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Aberrations in the Hedgehog (Hh) signaling pathway are significantly prevailed in various cancers, including B-cell lymphoma. A critical facet of Hh signal transduction involves the dynamic regulation of the suppressor of fused homolog (SUFU)-glioma-associated oncogene homolog (GLI) complex within the kinesin family member 7 (KIF7)-supported ciliary tip compartment. However, the specific post-translational modifications of SUFU-GLI complex within this context have remained largely unexplored. Our study reveals a novel regulatory mechanism involving prolyl 4-hydroxylase 2 (P4HA2), which forms a complex with KIF7 and is essential for signal transduction of Hh pathway. We demonstrate that, upon Hh pathway activation, P4HA2 relocates alongside KIF7 to the ciliary tip. Here, it hydroxylates SUFU to inhibit its function, thus amplifying the Hh signaling. Moreover, the absence of P4HA2 significantly impedes B lymphoma progression. This effect can be attributed to the suppression of Hh signaling in stromal fibroblasts, resulting in decreased growth factors essential for malignant proliferation of B lymphoma cells. Our findings highlight the role of P4HA2-mediated hydroxylation in modulating Hh signaling and propose a novel stromal-targeted therapeutic strategy for B-cell lymphoma.

Mutants lacking functional HYD2 homoeologs showed improved seedling growth, but comparable or increased susceptibility to salt stress in tillering plants, suggesting a developmentally restricted role of HYD2 in salt response. Salinity stress threatens global food security by reducing the yield of staple crops such as wheat (Triticum ssp.). Understanding how wheat responds to salinity stress is crucial for developing climate resilient varieties. In this study, we examined the interplay between carotenoid metabolism and the response to salt (NaCl) stress, a specific form of salinity stress, in tetraploid wheat plants with mutations in carotenoid β-hydroxylase 1 (HYD1) and HYD2. Our investigation encompassed both the vulnerable seedling stage and the more developed tillering stage of wheat plant growth. Mutant combinations lacking functional HYD2 homoeologs, including hyd-A2 hyd-B2, hyd-A1 hyd-A2 hyd-B2, hyd-B1 hyd-A2 hyd-B2, and hyd-A1 hyd-B1 hyd-A2 hyd-B2, had longer first true leaves and slightly enhanced root growth during germination under salt stress compared to the segregate wild-type (control) plants. Interestingly, these mutant seedlings also showed decreased levels of neoxanthin and violaxanthin (xanthophylls derived from β-carotene) and an increase in β-carotene in roots. However, tillering hyd mutant and segregate wild-type plants generally did not differ in their height, tiller count, and biomass production under acute or prolonged salt stress, except for decreases in these parameters observed in the hyd-A1 hyd-B1 hyd-A2 hyd-B2 mutant that indicate its heightened susceptibility to salt stress. Taken together, these findings suggest a significant, yet developmentally restricted role of HYD2 homoeologs in salt-stress response in tetraploid wheat. They also show that hyd-A2 hyd-B2 mutant plants, previously demonstrated for possessing enriched nutritional (β-carotene) content, maintain an unimpaired ability to withstand salt stress.

Nonsymmetrical oxygen-bridged binuclear copper centers have been proposed and modeled as intermediates and transition states in several C-H oxidation pathways, leading to the postulation that structural dissymmetry enhances the reactivity of the bridging oxygen. However, experimentally characterizing the structure and reactivity of these transient species is remarkably challenging. Here, we report the high-pressure synthesis of a metastable nonsymmetrical dicopper-µ-oxo compound with exceptional reactivity toward the mono-oxygenation of aliphatic C-H bonds. The nonequivalent coordination environment of copper stabilizes localized mixed valency and greatly enhances the hydrogen atom abstraction activity of the bridging oxygen, enabling room-temperature hydroxylation of methane under pressure. These findings highlight the role of dissymmetry in the reactivity of binuclear copper centers and demonstrate precise control of molecular structures by mechanical means. [ABSTRACT FROM AUTHOR]

Mycoparasite secondary metabolites control fungal infections or diseases in agriculture and human health. Among genes involved in synthesizing secondary metabolites, cytochrome P450 monooxygenases (CYPs/P450s) play a key role in synthesizing and attributing diversity to the secondary metabolites. Despite the importance of P450s, a comparative analysis of P450s in mycoparasites has yet to be reported. This study is aimed at addressing this research gap. Genome-wide analysis of P450s in 43 fungi representing six fungal phyla and three distinct lifestyles, such as mycoparasitic (24 species), saprophytic (5 species), and ectomycorrhizal (14 species), revealed the expansion of P450s in Pezizomycete mycoparasites for the synthesis of secondary metabolites. The number of P450s and their families and subfamilies, the number of secondary-metabolite biosynthetic gene clusters (SMBGCs), and the number of P450s that are part of these SMBGCs were found to be highest in Pezizomycete mycoparasites compared to their counterparts of saprophytes and ectomycorrhiza, indicating P450s also play a key role in mycoparasitism. An analysis of P450 location as part of SMBGCs and the available literature on Pezizomycete P450s revealed that P450s play a key role in the synthesis of anti-fungal secondary metabolites such as trichothecene sesquiterpene, harzianum A, heptelidic acid, and gliotoxin. The mycoparasite Trichoderma virens Tv29.8 P450 CYP68Q3 is found to be a bifunctional enzyme with epoxidation and oxidation capability, and CYP5117A3 performs a Baeyer–Villiger oxidation reaction with regioselectivity. This study serves as a reference for future annotation of P450s in mycoparasites. [ABSTRACT FROM AUTHOR]

FeII/α-ketoglutarate-dependent dioxygenases (Fe/αKG) make up a large enzyme family that functionalize C-H bonds on diverse organic substrates. Although Fe/αKG homologues catalyze an array of chemically useful reactions, hydroxylation typically predominates. Microalgal DabC uniquely forms a novel C-C bond to construct the bioactive pyrrolidine ring in domoic acid biosynthesis; however, we have identified that this kainoid synthase exclusively performs a stereospecific hydroxylation reaction on its cis substrate regioisomer. Mechanistic and kinetic analyses with native and alternative substrates identified a 20-fold rate increase in DabC radical cyclization over β-hydroxylation with no observable 1,5-hydrogen atom transfer. Moreover, this dual activity was conserved among macroalgal RadC1 and KabC homologues and provided insight into substrate recognition and reactivity trends. Investigation of this substrate-dependent chemistry improves our understanding of kainoid synthases and their biocatalytic application.

Abstract Flavin-dependent monooxygenases (FMOs) are a valuable group of biocatalysts that can regioselectively introduce a hydroxy group for the targeted modification of biologically active compounds. Here, we present the fdeE, the FMO from Herbaspirillum seropedicae SmR1 that is a part of the naringenin degradation pathway and is active towards a wide range of flavonoids—flavanones, flavones, isoflavones, and flavonols. Bioinformatics and biochemical analysis revealed a high similarity between the analyzed enzyme and other F8H FMOs what might indicate convergent evolutionary mechanism of flavonoid degradation pathway emergence by microorganism. A simple approach with the manipulation of the reaction environment allowed the stable formation of hydroxylation products, which showed very high reactivity in both in vivo and in vitro assays. This approach resulted in an 8-hydroxyquercetin—gossypetin titer of 0.16 g/L and additionally it is a first report of production of this compound.

Mycoparasite secondary metabolites control fungal infections or diseases in agriculture and human health. Among genes involved in synthesizing secondary metabolites, cytochrome P450 monooxygenases (CYPs/P450s) play a key role in synthesizing and attributing diversity to the secondary metabolites. Despite the importance of P450s, a comparative analysis of P450s in mycoparasites has yet to be reported. This study is aimed at addressing this research gap. Genome-wide analysis of P450s in 43 fungi representing six fungal phyla and three distinct lifestyles, such as mycoparasitic (24 species), saprophytic (5 species), and ectomycorrhizal (14 species), revealed the expansion of P450s in Pezizomycete mycoparasites for the synthesis of secondary metabolites. The number of P450s and their families and subfamilies, the number of secondary-metabolite biosynthetic gene clusters (SMBGCs), and the number of P450s that are part of these SMBGCs were found to be highest in Pezizomycete mycoparasites compared to their counterparts of saprophytes and ectomycorrhiza, indicating P450s also play a key role in mycoparasitism. An analysis of P450 location as part of SMBGCs and the available literature on Pezizomycete P450s revealed that P450s play a key role in the synthesis of anti-fungal secondary metabolites such as trichothecene sesquiterpene, harzianum A, heptelidic acid, and gliotoxin. The mycoparasite Trichoderma virens Tv29.8 P450 CYP68Q3 is found to be a bifunctional enzyme with epoxidation and oxidation capability, and CYP5117A3 performs a Baeyer–Villiger oxidation reaction with regioselectivity. This study serves as a reference for future annotation of P450s in mycoparasites.

Abstract Regioselective and enantioselective hydroxylation of propargylic C-H bonds are useful reactions but often lack appropriate catalysts. Here a green and efficient asymmetric hydroxylation of primary and secondary C–H bonds at propargylic positions has been established. A series of optically active propargylic alcohols were prepared with high regio- and enantioselectivity (up to 99% ee) under mild reaction conditions by using P450tol, while the C≡C bonds in the molecule remained unreacted. This protocol provides a green and practical method for constructing enantiomerically chiral propargylic alcohols. In addition, we also demonstrated that the biohydroxylation strategy was able to scaled up to 2.25 mmol scale with the production of chiral propargyl alcohol 2a at a yield of 196 mg with 96% ee, which’s an important synthetic intermediate of antifungal drug Ravuconazole. Graphical Abstract

Iodosilarene derivatives (PhIO, PhI(OAc)2) constitute an important class of oxygen atom transfer reagents in organic synthesis and are often used together with iron-based catalysts. Since the factors controlling the ability of iron centers to catalyze alkane hydroxylation are not yet fully understood, the aim of this report is to develop bioinspired non-heme iron catalysts in combination with PhI(OAc)2, which are suitable for performing C-H activation. Overall, this study provides insight into the iron-based ([FeII(PBI)3(CF3SO3)2] (1), where PBI = 2-(2-pyridyl)benzimidazole) catalytic and stoichiometric hydroxylation of triphenylmethane using PhI(OAc)2, highlighting the importance of reaction conditions including the effect of the co-ligands (para-substituted pyridines) and oxidants (para-substituted iodosylbenzene diacetates) on product yields and reaction kinetics. A number of mechanistic studies have been carried out on the mechanism of triphenylmethane hydroxylation, including C-H activation, supporting the reactive intermediate, and investigating the effects of equatorial co-ligands and coordinated oxidants. Strong evidence for the electrophilic nature of the reaction was observed based on competitive experiments, which included a Hammett correlation between the relative reaction rate (logkrel) and the σp (4R-Py and 4R'-PhI(OAc)2) parameters in both stoichiometric (ρ = +0.87 and +0.92) and catalytic (ρ = +0.97 and +0.77) reactions. The presence of [(PBI)2(4R-Py)FeIIIOIPh-4R']3+ intermediates, as well as the effect of co-ligands and coordinated oxidants, was supported by their spectral (UV–visible) and redox properties. It has been proven that the electrophilic nature of iron(III)-iodozilarene complexes is crucial in the oxidation reaction of triphenylmethane. The hydroxylation rates showed a linear correlation with the FeIII/FeII redox potentials (in the range of −350 mV and −524 mV), which suggests that the Lewis acidity and redox properties of the metal centers greatly influence the reactivity of the reactive intermediates. [ABSTRACT FROM AUTHOR]

The peroxygenases are ideal biocatalysts for the selective oxyfunctionalisation of stable C-H bonds. However, the catalytic efficiency of this approach is limited due to enzyme lability toward oxidant H2O2. Although the reported in-situ H2O2 generation system enables the stable biocatalytic process without deactivating the enzyme, the greatest catalytic potential of peroxygenases still cannot be fulfilled effectively. To address the above issue, a H2O2 generation-detection-regulation platform that integrated an effective organocatalyst-driven H2O2 generation system, a precise electrochemical H2O2 real-time detection device, and a convenient H2O2 regulation strategy was first developed. The suitable range of H2O2 generation rate for maximizing the catalytic efficiency of perox-ygenases while minimizing inactivation of the enzyme was firstly obtained by simply adjusting the amount of organocatalyst. According to the determined suitable range, the C-H oxyfunctionalisation efficiency of peroxygenases for each substrate was significantly boosted, achieving ~3-fold of the reported highest turnover frequency. [ABSTRACT FROM AUTHOR]

Flavonoids comprise a group of natural compounds with diverse bioactivities; however, their low water solubility and limited bioavailability often impede their potential health benefits for humans. In this study, five derivatives, namely 2′,5′-dihydroxyflavanone (1), 2′-dihydroxyflavanone-5′- O -4″- O -methyl- β - d -glucoside (2), 2′-dihydroxyflavanone-6- O -4″- O -methyl- β - d -glucoside (3), 2′-dihydroxyflavanone-3′- O -4″- O -methyl- β - d -glucoside (4) and hydroxyflavanone-2′- O -4″- O -methyl- β - d -glucoside (5), were biosynthesized from 2′-hydroxyflavanone through microbial transformation using Beauveria bassiana ATCC 7159. Product 1 was identified as a known compound while 2 – 5 were structurally characterized as new structures through extensive 1D and 2D NMR analysis. The water solubility of biotransformed products 1 – 5 was enhanced by 30–280 times compared to the substrate 2′-hydroxyflavanone. Moreover, the antioxidant assay revealed that 1 and 2 exhibited improved 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity relative to the substrate, decreasing the logIC 50 from 8.08 ± 0.11 μM to 6.19 ± 0.08 μM and 7.15 ± 0.08 μM, respectively. Compound 5 displayed significantly improved anticancer activity compared to the substrate 2′-hydroxyflavanone against Glioblastoma 33 cancer stem cells, decreasing the IC 50 from 25.05 μM to 10.59 μM. Overall, fungal biotransformation represents an effective tool to modify flavonoids for enhanced water solubility and bioactivities. [Display omitted] [ABSTRACT FROM AUTHOR]

Background: Polysaccharide from Garcinia mangostana rind has many biological activities and deserves further research. Methods: The antioxidant properties of UAEE-GMRP, UAEE-GMRP-1 A, CM-30, and Ac-30 were evaluated through two different antioxidant activity experimental systems. Results: The four polysaccharides had a better scavenging effect on hydroxyl radicals, while their inhibitory effect on lipid peroxidation was relatively weak. However, overall, the four polysaccharides showed a certain degree of potential application in the two antioxidant experiments mentioned above, especially the chemically modified polysaccharides from Garcinia mangostana rind, which effectively improved their antioxidant activity. This also indicates that chemical modification is a better method to improve polysaccharide activity. In addition, in these two antioxidant exploration experiments, carboxymethylated polysaccharide showed stronger activity compared to the other three polysaccharides. Conclusion: The carboxymethylation modification may have great potential for application. [ABSTRACT FROM AUTHOR]

Regioselective and enantioselective hydroxylation of propargylic C-H bonds are useful reactions but often lack appropriate catalysts. Here a green and efficient asymmetric hydroxylation of primary and secondary C–H bonds at propargylic positions has been established. A series of optically active propargylic alcohols were prepared with high regio- and enantioselectivity (up to 99% ee) under mild reaction conditions by using P450tol, while the C≡C bonds in the molecule remained unreacted. This protocol provides a green and practical method for constructing enantiomerically chiral propargylic alcohols. In addition, we also demonstrated that the biohydroxylation strategy was able to scaled up to 2.25 mmol scale with the production of chiral propargyl alcohol 2a at a yield of 196 mg with 96% ee, which's an important synthetic intermediate of antifungal drug Ravuconazole. [ABSTRACT FROM AUTHOR]

The aim of this study was to obtain new halolactones with a gem-dimethyl group in the cyclohexane ring (at the C-3 or C-5 carbon) and a methyl group in the lactone ring and then subject them to biotransformations using filamentous fungi. Halolactones in the form of mixtures of two diasteroisomers were subjected to screening biotransformations, which showed that only compounds with a gem-dimethyl group located at the C-5 carbon were transformed. Strains from the genus Fusarium carried out hydrolytic dehalogenation, while strains from the genus Absidia carried out hydroxylation of the C-7 carbon. Both substrates and biotransformation products were then tested for antimicrobial activity against multidrug-resistant strains of both bacteria and yeast-like fungi. The highest antifungal activity against C. dubliniensis and C. albicans strains was obtained for compound 5b, while antimicrobial activity against S. aureus MRSA was obtained for compound 4a. [ABSTRACT FROM AUTHOR]

Zastaprazan (JP-1366), a novel potassium-competitive acid blocker, is a new drug for the treatment of erosive esophagitis. JP-1366 is highly metabolized in human, mouse, and dog hepatocytes but moderately metabolized in rat and monkey hepatocytes when estimated from the metabolic stability of this compound in hepatocyte suspension and when 18 phase I metabolites and 5 phase II metabolites [i.e., N-dearylation (M6), hydroxylation (M1, M19, M21), dihydroxylation (M7, M8, M14, M22), trihydroxylation (M13, M18), hydroxylation and reduction (M20), dihydroxylation and reduction (M9, M16), hydrolysis (M23), hydroxylation and glucuronidation (M11, M15), hydroxylation and sulfation (M17), dihydroxylation and sulfation (M10, M12), N-dearylation and hydroxylation (M3, M4), N-dearylation and dihydroxylation (M5), and N-dearylation and trihydroxylation (M2)] were identified from JP-1366 incubation with the hepatocytes from humans, mice, rats, dogs, and monkeys. Based on the cytochrome P450 (CYP) screening test and immune-inhibition analysis with CYP antibodies, CYP3A4 and CYP3A5 played major roles in the metabolism of JP-1366 to M1, M3, M4, M6, M8, M9, M13, M14, M16, M18, M19, M21, and M22. CYP1A2, 2C8, 2C9, 2C19, and 2D6 played minor roles in the metabolism of JP-1366. UDP-glucuronosyltransferase (UGT) 2B7 and UGT2B17 were responsible for the glucuronidation of M1 to M15. However, JP-1366 and active metabolite M1 were not substrates for drug transporters such as organic cation transporter (OCT) 1/2, organic anion transporter (OAT) 1/3, organic anion transporting polypeptide (OATP)1B1/1B3, multidrug and toxic compound extrusion (MATE)1/2K, P-glycoprotein (P-gp), and breast cancer-resistant protein (BCRP). Only M1 showed substrate specificity for P-gp. The findings indicated that drug-metabolizing enzymes, particularly CYP3A4/3A5, may have a significant role in determining the pharmacokinetics of zastaprazan while drug transporters may only have a small impact on the absorption, distribution, and excretion of this compound. [ABSTRACT FROM AUTHOR]

Three types of smectite with various crystallochemical compositions and interlayer cations as well as kaolinite and illite were fired at 800°C and 650°C and tested for their rehydroxylation's (RHX) potential and kinetics in the presence of water vapor at 200°C–350°C. A dehydroxylated structure of 2:1 Al‐rich mineral with the interlayer pillared by a large cation (like K+ or Cs+) is wide enough to allow H2O diffusion which results in advanced RHX, that is, restoring up to several tens of percent of the original OH content. Such 2:1 layer structures (beidellite, illite) do not follow the time‐to‐the‐quarter (TTTQ) kinetics during RHX and show a non‐Arrhenius behavior for isothermal RHX. Because TTTQ kinetics is assumed in an RHX dating of ceramic artifacts in archaeometry, fired‐clay ceramics prepared from material dominated by Al‐rich 2:1 minerals was found unfeasible for RHX dating. Kaolinite and Mg2+‐ or Ca2+‐exchanged smectites show the Arrhenius behavior and follow the TTTQ kinetics of RHX, resulting in apparent Ea increase with the progress of reaction (up to α ∼0.2) of ∼20–50 kJ/mol in beidellite and 15–35 kJ/mol in montmorillonite. We suggest using 'hydroxylation' rather than 'rehydroxylation' for structurally‐disordered fired clays gaining OH groups in an unknown position. [ABSTRACT FROM AUTHOR]

A phytoalexin polyphenolic chemical, resveratrol, can be found in a variety of foods, including cereals, peanuts, grapes, strawberries, and raspberries. It is also known that resveratrol protects the body against cardiovascular diseases as well as various types of cancer. In addition to these health issues, resveratrol is currently the subject of research since it helps treat and prevent a number of illnesses. More clinical research is needed to validate resveratrol's potential as a therapeutic agent, despite the plethora of in vitro and in vivo evidence to support this. When the literature data are evaluated, the fact that resveratrol has a therapeutic effect in these studies, but it is known to be subject to rapid metabolism despite its low bioavailability and oral absorption of approximately 75%, has directed the studies to resveratrol derivatives, especially piceatannol. Based on recent studies, 4 types of resveratrol derivatives were assessed in this work: hydroxylated compounds, methoxylated compounds, glycosides, and oligomers. Because of their advantageous bioactivities, methoxylated, hydroxylated, and halogenated derivatives have drawn the most interest among these classes. However, as a result of these studies, more studies should be conducted to better understand whether resveratrol derivatives can be recommended as therapeutic agents. [ABSTRACT FROM AUTHOR]

The mechanism of the combined process of ion beam sputtering (IBS) and HF acid etching on the chemical structure defects of fused silica and its laser damage resistance performance were investigated in this paper. During the removal process of surface material, the sputtering effect causes lattice atoms to flee their native space locations, and a large amount of unsaturated chemical structures are produced on the silica surface, which improves the chemical activity of Si and O atoms, accelerates the chemical reaction process between surface atoms and water molecules, increases the content of hydroxyl groups (OH-) in the shallow layer, and enhances the photothermal weak absorption intensity. However, the increase in hydroxyl content weakens the binding strength of silicon–oxygen bonds, destroys the spatial network structure of silica bulk, and reduces its mechanical strength, resulting in a decrease in its laser damage resistance performance. The paper reveals for the first time the mechanism by which IBS changes the structure characteristics of silica material, accelerates the surface hydroxylation process, and thereby reduces the laser damage resistance performance. This work provides technical guidance for effectively suppressing chemical structure defects on silica surfaces and improving the laser damage resistance performance of optical components under high-flux laser irradiation. [ABSTRACT FROM AUTHOR]

With a rising demand of cocaine over the last years, it is likely that unregulated new psychoactive substances with similar effects such as indatraline ((1R,3S)-3-(3,4-dichlorophenyl)-N-methyl-2,3-dihydro-1H-inden-1-amine) and troparil (Methyl (1R,2S,3S,5S)-8-methyl-3-phenyl-8-azabicyclo[3.2.1]octane-2-carboxylate) become popular as well. Both substances share a similar pharmacological profile as cocaine, while their potency is higher, and their duration of action is longer. This study investigated their metabolic fate in rat urine and incubations using pooled human liver S9 fraction (pHLS9). Indatraline formed two phase I and four phase II metabolites, with aromatic hydroxylation and glucuronidation being the main metabolic steps. All metabolites were detected in rat urine, while the parent compound was not detectable. Although low in abundance, indatraline metabolites were well identifiable due to their specific isotopic patterns caused by chlorine. Troparil formed four phase I and three phase II metabolites, with demethylation being the main metabolic step. Hydroxylation of the tropane ring, the phenyl ring, and combinations of these steps, as well as glucuronidation, were found. Phase I metabolites were detectable in rat urine and pHLS9, while phase II metabolites were only detectable in rat urine. [ABSTRACT FROM AUTHOR]

Triclosan (TCS) is a widespread antimicrobial agent that is associated with many adverse health outcomes. Its gut toxicity has been attributed to the molecular modifications mediated by commensal microbes, but microbial transformations of TCS derivatives in the gut lumen are still largely unknown. Aromatic hydroxylation is the predominant oxidative metabolism of TCS that linked to its toxicological effects in host tissues. Here, we aimed to reveal the biological fates of hydroxyl-TCS (OH-TCS) in the colon, where intestinal microbes mainly reside. Unlike the profiles generated via host metabolism, OH-TCS species remain unconjugated in human stools from a cohort study. Through tracking molecular compositions in mouse intestinal tract, elevated abundance of free-form OH-TCS while reduced abundance of conjugated forms was observed in the colon digesta and mucosa. Using antibiotic-treated and germ-free mice, as well as in vitro approaches, we demonstrate that gut microbiota-encoded enzymes efficiently convert glucuronide/sulfate-conjugated OH-TCS, which are generated from host metabolism, back to their bioactive free-forms in colon tissues. Thus, host-gut microbiota metabolic interactions of TCS derivatives were proposed. These results shed light on the crucial roles of microbial metabolism in TCS toxicity, and highlight the importance of incorporating gut microbial transformations in health risk assessment of environmental chemicals.

A catalytic diastereoselective Prins reaction for hydroxymethylation and hydroxylation of 1,3-diarylpropene was successfully utilized to prepare various 1,3-dioxanes 7 in 14–88% yields. Take advantage of the synthetic intermediate 7h, the key B/C rings in brazilin core could be constructed by the sequential of Friedel–Crafts/Ullmann-Ma rather than Ullmann-Ma/Friedel–Crafts reactions. [ABSTRACT FROM AUTHOR]

All biological hydroxylation reactions are thought to derive the oxygen atom from one of three inorganic oxygen donors, O2, H2O2 or H2O. Here, we have identified the organic compound prephenate as the oxygen donor for the three hydroxylation steps of the O2-independent biosynthetic pathway of ubiquinone, a widely distributed lipid coenzyme. Prephenate is an intermediate in the aromatic amino acid pathway and genetic experiments showed that it is essential for ubiquinone biosynthesis in Escherichia coli under anaerobic conditions. Metabolic labeling experiments with 18O-shikimate, a precursor of prephenate, demonstrated the incorporation of 18O atoms into ubiquinone. The role of specific iron--sulfur enzymes belonging to the widespread U32 protein family is discussed. Prephenate-dependent hydroxylation reactions represent a unique biochemical strategy for adaptation to anaerobic environments. [ABSTRACT FROM AUTHOR]

Unspecific peroxygenases (UPOs) are glycosylated enzymes that provide an efficient method for oxyfunctionalizing a variety of substrates using only hydrogen peroxide (H2O2) as the oxygen donor. However, their poor heterologous expression has hindered their practical application. Here, a novel UPO from Marasmius fiardii PR910 (MfiUPO) was identified and heterologously expressed in Pichia pastoris. By employing a two-copy expression cassette, the protein titer reached 1.18 g L−1 in a 5 L bioreactor, marking the highest record. The glycoprotein rMfiUPO exhibited a smeared band in the 40 to 55 kDa range and demonstrated hydroxylation, epoxidation and alcohol oxidation. Moreover, the peroxidative activity was enhanced by 150% after exposure to 50% (v/v) acetone for 40 h. A semi-preparative production of 4-OH-β-ionone on a 100 mL scale resulted in a 54.2% isolated yield with 95% purity. With its high expression level, rMfiUPO is a promising candidate as an excellent parental template for enhancing desirable traits such as increased stability and selectivity through directed evolution, thereby meeting the necessary criteria for practical application. [ABSTRACT FROM AUTHOR]

The Von Hippel–Lindau (VHL) protein, which is frequently mutated in clear-cell renal cell carcinoma (ccRCC), is a master regulator of hypoxia-inducible factor (HIF) that is involved in oxidative stresses. However, whether VHL possesses HIF-independent tumor-suppressing activity remains largely unclear. Here, we demonstrate that VHL suppresses nutrient stress-induced autophagy, and its deficiency in sporadic ccRCC specimens is linked to substantially elevated levels of autophagy and correlates with poorer patient prognosis. Mechanistically, VHL directly binds to the autophagy regulator Beclin1, after its PHD1-mediated hydroxylation on Pro54. This binding inhibits the association of Beclin1-VPS34 complexes with ATG14L, thereby inhibiting autophagy initiation in response to nutrient deficiency. Expression of non-hydroxylatable Beclin1 P54A abrogates VHL-mediated autophagy inhibition and significantly reduces the tumor-suppressing effect of VHL. In addition, Beclin1 P54-OH levels are inversely correlated with autophagy levels in wild-type VHL-expressing human ccRCC specimens, and with poor patient prognosis. Furthermore, combined treatment of VHL-deficient mouse tumors with autophagy inhibitors and HIF2α inhibitors suppresses tumor growth. These findings reveal an unexpected mechanism by which VHL suppresses tumor growth, and suggest a potential treatment for ccRCC through combined inhibition of both autophagy and HIF2α. Synopsis: PHD1-mediated prolyl hydroxylation targets HIF-1α for VHL-dependent ubiquitination and is a key step in the cell's oxygen sensing machinery. This work shows that PHD1 and VHL also inhibit Beclin1 and autophagy initiation, with dysregulation leading to clear-cell renal cell carcinoma progression. PHD1 mediates Beclin1 Pro54 hydroxylation on pre-autophagosomal structures in clear-cell renal cell carcinoma cells. VHL binds to Pro54-hydroxylated Beclin1 and prevents the association between ATG14L and Beclin1/VPS34. VHL inhibits VPS34-dependent PI(3)P production, autophagy initiation, and kidney tumor growth. The Von Hippel-Lindau (VHL) E3 ligase binds to proline-hydroxylated Beclin1, inhibiting the initiation of autophagy and blocking kidney tumor growth. [ABSTRACT FROM AUTHOR]

Flavoprotein monooxygenases catalyze reactions, including hydroxylation and epoxidation, involved in the catabolism, detoxification, and biosynthesis of natural substrates and industrial contaminants. Among them, the 6-hydroxy-3-succinoyl-pyridine (HSP) monooxygenase (HspB) from Pseudomonas putida S16 facilitates the hydroxylation and C-C bond cleavage of the pyridine ring in nicotine. However, the mechanism for biodegradation remains elusive. Here, we refined the crystal structure of HspB and elucidated the detailed mechanism behind the oxidative hydroxylation and C-C cleavage processes. Leveraging structural information about domains for binding the cofactor flavin adenine dinucleotide (FAD) and HSP substrate, we used molecular dynamics simulations and quantum/molecular mechanics calculations to demonstrate that the transfer of an oxygen atom from the reactive FAD peroxide species (C4a-hydroperoxyflavin) to the C3 atom in the HSP substrate constitutes a rate-limiting step, with a calculated reaction barrier of about 20 kcal/mol. Subsequently, the hydrogen atom was rebounded to the FAD cofactor, forming C4a-hydroxyflavin. The residue Cys218 then catalyzed the subsequent hydrolytic process of C-C cleavage. Our findings contribute to a deeper understanding of the versatile functions of flavoproteins in the natural transformation of pyridine and HspB in nicotine degradation.IMPORTANCE Pseudomonas putida S16 plays a pivotal role in degrading nicotine, a toxic pyridine derivative that poses significant environmental challenges. This study highlights a key enzyme, HspB (6-hydroxy-3-succinoyl-pyridine monooxygenase), in breaking down nicotine through the pyrrolidine pathway. Utilizing dioxygen and a flavin adenine dinucleotide cofactor, HspB hydroxylates and cleaves the substrate’s side chain. Structural analysis of the refined HspB crystal structure, combined with state-ofthe- art computations, reveals its distinctive mechanism. The crucial function of Cys218 was never discovered in its homologous enzymes. Our findings not only deepen our understanding of bacterial nicotine degradation but also open avenues for applications in both environmental cleanup and pharmaceutical development. [ABSTRACT FROM AUTHOR]

In this study, an electrochemical-assisted ferric ion/persulfate (EC/Fe3+/PS) process was proposed to degrade bezafibrate (BZF), a widespread hypolipidemic drug, in water. By promoting the reduction of Fe3+ to Fe2+ at the cathode, the introduction of an electric field successfully overcomes the limitation of non-regenerable Fe2+ inherent in Fe2+/PS systems, significantly improving the degradation efficiency of BZF. The predominant reactive species identified were •OH and SO4●−, with 1O2 also playing a role. Various key operational parameters were investigated and optimized, including the current intensity, Fe3+ dosage, PS concentration, and initial pH. With a current intensity of 50 mA, an Fe3+ concentration of 50 μΜ, a PS dosage of 50 μM, and an initial pH of 3, the degradation efficiency of BZF demonstrated an exceptional achievement, reaching up to 98.8% within 30 min. The influence of anions and humic acid was also assessed. An LC/TOF/MS analysis revealed four major degradation pathways of BZF: hydroxylation, amino bond cleavage, dechlorination, and fibrate chain removal. The acute and chronic toxicities of BZF and its degradation intermediates were then assessed using the ECOSAR program. These findings highlight the wide-ranging applications of the EC/Fe3+/PS system and its potential for remediating water contaminated with micropollutants. [ABSTRACT FROM AUTHOR]

Laboratory studies of the disposition and toxicity of hydroxylated polychlorinated biphenyl (OH-PCB) metabolites are challenging because authentic analytical standards for most unknown OH-PCBs are not available. To assist with the characterization of these OH-PCBs (as methylated derivatives), we developed machine learning-based models with multiple linear regression (MLR) or random forest regression (RFR) to predict the relative retention times (RRT) and MS/MS responses of methoxylated (MeO-)PCBs on a gas chromatograph-tandem mass spectrometry system. The final MLR model estimated the retention times of MeO-PCBs with a mean absolute error of 0.55 min (n = 121). The similarity coefficients cos θ between the predicted (by RFR model) and experimental MS/MS data of MeO-PCBs were >0.95 for 92% of observations (n = 96). The levels of MeO-PCBs quantified with the predicted MS/MS response factors approximated the experimental values within a 2-fold difference for 85% of observations and 3-fold differences for all observations (n = 89). Subsequently, these model predictions were used to assist with the identification of OH-PCB 95 or OH-PCB 28 metabolites in mouse feces or liver by suggesting candidate ranking information for identifying the metabolite isomers. Thus, predicted retention and MS/MS response data can assist in identifying unknown OH-PCBs.

Deoxycholic acid (DCA) has been authorized by the Federal Drug Agency for cosmetic reduction of redundant submental fat. The hydroxylated product (6β-OH DCA) was developed to improve the solubility and pharmaceutic properties of DCA for further applications. Herein, a combinatorial catalytic strategy was applied to construct a powerful Cytochrome P450 biocatalyst (CYP107D1, OleP) to convert DCA to 6β-OH DCA. Firstly, the weak expression of OleP was significantly improved using pRSFDuet-1 plasmid in the E. coli C41 (DE3) strain. Next, the supply of heme was enhanced by the moderate overexpression of crucial genes in the heme biosynthetic pathway. In addition, a new biosensor was developed to select the appropriate redox partner. Furthermore, a cost-effective whole-cell catalytic system was constructed, resulting in the highest reported conversion rate of 6β-OH DCA (from 4.8% to 99.1%). The combinatorial catalytic strategies applied in this study provide an efficient method to synthesize high-value-added hydroxylated compounds by P450s.

Hydroxylation of aryl sulfonium salts could be realized by utilizing acetohydroxamic acid and oxime as hydroxylative agents in the presence of cesium carbonate as a base, leading to a variety of structurally diverse hydroxylated arenes in 47–95% yields. In addition, the reaction exhibited broad functionality tolerance, and a range of important functional groups (e.g., cyano, nitro, sulfonyl, formyl, keto, and ester) could be well amenable to the mild reaction conditions. [ABSTRACT FROM AUTHOR]

In the present work, we report a neutral dinuclear copper(II) complex, [Cu2(L1)(OH)], derived from a new [N,O] donor Schiff base ligand L1 that was formed after the endogenous hydroxylation of an initial carbamate Schiff base H2L coordinated with copper ions in an electrochemical cell. The copper(II) complex has been fully characterized using different techniques, including X-ray diffraction. Direct current (DC) magnetic susceptibility measurements were also performed at variable temperatures, showing evidence of antiferromagnetic behavior. Its catalase-like activity was also tested, demonstrating that this activity is affected by temperature. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA) is a multifactorial autoimmune disease in which hypovitaminosis D by calcidiol quantification has been associated with disease severity. However, other vitamin D molecules could be implicated in RA pathophysiology and its comorbidities such as cardiovascular disease (CVD), which impacts the severity and mortality of RA patients. This study aimed to assess the relationship between calcidiol, calcitriol, its hydroxylation efficiency ratio, and the soluble vitamin D receptor (sVDR) and clinical and CVD risk variables to propose potential vitamin D molecule biomarkers for RA. A cross-sectional study of females was conducted on 154 RA patients and 201 healthy subjects (HS). Calcidiol, calcitriol, and the sVDR were measured in blood serum, and vitamin D hydroxylation efficiency was estimated using the calcitriol/calcidiol ratio score. CVD risk was calculated by the high-sensitivity C-reactive protein (hs-CRP) cutoff values. Disease activity was evaluated with the Disease Activity Score for 28 standard joints (DAS28-CRP). Results: The hydroxylation efficiency ratio and calcitriol serum levels were higher in RA patients with hypovitaminosis D (p < 0.001). Moreover, RA patients had a higher probability of a high hydroxylation efficiency ratio (OR = 2.02; p = 0.02), calcitriol serum levels (OR = 2.95; p < 0.001), and sVDR serum levels (OR = 5.57; p < 0.001) than HS. This same pattern was also observed in RA patients with high CVD risk using CRP serum levels; they showed a higher hydroxylation efficiency ratio (OR = 4.51; p = 0.04) and higher calcitriol levels (OR = 5.6; p < 0.01). Calcitriol correlates positively with the sVDR (r = 0.21, p = 0.03), CRP (r = 0.28, p < 0.001), and cardiometabolic indexes (p < 0.001) also showed discrimination capacity for CVD risk in RA patients with CRP ≥ 3 mg/L (AUC = 0.72, p < 0.01). In conclusion, hypovitaminosis D in RA patients was characterized by a pattern of a higher hydroxylation efficiency ratio and higher calcitriol and sVDR serum levels. Notably, higher calcitriol serum levels and a higher vitamin D hydroxylation efficiency ratio were associated with higher CVD risk in RA patients. [ABSTRACT FROM AUTHOR]

The synthetic cytokinin forchlorfenuron (FCF), while seemingly presenting relatively low toxicity for mammalian organisms, has been the subject of renewed scrutiny in the past few years due to its increasing use in fruit crops and potential for bioaccumulation. Despite many toxicological properties of FCF being known, little research has been conducted on the toxicological effects of its secondary metabolites. Given this critical gap in the existing literature, understanding the formation of relevant FCF secondary metabolites and their association with mammalian metabolism is essential. To investigate the formation of FCF metabolites in sufficient quantities for toxicological studies, a panel of four fungi were screened for their ability to catalyze the biotransformation of FCF. Of the organisms screened, Cunninghamella elegans (ATCC 9245), a filamentous fungus, was found to convert FCF to 4-hydroxyphenyl-forchlorfenuron, the major FCF secondary metabolite identified in mammals, after 26 days. Following the optimization of biotransformation conditions using a solid support system, media screening, and inoculation with a solid pre-formed fungal mass of C. elegans, this conversion time was significantly reduced to 7 days—representing a 73% reduction in total reaction time as deduced from the biotransformation products and confirmed by LC-MS, NMR spectroscopic data, as well as a comparison with synthetically prepared metabolites. Our study provides the first report of the metabolism of FCF by C. elegans. These findings suggest that C. elegans can produce FCF secondary metabolites consistent with those produced via mammalian metabolism and could be used as a more efficient, cost-effective, and ethical alternative for producing those metabolites in useful quantities for toxicological studies. [ABSTRACT FROM AUTHOR]

Objective: YZJ-4729 is a novel G protein-biased μ-opioid receptor agonist for the treatment of acute pain in adult patients who require intravenous opioid analgesic therapy. The aim of this study was to assess the pharmacokinetics, metabolite profiling, safety and tolerability of YZJ-4729 in healthy Chinese subjects following the single intravenous doses ranged from 0.2 mg to 6 mg. Methods: This single-center, randomized, double-blind, placebo-controlled clinical study was conducted in 54 healthy male and female Chinese subjects after single ascending doses of YZJ-4729 tartrate (0.2, 0.5, 1.5, 3, 4.5, and 6 mg). Subjects in each cohort were assigned randomly to receive a single intravenous dose of YZJ-4729 tartrate injection or placebo at a ratio of 4:1. Pharmacokinetic characteristics, metabolite profiling, safety and tolerability profiles of the study drug were evaluated. Results: Overall, YZJ-4729 was safe and well tolerated in healthy Chinese subjects. The study drug reached peak plasma concentrations nearly at the end of the infusion. After administration, YZJ-4729 was eliminated rapidly with a terminal elimination half-life of 0.862-2.50 h, and excreted little in human excreta. The maximum drug concentration and area under the plasma concentration-time curve increased with dose escalation across the entire dose range. YZJ-4729 experienced extensive metabolism in human body. A total of 19 metabolites were identified and the characteristic metabolic pathways involved hydroxylation, ketone formation, N-dealkylation and glucuronide conjugation. Metabolite M10 was the most abundant circulating metabolite, and represented over 10% of total drug-related systemic exposure. Further PK and safety evaluation of M10 was necessary. Conclusion: The clinical study results laid a foundation for the further clinical studies of YZJ-4729 in patients. [ABSTRACT FROM AUTHOR]

HO enzyme catalyzes the degradation of free heme to biliverdin, CO, and Fe in three consecutive steps. The upregulated activity of heme oxygenase is thought to be correlated with the antioxidant role of HO-1 in an oxidative stress environment. HO enzyme regiospecificity oxidizes heme at a meso position in a three oxygenation steps process. Although hydroperoxy-ferric heme, generated in the first step, has been indicated as an intermediate in most heme enzyme, heme degradation is only occurred in HO reaction. Therefore, a different mechanism from the other heme enzymes must be responsible for the heme hydroxylation in HO-catalyzed reaction in the first step. In the second step of the process, there are also uncertainties regarding electron requirement and a binding site for O2 molecule. In this article, we review researchers' attempts to elucidate complicated heme catabolism mechanism, especially in the less known process steps which have been done to shed light on the determinants of specificity and better contribute to developing new medicines. Special focus is placed on the experimental and theoretical studies on the structural characteristics and electronic configurations of heme catabolism intermediates catalyzed by HO. The fascinating electronic communication between the metal and the ring in this process has been discussed, as well. An overview of the non-precedent route for the direct conversion of oxophlorin to biliverdin is also presented. [ABSTRACT FROM AUTHOR]

This research aimed at obtaining new derivatives of pregn-1,4-diene-3,20-dione (Δ1-progesterone) (2) through microbiological transformation. For the role of catalysts, we used six strains of entomopathogenic filamentous fungi (Beauveria bassiana KCh J1.5, Beauveria caledonica KCh J3.3, Isaria fumosorosea KCh J2, Isaria farinosa KCh KW1.1, Isaria tenuipes MU35, and Metarhizium robertsii MU4). The substrate (2) was obtained by carrying out an enzymatic 1,2-dehydrogenation on an increased scale (3.5 g/L) using a recombinant cholest-4-en-3-one Δ1-dehydrogenase (AcmB) from Sterolibacterium denitrificans. All selected strains were characterized by the high biotransformation capacity for the used substrate. As a result of the biotransformation, six steroid derivatives were obtained: 11α-hydroxypregn-1,4-diene-3,20-dione (3), 6β,11α-dihydroxypregn-1,4-diene-3,20-dione (4), 6β-hydroxypregn-1,4-diene-3,11,20-trione (5), 6β,17α-dihydroxypregn-1,4-diene-3,20-dione (6), 6β,17β-dihydroxyandrost-1,4-diene-3-one (7), and 12β,17α-dihydroxypregn-1,4-diene-3,20-dione (8). The results show evident variability of the biotransformation process between strains of the tested biocatalysts from different species described as entomopathogenic filamentous fungi. The obtained products were tested in silico using cheminformatics tools for their pharmacokinetic and pharmacodynamic properties, proving their potentially high biological activities. This study showed that the obtained compounds may have applications as effective inhibitors of testosterone 17β-dehydrogenase. Most of the obtained products should, also with a high probability, find potential uses as androgen antagonists, a prostate as well as menopausal disorders treatment. They should also demonstrate immunosuppressive, erythropoiesis-stimulating, and anti-inflammatory properties. [ABSTRACT FROM AUTHOR]

Amino alcohols are important compounds that are widely used in the polymer and pharmaceutical industry, particularly when used as chiral scaffolds in organic synthesis. The hydroxylation of polyamide polymers may allow crosslinking between molecular chains through the esterification reactions of hydroxyl and carboxyl groups. Therefore, this may alter the functional properties of polyamide polymers. 2-hydroxycadaverine (2HyC), as a new type of chiral amino alcohol, has potential applications in the pharmaceutical, chemical, and polymer industries. Currently, 2HyC production has only been realized via pure enzyme catalysis or two-stage whole-cell biocatalysis, which faces great challenges for scale-up production. However, the use of a cell factory is very promising for the production of 2HyC in industrial applications. Here, we designed and constructed a promising artificial pathway in Escherichia coli for producing 2HyC from biomass-derived lysine. This biosynthesis route expands the lysine catabolism pathway and employs two enzymes to sequentially convert lysine into 2HyC. However, the catalytic activity of wild-type pyridoxal phosphate-dependent decarboxylase from Chitinophage pinensis (DCCp) toward 3-hydroxylysine is lower, resulting in the lower production of 2HyC. Thus, the higher catalytic activity of DCCp is desired for low-cost and expanded industrial applications of 2HyC. To improve the catalytic activity of DCCp, a mutant library of DCCp was first built using a semi-rational design. The Kcat/Km of mutant DCCp (R53D/V94I) increased by 63%. A titer of 359 mg/L 2HyC was produced in shake flasks, with a 2HyC titer increase of 54% compared to control strain ML101. The results show that the production of 2HyC was effectively increased through a semi-rational design strategy. These findings lay the foundation for the development and utilization of renewable resources to produce 2HyC in microorganisms via an efficient, green, and sustainable biosynthetic strategy for further industrial application. [ABSTRACT FROM AUTHOR]

The electroenzymatic hydroxylation of 4-ethylbenzoic acid catalyzed by the recombinant unspecific peroxygenase from the fungus Agrocybe aegerita (r Aae UPO) was performed in a gas diffusion electrode (GDE)-based system. Enzyme stability and productivity are significantly affected by the way the co-substrate hydrogen peroxide (H 2 O 2) is supplied. In this study, two in-situ electrogeneration modes of H 2 O 2 were established and compared. Experiments under galvanostatic conditions (constant productivity of H 2 O 2) were conducted at current densities spanning from 0.8 mA cm−2 to 6.4 mA cm−2. For comparison, experiments under H 2 O 2 -stat mode (constant H 2 O 2 concentration) were performed. Here, four H 2 O 2 concentrations between 0.06 mM and 0.28 mM were tested. A maximum H 2 O 2 productivity of 5.5 µM min−1 cm−2 and productivity of 10.5 g L−1 d−1 were achieved under the galvanostatic condition at 6.4 mA cm−2. Meanwhile, the highest total turnover number (TTN) of 710,000 mol mol−1 and turnover frequency (TOF) of 87.5 s−1 were obtained under the H 2 O 2 -stat mode at concentration limits of 0.15 mM and 0.28 mM, respectively. The most favorable outcome in terms of maximum achievable TTN, TOF and productivity was found under the H 2 O 2 -stat mode at concentration limit of 0.2 mM. Here, a TTN of 655,000 mol mol−1, a TOF of 80.3 s−1 and a productivity of 6.1 g L−1 d−1 were achieved. The electrochemical H 2 O 2 -stat mode not only offers a promising alternative reaction concept to the well-established galvanostatic mode but also enhances the process performance of unspecific peroxygenases. [Display omitted] • In-situ electrochemical H 2 O 2 -stat mode as a promising alternative reaction concept. • Combination of electrochemical H 2 O 2 -stat mode with an enzymatic hydroxylation. • Enhancement of process performance of unspecific peroxygenase. • Achievement of TTN up to 710,000 mol mol−1 and TOF as high as 87.5 s−1 [ABSTRACT FROM AUTHOR]

The hydroxylation of C–H bonds can be carried out by the high-valent CoIII,IV 2(µ-O)2 complex 2a supported by the tetradentate tris(2-pyridylmethyl)amine ligand via a CoIII 2(µ-O)(µ-OH) intermediate (3a). Complex 3a can be independently generated either by H-atom transfer (HAT) in the reaction of 2a with phenols as the H-atom donor or protonation of its conjugate base, the CoIII 2(µ-O)2 complex 1a. Resonance Raman spectra of these three complexes reveal oxygen-isotope-sensitive vibrations at 560 to 590 cm−1 associated with the symmetric Co–O–Co stretching mode of the Co2O2 diamond core. Together with a Co•••Co distance of 2.78(2) Å previously identified for 1a and 2a by Extended X-ray Absorption Fine Structure (EXAFS) analysis, these results provide solid evidence for their “diamond core” structural assignments. The independent generation of 3a allows us to investigate HAT reactions of 2a with phenols in detail, measure the redox potential and pKa of the system, and calculate the O–H bond strength (DO–H) of 3a to shed light on the C–H bond activation reactivity of 2a. Complex 3a is found to be able to transfer its hydroxyl ligand onto the trityl radical to form the hydroxylated product, representing a direct experimental observation of such a reaction by a dinuclear cobalt complex. Surprisingly, reactivity comparisons reveal 2a to be 106 -fold more reactive in oxidizing hydrocarbon C–H bonds than corresponding FeIII,IV 2(µ-O)2 and MnIII,IV 2(µ-O)2 analogs, an unexpected outcome that raises the prospects for using CoIII,IV 2(µ-O)2 species to oxidize alkane C–H bonds. [ABSTRACT FROM AUTHOR]

Oxygen is essential for viability in mammalian organisms. However, cells are often exposed to changes in oxygen availability, due to either increased demand or reduced oxygen supply, herein called hypoxia. To be able to survive and/or adapt to hypoxia, cells activate a variety of signalling cascades resulting in changes to chromatin, gene expression, metabolism and viability. Cellular signalling is often mediated via post‐translational modifications (PTMs), and this is no different in response to hypoxia. Many enzymes require oxygen for their activity and oxygen can directly influence several PTMS. Here, we review the direct impact of changes in oxygen availability on PTMs such as proline, asparagine, histidine and lysine hydroxylation, lysine and arginine methylation and cysteine dioxygenation, with a focus on mammalian systems. In addition, indirect hypoxia‐dependent effects on phosphorylation, ubiquitination and sumoylation will also be discussed. Direct and indirect oxygen‐regulated changes to PTMs are coordinated to achieve the cell's ultimate response to hypoxia. However, specific oxygen sensitivity and the functional relevance of some of the identified PTMs still require significant research. [ABSTRACT FROM AUTHOR]

An efficient and convenient method for the synthesis of phenols and aliphatic alcohols is described in this paper. The oxidative hydroxylation reaction of various organoboron compounds proceeded smoothly by employing H2O2 as the oxidant and citric acid as the catalyst in water at room temperature to produce phenols and aliphatic alcohols in satisfactory to excellent yields (up to 99% yield). Various synthetically useful functional groups, such as halogen atom, cyano, and nitro groups, remain intact during the oxidative hydroxylation. The developed catalytic system also could accommodate phenylboronic pinacol ester and potassium phenyltrifluoroborate to give the target product good yields. [ABSTRACT FROM AUTHOR]

Flavin-dependent monooxygenases (FDMOs) are known for their remarkable versatility and for their crucial roles in various biological processes and applications. Extensive research has been conducted to explore the structural and functional relationships of FDMOs. The majority of reported FDMOs utilize C4a-(hydro)peroxyflavin as a reactive intermediate to incorporate an oxygen atom into a wide range of compounds. This review discusses and analyzes recent advancements in our understanding of the structural and mechanistic features governing the enzyme functions. State-of-the-art discoveries related to common and distinct structural properties governing the catalytic versatility of the C4a-(hydro)peroxyflavin intermediate in selected FDMOs are discussed. Specifically, mechanisms of hydroxylation, dehalogenation, halogenation, and light-emitting reactions by FDMOs are highlighted. We also provide new analysis based on the structural and mechanistic features of these enzymes to gain insights into how the same intermediate can be harnessed to perform a wide variety of reactions. Challenging questions to obtain further breakthroughs in the understanding of FDMOs are also proposed. [ABSTRACT FROM AUTHOR]

The aim of this study was to obtain new halolactones with a gem-dimethyl group in the cyclohexane ring (at the C-3 or C-5 carbon) and a methyl group in the lactone ring and then subject them to biotransformations using filamentous fungi. Halolactones in the form of mixtures of two diasteroisomers were subjected to screening biotransformations, which showed that only compounds with a gem-dimethyl group located at the C-5 carbon were transformed. Strains from the genus Fusarium carried out hydrolytic dehalogenation, while strains from the genus Absidia carried out hydroxylation of the C-7 carbon. Both substrates and biotransformation products were then tested for antimicrobial activity against multidrug-resistant strains of both bacteria and yeast-like fungi. The highest antifungal activity against C. dubliniensis and C. albicans strains was obtained for compound 5b, while antimicrobial activity against S. aureus MRSA was obtained for compound 4a.

Eighteen short- to medium-chain monounsaturated fatty acids were screened for hydroxylation and epoxidation using eleven different peroxygenase preparations. Most of these unspecific peroxygenases (UPOs) are secreted by fungal species of the dark-spored basidiomycetous families Psathyrellaceae and Strophariaceae, two belonged to the white-spored genus Marasmius (Marasmiaceae), and one belonged to the ascomycetous family Chaetomiaceae. The fatty acids (FAs) studied were categorized into three groups based on the position of the double bond: (i) terminal unsaturated FAs (between ω and ω-1), (ii) α-β-unsaturated FAs (between C2 and C3), and (iii) β-γ-unsaturated FAs (between C3 and C4). Their chain lengths ranged from three to nine carbon atoms. FAs with a terminal double bond were significantly oxidized by only two UPOs, namely CglUPO and CraUPO (peroxygenases from Chaetomium globosum and Coprinellus radians, respectively), producing different products. FAs with internal double bonds were converted by all tested UPOs. While epoxides were observed as products in the case of α-β-unsaturated fatty acids, only CglUPO formed β-γ-epoxides from the corresponding FAs. The product pattern of the other UPOs for β-γ-unsaturated FAs was quite similar. On the other hand, the product pattern for oxidized α-β-unsaturated FAs was more variable and, in some cases, specific to a particular UPO. For example, in the reaction with trans-2-nonenoic acid, the enzymes clustered into six groups based on the formed products.

The synthesis of vegetable oil-based polyols has been carried out through the epoxidation-hydroxylation process. However, Tung oil has never been explored in the process, even though Tung oil has a high double bond. Epoxidized Tung Oil (ETO) with oxirane numbers of 3.92 to 4.04 mmol/g were hydroxylated with methanol and catalyzed by Sulfuric Acid (H2SO4). The objective of this study is to produce polyols from ETO and to evaluate the influence of temperature and catalyst concentration on the hydroxylation process. A second-order reaction kinetic study was also developed to represent the reaction. The ETO hydroxylation was carried out in a batch reactor for four hours. The reaction rate was determined based on the concentration of ETO (oxirane number) and Hydroxyl Value (OHV). The result shows that temperature and catalyst concentration have a directly proportional correlation to OHV and are inversely proportional to the concentration of ETO (epoxy). For temperatures above 40°C, the decreasing rate of the epoxy concentration at the beginning was relatively much faster than at the end of the reaction. In the temperature variation, the highest OHV obtained was 3.70 mmolKOH/g or 207.39 mgKOH/g at 80°C. The optimum catalyst concentration obtained in this study was 3%. The evaluated kinetics model gave great results for all reaction temperatures, with the highest total SSE for epoxy concentration and OHV data fitting of 0.156 and 0.045, respectively. The calculated activation energy (Ea) was 30.41 kJ/mol and the pre-exponential factor (A) was 255.00 g.mmol-1.min-1.

Although lignin improves the strength and modulus of soil, it is less active when unmodified, and it exhibits more limited effects on soils in combination with traditional Ca-based curing agents. Lignin-solidified soil also exhibits deficiencies, such as poor durability under dry–wet cycling conditions, and thus, the amelioration effect is limited. This study investigated the enhancement of cement-solidified soil using hydroxylated lignin with sodium silicate and quicklime used as activators to improve the engineering performance and durability of the treated soil. Using respective cement, sodium silicate, quicklime, and lignin contents of 7%, 0.4%, 0.2%, and 0.2% with respect to the dry mass of the slag soil, the strength and cohesion of the composite-solidified soil were 1.5 times those of cement-solidified soil, whereas the internal friction angle increased by 5.1°. At a solidifying age of 14 d, the penetration resistance almost doubled, indicating a significant improvement in the bearing capacity of the soil. The results suggest that modified lignin-based admixtures may significantly enhance the performance of cement-solidified soil. The cement curing admixture used in this study provides theoretical and technological support for curing agent preparation and the utilization of slag. [ABSTRACT FROM AUTHOR]

Ubiquinone (UQ) is a lipophilic electron carrier that functions in the respiratory and photosynthetic electron transfer chains of proteobacteria and eukaryotes. Bacterial UQ biosynthesis is well studied in the gammaproteobacterium Escherichia coli, in which most bacterial UQ‐biosynthetic enzymes have been identified. However, these enzymes are not always conserved among UQ‐containing bacteria. In particular, the alphaproteobacterial UQ biosynthesis pathways contain many uncharacterized steps with unknown features. In this work, we identified in the alphaproteobacterium Rhodobacter capsulatus a new decarboxylative hydroxylase and named it UbiN. Remarkably, the UbiN sequence is more similar to a salicylate hydroxylase than the conventional flavin‐containing UQ‐biosynthetic monooxygenases. Under aerobic conditions, R. capsulatus ΔubiN mutant cells accumulate 3‐decaprenylphenol, which is a UQ‐biosynthetic intermediate. In addition, 3‐decaprenyl‐4‐hydroxybenzoic acid, which is the substrate of UQ‐biosynthetic decarboxylase UbiD, also accumulates in ΔubiN cells under aerobic conditions. Considering that the R. capsulatus ΔubiD‐X double mutant strain (UbiX produces a prenylated FMN required for UbiD) grows as a wild‐type strain under aerobic conditions, these results indicate that UbiN catalyzes the aerobic decarboxylative hydroxylation of 3‐decaprenyl‐4‐hydroxybenzoic acid. This is the first example of the involvement of decarboxylative hydroxylation in ubiquinone biosynthesis. This finding suggests that the C1 hydroxylation reaction is, at least in R. capsulatus, the first step among the three hydroxylation steps involved in UQ biosynthesis. Although the C5 hydroxylation reaction is often considered to be the first hydroxylation step in bacterial UQ biosynthesis, it appears that the R. capsulatus pathway is more similar to that found in mammalians. [ABSTRACT FROM AUTHOR]

The P450 monooxygenase CYP109A2 from Bacillus megaterium DSM319 was previously found to convert vitamin D3 (VD3) to 25‐hydroxyvitamin D3. Here, we show that this enzyme is also able to convert testosterone in a highly regio‐ and stereoselective manner to 16β‐hydroxytestosterone. To reveal the structural determinants governing the regio‐ and stereoselective steroid hydroxylation reactions catalyzed by CYP109A2, two crystal structures of CYP109A2 were solved in similar closed conformations, one revealing a bound testosterone in the active site pocket, albeit at a nonproductive site away from the heme‐iron. To examine whether the closed crystal structures nevertheless correspond to a reactive conformation of CYP109A2, docking and molecular dynamics (MD) simulations were performed with testosterone and vitamin D3 (VD3) present in the active site. These MD simulations were analyzed for catalytically productive conformations, the relative occurrences of which were in agreement with the experimentally determined stereoselectivities if the predicted stability of each carbon‐hydrogen bond was taken into account. Overall, the first‐time determination and analysis of the catalytically relevant 3D conformation of CYP109A2 will allow for future small molecule ligand screening in silico, as well as enabling site‐directed mutagenesis toward improved enzymatic properties of this enzyme. [ABSTRACT FROM AUTHOR]