, and other bioactive compounds. The proposed definitions unify most concepts related to the gastrointestinal fate of ingested food compounds.Item Whole-body protein kinetic models to quantify the anabolic response to dietary protein consumption(Elsevier Ltd d on behalf of European Society for Clinical Nutrition and Metabolism, 2021-04) Wolfe RR; Kim I-Y; Church DD; Moughan PJ; Park S; Ferrando AADetermination of whole body rates of protein synthesis, breakdown and net balance in human subjects still has an important role in nutrition research. Quantifying the anabolic response to dietary protein intake is a particularly important application. There are different models with which to accomplish this goal, each with advantages and limitations. The nitrogen (N)-flux method in which tracer is given orally has distinct advantages in terms of lack of invasiveness. In addition, the calculated results include all aspects of whole-body protein synthesis and breakdown. However, the prolonged timeframe of the method eliminates the possibility of the “pre-post” experimental design whereby each subject serves as their own control in the evaluation of the response to a meal. Models based on the primed-constant infusion of an essential amino acid (EAA) tracer enable the determination of baseline whole-body protein kinetics within 2 h, and can quantify a dynamic change from the basal state. The greatest challenge when using an EAA model is distinguishing exogenous and endogenous sources of the tracee in the blood. One approach is to use an intrinsically-labeled protein. This method has the advantage that the exogenous tracee is clearly distinguished from endogenous tracee. On the other hand, the intrinsically-labeled protein method suffers from unmeasured dilution that is likely to cause the systematic underestimation of the rate of appearance of exogenous tracee and thus overestimate the rate of whole-body protein breakdown. Alternatively, the “bioavailability” approach estimates the contribution of exogenous tracee to the peripheral circulation from the amount of tracee ingested, the true ileal digestibility of the tracee, and the irreversible loss of tracee prior to entry into the peripheral circulation. Errors in assumed values with the bioavailability method can potentially be significant, but are not likely to result in the systematic over- or under-estimations of rates of whole-body protein synthesis and breakdown. The optimal method depends on the degree of uncertainty regarding required assumptions in a particular circumstance. With all methods, it is advisable to calculate upper and lower bounds of whole body protein kinetics, in accord with reasonable maximal and minimal assumed values. Simultaneous use of two methods requiring different assumptions can also serve to confirm the validity of single approach.Item The role of holistic nutritional properties of diets in the assessment of food system and dietary sustainability(Taylor and Francis Group, 2023) Dave LA; Hodgkinson SM; Roy NC; Smith NW; McNabb WCAdvancing sustainable diets for nutrition security and sustainable development necessitates clear nutrition metrics for measuring nutritional quality of diets. Food composition, nutrient requirements, and dietary intake are among the most common nutrition metrics used in the current assessment of sustainable diets. Broadly, most studies in the area classify animal-source foods (ASF) as having a substantially higher environmental footprint in comparison to plant-source foods (PSF). As a result, much of the current dietary advice promulgates diets containing higher proportions of PSF. However, this generalization is misleading since most of these studies do not distinguish between the gross and bioavailable nutrient fractions in mixed human diets. The bioavailability of essential nutrients including β-carotene, vitamin B-12, iron, zinc, calcium, and indispensable amino acids varies greatly across different diets. The failure to consider bioavailability in sustainability measurements undermines the complementary role that ASF play in achieving nutrition security in vulnerable populations. This article critically reviews the scientific evidence on the holistic nutritional quality of diets and identifies methodological problems that exist in the way the nutritional quality of diets is measured. Finally, we discuss the importance of developing nutrient bioavailability as a requisite nutrition metric to contextualize the environmental impacts of different diets.Item Recent advances in the conjugation approaches for enhancing the bioavailability of polyphenols(Elsevier Ltd, 2024-01) Sahraeian S; Rashidinejad A; Golmakani M-TIn recent years, the consumption of functional foods containing health-beneficial ingredients has become increasingly popular. Polyphenols are among the most important functional and bioactive molecules found in a variety of fresh produce and food products. However, the limited solubility of most polyphenols in water can significantly affect their bioavailability, thereby reducing their potential health benefits. To overcome this limitation, various approaches have been explored, including molecular enhancers, nanoparticles, encapsulation systems, and conjugation methods. In this review, we focus on recent advances in conjugation methods for enhancing the bioavailability of polyphenols. We provide a concise overview of the types of polyphenols and bioavailability determination methods and, subsequently, discuss the concept of conjugation methods, including different synthesizing methods, confirmation procedures, and the effects of conjugation on polysaccharides and polyphenols. Overall, this review provides a comprehensive update on recent advances in conjugation methods that can be used to improve the bioavailability of polyphenols and highlights the potential of these approaches to enhance the health benefits of polyphenol-rich foods.Item Manipulating soil bioavailable copper as an innovative nitrate leaching mitigating strategy in New Zealand pastoral soils : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Soil Science, School of Agriculture and Environment, College of Sciences, Massey University, Palmerston North, New Zealand(Massey University, 2023) Matse, Dumsane ThembaUrine patches are the primary sources of nitrate (NO₃⁻ -N) leaching from pastoral dairy farms. Since NO₃⁻ -N is the product of nitrification, a clear understanding of the nitrification process is a vital step toward the development of effective and efficient mitigation approaches. The first step of ammonia (NH₄⁺) oxidation to hydroxylamine (NH₂OH) is catalyzed by the ammonia monooxygenase enzyme (AMO), and copper (Cu) is a co-factor in the activity of the AMO enzyme. Therefore, manipulating Cu bioavailability through the application of Cu-complexing organic compounds such as calcium lignosulphonate (LS) and co-poly acrylic-maleic acid (PA-MA) to soil could influence AMO activity and consequently limit the nitrification rate in soil. There are no published studies that have examined the effect of bioavailable Cu concentration changes on nitrification rate, ammonia-oxidizing bacteria (AOB) and archaea (AOA), and NO₃⁻ -N leaching. The overall aim of this thesis is to determine the significance of bioavailable Cu in the nitrification process in the context of developing novel Cu-complexing organic compounds to inhibit nitrification rate in pastoral soils. A soil incubation study was conducted to characterize the relationship between changes in soil bioavailable Cu concentration and nitrification rate. This study was conducted using three pastoral soils (Pumice, Pallic, and Recent soils) spiked with five Cu levels (0.1, 0.3, 0.5, 1, and 3 mg kg⁻¹). Treatments of Cu-complexing compounds were separately applied to each Cu level. The treatments were urea applied at 300 mg N kg⁻¹, urea + LS at 120 mg kg⁻¹, and urea + PA-MA at 10 mg kg⁻¹. Results show that increasing the added Cu concentration from 0.1 to 3 mg kg⁻¹ increased nitrification rate by 35, 22, and 33% in the Pumice, Pallic, and Recent soils, respectively. Application of LS and PA-MA significantly (P ˂ 0.05) decreased nitrification rate with the mean reduction being 59 and 56%, 32 and 26%, and 39 and 38% in the Pumice, Pallic, and Recent soils, respectively at Day 8 relative to the urea-only treatment. To further extend knowledge of the relationship between bioavailable Cu and the key nitrifying microorganisms in soils, a greenhouse-based pot trial using three soils (Pumice, Pallic, and Recent soils) planted with ryegrass and treated with synthetic urine applied at 300 kg N ha⁻¹ and three levels of Cu (0, 1, 10, 100 mg added Cu kg⁻¹) was established. Results show that AOB amoA gene abundance increased as a function of increasing added Cu from 1 to 10 mg kg⁻¹ but was inhibited at 100 mg added Cu kg⁻¹ in both Pallic and Recent soils. The effect of bioavailable Cu was not apparent in the Pumice soil. The increase in AOB amoA gene abundance positively correlated with nitrification rate in both the Pallic (r = 0.982, P < 0.01) and Recent soil (r = 0.943, P < 0.01) but not in the Pumice soil. There was no effect of increasing Cu concentration on AOA amoA gene abundance in all three soils. Results from both incubation and greenhouse pot trials provide strong evidence that Cu is an important trace element in the nitrification process and reducing Cu can reduce nitrification in soil. However, in order to definitively quantify this treatment effect, further field studies were necessary. Therefore, a field lysimeter study was conducted using Pumice soil (Manawatu climate) and Pallic soil (Canterbury climate). The following treatments were investigated to reduce NO₃⁻ -N leaching during late-autumn application; urine only at 600 kg N ha⁻¹, urine + PA-MA at 10 kg ha⁻¹, urine + LS at 120 kg ha⁻¹, urine + a split-application of calcium lignosulphonate (2LS at same rate, initial and after a month of first application), and urine + ProGibb SG (GA at 80 g ha⁻¹) + LS (GA + LS). Another set of treatment applications, urine only, urine + GA only, and urine + GA + LS, were applied mid-winter to both soils. The GA was applied to improve the effectiveness of these organic compounds during climatic periods of poor plant growth. Results showed that there was no significant reduction in mineral N leaching associated with the late-autumn application of both PA-MA and LS for the Pumice or Pallic soils. However, the application of 2LS reduced mineral N leaching by 16 and 11% in Pumice and Pallic soils, respectively, relative to urine-only. The late-autumn inclusion of GA increased the effectiveness of LS in both soils. This was confirmed by a significant reduction of mineral N leaching by 35% from both Pumice and Pallic soils. Mid-winter application of GA + LS significantly reduced mineral N leaching only in the Pumice soil (by 20%) but not in the Pallic soil relative to urine-only. In both late-autumn and mid-winter treatments application of the different Cu-complexing treatments did not have negative effects on pasture dry matter yield in either Pumice or Pallic soils. In this lysimeter study, the mechanistic effect of PA-MA and LS on reducing bioavailable, nitrification rate and AOB/AOA amoA gene abundance was not investigated. A second field lysimeter experiment was established using the Recent soil in Manawatu to explore the mechanism of Cu manipulation through the application of LS and PA-MA on nitrification rate, AOB/AOA amoA gene abundance, and mineral N leaching. The effect of combining organic inhibitors with GA on reducing mineral N leaching was also investigated. This study evaluated the same treatments used in the first lysimeter study and applications were again conducted at two different seasonal periods (late-autumn and mid-winter). The results showed that the effect of PA-MA and 2LS on bioavailable Cu corresponded with a reduction in nitrification rate and AOB amoA gene abundance. The effect of PA-MA and 2LS was associated with reduced mineral N leaching by values of 16 and 30%, respectively, relative to urine-only. The reduction in mineral N leaching induced by PA-MA and 2LS increased N uptake by 25 and 7.8% and herbage DM yield by factors of 11 and 8%, respectively, relative to the urine-only. The LS treatment did not induce a significant change of either bioavailable Cu or nitrification rate which corresponded to no significant effect on mineral N leaching. The late-autumn combination of GA + LS reduced mineral N leaching by 19% relative to urine-only, but there was no significant difference in mineral N leaching observed for the mid-winter application relative to urine-only. The overall results of this research show that bioavailable Cu is a vital trace element in the nitrification process and for AOB functioning in soil. Therefore, reduction in bioavailable Cu through the application of Cu-complexing compounds can inhibit nitrification. In this doctoral study, the application of Cu-complexing compounds (LS and PA-MA) showed potential to inhibit nitrification rate and subsequently reduce mineral N leaching in pastoral systems, but their efficacy depends on soil characteristics. Future work is recommended to investigate the effect of LS and PA-MA application on nitrous oxide emissions. Further research is recommended to investigate the short and long terms effects of these treatments on non-target soil microbiota.Item The economic significance of the phytoextraction of nickel, cobalt and gold from metalliferous soils : a thesis in partial fulfilment of the requirements for the degree of Master of Science at Massey University(Massey University, 2000) Keeling, Scott MPhytoextraction of heavy metals is a relatively new technology that has potential applications for the remediation of many contaminated sites around the world. The technology has significant applications in the minerals industry for the treatment of low-grade ores and metalliferous mine waste. This study concerns the investigation of the potential to remove heavy metals, in particular nickel, cobalt and gold, from artificial and lateritic substrates. Four experiments comprise this study of the phytoextraction of nickel, cobalt and gold using both accumulator and non-accumulator species. Nickel and cobalt bioavailability was determined by ammonium acetate extraction for both artificial and laterite substrates. It was found that ammonium acetate extractability was predictive for nickel accumulation from a nickel-only artificial substrate. Cobalt bioavailability did not predict the accumulation response of either Alyssum bertolonii or Berkheya coddii grown of artificial substrates. The potential for phytoextraction of nickel and cobalt was investigated using the known nickel hyperaccumulators A. bertolonii and B. coddii, grown on artificially prepared substrates. The substrates were nickel-only (4 mg/kg to 1000 mg/kg), cobalt-only (4 mg/kg to 1000 mg/kg) and nickel-cobalt mixed (1:1 ratio, 4 mg/kg to 500 mg/kg) amendments of sulphates to commercial potting mix. Hyperaccumulation from nickel-only and cobalt-only substrates resulted in typical logarithmic metal uptake by both species. The cobalt-only substrates were phytotoxic to B. coddii above a concentration of 15-20 mg/kg. Phytotoxicity significantly reduced biomass production in B. coddii without effecting the bioaccumulation coefficient. No corresponding cobalt phytotoxicity was observed in A. bertolonii over the experimental range, although biomass production appears to favour substrate concentrations below 30 mg/kg. The bioavailability and hyperaccumulation of cobalt from the mixed nickel-cobalt substrates dramatically reduced the nickel accumulation potential of both species at substrate concentrations below 300 mg/kg. At higher substrate metal concentrations both species return to nickel dominant hyperaccumulation. Induced gold accumulation in B. coddii and Iberis intermedia was investigated using, sequential ammonium thiocyanate and ammonium thiosulphate chelation to, a 5 mg/kg gold artificial substrate. An attempt to determine gold bioavailability by ammonium thiocyanate and ammonium thiosulphate extraction was made on the substrate. It was found that neither chelator extraction could be correlated with plant accumulation induced by the same concentration of the reagent. Ammonium thiocyanate induction resulted in plant gold accumulation at or below the substrate concentration. Ammonium thiosulphate induced gold accumulation in I. Intermedia reached 48.8 mg/kg when treatment with a 1% solution. B. coddii accumulated 9.3 mg/kg gold for the same treatment. Five consignments of metalliferous lateritic materials from Western Australia were investigated. Three substrates originated from Project Murrin Murrin nickel and cobalt mine operated by Anaconda Nickel Ltd. and two substrates originated from Boddington Gold Mine operated by Worsley Alumina Ltd. Nickel and cobalt accumulation by A. bertolonii and B. coddii was found to be significantly lower than observed using artificial substrates. Nickel and cobalt bioavailability, determined by ammonium acetate extraction, failed to predict the accumulation responses from laterite substrates. This is attributed to elemental interference by, and possibly ammonium acetate chelation of, other mobile heavy metals in these substrates. A hypothesis deserved of further research. Hyperaccumulation of nickel was observed for both species on the Anaconda Nickel Ltd. SAP substrate only. Appreciable cobalt accumulation (≈90 mg/kg) was observed on the SAP substrate for both species and on the Boddington Gold Mine B5 substrate for B. coddii. Phytomining scenarios were determined for both species grown on the SAP substrate. A. bertolonii could produce 13 kg of nickel and 0.8 kg of cobalt per hectare with a value of US$ 163. B. coddii could produce 23.8 kg of nickel and 2.1 kg of cobalt per hectare at a value of US$ 319. These levels of production could be improved by fertilisation and/or substrate acidification. A preliminary investigation into induced gold accumulation from laterite substrates by I. Intermedia, A. longiflora, Brassica juncea and Limum usitatissimum was made using the acid biased chelator ammonium thiocyanate. It was found that an acidified amendment of ammonium thiocyanate greatly improved the phytoaccumulation of gold from the lateritic substrates. An amendment of 2M HC1 produced appreciable gold mobility and phytoaccumulation and indicates that gold solubility is the primary control on plant uptake. Analysis of various plant tissues indicated that Acacia longiflora stored significant gold in its roots compared to foliar components. All plant-substrate combinations indicated a trend towards increasing acidification and gold phytoaccumulation. No plant-substrate-treatment combination produced an economically viable phytomining scenario.Item Antibacterial properties of diterpenes and their derivatives : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Microbiology at Massey University(Massey University, 1998) Nicolson, KirstyTotarol is a diterpene isolated in large quantities from P. totara and a range of other plants, that has been shown to possess significant antibacterial activity against Gram positive bacteria. It has not been possible to unequivocally determine the mode of action by which this activity occurs. This research aimed to determine the mode of action of the diterpene and study a range of derivatives to elucidate a structure-function relationship for the diterpene to enable directional synthesis of future derivatives possessing increased activity and bioavailability. The antibacterial activity of totarol and 29 derivatives was tested against H.pylori and S. aureus, two significant human pathogens,as representative Gram negative and Gram positive bacteria. Four compounds were found to possess significant activity against S. aureus, both MRSA and MSSA, although no significant activity was observed against H. pylori. The ability of the derivatives to potentiate the activity of existing β-lactam antibiotics such as methicillin was also investigated for MRSA and E. coli. Seven compounds including totarol were found to potentiate methicillin, one 256-fold, although no potentiation activity was exhibited against E .coli. The incorporation of radiolabelled precursors was used to investigate the effect of totarol on the synthesis of three macromolecules, DNA, protein and peptidoglycan, in MRSA. No primary inhibition was detected, indicating that the mode of action of the diterpene was not inhibition of synthesis of any of these macromolecules. The effect of totarol on the cellular respiration of MRSA was also investigated, showing 70 % inhibition of respiration at MIC levels, and complete inhibition of respiration at five times that concentration. It was therefore concluded that this was the most likely primary antibacterial effect of the compound. The effect of totarol on the production of PBP 2a, an important protein in theβ- lactam resistance mechanism of MRSA, was also investigated using a novel, non-radioactive labelling procedure to detect the protein. However, although a variety of strategies were employed to detect the protein, none were successful, and the experiment set aside until the arrival of anti-PBP 2a antibody for use in another strategy. Future work on this project that could be undertaken includes determination of the effect of the derivatives on cellular respiration under potentiation conditions, determination of the component(s) of the respiratory chain affected by totarol, and the investigation of the effect of the diterpene on PBP 2a production and function using antibody to detect the protein.Item Berry fruit anthocyanins in human nutrition : bioavailability and antioxidant effects : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Palmerston North, New Zealand(Massey University, 2006) Walton, Michaela C.Anthocyanins (ACNs), which are responsible for the red and blue colours displayed by many vegetables and fruits (particularly berries), belong to secondary plant metabolites, and are a component of our daily diet. There is an increasing interest on their biological activities as they are claimed to enhance health by protecting against some chronic diseases. However, before ACNs can perform health-promoting effects in vivo, they must first be sufficiently absorbed, distributed within the human body, and reach target tissues in adequate concentrations. To date, all studies investigating ACN absorption and metabolism came to the conclusion that their bioavailability is extremely low. To benefit from the proposed health effects of ACNs, their bioavailability, including absorption, metabolism, and excretion must first be understood. The main objective of this thesis was to provide further knowledge on ACN absorption, including the absorption site and mechanism, and the influence of food and other flavonoids on ACN absorption, as well as the investigation of their antioxidant effects in vivo. In vitro experiments using Ussing chambers showed that a strong absorption of ACNs occurred from the jejunum in mice. This was supported with a further in vivo study, where the major absorption site for ACNs may be the jejunum in rats. The limitation of ACN absorption to mainly one part of the intestine suggested the participation of a particular transport mechanism. In a further Ussing chamber study it was shown that flavonols, another common flavonoid group present in many fruits and vegetables, strongly inhibit ACN absorption, indicating a specific transport mechanism, with preference for other flavonoid compounds. Further in vivo studies have shown that the simultaneous ingestion of food components, such as breakfast cereals, resulted in a delayed absorption profile in two animal species. However, the additional food did not influence the antioxidant effect of ACNs. During a human intervention study, several measures of oxidative stress improved, but this improvement occurred equally in the treatments and placebo control, and may have resulted from changes in lifestyle. The results of these studies aid to understand details of ACN absorption and help to formulate future recommendations for ACN intake with increased bioavailability in humans.