An Improved Synthesis of the “Miracle Nutrient” Coenzyme Q10

Chemistry of Lipoquinones: Properties, Synthesis, and Membrane Location of Ubiquinones, Plastoquinones, and Menaquinones

Lipoquinones are the topic of this review and are a class of hydrophobic lipid molecules with key biological functions that are linked to their structure, properties, and location within a biological membrane. Ubiquinones, plastoquinones, and menaquinones vary regarding their quinone headgroup, isoprenoid sidechain, properties, and biological functions, including the shuttling of electrons between membrane-bound protein complexes within the electron transport chain. Lipoquinones are highly hydrophobic molecules that are soluble in organic solvents and insoluble in aqueous solution, causing obstacles in water-based assays that measure their chemical properties, enzyme activities and effects on cell growth. Little is known about the location and ultimately movement of lipoquinones in the membrane, and these properties are topics described in this review. Computational studies are particularly abundant in the recent years in this area, and there is far less experimental evidence to verify the often conflicting interpretations and conclusions that result from computational studies of very different membrane model systems. Some recent experimental studies have described using truncated lipoquinone derivatives, such as ubiquinone-2 (UQ-2) and menaquinone-2 (MK-2), to investigate their conformation, their location in the membrane, and their biological function. Truncated lipoquinone derivatives are soluble in water-based assays, and hence can serve as excellent analogs for study even though they are more mobile in the membrane than the longer chain counterparts. In this review, we will discuss the properties, location in the membrane, and syntheses of three main classes of lipoquinones including truncated derivatives. Our goal is to highlight the importance of bridging the gap between experimental and computational methods and to incorporate properties-focused considerations when proposing future studies relating to the function of lipoquinones in membranes.

A non-canonical vitamin K cycle is a potent ferroptosis suppressor

Ferroptosis, a non-apoptotic form of cell death marked by iron-dependent lipid peroxidation¹, has a key role in organ injury, degenerative disease and vulnerability of therapy-resistant cancers². Although substantial progress has been made in understanding the molecular processes relevant to ferroptosis, additional cell-extrinsic and cell-intrinsic processes that determine cell sensitivity toward ferroptosis remain unknown. Here we show that the fully reduced forms of vitamin K—a group of naphthoquinones that includes menaquinone and phylloquinone³—confer a strong anti-ferroptotic function, in addition to the conventional function linked to blood clotting by acting as a cofactor for γ-glutamyl carboxylase. Ferroptosis suppressor protein 1 (FSP1), a NAD(P)H-ubiquinone reductase and the second mainstay of ferroptosis control after glutathione peroxidase-4^4,5, was found to efficiently reduce vitamin K to its hydroquinone, a potent radical-trapping antioxidant and inhibitor of (phospho)lipid peroxidation. The FSP1-mediated reduction of vitamin K was also responsible for the antidotal effect of vitamin K against warfarin poisoning. It follows that FSP1 is the enzyme mediating warfarin-resistant vitamin K reduction in the canonical vitamin K cycle⁶. The FSP1-dependent non-canonical vitamin K cycle can act to protect cells against detrimental lipid peroxidation and ferroptosis.

Biochemical and lipidomic analyses identify an anti-ferroptotic function of vitamin K and reveal ferroptosis suppressor protein 1 (FSP1) as the enzyme mediating warfarin-resistant vitamin K reduction in the canonical vitamin K cycle.

Propargylation of CoQ0 through the Redox Chain Reaction

An efficient catalytic propargylation of CoQ0 is described by employing the cooperative effect of Sc(OTf)₃ and Hantzsch ester. It is suggested to work through the redox chain reaction, which involves hydroquinone and dimeric propargylic moiety intermediates. A broad range of propargylic alcohols can be converted into the appropriate derivatives of CoQ0 containing triple bonds in good to excellent yields. The mechanism of the given transformation is also discussed.

Access to 12-Membered Cyclic ortho,meta-Diarylheptanoids: Total Synthesis of Actinidione via Isomyricanone

We describe herein the first access to 12-membered cyclic[7,0]ortho,meta-diarylheptanoids. The key features of the synthesis include both a Suzuki-Miyaura coupling and a ring closing metathesis. Actinidione, a promising natural product, along with a bioactive tetracyclic derivative were obtained in 14 steps for the first time from cheap commercially available substrates with an overall yield of 18-21%. Our modus operandi complies with the principles of the synthesis ideality by using notably strategic reactions.

Preparation of Key Intermediates for the Syntheses of Coenzyme Q10 and Derivatives by Cross-Metathesis Reactions

An alternative catalytic strategy for the preparation of benzylmethacrylate esters, key intermediates in the synthesis of coenzyme Q₁₀ and derivatives, was reported. This strategy avoided undesirable stoichiometric reduction/oxidation processes by utilizing the catalytic formation of allylarenes and then cross-metathesis to selectively form E-benzylmethacrylate esters with good yields (58–64%) and complete E-selectivity. The ester intermediates were reduced to common key benzylallylic alcohols (90–92% yield), which were subsequently used in the formal syntheses of coenzyme Q₁₀ and one derivative.

Catalytic Redox Chain Ring Opening of Lactones with Quinones To Synthesize Quinone-Containing Carboxylic Acids

Catalytic ring opening of five- to eight-membered lactones with quinones is achieved through a redox chain mechanism. With low loading of a simple metal triflate Lewis acid catalyst and a chain initiator, C-H bonds of many quinones were efficiently functionalized with carboxylic acid-containing side chains. This method also features 100% atom economy and wide substrate scope. A novel route to the anti-asthma drug Seratrodast was developed. Mechanism study suggests that the redox chain reaction likely undergoes a carbocation intermediate.

CoQ10 a super-vitamin: review on application and biosynthesis

Coenzyme Q10 (CoQ) or ubiquinone is found in the biological system which is synthesized by the conjugation of benzoquinone ring with isoprenoid chain of variable length. Coenzyme Q10 supplementation energizes the body and increases body energy production in the form of ATP and helps to treat various human diseases such as cardiomyopathy, muscular dystrophy, periodontal disease, etc. Reports of these potential therapeutic advantages of CoQ10 have resulted in its high market demand, which focus the researchers to work on this molecule and develop better bioprocess methods for commercial level production. At the moment, chemical synthesis, semi-synthetic method as well as bio-production utilizing microbes as biofactory are in use for the synthesis of CoQ10. Chemical synthesis involves use of cheap and easily available precursor molecules such as isoprenol, chloromethylquinone, vinylalane, and solanesol. Chemical synthesis methods due to the use of various solvents and chemicals are less feasible, which limits its application. The microbial production of CoQ10 has added advantages of being produced in optically pure form with high yield using inexpensive medium composition. Several bacteria, e.g., Agrobacterium, Paracoccus, Rhodobacterium, and yeast such as Candida, Rhodotorula are the potent ubiquinone producer. Some alternative biosynthetic pathway for designing of CoQ10 production coupled with metabolic engineering might help to increase CoQ10 production. The most common practiced strategy for strain development for commercial CoQ10 production is through natural isolation and chemical mutagenesis. Here, we have reviewed the chemical, semi-synthetic as well as microbial CoQ10 production in detail.

Palladium-Catalyzed One-Pot Conversion of Aldehydes and Ketones into 4-Substituted Homopropargyl Alcohols and 5-En-3-yn-1-ols †

Sequential treatment of 2,3-dichloropropene with magnesium and n-BuLi generated the equivalent of 1,3-dilithiopropyne, which adds regiospecifically to aldehydes and ketones to produce homopropargyl alcohols. The lithium acetylide intermediate formed in this protocol can be further reacted with aromatic and vinyl halides, under palladium catalysis, to produce 4-substituted homopropargyl alcohols and 5-en-3-yn-1-ols, respectively, in one-pot with good overall yields.

Synthesis of coenzyme Q0 through divanadium-catalyzed oxidation of 3,4,5-trimethoxytoluene with hydrogen peroxide

The divanadium-substituted polyoxometalate (Bu₄N)_5−nH_n[γ-PW₁₀V₂O₄₀] (n = 1–2) is an efficient and recyclable catalyst used for the synthesis of coenzyme Q₀ using hydrogen peroxide as a green oxidant.

A convenient synthesis of 1-aralkyl-4-benzylpiperazine derivatives

An efficient two-step route was developed for the synthesis of 1-aralkyl-4-benzylpiperazine derivatives by a Blanc reaction and alkylation. The key intermediate, N-benzylpiperazine, was prepared in an excellent yield by direct benzylation of commercially available piperazine under metal-free conditions.

Automated statistical experimental design approach for rapid separation of coenzyme Q10 and identification of its biotechnological process related impurities using UHPLC and UHPLC-APCI-MS

A novel ultra high performance liquid chromatography method development strategy was ameliorated by applying quality by design approach. The developed systematic approach was divided into five steps (i) Analytical Target Profile, (ii) Critical Quality Attributes, (iii) Risk Assessments of Critical parameters using design of experiments (screening and optimization phases), (iv) Generation of design space, and (v) Process Capability Analysis (Cp) for robustness study using Monte Carlo simulation. The complete quality-by-design-based method development was made automated and expedited by employing sub-2 μm particles column with an ultra high performance liquid chromatography system. Successful chromatographic separation of the Coenzyme Q10 from its biotechnological process related impurities was achieved on a Waters Acquity phenyl hexyl (100 mm × 2.1 mm, 1.7 μm) column with gradient elution of 10 mM ammonium acetate buffer (pH 4.0) and a mixture of acetonitrile/2-propanol (1:1) as the mobile phase. Through this study, fast and organized method development workflow was developed and robustness of the method was also demonstrated. The method was validated for specificity, linearity, accuracy, precision, and robustness in compliance to the International Conference on Harmonization, Q2 (R1) guidelines. The impurities were identified by atmospheric pressure chemical ionization-mass spectrometry technique. Further, the in silico toxicity of impurities was analyzed using TOPKAT and DEREK software.

Efficient synthesis and antioxidant activities of N-heterocyclyl substituted Coenzyme Q analogues

A new strategy for the efficient synthesis of C-5 heterocyclyl substituted Coenzyme Q analogues was developed by N-alkylation of bromomethylated quinone 11 with a series of amines 12 under metal-free conditions. In vitro antioxidant activities of these Coenzyme Q analogues were evaluated and compared with commercial antioxidant Coenzyme Q10 by employing DPPH assay. All these N-heterocyclyl substituted Coenzyme Q analogues are found to be exhibiting good antioxidant properties and may be used as potent antioxidants for combating oxidative stress.

ONO-pincer ruthenium complex-bound norvaline for efficient catalytic oxidation of methoxybenzenes with hydrogen peroxide

A Ru-bound norvaline shows enhanced catalytic activity for the oxidation of methoxybenzenes with unique chemoselectivity.

A convergent stereocontrolled synthesis of [3-(14) C]solanesol

In this communication, we report the synthesis of ~5 mCi of [3-(14) C]solanesol (1) prepared from ethyl [3-(14) C]acetoacetate and (all-E)-octaprenyl bromide (2) in four steps, with a specific radioactivity of 19.83 mCi/mmol and with a chemical/stereochemical and radiochemical purity of ≥ 95%. (Figure ). Position 3 of the chain was selected for (14) C labelling because of the metabolic stability of this position. Unlabelled (all-E)-octaprenyl (18) (Scheme ) necessary for this work was prepared via a convergent iterative 'allyl-allyl' coupling approach of precursors easily derived from readily available inexpensive starting materials.(1)

Coenzyme Q10 production in plants: current status and future prospects

Coenzyme Q10 (CoQ10) or Ubiquinone10 (UQ10), an isoprenylated benzoquinone, is well-known for its role as an electron carrier in aerobic respiration. It is a sole representative of lipid soluble antioxidant that is synthesized in our body. In recent years, it has been found to be associated with a range of patho-physiological conditions and its oral administration has also reported to be of therapeutic value in a wide spectrum of chronic diseases. Additionally, as an antioxidant, it has been widely used as an ingredient in dietary supplements, neutraceuticals, and functional foods as well as in anti-aging creams. Since its limited dietary uptake and decrease in its endogenous synthesis in the body with age and under various diseases states warrants its adequate supply from an external source. To meet its growing demand for pharmaceutical, cosmetic and food industries, there is a great interest in the commercial production of CoQ10. Various synthetic and fermentation of microbial natural producers and their mutated strains have been developed for its commercial production. Although, microbial production is the major industrial source of CoQ10 but due to low yield and high production cost, other cost-effective and alternative sources need to be explored. Plants, being photosynthetic, producing high biomass and the engineering of pathways for producing CoQ10 directly in food crops will eliminate the additional step for purification and thus could be used as an ideal and cost-effective alternative to chemical synthesis and microbial production of CoQ10. A better understanding of CoQ10 biosynthetic enzymes and their regulation in model systems like E. coli and yeast has led to the use of metabolic engineering to enhance CoQ10 production not only in microbes but also in plants. The plant-based CoQ10 production has emerged as a cost-effective and environment-friendly approach capable of supplying CoQ10 in ample amounts. The current strategies, progress and constraints of CoQ10 production in plants are discussed in this review.

The production of coenzyme Q10 in microorganisms

Coenzyme Q10 has emerged as a valuable molecule for pharmaceutical and cosmetic applications. Therefore, research into producing and optimizing coenzyme Q10 via microbial fermentation is ongoing. There are two major paths being explored for maximizing production of this molecule to commercially advantageous levels. The first entails using microbes that naturally produce coenzyme Q10 as fermentation biocatalysts and optimizing the fermentation parameters in order to reach industrial levels of production. However, the natural coenzyme Q10-producing microbes tend to be intractable for industrial fermentation settings. The second path to coenzyme Q10 production being explored is to engineer Escherichia coli with the ability to biosynthesize this molecule in order to take advantage of its more favourable fermentation characteristics and the well-understood array of genetic tools available for this bacteria. Although many studies have attempted to over-produce coenzyme Q10 in E. coli through genetic engineering, production titres still remain below those of the natural coenzyme Q10-producing microorganisms. Current research is providing the knowledge needed to alleviate the bottlenecks involved in producing coenzyme Q10 from an E. coli strain platform and the fermentation parameters that could dramatically increase production titres from natural microbial producers. Synthesizing the lessons learned from both approaches may be the key towards a more cost-effective coenzyme Q10 industry.

Solanesol: added value from Solanaceous waste

Isoprenoids, also known as terpenoids, are the largest and oldest class of natural products known. They are comprised of more than 40,000 different molecules all biosynthetically related via a common five carbon building block (isopentenyl). Many isoprenoids are of commercial interest and are used as fragrances in cosmetics and flavours, colorants and nutritional supplements in foods and feeds as well as being phytomedicines. Their industrial relevance also means they are compounds of high value with global markets in the range of $1 billion per annum. Solanesol is a 45-carbon, unsaturated, all-trans-nonaprenol isoprenoid of high value. Recently this molecule has received particular attention because of its utility, both in its own right and as a precursor in the production of numerous compounds used in the treatment of disease states. Instability in supply and spiralling costs have also lead to the search for sources. In this article existing sources and the potential strategies and tools available to create sustainable biosources are reviewed.

Alternative Synthesis of 2-(4-Benzoyl-Piperazin-1-Ylmethyl)-5, 6-Dimethoxy-3-Methyl-[1, 4]Benzoquinone

The title compound was prepared by a reaction sequence starting from 2, 3, 4, 5-tetramethoxytoluene via Blanc chloromethylation reaction, oxidation and alkylation. The described method provides a good yield of the heterocyclic-Coenzyme Q analogue and is suitable for the synthesis of other analogues.

Synthesis of the Key Intermediate of Coenzyme Q10

(2’E)-1-(3-methyl-4-p-toluenesulfonyl-2-butene)-6-methyl-2,3,4,5-tetramethoxybenzene (4) is the key intermediate in the synthesis of coenzyme Q₁₀via a coupling reaction with solanesyl bromide. In this paper, we report a simple and effective synthesis of compound 4, starting with the readily available and inexpensive precursors p-toluenesulfonyl chloride (TsCl) and isoprene to obtain (2E)-1-p-toluenesulfonyl-2-methyl-4-hydroxy-2-butene (3) by addition, esterification and hydrolysis. Application of the Friedel-Crafts alkylation to compound 3, followed by the addition of 2,3,4,5-tetramethoxytoluene (TeMT), assembled the two parts into compound 4. The key parameters of each reaction were optimized at the same time, and the four total operations needed to produced compound 4 had a 27.9% overall yield under the optimized conditions. The structures of the compounds were characterized by ¹H-NMR, IR and MS. This alternative process has the potential to be used for large-scale process.

Alternative Synthesis of 5-Chloromethyl-2,3-Dimethoxy-6-Methyl-1,4-Benzoquinone: A Key Intermediate for Preparing Coenzyme Q Analogues

The title compound, a key intermediate for preparing Coenzyme Qn family, was prepared in high yield by a reaction sequence starting from the commercially available 3, 4, 5-trimethoxy-benzadehyde via Wolff–Kishner reduction, Vilsmeier–Haack reaction, Blanc chloromethylation reaction, Dakin reaction and oxidation.

Radical-scavenging polyphenols: new strategies for their synthesis

New strategies for the synthesis of polyphenols, compounds with antioxidant properties contained in every kind of plants, are discussed. Syntheses of different classes of polyphenols, namely ubiquinones, present in many natural systems in which electron-transfer mechanisms are involved, hydroxy-tyrosol, one of the main components of the phenol fraction in olives, and flavonoids, widespread in the plant kingdom, were approached by simple and environmentally sustainable methods.

Recovery of solanesol from tobacco as a value-added byproduct for alternative applications

Solanesol in the waste streams of a bioprocess designed for alternative applications of low-alkaloid tobacco was recovered using three different extraction methods. Compared to the conventional heat-reflux extraction (HRE) and ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) using 1:3 hexane:ethanol (v/v) as the solvent after saponification treatment of tobacco biomass was found the most effective in terms of solanesol yield, processing time, and volume of solvent consumed. Quantification of solanesol was achieved by optimizing the mobile phase at 60/40 acetonitrile-isopropanol and lowering the oven temperature to 22 degrees C using a standard reverse-phase high performance liquid chromatography (RP-HPLC). The total solanesol recovered from tobacco biomass and chloroplast accounted for 30% (w/w) of the total solanesol in the fresh leaves. Since solanesol is the precursor of metabolically active quinones such as coenzyme Q10 and vitamin K analogues, extraction of solanesol from tobacco bioprocess waste is a feasible operation and could leverage the overall profitability of biorefining tobacco for alternative, value-added uses.

An Alternative Route for the Synthesis of 2,3,4,5-tetramethoxytoluene

The transformation of the commercially available 2,3.4-trimethoxybenzaldehyde to 2,3,4,5-tetramethoxytoluene using a Dakin reaction to insert the extra oxygen, formylation, reduction and methylation of the phenolic hydroxyl group is described.

Total synthesis of piericidin A1. Application of a modified Negishi carboalumination-nickel-catalyzed cross-coupling

A total synthesis of the mitochondrial complex I inhibitor piericidin A1 is described. It features a unique strategy for the key disconnection, highlighting a modified Negishi carboalumination/Ni-catalyzed cross-coupling on a polyenyne precursor.

Rapid and quantitative determination of solanesol in Nicotiana tabacum by liquid chromatography-tandem mass spectrometry

A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with multiple reaction monitoring (MRM) was developed for the determination of solanesol in Nicotiana tabacum. Sample preparation was performed by ultrasonic extraction with methanol for 20 min and then supernatant was extracted with hexane. The method used atmospheric pressure chemical ionization (APCI) detection in positive-ion mode. The separation of solanesol was performed on a Symmetry Shield RP18 column with a mixture of acetonitrile and isopropanol (1:1, v/v) containing 2mM ammonium acetate as mobile phase. Quantification of solanesol was performed by the standard addition method. The limit of quantification (LOQ) and limit of detection (LOD) of solanesol were, respectively, 5.0 ng/ml (S/N=10) and 1.5 ng/ml (S/N=3). The relative standard deviations of peak area were 0.89 and 1.12% for intra-day and inter-day, respectively. The recoveries of solanesol ranged from 97.72 to 99.67% and the corresponding R.S.D.s were less than 2.7%. Analysis took 5 min, making the method suitable for rapid determination of solanesol in N. tabacum. The proposed method has been successfully applied to the analysis of solanesol in various organs of N. tabacum.

Controlling Regiochemistry in Negishi Carboaluminations. Fine Tuning the Ligand on Zirconium

The species on the zirconocene catalyst is changed from two Cp's to the Brintzinger ligand and catalytic amounts of MAO are used to usually effect a >99% regiocontrol of Negishi carboaluminations of 1-alkynes in toluene.

Microwave-Assisted Heterogeneous Cross-Coupling Reactions Catalyzed by Nickel-in-Charcoal (Ni/C)

A study involving the relatively rare combination of heterogeneous catalysis conducted under microwave conditions is presented. Carbon-carbon bond formation, including Negishi and Suzuki couplings, can be quickly effected with aryl chloride partners by using a base metal (nickel) adsorbed in the pores of activated charcoal. Aminations were also studied, along with cross-couplings of vinyl alanes with benzylic chlorides as a means to stereodefined allylated aromatics. Reaction times for all these processes are typically reduced from several hours to minutes in a microwave reactor.