Lubricants are essential for industrial and mobility applications; their long-term stability depends on antioxidant additives that are often derived from petrochemistry and are associated with environmental and ecotoxicological concerns. This study investigates xanthohumol (XN), a naturally occurring substance derived from hops and recoverable from brewing industry waste streams, as a sustainable, plant-based antioxidant for lubricant applications. Oxidation stability and tribological performance were evaluated using an ester base oil containing 1 wt% XN and compared to the neat base oil under accelerated oxidative and tribological testing conditions. The addition of XN resulted in a substantial increase in oxidation induction time, reaching approximately 250% relative to the base oil. Oxidative degradation, including oxygen uptake, acid formation, and water accumulation, was effectively suppressed. Following oxidation testing, the base oil exhibited markedly increased friction and wear, whereas the XN-containing formulation remained comparable to fresh oil samples. Beyond its functional performance, XN offers significant sustainability benefits. It is derived from renewable biomass, can be extracted using environmentally benign solvents, and exhibits a favorable toxicological and biodegradability profile compared to conventional phenolic and aminic antioxidants. These characteristics align with circular-economy principles and current sustainability objectives in lubricant formulation, in particular for highly specialized lubricants.
Microalgae are sustainable sources of structurally diverse biomolecules with growing pharmaceutical relevance. Among these, sulfated polysaccharides (SPs) and metallothioneins (MTs) have attracted increasing attention because of their diverse biological activities and stress-responsive biosynthesis. This review proposes an integrated SP–MT dual-platform concept, providing a conceptual framework for exploring how the complementary extracellular functions of SPs and intracellular protective roles of MTs may collectively inform future pharmaceutical research and biomanufacturing. Current knowledge on their biosynthesis, structural diversity, biological activities, and production technologies is critically evaluated. Experimental evidence demonstrates that SPs possess antiviral, anticoagulant, antioxidant, immunomodulatory, and anticancer activities, whereas MTs contribute to metal homeostasis, detoxification, redox regulation, and protection against oxidative stress. Although their co-induction under environmental stress provides a biological rationale for coordinated applications, evidence supporting synergistic therapeutic effects remains limited, and the proposed dual-platform concept requires rigorous experimental and clinical validation. The review also highlights recent advances in cultivation engineering, systems biology, synthetic biology, nanotechnology, and artificial intelligence that may accelerate the discovery, optimization, and standardized production of these biomolecules. The key priorities for future research include elucidating biosynthetic pathways, establishing structure–activity relationships, developing scalable manufacturing processes, and conducting comprehensive preclinical evaluation to support their future pharmaceutical translation.
A sustainable and versatile method for the synthesis of isoquinolones is reported. This operationally simple protocol relies on cobalt catalysis under visible-light irradiation at room temperature, avoiding stoichiometric oxidants and using readily available starting materials. Aryloxy allenes are identified as optimal coupling partners, enabling an efficient and fully regioselective formation of highly substituted isoquinolones and overcoming key limitations of related C–H functionalization strategies. The products feature a synthetically valuable diene motif, which significantly expands their potential for downstream functionalization and molecular diversification. The method shows a broad substrate scope, accommodating electronically and sterically diverse benzamides as well as heteroaromatic and complex bioactive scaffolds, with good to excellent yields and high functional group tolerance. Its applicability is further demonstrated through selective late-stage modification of pharmaceutically relevant molecules, underscoring its utility in medicinal chemistry contexts. In addition, the protocol operates under mild conditions, employs an earth-abundant cobalt catalyst, and is amenable to scale-up, collectively enhancing its synthetic and environmental appeal. Mechanistic studies support a cobaltaphotocatalytic cycle involving radical intermediates and provide insight into the key C–H activation and allene insertion steps governing regioselectivity and reactivity.
In light of growing concerns toward greener and more eco-friendly methods of organic synthesis, ultrasound-mediated nanocatalysis has emerged as a potent and robust technique in current organic chemistry, particularly for the preparation of heterocycles by means of multicomponent reactions (MCRs). The effect of ultrasonic irradiation via acoustic cavitation increases reaction rate, yield, and decreases energy input. In such circumstances, nanoparticles show increased catalytic efficiency because of improved mass transport and increased surface activity. This review offers a brief insight into recent trends in ultrasound-assisted nanoparticle-catalyzed MCRs for the synthesis of nitrogen- and oxygen-containing heterocycles in a green fashion. Particular attention will be paid to the significance of magnetic nanoparticles as catalysts for sustainable generation of various heterocyclic frameworks, namely, pyrazoles, chromenes, tetrazoles, triazoles, xanthenes, furans, imidazoles, indoles, pyridines, isooxazoles, pyrimidines, and acridines. This review discusses the latest trends in the modification of magnetic nanocatalysts reported during 2018–2026. Furthermore, a wide range of nanocatalysts–including metals, metal oxides, magnetic, and mixed nanomaterials–have been successfully employed under ultrasonic conditions to facilitate key organic transformations such as reduction, oxidation, condensation, C–C coupling, and cyclization, offering high yields, selectivity, and reusability.
Quinazolinone, a promising N-heterocyclic framework, often exists in a broad range of natural products, alkaloids, and US FDA-approved drugs. Moreover, quinazolinone-directed C(sp2)-H and C(sp3)-H functionalizations under transition-metal (Ru, Rh, Pd)-catalyzed conditions are important in the regioselective synthesis of bioactive products. Owing to the flexible redox behavior of iodine under photochemical, electrochemical, and iodine-peroxide-based conditions, quinazolinones have been assembled over the years through iodine-based annulations, oxidative cyclizations, and intramolecular C–N couplings from readily available anilines, 2-aminobenzamides, isatins, and isatoic anhydrides, etc. Existing literature reviews on the synthesis of quinazolinones are mainly focused on transition-metal-catalyzed approaches, leaving I2-based, metal-free strategies underrepresented. Herein, we present a systematic survey of I2 and in situ generated I2-based preparation of quinazolinone derivatives (quinazolin-4(3H)-ones, 2,3-fused quinazolinones, dihydroquinazolinones) under I2-mediated, I2-O2-mediated, I2-peroxide-mediated, I2-PPh3₃-mediated, photochemical, electrochemical, and miscellaneous conditions (from 2016 to present). The novel strategies discussed in this report possess notable merits such as transition-metal-free conditions, one-pot operations, gram-scale experiments, etc. Reaction conditions, limitations, representative examples, mechanisms, and post-synthetic applications are highlighted wherever applicable. Overall, we expect that the iodine-based synthetic advancements discussed in this report would enable expansions in this field by serving as a comprehensive reference tool.
