Manganese complex catalyst for valencene oxidation: The first use of metalloporphyrins for the selective production of nootkatone

Selective Photooxidation of Valencene and Thymol with Nano-TiO2 and O2 as Oxidant

The selective photocatalytic oxidation with O₂ as oxidant of valencene and thymol was evaluated using nanostructured TiO₂ under UV-Vis radiation at atmospheric conditions. The effect of the morphology and optical properties of TiO₂ nanotubes and aminate nanoparticles was studied. Different scavengers were used to detect the presence of positive holes (h⁺), electrons (e^-), hydroxyl radicals (•OH), and the superoxide radical anion (O₂^-) during the photooxidation reaction. Superoxide anion radical is the main oxidizing specie formed, which is responsible for the selective formation of nootkatone and thymoquinone using aminated TiO₂ nanoparticles under 400 nm radiation.

Production, Function, and Applications of the Sesquiterpenes Valencene and Nootkatone: a Comprehensive Review

Valencene and nootkatone, two sesquiterpenes, extracted from natural sources, have great market potential with diverse applications. This paper aims to comprehensively review the recent advances in valencene and nootkatone, including source, production, physicochemical and biological properties, safety and pharmacokinetics evaluation, potential uses, and their industrial applications as well as future research directions. Microbial biosynthesis offers a promising alternative approach for sustainable production of valencene and nootkatone. Both compounds exert various beneficial activities, including antimicrobial, insecticidal, antioxidant, anti-inflammatory, anticancer, cardioprotective, neuroprotective, hepatoprotective, and nephroprotective and other activities. However, most of the studies are performed in animals and in vitro, making it difficult to give a conclusive description about their health benefits and extend their application. Hence, more attention should be paid to in vivo and long-term clinical studies in the future. Moreover, valencene and nootkatone are considered safe for consumption and show great promise in the applications of food, cosmetic, pharmaceutical, chemical, and agricultural industries.

Differential proteomic analysis of citrus flavor (+)-valencene biotransformation to (+)-nootkatone by Yarrowia lipolytica

Natural products (+)-nootkatone is an important sesquiterpene compound and is widely used in pharmaceutical, cosmetic, agricultural and food industries. The aim of this study was to analyze the differentially expressed proteins (DEPs) during citrus aroma compound (+)-valencene biotransformation to (+)-nootkatone by Yarrowia lipolyticaby with high-throughput LC-MS/MS. A total of 778 proteins were differentially expressed, 385 DEPs were significantly up-regulated and 393 DEPs were markedly down-regulated. It was found that the enzymes transformed (+)-valencene to (+)-nootkatone were mainly existed in yeast intracellular and precipitated under the condition of 30-40 % ammonium sulfate. Most DEPs involved in amino acid and fatty acid metabolism were down-regulated during (+)-valencene biotransformation. The DEPs related to the carbohydrate metabolism, energy metabolism and most of transporter proteins were significantly up-regulated. Furthermore, the key enzymes involved in (+)-valencene transformation might be related to cytochrome P450s (gene2215 and gene2911) and dehydrogenases (gene6493). This is the first time that proteomics was used to investigate the metabolism mechanism of Yarrowia lipolytica during (+)-valencene biotransformation. The proteomic analysis of Yarrowia lipolytica provided a foundation for the molecular regulatory mechanism in the biotransformation to (+)-nootkatone from (+)-valencene.

The polymerization of carvacrol catalyzed by Mn-porphyrins: obtaining the desired product guided by the choice of solvent, oxidant, and catalyst

Less polar solvents could modulate the catalytic activity of Mn(iii)-porphyrins in carvacrol's oxidation leading to polymer/oligomer formation instead of thymoquinone formation.

Currently Applied Extraction Processes for Secondary Metabolites from Lippia turbinata and Turnera diffusa and Future Perspectives

The poleo (Lippia turbinata Griseb.) and damiana (Turnera diffusa Wild) are two of the most valued species in the Mexican semidesert due to their medicinal uses. The conventional essential oil extraction process is hydrodistillation, and for the extraction of antioxidants, the use of organic solvents. However, these techniques are time-consuming and degrade thermolabile molecules, and the efficiency of the process is dependent on the affinity of the solvent for bioactive compounds. Likewise, they generate solvent residues such as methanol, hexane, petroleum ether, toluene, chloroform, etc. Therefore, in recent years, ecofriendly alternatives such as ohmic heating, microwaves, ultrasound, and supercritical fluids have been studied. These methodologies allow reducing the environmental impact and processing times, in addition to increasing yields at a lower cost. Currently, there is no up-to-date information that provides a description of the ecofriendly trends for the recovery process of essential oils and antioxidants from Lippia turbinata and Turnera diffusa. This review includes relevant information on the most recent advancements in these processes, including conditions and methodological foundation.

Advances on (+)-nootkatone microbial biosynthesis and its related enzymes

(+)-Nootkatone is an important functional sesquiterpene and is comprehensively used in pharmaceutical, cosmetic, agricultural and food flavor industries. However, (+)-nootkatone is accumulated trace amounts in plants, and the demand for industry is mainly met by chemical methods which is harmful to the environment. The oxygen-containing sesquiterpenes prepared using microbial methods can be considered as "natural." Microbial transformation has the advantages of mild reaction conditions, high efficiency, environmental protection, and strong stereoselectivity, and has become an important method for the production of natural spices. The microbial biosynthesis of (+)-nootkatone from the main precursor (+)-valencene is summarized in this paper. Whole-cell systems of fungi, bacteria, microalgae, and plant cells have been employed. It was described that the enzymes involved in the microbial biosynthesis of (+)-nootkatone, including cytochrome p450 enzymes, laccase, lipoxygenase, and so on. More recently, the related enzymes were expressed in microbial hosts to heterologous produce (+)-nootkatone, such as Escherichia coli, Pichia pastoris, Yarrowia lipolytica, and Saccharomyces cerevisiae. Finally, the development direction of research for realizing industrialization of microbial transformation was summarized and it provided many options for future improved bioprocesses.