Nonallergenic urushiol derivatives inhibit the oxidation of unilamellar vesicles and of rat plasma induced by various radical generators

Improving physicochemical characteristics and cytotoxicity of baicalin esters by liposome encapsulation

The instability of ester bonds, low water solubility, and increased cytotoxicity of flavonoid glycoside esters significantly limit their application in the food industry. Therefore, the present study attempted to resolve these issues through liposome encapsulation. The results showed that baicalin butyl ester (BEC4) and octyl ester (BEC8) have higher encapsulation and loading efficiencies and lower leakage rate from liposomes than baicalin. FTIR results revealed the location of BEC4 and BEC8 in the hydrophobic layer of liposomes, which was different from baicalin. Additionally, liposome encapsulation improved the water solubility and stability of BEC4 and BEC8 in the digestive system and PBS but significantly reduced their cytotoxicity. Furthermore, the release rate of BEC4 and BEC8 from liposomes was lower than that of baicalin during gastrointestinal digestion. These results indicate that liposome encapsulation alleviated the negative effects of fatty chain introduction into flavonoid glycosides.

3-Methylcatechol mediates anti-fecundity effect by inhibiting estrogen-related receptor-induced glycolytic gene expression in Myzus persicae

Aphids are a major problem in agriculture, horticulture, and forestry by feeding on leaves and stems, causing discoloration, leaf curling, yellowing, and stunted growth. Although urushiol, a phenolic compound containing a catechol structure, is known for its antioxidant and anticancer properties, using small molecules to control aphids via catechol-mediated mechanisms is poorly understood. In this study, we investigated the effects of 3-methylcatechol (3-MC) on Myzus persicae fecundity. Our results showed that treatment with 3-MC significantly reduced the intrinsic transcriptional activity of the aphid estrogen-related receptor (MpERR), which regulates the expression of glycolytic genes. Additionally, 3-MC treatment suppressed the promoter activity of MpERR-induced rate-limiting enzymes in glycolysis, such as phosphofructokinase and pyruvate kinase, by inhibiting MpERR binding. Finally, 3-MC also suppressed MpERR-induced glycolytic gene expression and reduced the number of offspring produced by viviparous female aphids. Overall, our findings suggest that 3-MC has the potential to be used as a new strategy for managing aphid populations by controlling their offspring production.

Effect of etchant containing an Urushiol monomer from lacquer sap on dentin biostability and bonding performance

Objectives: This study aimed to evaluate the effectiveness of urushiol as an additive to surface acid etchant on dentin structure, by assessing the biostability of dentin, and determine the bonding strengths of dentin and enamel to the composite in the complicated oral microecology. Methods: Etchants with different concentrations of urushiol (0.5, 1, or 3 wt%) were formulated and tested for their bonding performance. Demineralized dentin beams that were etched with experimental etchants were incubated in simulated body fluid solutions by evaluating the weight decrement after 1 month. The effects of urushiol on dentin and matrix metalloproteinases were confirmed by scanning electron microscopy (SEM). Moreover, the antibiotic actions of urushiol on the common cariogenic bacteria Streptococcus mutans, Streptococcus sanguinis, and Streptococcus gordonii as well as the biofilm were evaluated, and its effect on bacterial morphology was observed by scanning electron microscopy. Finally, enamel and dentin specimens were prepared from human molars to determine the depth of demineralization by the etchants and the relationship with the resin bond strengths to enamel and dentin (μTBS) and the morphology of the bonding interface. Results: Urushiol could interact with dentine and inhibit collagenase activity, resulting in biostable dentine. The application of the etchants containing 0.5, 1, or 3 wt% urushiol significantly improved the durability of the dentin bonding interface with its instinctive antibacterial property (p < 0.05). Conclusion: Urushiol not only improves dentin stability by interacting with collagen and inactivating MMP activity but also plays a role in the antibacterial effects in the complicated oral microecology. The effectiveness of urushiol etchant prolongs the longevity of bonded dental restorations without compromising clinical operation time.

Polyphenol-Enriched Extract of Lacquer Sap Used as a Dentine Primer with Benefits of Improving Collagen Cross-Linking and Antibacterial Functions

Commercial dentin adhesive systems are applied to restorations due to their resistant bonding properties, but they suffer from the lack of bioactivity and are prone to hydrolysis. Therefore, to overcome these limitations, an eco-friendly natural monomer, urushiol, was adopted to be a primer in dentin bonding due to its interaction with collagen and antibacterial activity, preventing further hydrolysis development. First, urushiol was determined to be capable of improving the biological stability of dentin collagen through cross-linking. Using high-fidelity analytical chemistry techniques, such as Fourier transform infrared spectroscopy, we quantified the effects of urushiol on collagen molecules. It could also effectively decrease weight loss after collagenase ingestion by improving the stability of dentin. Moreover, urushiol inhibited Streptococcus mutans growth as well as its biofilm formation. Finally, we demonstrated that the urushiol primer could improve the bonding strength, particularly after aging. The cross-linking and antibacterial functions of urushiol have provided promising developmental prospects for biomaterials in dentin adhesion.

3-Pentylcatechol, a Non-Allergenic Urushiol Derivative, Displays Anti-Helicobacter pylori Activity In Vivo

We previously reported that 3-pentylcatechol (PC), a synthetic non-allergenic urushiol derivative, inhibited the growth of Helicobacter pylori in an in vitro assay using nutrient agar and broth. In this study, we aimed to investigate the in vivo antimicrobial activity of PC against H. pylori growing in the stomach mucous membrane. Four-week-old male C57BL/6 mice (n = 4) were orally inoculated with H. pylori Sydney Strain-1 (SS-1) for 8 weeks. Thereafter, the mice received PC (1, 5, and 15 mg/kg) and triple therapy (omeprazole, 0.7 mg/kg; metronidazole, 16.7 mg/kg; clarithromycin, 16.7 mg/kg, reference groups) once daily for 10 days. Infiltration of inflammatory cells in gastric tissue was greater in the H. pylori-infected group compared with the control group and lower in both the triple therapy- and PC-treated groups. In addition, upregulation of cytokine mRNA was reversed after infection, upon administration of triple therapy and PC. Interestingly, PC was more effective than triple therapy at all doses, even at 1/15th the dose of triple therapy. In addition, PC demonstrated synergism with triple therapy, even at low concentrations. The results suggest that PC may be more effective against H. pylori than established antibiotics.

Ionization Neutralizes the Allergy-Inducing Property of 3-Pentadecylcatechol: A Urushiol Derivative

Urushiols are amphipathic compounds found in Rhus verniciflua Stokes that exhibit various biological activities. However, their practical use is very restricted due to their contact dermatitis-inducing property. Therefore, we applied the ionization method to remove the allergenic properties of the urushiols and to increase their usability. One of the natural urushiols, 3-pentadecylcatechol (PDC), was heated for 30 min with a solution of H₂O and sodium carbonate (Na₂CO₃). The reaction product was analyzed by electrospray ionization mass spectrometry (ESI-MS). Ionized PDC with an m/z value of 316.9 and complexed PDCs with Na⁺ of 1 - 3 atoms with m/z values of 340.8, 365.2, and 380.8 were detected. PDC and ionized PDC (3 μmol/3 mg of Vaseline) treatments were applied on the rear of left ear of Sprague-Dawley rats once daily for 10 days. Erythema and swelling were observed on the ear skin treated with PDC, but not in case of ionized PDC. Compared with control, contact hypersensitivity-related biomarkers (neutrophils, eosinophils, immunoglobulin E, and histamine) in the blood were significantly higher only in the PDC-treated group. In addition, Il-1b, Il-6, Tnfα, and Cox-2 mRNA expression levels were dramatically increased in the ear tissue of PDC-treated rats, but in the ionized PDC-treated group, they were similar to those in the control group. Overall, it was confirmed that the allergenic property of the urushiol PDC was removed by ionization. This method is expected to be useful for preventing allergy induction in cooking and food processing using R. verniciflua Stokes.

The Effects of Adding Different HALS on the Curing Process, Film Properties and Lightfastness of Refined Oriental Lacquer

Oriental lacquer is a natural polymeric coating with a satiny texture and excellent characteristics, such as chemical resistance and durability. However, the poor lightfastness resulted in the natural aromatic structures of the urushiol structures limited its suitability for outdoor application. This study aimed at the improvement of the lightfastness by adding the different hindered amine light stafbilizers (HALS) with 2 phr addition as well as the effects on the coating and film property of the refined oriental lacquers (RL). The Cryptomeria japonica plate, glass sheets, and the other substrates were used for finishing. The results showed that the lightfastness of RL film was obviously improved by adding 2 phr HALS of Bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (H90) containing -NH group and Bis (1,2,2,6,6-pentamethyl-4-piperidinyl)-[[3,5-bis(1,1-dimethyl ethyl) -4-hydroxyphenyl] methyl] butylmalonate (H60) containing -NCH₃ groups. The HALS additions increased the pH value of RL and improved the activities of laccase-catalyzed reaction. Meanwhile, the oxidative polymerization of the side chains of RL was inhibited, caused by a radical scavenging ability of HALS. The changes in the drying process affected not only the curing time, but also the film properties. Among the 2 phr additions of different HALS, the film containing H90 had the best lightfastness. Meanwhile, it kept the most similar properties with RL and shortened the drying time of RL, and it was selected as the best HALS addition under 2 phr in this study.

Catechol thioethers with physiologically active fragments: Electrochemistry, antioxidant and cryoprotective activities

A number of asymmetrical thioethers based on 3,5-di-tert-butylcatechol containing sulfur atom bonding with physiologically active groups in the sixth position of aromatic ring have been synthesized and the electrochemical properties, antioxidant, cryoprotective activities of new thioethers have been evaluated. Cyclic voltammetry was used to estimate the oxidation potentials of thioethers in acetonitrile. The electrooxidation of compounds at the first stage leads to the formation of o-benzoquinones. The antioxidant activities of the compounds were determined using 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH) assay, experiments on the oxidative damage of the DNA, the reaction of 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) induced glutathione depletion (GSH), the process of lipid peroxidation of rat liver (Wistar) homogenates in vitro, and iron(II) chelation test. Compounds 1-9 have greater antioxidant effectiveness than 3,5-di-tert-butylcatechol (CatH₂) in all assays. The variation of physiologically active groups at sulfur atom allows to regulate lipophilic properties and antioxidant activity of compounds. Thioethers 3, 4 and 7 demonstrate the combination of radical scavenging, antioxidant activity and iron(II) binding properties. The researched compounds 1-9 were studied as possible cryoprotectants of the media for cryopreservation of the Russian sturgeon sperm. Novel cryoprotective additives in cryomedium reduce significantly the content of membrane-permeating agent (DMSO). A cryoprotective effect of an addition of the catechol thioethers depends on the structure of groups at sulfur atom. The cryoprotective properties of compounds 3, 4 and 7 are caused by combination of catechol fragment, bonded by a thioether linker with a long hydrocarbon chain and a terminal ionizable group or with a biologically relevant acetylcysteine residue.

3-Decylcatechol induces autophagy-mediated cell death through the IRE1α/JNK/p62 in hepatocellular carcinoma cells

The natural, phenolic lipid urushiol exhibits both antioxidant and anticancer activities; however, its biological activity on hepatocellular carcinoma (HCC) has not been previously investigated. Here, we demonstrate that an urushiol derivative, 3-decylcatechol (DC), induces human HCC Huh7 cell death by induction of autophagy. DC initiates the autophagic process by activation of the mammalian target of rapamycin signaling pathway via Unc-51-like autophagy activating kinase 1, leading to autophagosome formation. The autophagy inhibitor, chloroquine, suppressed autolysosome formation and cell death induction by DC, indicating an autophagic cell death. Interestingly, DC also activated the endoplasmic reticulum (ER) stress response that promotes autophagy via p62 transcriptional activation involving the inositol-requiring enzyme 1α/c-Jun N-terminal kinase/c-jun pathway. We also show that cytosolic calcium mobilization is necessary for the ER stress response and autophagy induction by DC. These findings reveal a novel mechanism by which this urushiol derivative induces autophagic cell death in HCC.

Enhancement of antioxidative and antimicrobial activities of immature pear (Pyrus pyrifolia cv. Niitaka) fruits by fermentation with Leuconostoc mesenteroides

Immature pear (Pyrus pyrifolia cv. Niitaka) fruits were fermented with Leuconostoc mesenteroides and Aspergillus oryzae, which are commonly used as starters for manufacturing fermented foods. Fermented immature pear fruit extracts (FIPF) by L. mesenteroides showed significantly higher radical-scavenging activity using DPPH, ABTS, superoxide anion, and hydroxyl radicals and reducing power capacity than unfermented immature pear fruit extracts. L. mesenteroides-FIPF more effectively inhibited the formation of cholesteryl ester hydroperoxide in copper ion-induced rat blood plasma. In addition, the L. mesenteroides-FIPF strongly inhibited tyrosinase activity and the growth of pathogenic skin bacteria. In contrast, enhanced antioxidative and antibacterial activities were not apparent in A. oryzae-FIPF. The antioxidative and antimicrobial activities of the fermented and unfermented immature pear fruits were correlated with the flavonoid contents. These results indicate that fermentation enhances antioxidative and antimicrobial activities of immature pear fruits.

Antimicrobial activity of the synthesized non-allergenic urushiol derivatives

Synthesized urushiol derivatives possessing different carbon atomic length in the alkyl side chain inhibited the growth of food spoilage and pathogenic microorganisms. Particularly, non-allergenic 3-pentylcatechol showed a broad antimicrobial spectrum on an agar plate. Most food spoilage and pathogenic microorganisms were sensitive to urushiol derivatives in the liquid culture. The morphologies of the microorganisms were changed after treatment of 3-pentylcatechol.

Preparation and Characterization of Urushiol Methylene Acetal Derivatives with Various Degrees of Unsaturation in Alkyl Side Chain

Preparation of urushiol derivatives was carried out in response to the drug industry’s increasing demand for new synthetic anticancer agents. Urushiol methylene acetal derivatives were synthesized in high yields by reaction of urushiol with methylene chloride under the catalytic action of NaOH. Four kinds of urushiol methylene acetal monomers were separated by silica-gel column and preparative HPLC, and their structures were elucidated by extensive spectroscopic methods, including 1D-NMR and 2D-NMR (1H,13C-NMR,1H-1HCOSY, HSQC, and HMBC) as well as TOF-MS. They were identified as 3-[pentadecyl] benzene methylene ether (compound 1), 3-[8′-pentadecatrienyl] benzene methylene ether (compound 2), 3-[8′,11′-pentadecatrienyl] benzene methylene ether (compound 3), and 3-[8′,11′,14′-pentadecatrienyl] benzene methylene ether (compound 4). This research provides a theoretical reference for exploration of these interesting and potentially bioactive compounds.