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    Smoking, coffee intake, and Parkinson's disease: Potential protective mechanisms and components.
    (Elsevier B.V., 2024-12-20) Hong SW; Page R; Truman P
    Parkinson's disease (PD) is a common progressive neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Environmental and lifestyle factors, such as smoking and coffee drinking, have been associated with a decreased risk for PD. However, the biological mechanisms underlying protective effects on PD are still not fully understood. It has been suggested that non-nicotine components in cigarette smoke and non-caffeine components in coffee may contribute to this protective effect. The aim of this review was to explore candidate molecules and mechanisms behind the effects of smoking and coffee drinking on PD by integrating findings from previous studies. By cross-referencing an index of tobacco constituents and a list of coffee constituents with existing literature on natural compounds and their structural analogs that show inhibitory activities against monoamine oxidase B, catechol O-methyltransferase, and α-synuclein fibrillation, we have identified tobacco and coffee components that inhibit these targets. Furthermore, tobacco and coffee components potentially play roles in suppressing neuroinflammation, activating the Nrf2 pathway as natural activators, and altering the gut microbiome. This review suggests that the phenolic compounds from tobacco and coffee investigated may contribute to the low incidence of PD in smokers and coffee drinkers, showing moderate to strong potential as therapeutic interventions. The current review suggests that multifunctional molecules found in coffee and cigarette smoke may have potential neuroprotective effects, but none of the data indicates that multifunctionality is required for these effects. This review will deepen our understanding of how smoking and coffee drinking are linked to a reduced risk of PD and will also be important in elucidating the mechanisms underlying the protective effects of smoking and coffee drinking on PD.
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    Phenolic compounds from macadamia husk: An updated focused review of extraction methodologies and antioxidant activities
    (Elsevier Ltd on behalf of the Institution of Chemical Engineers, 2024-12) Ahmed MF; Popovich DG; Whitby CP; Rashidinejad A
    This review explores the potential of agri-food waste materials, with a particular focus on macadamia nut by-products. Industrial processing of macadamia nuts yields a significant volume of by-products, including green husk and woody shell. Recent research has highlighted these by-products as readily available, cost-effective rich sources of phenolic compounds, renowned for their potent antioxidant and antibacterial properties. This paper emphasizes the importance of selecting an optimal extraction method to fully harness the bioactive potential of these phenolic compounds. In this work, we provide a comprehensive overview of conventional and advanced extraction techniques that are used to extract phenolic compounds from macadamia by-products, with a particular focus on the methods applied to macadamia green husk. Among the various techniques, it appears that ultrasound-assisted extraction, especially when combined with aqueous organic solvents, is more efficient than other methods for this purpose. This review also addresses the challenges in phenolic compound recovery, primarily due to the lack of a standardized extraction process. This often results in the extensive use of extraction solvents to achieve an extract that is rich in phenolic compounds. Overall, this research offers a valuable understanding of the most effective methods for the extraction and recovery of phenolic compounds from macadamia by-products and discusses the potential for scaling up these extraction processes. Hence, it can serve as a useful resource for researchers and industry professionals interested in sustainable and efficient utilization of by-products of the nut industry.
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    Extraction of antioxidant compounds from olive (Olea europaea) leaf : a thesis present [i.e. presented] in partial fulfilment of the requirements for the degree of Master of Technology in Food Technology at Massey University, Albany, New Zealand
    (Massey University, 2011) Luo, Helen
    Olive leaves are by products of olive oil industry, which are also regarded as a rich source of antioxidants. The objective of the present work was to extract antioxidant compounds from olive leaves. The effects of extraction conditions on the total phenolic content were investigated. Three extraction methods were used in this research for recovery of phenolic compounds from olive leaves. A multilevel experimental design was implemented with the aim of optimising the recovery of phenolic compounds from olive leaves by using nontoxic water/ethanol-based solvent. The factors considered were (i) the extraction time, (ii) the extraction temperature, (iii) solvent: solid ratio and (iv) the ethanol concentration. The results suggest that a good recovery of phenolic compound from olive leaves may be achieved at 40°C with a solvent/ solid ratio of 30:1 and ethanol concentration of 80 % (v/v). Drying of fresh leaves before extraction is highly recommended to achieve better recovery of important phenolic compounds including oleuropein. Ultrasonic probe may be useful to improve extraction efficiency and also reduce extraction time. The quantitative and qualitative determinations of phenolic compounds were performed by high-performance liquid chromatography (HPLC), which revealed that oleuropein, luteolin-4-O-glucoside, luteolin-7-O-glucoside and apigenin 7-O-glucoside were the major phenolic compounds present. In this study phenolic compounds extracted from olive leaves of two cultivars (Frantoio & Barnea) were analysed. A comparison among two cultivars shows quantitative differences in some phenolic compounds. The antioxidant capacities of the extracts were evaluated by measuring the radical scavenging effect on 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical and by using Oxygen Radical Absorbance Capacity (ORAC). Olive leaf extracts exhibited high antioxidant capacity which suggests olive leaf extract is effective in the function of scavenging free radical. The stability of olive leaf extract stored at four temperatures has also been investigated. The results show increasing temperatures caused greater extent of degradation of phenolic compounds. The best storage condition for olive leaf extracts was at -20 °C in absence of light and oxygen.