Whole-Cell Catalytic Synthesis of Puerarin Monoesters and Analysis of Their Antioxidant Activities

Pueraria: A Comprehensive Review of Chemical Composition, Health Benefits, and Current Applications

Pueraria as a legume vine is mainly produced in East Asia and Southeast Asia. Its most widely used part is the tuber. Pueraria is often used to treat various diseases such as fever and headache since ancient times. Recently, pueraria as a valuable source of polysaccharides, phytochemicals, proteins, minerals, and other nutrients has anticancer, immunomodulatory, hypoglycemic, lipid-lowering, antiatherosclerotic, neuroprotective, hepatointestinal regulatory, hormonal regulatory activities, and so forth. This review provides a comprehensive overview of the resources and distribution, processing procedures and application, nutritional and phytochemical composition, and biological activities of pueraria, and gives insights into developing pueraria as a potential and novel ingredient for its versatile food and nonfood applications along with the latest researches conducted worldwide. Furthermore, it highlights the safety and regulatory issues for consumption of pueraria as food ingredient.

Therapeutic potential of flavonoids in gastrointestinal cancer: Focus on signaling pathways and improvement strategies (Review)

Flavonoids are a group of polyphenolic compounds distributed in vegetables, fruits and other plants, which have considerable antioxidant, anti‑tumor and anti‑inflammatory activities. Several types of gastrointestinal (GI) cancer are the most common malignant tumors in the world. A large number of studies have shown that flavonoids have inhibitory effects on cancer, and they are recognized as a class of potential anti‑tumor drugs. Therefore, the present review investigated the molecular mechanisms of flavonoids in the treatment of different types of GI cancer and summarized the drug delivery systems commonly used to improve their bioavailability. First, the classification of flavonoids and the therapeutic effects of various flavonoids on human diseases were briefly introduced. Then, to clarify the mechanism of action of flavonoids on different types of GI cancer in the human body, the metabolic process of flavonoids in the human body and the associated signaling pathways causing five common types of GI cancer were discussed, as well as the corresponding therapeutic targets of flavonoids. Finally, in clinical settings, flavonoids have poor water solubility, low permeability and inferior stability, which lead to low absorption efficiency in vivo. Therefore, the three most widely used drug delivery systems were summarized. Suggestions for improving the bioavailability of flavonoids and the focus of the next stage of research were also put forward.

Transforming Poly(butylene adipate-co-terephthalate) into Protocatechuic Acid via Enzymatic Degradation and Whole-Cell Catalysis

Poly(butylene adipate-co-terephthalate) (PBAT) is a biodegradable plastic with increasing applications that degrades rapidly in composting, but its sole degradation limits residual value utilization. Therefore, new strategies for converting PBAT to valuable products are needed. In this study, enzymatic degradation was applied to hydrolyze PBAT, and an engineered Escherichia coli strain was constructed and utilized as a whole-cell catalyst to synthesize protocatechuic acid (PCA), a valuable platform compound, from degradation products. By fine-tuning the overexpression of four enzymes in the biosynthetic pathway and optimizing catalytic conditions, the titer of PCA was increased 5.07-fold to 5.28 ± 0.05 g/L, achieving a 15.45 ± 1.04 wt % conversion rate from pure PBAT particles. Furthermore, the strategy was applicable to commercial PBAT/poly(lactic acid) (PLA), achieving a maximum conversion rate of 25.05 ± 1.21 wt %. Thus, a novel strategy to utilize the PBAT waste was established, which provides a reference for upgrading other macrowaste resources.

Botanical Flavonoids: Efficacy, Absorption, Metabolism and Advanced Pharmaceutical Technology for Improving Bioavailability

Flavonoids represent a class of natural plant secondary metabolites with multiple activities including antioxidant, antitumor, anti-inflammatory, and antimicrobial properties. However, due to their structural characteristics, they often exhibit low bioavailability in vivo. In this review, we focus on the in vivo study of flavonoids, particularly the effects of gut microbiome on flavonoids, including common modifications such as methylation, acetylation, and dehydroxylation, etc. These modifications aim to change the structural characteristics of the original substances to enhance absorption and bioavailability. In order to improve the bioavailability of flavonoids, we discuss two feasible methods, namely dosage form modification and chemical modification, and hope that these approaches will offer new insights into the application of flavonoids for human health. In this article, we also introduce the types, plant sources, and efficacy of flavonoids. In conclusion, this is a comprehensive review on how to improve the bioavailability of flavonoids.

Green and sustainable production of isofraxidin from Acanthopanax senticosus with cellulose-based immobilized probiotics

This study utilizes deep eutectic solvent (DES)-assisted enhancement of cellulose-based immobilized probiotics for efficient biotransformation of isofraxidin from Acanthopanax senticosus. Among seven probiotic strains tested, Lactiplantibacillus plantarum CICC 20767 exhibited the best catalytic activity. We explored the effects of 12 different DESs with varying hydrogen bond donors on the conversion capacity of the immobilized probiotics, with the highest efficiency observed using ChCl/EG (4.0 wt %). The optimized process, with a solid-to-liquid ratio of 1:5 (g/mL), a temperature of 35.6 °C, a reaction time of 4 d, and a pH of 6.9, resulted in a 5.53-folds increase in isofraxidin yield, reaching 0.4034 mg/g, compared to the untreated sample (0.0729 mg/g). The immobilized probiotics retained excellent catalytic activity after 12 cycles of use, demonstrating their stability and potential for large-scale, green production of isofraxidin. This study presents a valuable method for industrial isofraxidin production and highlights the broad potential of this environmentally friendly bioconversion process in the pharmaceutical industry.

Puerarin Attenuates Podocyte Damage in Mice With Diabetic Kidney Disease by Modulating the AMPK/Nrf2 Pathway

Background: This study aimed to investigate the potential mechanisms of puerarin in alleviating diabetic nephropathy (DKD) in mice. Method: The DKD model was induced by multiple low-dose injections of streptozotocin (STZ) and a high-sugar and high-fat diet in male C57BL/6J mice. After confirming the onset of DKD, mice were given irbesartan, distilled water, or different concentrations of puerarin (40 and 80 mg/kg/d) by gavage for 8 weeks. HE staining and PAS staining were adopted to assess the pathological changes in the kidney tissues. Meanwhile, the levels of superoxide dismutase, catalase, creatinine, and cystatin C in the serum and the urine albumin and creatinine were measured, and the renal indices as well as the urinary albumin-to-creatinine ratio (UACR) were calculated. The changes of podocin and protein expression levels associated with AMPK/Nrf2 signaling pathway were evaluated by western blot. Results: Puerarin significantly reduced the level of fasting blood glucose, renal index, glomerular mesangial expansion index, renal function, and oxidative stress induced by STZ (p < 0.05). The pathological injuries in kidney tissues were also alleviated. Furthermore, we demonstrated that the expression level of podocin and protein related to the AMPK/Nrf2 signaling pathway was also decreased significantly by the treatment of puerarin. At the same time, the efficacy of puerarin in the treatment of DKD was better than that of irbesartan, and the treatment effect of the high-dose group (80 mg/kg/d) was also significantly better than that of the low-dose group (40 mg/kg/d). Conclusion: Puerarin could attenuate the severity of DKD and protect the podocyte in mice in a dose-dependent way. Also, it might be performed by regulating the AMPK/Nrf2 pathway. These findings may provide a theoretical basis for updating the clinical management of DKD.

Improving complexation of puerarin with kudzu starch by various ultrasonic pretreatment: Interaction mechanism analysis

The industrial preparation of kudzu starch (KS) significantly reduces the remaining of flavonoids like puerarin (PU) in the product, weakening its biological activity and making pre-treatments on kudzu crucial. Ultrasonic technique, widely used for modifying biomolecules, can enhance nutrient interactions like those between starch and polyphenols in foods. Thus, a puerarin-kudzu starch (PKS) complex was prepared with the introduction of ultrasonic pretreatment. The results indicated that sonication increased the binding of PU to KS from 0.399 ± 0.01 to 0.609 ± 0.05 mg/g. Particle size analysis and SEM revealed that the particles of the ultrasonic puerarin-kudzu starch complex (UPKS) were larger than those of the untreated complexes. XRD, UV-vis, and FT-IR spectroscopic analyses indicated that hydrogen bonding primarily governs the interaction between PU and KS. Additionally, incorporating PU decreased the starch structure's orderliness, while ultrasonic treatment altered the helical configuration of straight-chain starch, leading to the formation of a new, ordered structure through the creation of new hydrogen bonds. Additionally, gels formed from UPKS exhibited higher viscosity, elasticity, and shear stress, suggesting that ultrasound significantly altered the intermolecular interactions between PKS. In conclusion, the use of ultrasound under optimal conditions has demonstrated its effectiveness in preparing PKS complexes, highlighting its significant potential to produce high value-added kudzu-based products.

The beneficial health effects of puerarin in the treatment of cardiovascular diseases: from mechanisms to therapeutics

Cardiovascular diseases (CVDs) are the leading causes of death globally that seriously threaten human health. Although novel western medicines have continued to be discovered over the past few decades to inhibit the progression of CVDs, new drug research and development for treating CVDs with less side effects and adverse reactions are continuously being desired. Puerarin is a natural product found in a variety of medicinal plants belonging to the flavonoid family with potent biological and pharmacological activities. Abundant research findings in the literature have suggested that puerarin possesses a promising prospect in treating CVDs. In recent years, numerous new molecular mechanisms of puerarin have been explored in experimental and clinical studies, providing new evidence for this plant metabolite to protect against CVDs. This article systematically introduces the history of use, bioavailability, and various dosage forms of puerarin and further summarizes recently published data on the major research advances and their underlying therapeutic mechanisms in treating CVDs. It may provide references for researchers in the fields of pharmacology, natural products, and internal medicine.

Enhanced Enzymatic Synthesis of Puerarin Palmitate with Different Acyl Donors for Lipid Solubility Improvement

Puerarin is a flavonoid known as a natural antioxidant found in the root of Pueraria robata. Its antioxidant, anticancer, and anti-inflammatory effects have attracted attention as a potential functional ingredient in various bioindustries. However, puerarin has limited bioavailability owing to its low lipid solubility and stability. Acylation is proposed as a synthesis method to overcome this limitation. In this study, lipase-catalyzed acylation of puerarin and various acyl donors was performed, and the enzymatic synthetic condition was optimized. Under the condition (20 g/L of Novozym 435, palmitic anhydride, 1:15, 40 °C, tetrahydrofuran (THF)), the synthesis of puerarin ester achieved a significantly high conversion (98.97%) within a short time (3 h). The molecule of the synthesized puerarin palmitate was identified by various analyses such as liquid chromatography-mass spectrometry (LC-MS), Fourier-transform infrared spectroscopy (FT-IR), and carbon-13 nuclear magnetic resonance (13C NMR). The lipid solubility and the radical scavenging activity were also evaluated. Puerarin palmitate showed a slight decrease in antioxidant activity, but lipid solubility was significantly improved, improving bioavailability. The high conversion achieved for puerarin esters in this study will provide the foundation for industrial applications.

The mechanism of ferroptosis in early brain injury after subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a cerebrovascular accident with an acute onset, severe disease characteristics, and poor prognosis. Within 72 hours after the occurrence of SAH, a sequence of pathological changes occur in the body including blood-brain barrier breakdown, cerebral edema, and reduced cerebrovascular flow that are defined as early brain injury (EBI), and it has been demonstrated that EBI exhibits an obvious correlation with poor prognosis. Ferroptosis is a novel programmed cell death mode. Ferroptosis is induced by the iron-dependent accumulation of lipid peroxides and reactive oxygen species (ROS). Ferroptosis involves abnormal iron metabolism, glutathione depletion, and lipid peroxidation. Recent study revealed that ferroptosis is involved in EBI and is significantly correlated with poor prognosis. With the gradual realization of the importance of ferroptosis, an increasing number of studies have been conducted to examine this process. This review summarizes the latest work in this field and tracks current research progress. We focused on iron metabolism, lipid metabolism, reduction systems centered on the GSH/GPX4 system, other newly discovered GSH/GPX4-independent antioxidant systems, and their related targets in the context of early brain injury. Additionally, we examined certain ferroptosis regulatory mechanisms that have been studied in other fields but not in SAH. A link between death and oxidative stress has been described. Additionally, we highlight the future research direction of ferroptosis in EBI of SAH, and this provides new ideas for follow-up research.

Puerarin Attenuates Oxidative Stress and Ferroptosis via AMPK/PGC1α/Nrf2 Pathway after Subarachnoid Hemorrhage in Rats

Puerarin was shown to exert anti-oxidative and anti-ferroptosis effects in multiple diseases. The goal of this study was to explore the neuroprotective effect of puerarin on early brain injury (EBI) after subarachnoid hemorrhage (SAH) in rats. A total of 177 adult male Sprague Dawley rats were used. SAH was included via endovascular perforation. Intranasal puerarin or intracerebroventricular dorsomorphin (AMPK inhibitor) and SR18292 (PGC1α inhibitor) were administered. The protein levels of pAMPK, PGC1α, Nrf2, 4HNE, HO1, MDA, ACSL4, GSSG, and iron concentration in the ipsilateral hemisphere were significantly increased, whereas SOD, GPX4, and GSH were decreased at 24 h after SAH. Moreover, puerarin treatment significantly increased the protein levels of pAMPK, PGC1α, Nrf2, HO1, SOD, GPX4, and GSH, but decreased the levels of 4HNE, MDA, ACSL4, GSSG, and iron concentration in the ipsilateral hemisphere at 24 h after SAH. Dorsomorphin or SR18292 partially abolished the beneficial effects of puerarin exerted on neurological dysfunction, oxidative stress injury, and ferroptosis. In conclusion, puerarin improved neurobehavioral impairments and attenuated oxidative-stress-induced brain ferroptosis after SAH in rats. The neuroprotection acted through the activation of the AMPK/PGC1α/Nrf2-signaling pathway. Thus, puerarin may serve as new therapeutics against EBI in SAH patients.

Modification of flavonoids: methods and influences on biological activities

Flavonoids are important active ingredients in plant-based food, which have many beneficial effects on health. But the low solubility, poor oral bioavailability, and inferior stability of many flavonoids may limit their applications in the food, cosmetics, and pharmaceutical industries. Structural modification can overcome these shortcomings to improve and extend the application of flavonoids. The study of how to modify flavonoids and the influence of various modifications on biological activity have drawn great interest in the current literature. In this review, the working principles and operating conditions of modification methods were summarized along with their potential and limitations in terms of operational safety, cost, and productivity. The influence of various modifications on biological activities and the structure-activity relationships of flavonoids derivatives were discussed and highlighted, which may give guidance for the synthesis of highly effective active agents. In addition, the safety of flavonoids derivatives is reviewed, and future research directions of flavonoid modification research are discussed.

Biocatalytical Acyl-Modification of Puerarin: Shape Gut Microbiota Profile and Improve Short Chain Fatty Acids Production in Rats

Gut microbiota balance and metabolites have become a potentially mechanism in maintaining health. The specific aim of this study was to compare the modulation of puerarin and puerarin acid esters on gut microbial composition and metabolites. Male mice were fed a control diet or diets supplemented with puerarin, puerarin propanoate ester, puerarin hexanoate ester, puerarin myristate ester for 24 h, respectively. The result revealed that puerarin acid esters with different chain lengths showed different activities to create more own impacted bacterial. Puerarin propanoate and puerarin hexanoate ester significantly improved the diversity of microbiota and promoted the relative abundance of beneficial gut microbiota such as Lactobacillus, Barnesiella, Clostridium IV, Prevotella. Additionally, the puerarin propanoate ester group showed the capacity to deliver specific propionic acid to the colon. But esters with medium-long chain lengths had more opportunity to alter gut microbiota for enhancing the short chain fatty acids production. As a whole, puerarin acid esters with different chain lengths supplements shaped different gut microbial and short chain fatty acids metabolism, which could improve human health.

Metabolic Profiling of Carbonyl Compounds for Unveiling Protective Mechanisms of Pueraria lobata against Diabetic Nephropathy by UPLC-Q-Orbitrap HRMS/MS Analysis

Carbonyl compounds play a critical role in the pathogenesis of diabetic nephropathy (DN). Pueraria lobata (PL), also known as "Kudzu", is a widely consumed functional food or nutraceutical and has shown promise in the prevention of diabetes and complications such as DN. To explore the beneficial effects and the underlying mechanisms of PL against DN, a new strategy for in-depth metabolic profiling of carbonyl compounds in DN mice plasma by chemical derivatization combined with UPLC-Q-Orbitrap high-resolution mass spectrometry (HRMS)/MS analysis was developed for the first time. Pharmacological evaluation revealed that PL extracts containing a total of 73 identified compounds could ameliorate kidney injury and regulate abnormal glycolipid metabolism. In metabolomics analysis, 19 carbonyl compounds with significant differences were identified between DN mice and normal mice. Moreover, 12 metabolites had a tendency to return to normal levels after PL treatment. Overall, PL exerts beneficial effects on DN by regulating abnormal glycolipid metabolism and carbonyl stress, and endogenous carbonyl compounds might serve as potential biomarkers for DN.

Highly efficient whole-cell biosynthesis and cytotoxicity of esculin esters

Esculin is a polyphenol with multiple bioactivities and poor lipophilicity. Therefore, a whole-cell catalytic strategy for esculin acylation was developed to improve its lipophilicity. A total of 12 strains were tested, among which Pseudomonas stutzeri exhibited the highest catalytic activity and mono-acylated regioselectivity. The conversion reached the highest level of 92.7 % at 24 h under the optimal conditions, when vinyl acetate was used as an acyl donor. The catalytic ability of P. stutzeri remained above 60 % after three cycles. Subsequently, five esculin esters with different lengths of fatty chains were synthesized and structurally identified. Of them, esculin-6'-O-octanoate, esculin-6'-O-laurate, and esculin-6'-O-myristate exhibited cytotoxicity on LO2 cells by inducing apoptosis and necrosis. The cytotoxicity of these three esters may attribute to their membrane-disrupting properties. This study provides a novel whole-cell biocatalytic strategy for the acylation of esculin and insight for application of esculin esters as a food additive or drug.

Diacerein as a Promising Acyl Donor in Biosynthetic Acetyl-CoA and Glycosyl Esters Mediated by a Multifunctional Maltose O-Acetyltransferase from Escherichia coli

Acetyl-coenzyme A (acetyl-CoA) is an important donor for acetylation modifications of nutritional supplements. The existing enzymatic methods for acetyl-CoA synthesis suffer from cofactor dependence, donor inaccessibility, and biocatalyst instability, leading to its high cost. Hence, a promising alternative is highly desired. Herein, a maltose O-acetyltransferase (MAT) with cofactor independence had been identified as a stable acetyl-CoA-synthesizing biocatalyst in a screen of the Escherichia coli genome. Under the action of MAT, an anthraquinone medicine containing two acetyl groups, diacerein, was screened as an acetyl donor. Saturation mutagenesis at Glu125 was performed to increase the acetyl-CoA-synthesizing capacity of MAT, while decreasing the accompanying hydrolase activities. A mutant MAT-E125F was thus generated and could convert diacerein and CoA into the highest yield of 3892.70 mg/L acetyl-CoA. Moreover, MAT could synthesize puerarin 6″-O-acetate and other glycosyl esters through acetyl-CoA-dependent acetylation or diacerein-based transesterification reaction. To most of the tested glycosides, the transesterification efficiency was higher than that of acetylation. The mutant MAT-E125V acquired the highest conversion of 94.0% to puerarin 6″-O-acetate through transesterification, while MAT-E125N yielded the highest conversion of 68.5% through acetylation. Taking together, the multifunctional MAT displayed a potent acetyl-CoA- and glycosyl ester-synthesizing capacity using diacerein as an acetyl donor.

Evaluation of the digestion and transport profiles and potential immunocompetence of puerarin and its acylated derivatives

Acylation has become one of the most widely used methods to improve the lipid solubility and bioavailability of flavonoids. In this study, puerarin acid esters (PAES) with different chain lengths were synthesized via biocatalytic acylation. This was the first study to evaluate the digestion and transport profiles and immunocompetence of PAES. The relationship between the digestion and transport profiles and potential immunocompetence of the acylated derivatives in Caco-2 cell monolayers was also explored. Puerarin and PAES remained stable in gastric phases, whereas different degrees of hydrolysis of PAES were found in the intestine. PAES with less than 12 carbon chains were positively correlated with the degree of hydrolysis, while those with more than 12 carbon chains showed higher resistance to hydrolysis by the artificial human digestive juice. The apparent permeability coefficients of puerarin, puerarin acetate, puerarin propanoate, puerarin butyrate, puerarin hexanoate, puerarin octanate and puerarin laurate were 1.62 ± 0.09, 1.70 ± 0.15, 1.89 ± 0.19, 1.86 ± 0.18, 2.29 ± 0.12, 4.06 ± 1.01 and 2.32 ± 0.88 × 10-6 cm s-1, respectively, in Caco-2 cell monolayers. The results of the immune factor assays indicated that puerarin propanoate, puerarin hexanoate and puerarin myristate could significantly promote the secretion of IL-6, TNF-α and IL-10. These findings suggested that a better absorption could be predicted after oral intake using PAES. Meanwhile, the concentration of esters and their metabolites (puerarin) found in the digestion and transport profiles directly affected their potential immunocompetence.

One-pot biocatalytic synthesis and antioxidant activities of highly lipophilic naringin derivatives by using bi-functional whole-cells

Citrus peel wastes are an important renewable resource and rich in naringin, a flavonoid compound with multiple bioactivities. To cope with the low bioavailability of naringin, a new bienzyme whole-cell system was developed for bioconversion of naringin into two lipophilic derivatives. A series of naringin esters with different fatty acid chain length were successfully synthesized via cell-bound lipase catalyzed acylation, and another lipophilic product naringenin was simultaneously yielded via intracellular naringinase-catalyzed hydrolysis. The naringin esters obtained showed higher log P values and free radical-scavenging capacities against DPPH and ABTS than naringin itself. These esters also showed markedly enhanced permeability across the human intestinal Caco-2 cells. The whole-cell mediated conversion of naringin offers a two-fold advantage: naringin esters are produced as new high-valued derivatives with high lipophilicity and antioxidant activity; and the tasteless product naringenin was obtained simultaneously, which can reduce the bitterness of the total product and benefited its industrial applications.

Synthesis of Hydrophobic Propionyl Neohesperidin Ester Using an Immobilied Enzyme and Description of Its Anti-proliferative and Pro-apoptotic Effects on MCF-7 Human Breast Cancer Cells

Neohesperidin (NH) is a natural flavonoid glycoside compound with considerable physiological and pharmacological activities. However, its bioavailability is limited due to poor solubility, and few studies have so far attempted improve the solubility and bioavailability of NH. In this study, we structurally modified NH using an immobilized lipase to improve lipophilicity and therefore expand its applicability in lipophilic media as well as enhance its bioavailability in vivo. In addition, we aimed investigated the pro-apoptoptotic activity of this new compound (propionyl neohesperidin ester, PNHE) in MCF-7 breast cancer cells using a variety of cellular assays, including the MTT (3-(4, 5-dimethyl- 2-thiazolyl)-2, 5-diphenyl-2-h-tetrazolium bromide assay, assessment of intracellular reactive oxygen species (ROS) levels, and flow cytometry. We successfully synthesized PNHE using immobilized lipases, and the esterification of NH was confirmed by Fourier transform-infrared spectroscopy (FT-IR). Compared to NH, HNPE showed higher anti-proliferative and pro-apoptotic in MCF-7 breast cancer cells, which may be explained by its increased lipophilicity compared to neohesperidin, benefiting to the action of NH on the cancer cell wall. The IC₅₀ of PNHE for inducing apoptosis of MCF-7 cells was 185.52 μg/mL. PNHE increased both the proportion of cells in Sub-G1 phase and the cellular ROS content, indicating a certain therapeutic effect of HNPE on breast cancer.

Puerarin Inhibits Endothelium-Dependent Contractions in Mouse Carotid Arteries

Background

Many bioactive ingredients of medicinal plants are known to produce vaso-protective benefits. Puerarin is one of the major isoflavone glucosides found in the root of kudzu vine and it exerts an anti-inflammatory effect and many other pharmacological actions. However, the mechanism underlying the vascular effect of puerarin is incompletely understood. Therefore, the present study aims to examine how puerarin reduces endothelium-dependent contractions (EDCs) in mouse arteries.

Material/Methods

EDCs were evoked by acetylcholine (ACh) in isolated mouse carotid arteries with intact endothelium pretreated with Nω-NO2-L-Arg-OMe (L-NAME). The arteries were pretreated with puerarin and other pharmacological inhibitors before the addition of cumulative concentrations of ACh. The concentration of several prostaglandins (PGs) was measured by high performance liquid chromatography-coupled spectrometry (HPLC-MS).

Results

EDCs induced by ACh only presented in endothelium-intact arteries pretreated by L-NAME and EDCs were prevented by the treatment with cyclooxygenase (COX) inhibitor indomethacin (3 μmol/L) or thromboxane prostanoid receptor (TP receptor) antagonist S18886 (30 nmol/L). Acute 40-minute treatment with puerarin reduced EDCs in a concentration-dependent manner without affecting U46619-induced contraction. However, treatment with puerarin did not inhibit ACh-induced production of prostaglandins (PGs) in endothelium-intact arteries.

Conclusions

The present results show that puerarin is able to suppress EDCs in mouse carotid arteries, independent of inhibition of TP receptor or COX2-derived PGs.

Low-Level Organic Solvents Improve Multienzyme Whole-Cell Catalytic Synthesis of Myricetin-7-O-Glucuronide

Multienzyme whole-cell biocatalysts are preferred in industrial applications, and two major concerns regarding the use of these biocatalysts, cell viability and cell membrane integrity, must be addressed. In this work, the transformation of myricetin to myricetin-7-O-glucuronide catalyzed by an engineered Escherichia coli strain was taken as the model reaction to examine the impacts of low-level organic solvents on whole-cell biocatalysis. Low-level organic solvents (2%, v/v) showed a significant increase (roughly 13-fold) in myricetin-7-O-glucuronide yields. No obvious compromises of cellular viability and integrity were observed by a flow cytometry assay or in the determination of extracellular protein leakage, suggesting the addition of low-level organic solvents accommodates whole E. coli cells. Furthermore, a scaled-up reaction was conducted to test the capability and efficiency of whole-cell catalysis in the presence of organic solvents. This study presents a promising and simple means to enhance the productivity of multienzyme whole-cell catalysis without losing the barrier functions of the cell membrane.