UBIQUINONE-10 AS AN ANTIOXIDANT

Recent research on the physicochemical properties and biological activities of quinones and their practical applications: a comprehensive review

Quinones represent a class of crude organic compounds ubiquitously distributed in nature. Their distinctive quinone-type structure confers upon them unique properties and applications. Quinones demonstrate significant biological activities, including antioxidant, antimicrobial, and antitumor properties. Additionally, they demonstrate noteworthy physicochemical characteristics, including excellent dyeing properties and stability. Given their diverse qualities, quinones hold significant promise for applications in industrial manufacturing, healthcare, and food production, thus garnering considerable attention in recent years. While there is a growing body of research on quinones, the existing literature falls short of providing a comprehensive review encompassing recent advancements in this field along with established knowledge. This paper offers a comprehensive review of research progress for quinones, encompassing structural classification, source synthesis, extraction methods, properties, functions, and specific applications. It serves as a reference and theoretical foundation for the further development and utilization of quinones.

Oxidative Stability of Refined Red Palm Olein under two Malaysian Storage Conditions

Refined red palm olein (RPOo) is the first cooking oil that is a pro-Vitamin A source due to its high carotenoid concentration. The quality specifications from the manufacturers are usually applied to freshly produced oil. However, there is currently no information regarding the oxidative stability and phytonutrient content (Vitamin E and Carotene) for RPOo after prolonged storage time. The objective then is to study the effect of two local storage conditions and storage period(s) on the oxidative stability of RPOo. In this study, peroxide value (PV), p-anisidine value (AnV), induction period (IP), free fatty acid (FFA), and Vitamin E content were determined periodically for twelve months under local storage conditions (supermarket and kitchen). Carotene content, however, was determined only at initial and at the 12^th month of storage time periods. It was found that there was an overall progressive but slow increase in PV and p-AnV. For PV, the storage effects were inconsistent. However, the effects were significant (p < 0.01) on the AnV throughout storage. At the end of the 12-months, for both storage conditions, the PV < 10 meq O₂ g^-1, the AnV < 10, the FFA < 0.2 % (palmitic acid), with a 30% drop in the total Vitamin E, and carotenoids content showed no significant drop (p < 0.01). The PV and AnV were also within Codex Alimentarius' recommended limits. Finally, the oxidative parameters showed that RPOo remains stable after year storage under the two simulated local storage conditions (the aforementioned supermarket and kitchen).

Nanoemulsions as delivery systems for lipophilic nutraceuticals: strategies for improving their formulation, stability, functionality and bioavailability

The food and beverage industry often need to encapsulate hydrophobic functional ingredients in their products, including colors, flavors, lipids, nutraceuticals preservatives, and vitamins. Encapsulation can improve the handling, water-dispersibility, chemically stability, and efficacy of these functional ingredients. In this review article, we focus on the design of nanoemulsion-based delivery systems to encapsulate, protect, and deliver non-polar bioactive agents, such as vitamin A, D and E, β-carotene, lycopene, lutein, curcumin, resveratrol, and coenzyme Q10. Initially, the challenges associated with incorporating these different bioactives into foods are highlighted. The relative merits and drawbacks of different nanoemulsion fabrication methods are then discussed. Finally, examples of the application of nanoemulsions for improving the stability and bioavailability of various kinds of hydrophobic vitamins and nutraceuticals are provided.

Deactivation of Co-Schiff base catalysts in the oxidation of para-substituted lignin models for the production of benzoquinones

Those features which enhance the reactivity of Co-Schiff base oxidation catalysts can also contribute to their demise.

Occurrence, biosynthesis and function of isoprenoid quinones

Isoprenoid quinones are one of the most important groups of compounds occurring in membranes of living organisms. These compounds are composed of a hydrophilic head group and an apolar isoprenoid side chain, giving the molecules a lipid-soluble character. Isoprenoid quinones function mainly as electron and proton carriers in photosynthetic and respiratory electron transport chains and these compounds show also additional functions, such as antioxidant function. Most of naturally occurring isoprenoid quinones belong to naphthoquinones or evolutionary younger benzoquinones. Among benzoquinones, the most widespread and important are ubiquinones and plastoquinones. Menaquinones, belonging to naphthoquinones, function in respiratory and photosynthetic electron transport chains of bacteria. Phylloquinone K(1), a phytyl naphthoquinone, functions in the photosynthetic electron transport in photosystem I. Ubiquinones participate in respiratory chains of eukaryotic mitochondria and some bacteria. Plastoquinones are components of photosynthetic electron transport chains of cyanobacteria and plant chloroplasts. Biosynthetic pathway of isoprenoid quinones has been described, as well as their additional, recently recognized, diverse functions in bacterial, plant and animal metabolism.