Evaluation physical characteristics and comparison antimicrobial and anti-inflammation potentials of dental root canal sealers containing hinokitiol in vitro

Therapeutic Efficacy Studies on the Monoterpenoid Hinokitiol in the Treatment of Different Types of Cancer

Hinokitiol (HK), a monoterpenoid that naturally occurs in plants belonging to the Cupressaceae family, possesses important biological activities, including an anticancer effect. This review summarizes its anticancer potential and draws possible molecular interventions. In addition, it evaluates the biopharmaceutical, toxicological properties, and clinical application of HK to establish its viability for future advancement as a dependable anticancer medication. The assessment is based on the most recent information available from various databases. Findings demonstrate that HK possesses substantial therapeutic advantages against diverse types of cancer (colon, cervical, breast, bone, endometrial, liver, prostate, oral, and skin) through various molecular mechanisms. HK induces oxidative stress, cytotoxicity, apoptosis, cell-cycle arrest at the G and S phases, and autophagy through modulation of phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR), p38/ERK/MAPK, nuclear factor kappa B, and c-Jun N-terminal kinase signaling pathways. Furthermore, this compound exhibits good oral bioavailability with excellent plasma clearance. Clinical uses of HK demonstrate therapeutic advantages without any significant negative effects. A thorough study of the pertinent data suggests that HK may serve as a viable candidate for developing novel cancer therapies. Consequently, more extensive studies are necessary to evaluate its cancer treatment efficacy, safety, and possible long-term hazards.

Betulin inhibits the production of inflammatory cytokines in human gingival fibroblasts and ligature-induced periodontitis

Chronic inflammation of the tissues surrounding and supporting the teeth is known as periodontal disease. Human gingival fibroblasts (HGFs) are among the greatest prevalent cells in gingival tissue and play a crucial role in oral infections. Data from the GSE dataset revealed that the inflammatory cytokines IL-1β, IL-6, and IL-8 were up-regulated in periodontitis patients compared to healthy individuals. Betulin, a lupane-type pentacyclic triterpene alcohol extracted from the birch trees, inhibits lipopolysaccharide (LPS; component of gram-negative bacteria)-induced synthesis of IL-1β, IL-6, and IL-8 in HGFs. We also demonstrated that the MAPK and AP-1 signaling cascades mediate betulin's inhibition of inflammatory cytokine production in HGFs. Importantly, betulin reduces the expression of inflammatory cytokines and prevents the progression of ligature-induced periodontitis in vivo. This study provides evidence that betulin is a promising candidate for the management of periodontal disease.

Dipotassium glycyrrhizate and hinokitiol enhance macrophage efferocytosis by regulating recognition, uptake, and metabolism of apoptotic cells in vitro

BACKGROUND AND OBJECTIVE

Efferocytosis is a process whereby macrophages remove apoptotic cells, such as neutrophils, that have accumulated in tissues, which is required for resolution of inflammation. Efferocytosis is impaired in individuals with increasing age and in those with various systemic diseases. Recently, efferocytosis has been reported to be related to the pathogenesis and progression of periodontitis, and enhancement of efferocytosis, especially in the subjects with impaired efferocytosis, was suggested to lead to periodontitis prevention and care. Various anti-inflammatory ingredients are used in oral care products, but their effect on efferocytosis is unclear. Here, we aimed to identify ingredients contained in oral care products that are effective for efferocytosis regulation.

METHODS

The ability of dead cells to induce inflammation in human gingival fibroblast (HGF) cells were evaluated by measuring IL-6 secretion. Six ingredients in oral care products used as anti-inflammatory agents were evaluated for their effect on efferocytosis using flow cytometry. The expression of various efferocytosis-related molecules, such as MERTK and LRP1 involved in recognition, and LXRα and ABCA1 that function in metabolism, were measured in RAW264.7 cells with or without ingredient treatment. Rac1 activity, which is related to the uptake of dead cells, was measured using the G-LISA kit.

RESULTS

Dead cells elicited IL-6 secretion in HGF cells. Among the six ingredients, GK2 and hinokitiol enhanced efferocytosis activity. GK2 and hinokitiol significantly increased the expression of MERTK and LRP1, and also enhanced LXRα and ABCA1 expression after efferocytosis. Furthermore, they increased Rac1 activity in the presence of dead cells.

CONCLUSION

Among the six ingredients tested, GK2 and hinokitiol promoted efferocytosis by regulating apoptotic cell recognition, uptake, and metabolism-related molecules. Efferocytosis upregulation may be one of the mechanisms of GK2 and hinokitiol in the treatment of inflammatory diseases, such as periodontitis.

Fabrication and characterization of sodium alginate/blueberry anthocyanins/hinokitiol loaded ZIF-8 nanoparticles composite films with antibacterial activity for monitoring pork freshness

A smart film was developed to detect the freshness of pork by incorporating blueberry anthocyanins (BAs) and hinokitiol (HIN) loaded zeolite-imidazolium framework (HIN@ZIF-8) with into a sodium alginate matrix, and its microstructure and physicochemical properties were studied. The SA matrix was doped with BAs and HIN@ZIF-8 nanoparticles (SA-BAs/HIN@ZIF-8) to increase its tensile strength and reduce its water vapor permeability. HIN@ZIF-8 has low cytotoxicity, and SA-BAs/HIN@ZIF-8 membranes have long-lasting antimicrobial and highly sensitive color development properties against Escherichia coli and Staphylococcus aureus. The results of pork preservation experiments showed that SA-BA/HIN@ZIF-8 could extend the shelf life of pork to 6 days at 4 ℃. E-nose evaluation experiments showed that SA-BAs/HIN@ZIF-8 could inhibit compounds that cause unpleasant and irritating odours. Therefore, SA-BAs/HIN@ZIF-8 was considered to be an effective method to improve the freshness of pork, and the results showed that it has a promising application in food preservation.

Characterisation and evaluation of physical properties of AH-Plus sealer with and without the incorporation of petasin, pachymic acid, curcumin and shilajit-an invitro study

BACKGROUND

AH Plus, an epoxy resin-based sealer, is widely used in endodontic practice, owing to its good physical properties that confers longstanding dimensional stability and good adhesion to dentin. Nevertheless, its propensity to trigger inflammation, especially in its freshly mixed state, has been extensively documented. Phytochemicals such as Petasin, Pachymic acid, Curcumin, and Shilajit are known for their anti-inflammatory and analgesic effects. This study aimed to analyze and determine the effect of these natural products on the physical properties of AH Plus sealer when incorporated with the sealer.

METHODS

AH Plus (AHR) sealer was mixed with 10% petasin, 0.75% pachymic, 0.5% and 6%shilajit to obtain AHP, AHA, AHC and AHS in the ratio of 10:1 and 5:1 respectively. Five samples of each material were assessed for setting time, solubility, flow, and dimensional stability in accordance with the ISO 6876:2012 standardization. Sealers were characterized through scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Statistical evaluation involved the Kolmogorov-Smirnov and Shapiro-Wilks tests for normality and the one-way ANOVA test for analysis.

RESULTS

In this investigation, the characterisation analysis revealed a relatively similar microstructure in all the experimental root canal sealers. All experimental groups, excluding the control group, exhibited an increase in flow ranging from 11.9 to 31.4% at a 10:1 ratio. Similarly, for the 5:1 ratio, the increase ranged from 12.02 to 31.83%. In terms of dimensional stability, all groups at the 10:1 ratio showed a decrease compared to the control group. The addition of natural agents to AHR in 10:1 ratio led to a reduction in setting time by 8.9-31.6%, and at a 5:1 ratio, the reduction ranged from 8.1 to 31.5%. However, regarding solubility, the addition of natural agents did not induce any significant alterations.

CONCLUSION

Based on the results of this study, it can be concluded that all tested root canal sealers exhibited properties that met the acceptable criteria outlined in the ISO 6876:2012 standardization.

Caffeic Acid Phenethyl Ester and Caffeamide Derivatives Suppress Oral Squamous Cell Carcinoma Cells

Caffeic acid phenethyl ester (CAPE) contains antibiotic and anticancer activities. Therefore, we aimed to investigate the anticancer properties and mechanisms of CAPE and caffeamide derivatives in the oral squamous cell carcinoma cell (OSCC) lines SAS and OECM-1. The anti-OSCC effects of CAPE and the caffeamide derivatives (26G, 36C, 36H, 36K, and 36M) were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. Cell cycle and total reactive oxygen species (ROS) production were analyzed using flow cytometry. The relative protein expression of malignant phenotypes was determined via Western blot analysis. The results showed that 26G and 36M were more cytotoxic than the other compounds in SAS cells. After 26G or 36M treatment for 48 h, cell cycle S phase or G2/M phase arrest was induced, and cellular ROS increased at 24 h, and then decreased at 48 h in both cell lines. The expression levels of cell cycle regulatory and anti-ROS proteins were downregulated. In addition, 26G or 36M treatment inhibited malignant phenotypes through mTOR-ULK1-P62-LC3 autophagic signaling activated by ROS generation. These results showed that 26G and 36M induce cancer cell death by activating autophagy signaling, which is correlated with altered cellular oxidative stress.

Immunomodulatory Effects of Endodontic Sealers: A Systematic Review

Inflammation is a crucial step prior to healing, and the regulatory effects of endodontic materials on the immune response can influence tissue repair. This review aimed to answer whether endodontic sealers can modulate the immune cells and inflammation. An electronic search in Scopus, Web of Science, PubMed, and Google Scholar databases were performed. This systematic review was mainly based on PRISMA guidelines, and the risk of bias was evaluated by SYRCLEs and the Modified CONSORT checklist for in vivo and in vitro studies, respectively. In total, 28 articles: 22 in vitro studies, and six in vivo studies were included in this systematic review. AH Plus and AH 26 can down-regulate iNOS mRNA, while S-PRG sealers can down-regulate p65 of NF-κB pathways to inhibit the production of TNF-α, IL-1, and IL-6. In vitro and in vivo studies suggested that various endodontic sealers exhibited immunomodulatory impact in macrophages polarization and inflammatory cytokine production, which could promote healing, tissue repair, and inhibit inflammation. Since the paradigm change from immune inert biomaterials to bioactive materials, endodontic materials, particularly sealers, are required to have modulatory effects in clinical conditions. New generations of endodontic sealers could hamper detrimental inflammatory responses and maintain periodontal tissue, which represent a breakthrough in biocompatibility and functionality of endodontic biomaterials.

In Vitro Antimicrobial Potential of CAPE and Caffeamide Derivatives against Oral Microbes

Caffeic acid phenethyl ester (CAPE) is a natural component isolated from propolis and used in traditional medicine. We aimed to investigate the antimicrobial properties and action mechanism of CAPE and caffeamide derivatives (26G and 36M) against oral disease microbes. We resolved the minimum inhibitory and bactericidal concentrations of 26G and 36M and their stability at different temperatures and pH. We also evaluated their effect on biofilm formation and antibiotic resistance gene expression in methicillin-resistant Staphylococcus aureus (MRSA). Our results revealed that 26G and 36M showed the best anticancer and antimicrobial activities, respectively, compared with the other four caffeamide derivatives. Both 26G and 36M showed heat-dependent decreases in antimicrobial activity. The 36M derivative was stable irrespective of pH, whereas 26G was not stable under high pH conditions. Biofilm formation and antibiotic resistance-related gene expression were consistent with their respective phenotypes. This study provides evidence for the potential application of CAPE and caffeamide derivatives in dental medicine to cure or prevent oral diseases.

Different Cell Responses to Hinokitiol Treatment Result in Senescence or Apoptosis in Human Osteosarcoma Cell Lines

Hinokitiol is a tropolone-related compound isolated from the heartwood of cupressaceous plants. It is known to exhibit various biological functions including antibacterial, antifungal, and antioxidant activities. In the study, we investigated the antitumor activities of hinokitiol against human osteosarcoma cells. The results revealed that hinokitiol treatment inhibited cell viability of human osteosarcoma U-2 OS and MG-63 cells in the MTT assay. Further study revealed that hinokitiol exposure caused cell cycle arrest at the S phase and a DNA damage response with the induction of γ-H2AX foci in both osteosarcoma cell lines. In U-2 OS cells with wild-type tumor suppressor p53, we found that hinokitiol exposure induced p53 expression and cellular senescence, and knockdown of p53 suppressed the senescence. However, in MG-63 cells with mutated p53, a high percentage of cells underwent apoptosis with cleaved-PARP expression and Annexin V staining after hinokitiol treatment. In addition, up-regulated autophagy was observed both in hinokitiol-exposed U-2 OS and MG-63 cells. As the autophagy was suppressed through the autophagy inhibitor chloroquine, hinokitiol-induced senescence in U-2 OS cells was significantly enhanced accompanying more abundant p53 expression. In MG-63 cells, co-treatment of chloroquine increased hinokitiol-induced apoptosis and decreased cell viability of the treated cells. Our data revealed that hinokitiol treatment could result in different cell responses, senescence or apoptosis in osteosarcoma cell lines, and suppression of autophagy could promote these effects. We hypothesize that the analysis of p53 status and co-administration of autophagy inhibitors might provide more precise and efficacious therapies in hinokitiol-related trials for treating osteosarcoma.

Hinokitiol chelates intracellular iron to retard fungal growth by disturbing mitochondrial respiration

Introduction

The increasing morbidity of fungal infections and the prevalence of drug resistance highlighted the discovery of novel antifungal agents and investigation of their modes of action. Iron chelators have been used to treat superficial fungal infections or potentiate the efficacy of certain antifungal drugs. Hinokitiol exhibits potent antifungal activity and iron-chelating ability. However, their relationships have not been established.

Objectives

This study aims to explore the selectivity of hinokitiol against fungal cells and mammalian cells and determine the role of iron-chelating for the antifungal activity of hinokitiol.

Methods

Iron probe FeRhonox-1 was used to determine intracellular Fe²⁺ content. 5-Cyano-2,3-ditolyl tetrazolium chloride probe and Cell Counting Kit-8 were used to detect the mitochondrial respiratory activities. Quantitative real-time PCR and rescue experiments were performed to determine the effect of iron on the antifungal activity of hinokitiol. The effects of hinokitiol on fungal mitochondria were further evaluated using reactive oxygen species probes and several commercial Assay Kits. The ability of hinokitiol to induce resistance in Candida species was carried out using a serial passage method. The in vivo therapeutic effect of hinokitiol was evaluated using Galleria mellonella as an infectious model.

Results

Hinokitiol was effective against a panel of Candida strains with multiple azole-resistant mechanisms and persistently inhibited Candida albicans growth. Mechanism investigations revealed that hinokitiol chelated fungal intracellular iron and inhibited the respiration of fungal cells but had minor effects on mammalian cells. Hinokitiol further inhibited the activities of mitochondrial respiratory chain complexes I and II and reduced mitochondrial membrane potential, thereby decreasing intracellular ATP synthesis and increasing detrimental intracellular reductive stress. Moreover, hinokitiol exhibited low potential for inducing resistance in several Candida species and greatly improved the survival of Candida-infected Galleria mellonella.

Conclusions

These findings suggested the potential application of hinokitiol as an iron chelator to treat fungal infections.

Anticancer Properties of Eugenol: A Review

Conventional cancer treatments have shown several unfavourable adverse effects, as well as an increase in anticancer drug resistance, which worsens the impending cancer therapy. Thus, the emphasis is currently en route for natural products. There is currently great interest in the natural bioactive components from medicinal plants possessing anticancer characteristics. For example, clove (Syzygium aromaticum L.) (Family Myrtaceae) is a highly prized spice that has been historically utilized as a food preservative and for diverse medical uses. It is reckoned amongst the valued sources of phenolics. It is indigenous to Indonesia but currently is cultivated in various places of the world. Among diverse active components, eugenol, the principal active component of S. aromaticum, has optimistic properties comprising antioxidant, anti-inflammatory, and anticancer actions. Eugenol (4-allyl-2-methoxyphenol) is a musky oil that is mainly obtained from clove. It has long been utilized all over the world as a result of its broad properties like antioxidant, anticancer, anti-inflammatory, and antimicrobial activities. Eugenol continues to pique investigators’ interest because of its multidirectional activities, which suggests it could be used in medications to treat different ailments. Anticancer effects of eugenol are accomplished by various mechanisms like inducing cell death, cell cycle arrest, inhibition of migration, metastasis, and angiogenesis on several cancer cell lines. Besides, eugenol might be utilized as an adjunct remedy for patients who are treated with conventional chemotherapy. This combination leads to a boosted effectiveness with decreased toxicity. The present review focuses on the anticancer properties of eugenol to treat several cancer types and their possible mechanisms.

Health Benefits and Pharmacological Properties of Hinokitiol

Hinokitiol is a natural bioactive compound found in several aromatic and medicinal plants. It is a terpenoid synthetized and secreted by different species as secondary metabolites. This volatile compound was tested and explored for its different biological properties. In this review, we report the pharmacological properties of hinokitiol by focusing mainly on its anticancer mechanisms. Indeed, it can block cell transformation at different levels by its action on the cell cycle, apoptosis, autophagy via inhibiting gene expression and dysregulating cellular signaling pathways. Moreover, hinokitiol also exhibits other pharmacological properties, including antidiabetic, anti-inflammatory, and antimicrobial effects. It showed multiple and several effects through its inhibition, interaction and/or activation of the main cellular targets inducing these pathologies.

Improving the Antimicrobial and Mechanical Properties of Epoxy Resins via Nanomodification: An Overview

The main purpose of this work is to provide a comprehensive overview on the preparation of multifunctional epoxies, with improved antimicrobial activity and enhanced mechanical properties through nanomodification. In the first section, we focus on the approaches to achieve antimicrobial activity, as well as on the methods used to evaluate their efficacy against bacteria and fungi. Relevant application examples are also discussed, with particular reference to antifouling and anticorrosion coatings for marine environments, dental applications, antimicrobial fibers and fabrics, and others. Subsequently, we discuss the mechanical behaviors of nanomodified epoxies with improved antimicrobial properties, analyzing the typical damage mechanisms leading to the significant toughening effect of nanomodification. Some examples of mechanical properties of nanomodified polymers are provided. Eventually, the possibility of achieving, at the same time, antimicrobial and mechanical improvement capabilities by nanomodification with nanoclay is discussed, with reference to both nanomodified epoxies and glass/epoxy composite laminates. According to the literature, a nanomodified epoxy can successfully exhibit antibacterial properties, while increasing its fracture toughness, even though its tensile strength may decrease. As for laminates-obtaining antibacterial properties is not followed by improved interlaminar properties.

Effects of Hinokitiol and Dicalcium Phosphate on the Osteoconduction and Antibacterial Activity of Gelatin-Hyaluronic Acid Crosslinked Hydrogel Membrane In Vitro

Many hydrogel-based crosslinking membranes have been designed and tailored to meet the needs of different applications. The aim of this research is to design a bifunctional hydrogel membrane with antibacterial and osteoconducting properties to guide different tissues. The membrane uses gelatin and hyaluronic acid as the main structure, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride as the crosslinker, hinokitiol as the antibacterial agent, and dicalcium phosphate anhydrous (DCPA) micron particles for osteoconduction. Results show that the hydrogel membrane with added DCPA and impregnated hinokitiol has a fixation index higher than 88%. When only a small amount of DCPA is added, the tensile strength does not decrease significantly. The tensile strength decreases considerably when a large amount of modified DCPA is added. The stress–strain curve shows that the presence of a large amount of hinokitiol in hydrogel membranes results in considerably improved deformation and toughness properties. Each group impregnated with hinokitiol exhibits obvious antibacterial capabilities. Furthermore, the addition of DCPA and impregnation with hinokitiol does not exert cytotoxicity on cells in vitro, indicating that the designed amount of DCPA and hinokitiol in this study is appropriate. After a 14-day cell culture, the hydrogel membrane still maintains a good shape because the cells adhere and proliferate well, thus delaying degradation. In addition, the hydrogel containing a small amount of DCPA has the best cell mineralization effect. The developed hydrogel has a certain degree of flexibility, degradability, and bifunctionality and is superficial. It can be used in guided tissue regeneration in clinical surgery.

In vitro antimicrobial and antipro-inflammation potential of honokiol and magnolol against oral pathogens and macrophages

BACKGROUND/PURPOSE

Honokiol and magnolol are natural components isolated from Magnolia bark that is used in traditional Chinese and Japanese herbal medicine. These two isomers are used as a component of dietary supplements and cosmetic products. In this study, we investigated the antimicrobial effect of honokiol and magnolol on pathogens causing oral diseases, their mechanism of action in biofilm formation and drug resistance of oral pathogens, and inflammatory regulation in mammalian cells.

METHODS

We determined the minimum inhibitory concentration and minimum bactericidal concentration of honokiol and magnolol, and their stability at different temperatures and pH. We also evaluated their effect on biofilm formation, antibiotic-resistance gene expression in MRSA, and pro-inflammatory gene expression in mammalian cells.

RESULTS

Honokiol showed better antimicrobial activity than magnolol. Both honokiol and magnolol showed stable bacterial inhibitory activity over a wide range of temperature and pH, reduced biofilm formation, and antibiotic resistance in oral pathogens. The biofilm formation- and antibiotic resistance-related gene expression was consistent with the respective phenotypes. Furthermore, these two isomers repressed the expression of pro-inflammatory genes in RAW264.7 cells.

CONCLUSION

Our study provides evidence of the potential application of honokiol and magnolol in dental medicine to cure or prevent oral diseases.

Comparative Evaluation of Physicochemical Properties and Apical Sealing Ability of a Resin Sealer Modified with Pachymic Acid

Objective:

The addition of pachymic acid (PA) to AH Plus (an epoxy resin sealer) offsets the cytotoxicity of the latter. Prior to the clinical implementation of this formulation, a thorough knowledge of its physicochemical properties and sealing ability becomes mandatory. Hence, this in vitro study aimed to characterize and evaluate the physicochemical properties and apical sealing ability of AH Plus (AHP) with and without the addition of PA.

Methods:

Flow, setting time, film thickness, solubility and radiopacity of AHP (group 1) and AHP modified with PA (AHP/PA, group 2) were evaluated in accordance with the guidelines put forth by ISO 6876:2012. The percentage was determined under each parameter. Apical sealing ability was assessed using fluid filtration device. An independent samples t-test was used for inter- and intra-group comparisons of mean fluid flow (MFF).

Results:

Incorporating PA to AHP decreased its flow, setting time and film thickness by 24.34%, 2.14% and 31.71% respectively. The solubility of group 2 increased on day 1 by 85.71% and decreased on days 3, 7 and 14 by 46.67%, 34.79% and 13.8% respectively. The radiopacity of AHP was not altered by the addition of PA. MFF rates of group 2 was significantly higher than group 1 on day 1, but not significantly different on day 7.

Conclusion:

AHP/PA exhibited physicochemical properties that were within the requirements of ISO and with time, and showed fluid flow similar to AHP.

Inhibition of Fast Nerve Conduction Produced by Analgesics and Analgesic Adjuvants-Possible Involvement in Pain Alleviation

Nociceptive information is transmitted from the periphery to the cerebral cortex mainly by action potential (AP) conduction in nerve fibers and chemical transmission at synapses. Although this nociceptive transmission is largely inhibited at synapses by analgesics and their adjuvants, it is possible that the antinociceptive drugs inhibit nerve AP conduction, contributing to their antinociceptive effects. Many of the drugs are reported to inhibit the nerve conduction of AP and voltage-gated Na⁺ and K⁺ channels involved in its production. Compound action potential (CAP) is a useful measure to know whether drugs act on nerve AP conduction. Clinically-used analgesics and analgesic adjuvants (opioids, non-steroidal anti-inflammatory drugs, ₂-adrenoceptor agonists, antiepileptics, antidepressants and local anesthetics) were found to inhibit fast-conducting CAPs recorded from the frog sciatic nerve by using the air-gap method. Similar actions were produced by antinociceptive plant-derived chemicals. Their inhibitory actions depended on the concentrations and chemical structures of the drugs. This review article will mention the inhibitory actions of the antinociceptive compounds on CAPs in frog and mammalian peripheral (particularly, sciatic) nerves and on voltage-gated Na⁺ and K⁺ channels involved in AP production. Nerve AP conduction inhibition produced by analgesics and analgesic adjuvants is suggested to contribute to at least a part of their antinociceptive effects.

Pivotal Local Drug Delivery Systems in Endodontics; A Review of Literature

Endodontic pathosis is preliminary caused by bacteria and their by-products that interact with pulpal and periradicular host tissues. The purge of the root canal system (RCS) from bacteria is a necessity for successful endodontic treatment. Different approaches have been considered to reduce the number of microorganisms and confront microbiota in the radicular area; namely chemomechanical preparation and intracanal medication. However, various studies have shown that, due to the intricate anatomy of RCS, bacteria can persist in distant areas and significantly decrease the degree of success in endodontic ministrations. Thereby, elimination of bacteria remains a challenge, specifically from the infectious root canals. In recent years, local drug delivery systems (LDDS), loaded with drugs and/or antibacterial agents, have been deliberated for the removal of microorganisms or as a medicinal adjunct to mechanical instrumentation. Owing to the resistant species and complexities in the structure of root canals, it seems that LDDS may be able to closely affect microorganisms and improve the success rate of endodontic treatment. Furthermore, they are capable of limiting drugs to RCS, and can achieve a more effective therapeutic dose/concentration in the target site. Furthermore, and due to successful outcomes, administration of LDDS has also been given great attention for regenerative purposes. Micro/nanoparticles, liposomes, nanofibers, sealers and so forth represent typical delivery systems used for endodontic treatments. This study addresses pivotal LDDS used in endodontics and their applications.

Natural Antibacterial Reagents (Centella, Propolis, and Hinokitiol) Loaded into Poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] Composite Nanofibers for Biomedical Applications

Centella asiatica, propolis, and hinokitiol, as natural antibacterial reagents, were integrated into the poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] (PHBH) polymer to produce antibacterial wound dressings, using electrospinning process. The results showed that the fiber diameters and surface morphology of PHBH composite nanofibers were influenced by the addition of ethanol–centella (EC), methanol–centella (MC), ethanol–propolis (EP), and ethanol–hinokitiol (EH) at various ratios compared to pristine PHBH nanofibers. From FT-IR, the nanofibrous samples with higher contents of natural antibacterial substances showed the peaks of carboxylic acid, aromatic ring, and tropolone carbon ring from centella, propolis, and hinokitiol, respectively. Furthermore, the tensile strength of neat PHBH nanofibers was increased from 8.00 ± 0.71 MPa up to 16.35 ± 1.78 MPa by loading of propolis (EP) 7% into PHBH. X-ray analysis explained that the loading of propolis (EP) was also able to increase the crystallinity in PHBH composite nanofibers from 47.0% to 54.5%. The antibacterial results demonstrated that PHBH composite nanofibers containing natural antibacterial products were potent inhibitors against the growth of Escherichia coli and Staphylococcus aureus, amongst them hinokitiol and propolis proved to be the most effective. Additionally, the release studies displayed that centella and hinokitiol had faster release from PHBH composite nanofibers in comparison to propolis.

Effects of mineral trioxide aggregate and bioceramics on macrophage differentiation and polarization in vitro

BACKGROUND/PURPOSE

Mineral trioxide aggregate (Pro-Root MTA, PR-MTA) and bioceramics (iRoot^® SP Injectable Root Canal Sealer, iR-BC) are used for making apical plugs used in apexification, repairing root perforations during root canal therapy, and treating internal root resorption. The purpose of the present in vitro study was to compare the biological effects of PR-MTA- and iR-BC-based dental sealers in the mouse macrophage cell line RAW 264.7.

METHODS

Cytotoxicity and cell proliferation were analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and cell hemocytometer, respectively. Protein expression of biomarkers of cell proliferation, autophagy, and osteoclast differentiation was determined by western blotting. Pro-inflammatory gene expression was examined using quantitative reverse transcription-PCR.

RESULTS

PR-MTA induced cytotoxicity in RAW 264.7 cells in a dose-dependent manner, and iR-BC was more cytotoxic than PR-MTA. Low-dose and short-term treatments of both PR-MTA and iR-BC induced RAW 264.7 cell proliferation. PR-MTA induced autophagy, whereas iR-BC did not. Neither PR-MTA nor iR-BC induced osteoclastogenesis. Pro-inflammatory genes were activated by both materials. However, the expression of inducible nitric oxide synthase (iNOS) mRNA was upregulated by iR-BC treatment, but not by PR-MTA treatment.

CONCLUSION

Overall, dental PR-MTA and iR-BC induced pro-inflammatory genes but did not induce osteoclastogenesis in macrophages. PR-MTA and iR-BC induced M2 and M1 polarization, respectively, of RAW 264.7 cells.

Antibacterial Additives in Epoxy Resin-Based Root Canal Sealers: A Focused Review

Dental materials used in root canal treatment have undergone substantial improvements over the past decade. However, one area that still remains to be addressed is the ability of root canal fillings to effectively entomb, kill bacteria, and prevent the formation of a biofilm, all of which will prevent reinfection of the root canal system. Thus far, no published review has analysed the literature on antimicrobial additives to root canal sealers and their influence on physicochemical properties. The aim of this paper was to systematically review the current literature on antimicrobial additives in root canal sealers, their anti-fouling effects, and influence on physicochemical properties. A systematic search was performed in two databases (PubMed and Scopus) to identify studies that investigated the effect of antimicrobial additives in epoxy resin-based root canal sealers. The nature of additives, their antimicrobial effects, methods of antimicrobial testing are critically discussed. The effects on sealer properties have also been reviewed. A total of 31 research papers were reviewed in this work. A variety of antimicrobial agents have been evaluated as additives to epoxy resin-based sealers, including quaternary ammonium compounds, chlorhexidine, calcium hydroxide, iodoform, natural extracts, antibiotics, antifungal drugs, and antimicrobial agent-functionalised nanoparticles. Antimicrobial additives generally improved the antimicrobial effect of epoxy resin-based sealers mainly without deteriorating the physicochemical properties, which mostly remained in accordance with ISO and ANSI/ADA specifications.

Anti-inflammatory and antioxidative effects of the buds from different species of Populus in human gingival fibroblast cells: Role of bioflavanones

BACKGROUND

Poplar leaf-buds (Populi gemmae) are used traditionally as anti-inflammatory agents to the treatment of skin injuries or cough. They differ in their diverse chemical composition and different types of activities, whose mechanisms are not fully recognized.

PURPOSE

Evaluation and comparison of anti-inflammatory activity of leaf-buds extracts from Populus nigra, P. × berolinensis and P. lasiocarpa and flavanones - pinocembrin and pinostrobin towards human gingival fibroblasts (HGF-1) pro-inflammatory stimulated by silver nanoparticles (AgNPs). Determination of antioxidant activity associated with anti-inflammatory properties by means of bioautographic TLC tests.

METHODS

Phytochemical analysis was performed by TLC and videodensitometry analysis. The extracts were standardized on the pinocembrin and pinostrobin content. Bioautography was performed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and riboflavin-light blue tetrazolium chloride (riboflavin-light-NBT) radicals to assess the extracts and both flavanones radical scavenging properties as well as potential inhibition of xanthine oxidase (XO) activity. The protective effects of poplar buds extract and flavanones - pinocembrin and pinostrobin on HGF-1 line exposured to AgNPs were investigated by analysis of interleukin 6 (IL-6) and interleukin IL-1β (IL-1β) level measured by ELISA kit. The messenger ribonucleic acid (mRNA) of both cytokines was determined by real-time quantitative PCR. The involvement of cyclooxygenase 2 protein (COX-2) was studied using Western blot analysis.

RESULTS

The presence of several flavanones and phenolic acids, which have radical scavenging properties, was revealed in all of the bud poplar extracts analyzed. Treatment with particular flavanones or extracts from buds of P. × berolinensis and P. nigra decreased the IL-6 and IL-1β release in HGF-1 cells and down-regulation of mRNA for both cytokines was observed. The COX-2 protein expression was demonstrated for pinocembrin and P. × berolinensis buds. These effects were not observed for buds from P. lasiocarpa not containing of flavonoids.

CONCLUSION

The potential protective role of pinocembrin and pinostrobin and extracts from buds P. nigra and P. × berolinensis against AgNPs induced inflammation and cytotoxicity in HGF-1 cells is disclosed. In addition, the antioxidant properties of poplar bud extracts have been demonstrated. P. × berolinensis buds showed the highest activity in both the in vitro model and in the bioautographic tests.

Synthesis and Evaluation of Troponoids as a New Class of Antibiotics

Novel antibiotics are urgently needed. The troponoids [tropones, tropolones, and α-hydroxytropolones (α-HT)] can have anti-bacterial activity. We synthesized or purchased 92 troponoids and evaluated their antibacterial activities against Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosa. Preliminary hits were assessed for minimum inhibitory concentrations (MIC₈₀) and cytotoxicity (CC₅₀) against human hepatoma cells. Sixteen troponoids inhibited S. aureus/E. coli/A. baumannii growth by ≥80% growth at <30 μM with CC₅₀ values >50 μM. Two selected tropolones (63 and 285) inhibited 18 methicillin-resistant S. aureus (MRSA) strains with similar MIC₈₀ values as against a reference strain. Two selected thiotropolones (284 and 363) inhibited multidrug-resistant (MDR) E. coli with MIC₈₀ ≤30 μM. One α-HT (261) inhibited MDR-A. baumannii with MIC₈₀ ≤30 μM. This study opens new avenues for development of novel troponoid antibiotics to address the critical need to combat MDR bacterial infections.

An Overview on the Anti-inflammatory Potential and Antioxidant Profile of Eugenol

The bioactive compounds found in foods and medicinal plants are attractive molecules for the development of new drugs with action against several diseases, such as those associated with inflammatory processes, which are commonly related to oxidative stress. Many of these compounds have an appreciable inhibitory effect on oxidative stress and inflammatory response, and may contribute in a preventive way to improve the quality of life through the use of a diet rich in these compounds. Eugenol is a natural compound that has several pharmacological activities, action on the redox status, and applications in the food and pharmaceutical industry. Considering the importance of this compound, the present review discusses its anti-inflammatory and antioxidant properties, demonstrating its mechanisms of action and therapeutic potential for the treatment of inflammatory diseases.

The dentin permeability of anti-inflammatory and antibacterial drugs: In vitro study

BACKGROUND/PURPOSE

Stimuli from the oral cavity may penetrate through exposed dentinal tubules and evoke inflammatory pulp response. Anti-bacterial and anti-inflammatory drugs applied to exposed dentin may infiltrate through the dentinal tubules and cause pulp recovery. This study investigated the dentin permeability of anti-bacterial and anti-inflammation drugs via an in-vitro transwell dentin disc tube model.

METHODS

Twenty-seven dentin discs prepared from extracted human molars were collected. Nine kinds of drugs were investigated with three dentin discs in each group. These nine drugs included two anti-bacterial drugs (ampicillin sodium and clindamycin phosphate), two corticosteroids (betamethasone sodium phosphate and hydrocortisone sodium succinate), three non-steroidal anti-inflammatory drugs (NSAIDs, piroxicam, lysine acetylsalicylate, and diclofenac sodium), and two natural extracts with anti-inflammatory effect (Ginsenoside Rg1 and Hinokitol). The drugs were introduced to the transwell dentin disc tube model and the 4-hour cumulative release of the drug was detected and recorded by UV-visible spectroscopy.

RESULTS

We found that ampicilin sodium had better dentin permeability than clindamycin phosphate. Betamethasone sodium phosphate revealed better dentin permeability than hydrocortisone sodium succinate. Lysine acetylsalicylate showed the best dentin permeability among the three NSAIDs. Ginsenoside Rg1 had the best dentin permeability among the nine drugs tested. However, Hinokitiol could not penetrate the dentin disc after 4 h.

CONCLUSION

Regarding the dentin permeability, Ginsenoside Rg1 is the best among the seven anti-inflammatory drugs tested and ampicilin sodium is the better one between the two anti-bacterial drugs tested. Therefore, these two drugs may have high potential for treating exposed dentinal tubule diseases.

Identification of 4-isopropyl-thiotropolone as a novel anti-microbial: regioselective synthesis, NMR characterization, and biological evaluation

We have synthesized and separated tosylated thujaplicin isomers for the first time, and elucidated their structures using 1D, 2D-NMR techniques and X-ray crystallography. The tosylated isomers were used to synthesize 4-isopropyl–thiotropolone and 6-isopropyl–thiotropolone in a regioselective manner. ¹H and ¹³C Chemical shifts of synthesized isomers were fully assigned using several NMR experiments, and their isotropic magnetic shielding was calculated using the GIAO (Gauge Including Atomic Orbitals) method and the B3LYP def2-TZVPP level of theory. The calculated chemical shift values were in a good agreement with the experimental results. The biological activity of all synthesized compounds was evaluated against the fungal pathogen Cryptococcus neoformans and four different bacterial strains (Staphylococcus aureus (ATCC 29213), E. coli (ATCC 35218), Acinetobacter baumannii and Pseudomonas aeruginosa (ATCC 27853)). 4-Isopropyl–thiotropolone was found to inhibit Staphylococcus aureus in a low micro molar range and exhibit good therapeutic index and ADME properties. This compound can be used for future lead optimization to design inhibitors against Staphylococcus aureus (ATCC 29213).

4-Isopropyl–thiotropolone was identified as a novel anti-microbial agent with good therapeutic index and ADME properties.

Hinokitiol ablates myofibroblast activation in precancerous oral submucous fibrosis by targeting Snail

Oral submucous fibrosis (OSF) is a precancerous condition with symptoms of limited mouth opening and areca nut chewing habit has been implicated in its pathogenesis. Hinokitiol, a natural tropolone derived from Chamacyparis taiwanensis, has been reported to improve oral lichen planus and inhibit various cancer cells. Here, we showed that hinokitiol reduced the myofibroblast activities in fBMFs and prevented the arecoline-induced transdifferentiation. Treatment of hinokitiol dose-dependently downregulated the myofibroblast markers as well as various EMT transcriptional factors. In particular, we identified that Snail was able to bind to the E-box in the α-SMA promoter. Our data suggested that exposure of fBMFs to hinokitiol mitigated the hallmarks of myofibroblasts, while overexpression of Snail eliminated the effect of hinokitiol. These findings revealed that the inhibitory effect of hinokitiol on myofibroblasts was mediated by repression of α-SMA via regulation of Snail and showed the anti-fibrotic potential of hinokitiol in the treatment of OSF.

Hinokitiol Inhibits Migration of A549 Lung Cancer Cells via Suppression of MMPs and Induction of Antioxidant Enzymes and Apoptosis

Hinokitiol, a natural monoterpenoid from the heartwood of Calocedrus formosana, has been reported to have anticancer effects against various cancer cell lines. However, the detailed molecular mechanisms and the inhibiting roles of hinokitiol on adenocarcinoma A549 cells remain to be fully elucidated. Thus, the current study was designed to evaluate the effect of hinokitiol on the migration of human lung adenocarcinoma A549 cells in vitro. The data demonstrates that hinokitiol does not effectively inhibit the viability of A549 cells at up to a 10 µM concentration. When treated with non-toxic doses (1–5 µM) of hinokitiol, the cell migration is markedly suppressed at 5 µM. Hinokitiol significantly reduced p53 expression, followed by attenuation of Bax in A549 cells. A dose-dependent inhibition of activated caspase-9 and -3 was observed in the presence of hinokitiol. An observed increase in protein expression of matrix metalloproteinases (MMPs) -2/-9 in A549 cells was significantly inhibited by hinokitiol. Remarkably, when A549 cells were subjected to hinokitiol (1–5 µM), there was an increase in the activities of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) from the reduction in cells. In addition, the incubation of A549 cells with hinokitiol significantly activated the cytochrome c expression, which may be triggered by activation of caspase-9 followed by caspase-3. These observations indicate that hinokitiol inhibited the migration of lung cancer A549 cells through several mechanisms, including the activation of caspases-9 and -3, induction of p53/Bax and antioxidant CAT and SOD, and reduction of MMP-2 and -9 activities. It also induces cytochrome c expression. These findings demonstrate a new therapeutic potential for hinokitiol in lung cancer chemoprevention.

Calcium Phosphate Cement with Antimicrobial Properties and Radiopacity as an Endodontic Material

Calcium phosphate cements (CPCs) have several advantages for use as endodontic materials, and such advantages include ease of use, biocompatibility, potential hydroxyapatite-forming ability, and bond creation between the dentin and appropriate filling materials. However, unlike tricalcium silicate (CS)-based materials, CPCs do not have antibacterial properties. The present study doped a nonwashable CPC with 0.25–1.0 wt % hinokitiol and added 0, 5, and 10 wt % CS. The CPCs with 0.25–0.5 wt % hinokitiol showed appreciable antimicrobial properties without alterations in their working or setting times, mechanical properties, or cytocompatibility. Addition of CS slightly retarded the apatite formation of CPC and the working and setting time was obviously reduced. Moreover, addition of CS dramatically increased the compressive strength of CPC. Doping CS with 5 wt % ZnO provided additional antibacterial effects to the present CPC system. CS and hinokitiol exerted a synergic antibacterial effect, and the CPC with 0.25 wt % hinokitiol and 10 wt % CS (doped with 5 wt % ZnO) had higher antibacterial properties than that of pure CS. The addition of 10 wt % bismuth subgallate doubled the CPC radiopacity. The results demonstrate that hinokitiol and CS can improve the antibacterial properties of CPCs, and they can thus be considered for endodontic applications.

Hypoxia-inducible factor-1α and glucose transporter 1 in the malignant transformation of oral lichen planus

Hypoxia-inducible factor-1α (HIF-1α) and glucose transporter 1 (GLUT1) are key factors in numerous physiological and pathological processes. However, studies on their involvement in the pathogenesis of oral lichen planus (OLP) and its progression toward oral squamous cell carcinomas (OSCC) are scarce. In this study, we examined the protein and gene expressions of both HIF-1α and GLUT1 in normal mucosa, nonatrophic OLP (OLPI), atrophic OLP (OLPII), and OSCC resulting from OLP. Tissues were obtained from 60 cases of OLP patients (n=36 for OLPI, n=24 for OLPII), 20 cases of OSCC patients and 30 healthy control individuals. In addition, in order to investigate if the pathological changes are due to hypoxia, we cultured keratinocytes under hypoxia conditions and measured the expression of HIF-1α and GLUT1. The results indicated that the expressions of HIF-1α and GLUT1 were gradually amplified from normal mucosa to OLPI, OLPII, and OSCC. The expression of both HIF-1α and GLUT1 in OLPII was significantly greater than OLPII. Likewise, the HIF-1α and GLUT1 expressions in OSCC were markedly higher compared to both OLPI and OLPII. Similar trends were obtained in real time PCR and Western blot analyses. A progressive increased micro-vessel density (MVD) was also recorded from normal mucosa to OLPI, OLPII, and OSCC. Moreover, the correlation analysis revealed significant positive correlations between HIF-1α and GLUT1 which were both correlated with MVD in the OLP and OSCC groups. Culture of keratinocytes isolated from OLP tissues under hypoxic and normoxic conditions showed a time-dependent inhibition of keratinocyte proliferation and increased expression of HIF-1α and GLUT1 under hypoxia conditions. In summary, we provided new evidence that hypoxia markers HIF-1α and GLUT1 are upregulated in OLP and are potentially involved in pathological changes leading to malignant transformation of OLP. Further characterization of these factors will provide new ideas for the diagnosis and treatment of OLP.

Hinokitiol suppresses cancer stemness and oncogenicity in glioma stem cells by Nrf2 regulation

PURPOSE

Glioma is one of the lethal malignancies with poor prognosis. In addition, glioma stem cells (GSCs) have been considered as the crucial player that attributed to the tumorigenesis and drug resistance. In the current study, we investigated the therapeutic effect of hinokitiol, a natural bioactive compound of aromatic tropolone, on the characteristics of GSCs and the possible mechanism.

METHODS

U87MG and T98G glioma cells were used to isolate GSCs. CD133 positivity and ALDH1 activity of GSCs following hinokitiol treatment were assessed by flow cytometry analysis. Secondary sphere formation, migration, invasion, and colony-forming assays were performed to examine the self-renewal capacity and oncogenicity in GCS after hinokitiol administration. The expression of Nrf2 was evaluated by RT-PCR and western blot analyses.

RESULTS

We demonstrated that hinokitiol effectively inhibited the CD133 positivity and ALDH1 activity along with the reduced self-renewal, migration, invasion, and colony formation properties of GSCs. In addition, hinokitiol repressed the gene and protein expression of Nrf2, which has been shown to be critical for those GSCs features. Furthermore, we showed that administration of exogenous Nrf2 counteracted the inhibitory effect of hinokitiol on self-renewal and invasiveness of GSCs.

CONCLUSION

These evidences suggest that treatment of hinokitiol significantly attenuates the hallmarks of GSCs due to downregulation of Nrf2 expression. Hence, hinokitiol may serve as a promising agent for the therapy of glioma.

Hinokitiol up-regulates miR-494-3p to suppress BMI1 expression and inhibits self-renewal of breast cancer stem/progenitor cells

Hinokitiol (β-thujaplicin) is a tropolone-related compound that has anti-microbe, anti-inflammation, and anti-tumor effects. Cancer stem/progenitor cells (CSCs) are a subpopulation of cancer cells with tumor initiation, chemoresistant, and metastatic properties and have been considered the important therapeutic target in future cancer therapy. Previous studies reported that hinokitiol exhibits an anti-cancer activity against murine tumor cells through the induction of autophagy. The current research revealed that hinokitiol suppressed the self-renewal capabilities of human breast CSCs (BCSCs) and inhibited the expression of BMI1 at protein level without suppressing its mRNA. Treatment of hinokitiol in mammospheres induced the expression of miR-494-3p and inhibition of miR-494-3p expression in BCSCs. This treatment abolished the suppressive effects of hinokitiol in mammosphere formation and BMI1 expression. BMI1 is a target of miR-494-3p by luciferase-based 3′UTR reporter assay. Overexpression of miR-494-3p in BCSCs caused the down-regulation of BMI1 protein, inhibition of mammosphere forming capability, and suppression of their tumorigenicity. Moreover, miR-494-3p expression was significantly and inversely correlated with patient survival in two independent public database sets. Furthermore, treatment of hinokitiol in vivo suppressed the growth of xenograft human breast tumors as well as the expression of BMI1 and ALDH1A1 in xenograft tumors. In conclusion, these data suggest that hinokitiol targets BCSCs through the miR-494-3p-mediated down-modulation of BMI1 expression.

SIRT1, a Class III Histone Deacetylase, Regulates LPS-Induced Inflammation in Human Keratinocytes and Mediates the Anti-Inflammatory Effects of Hinokitiol

Skin inflammation is a response of the immune system to infection and injury. In this study, we report that hinokitiol, a tropolone-related natural compound that exhibits antioxidant, anti-inflammatory, and anticancer properties in various cell types, can modulate the inflammatory responses of primary human keratinocytes challenged with lipopolysaccharide (LPS). Hinokitiol treatment inhibited LPS-mediated up-regulation of proinflammatory factors including tumor necrosis factor alpha, IL-6, and prostaglandin E₂ (PGE₂). NF-κB activation and cell migration induced by LPS were blocked in keratinocytes treated with hinokitiol. Sirt1, a class Ⅲ histone deacetylase, was up-regulated by hinokitiol treatment, and the inhibition of Sirt1 activity using a pharmacological inhibitor or genetic silencing blocked hinokitiol-mediated anti-inflammatory effects. Further, hyperactivation of Sirt1 deacetylase using an adenoviral vector also attenuated LPS-induced inflammatory responses. We thus show that hinokitiol can attenuate LPS-mediated proinflammatory signals via Sirt1 histone deacetylase activation in primary human keratinocytes and suggest that hinokitiol may be a potential therapeutic agent in skin inflammatory diseases like psoriasis.

Resveratrol-induced autophagy and apoptosis in cisplatin-resistant human oral cancer CAR cells: A key role of AMPK and Akt/mTOR signaling

Resveratrol is known to be an effective chemo-preventive phytochemical against multiple tumor cells. However, the increasing drug resistance avoids the cancer treatment in oral cavity cancer. In this study, we investigated the oral antitumor activity of resveratrol and its mechanism in cisplatin-resistant human oral cancer CAR cells. Our results demonstrated that resveratrol had an extremely low toxicity in normal oral cells and provoked autophagic cell death to form acidic vesicular organelles (AVOs) and autophagic vacuoles in CAR cells by acridine orange (AO) and monodansylcadaverine (MDC) staining. Either DNA fragmentation or DNA condensation occurred in resveratrol-triggered CAR cell apoptosis. These inhibitors of PI3K class III (3-MA) and AMP-activated protein kinase (AMPK) (compound c) suppressed the autophagic vesicle formation, LC3-II protein levels and autophagy induced by resveratrol. The pan-caspase inhibitor Z-VAD-FMK attenuated resveratrol-triggered cleaved caspase-9, cleaved caspase-3 and cell apoptosis. Resveratrol also enhanced phosphorylation of AMPK and regulated autophagy- and pro-apoptosis-related signals in resveratrol-treated CAR cells. Importantly, resveratrol also stimulated the autophagic mRNA gene expression, including Atg5, Atg12, Beclin-1 and LC3-II in CAR cells. Overall, our findings indicate that resveratrol is likely to induce autophagic and apoptotic death in drug-resistant oral cancer cells and might become a new approach for oral cancer treatment in the near future.

Evaluation of the Antibacterial Potential of Liquid and Vapor Phase Phenolic Essential Oil Compounds against Oral Microorganisms

The aim of the present study was to determine the antibacterial activities of the phenolic essential oil (EO) compounds hinokitiol, carvacrol, thymol, and menthol against oral pathogens. Aggregatibacter actinomycetemcomitans, Streptococcus mutans, Methicillin-resistant Staphylococcus aureus (MRSA), and Escherichia. coli were used in this study. The minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs), bacterial growth curves, temperature and pH stabilities, and synergistic effects of the liquid and vapor EO compounds were tested. The MIC/MBC of the EO compounds, ranging from the strongest to weakest, were hinokitiol (40-60 μg/mL/40-100 μg/mL), thymol (100-200 μg/mL/200-400 μg/mL), carvacrol (200-400 μg/mL/200-600 μg/mL), and menthol (500-more than 2500 μg/mL/1000-more than 2500 μg/mL). The antibacterial activities of the four EO phenolic compound based on the agar diffusion test and bacterial growth curves showed that the four EO phenolic compounds were stable under different temperatures for 24 h, but the thymol activity decreased when the temperature was higher than 80°C. The combination of liquid carvacrol with thymol did not show any synergistic effects. The activities of the vaporous carvacrol and thymol were inhibited by the presence of water. Continual violent shaking during culture enhanced the activity of menthol. Both liquid and vaporous hinokitiol were stable at different temperatures and pH conditions. The combination of vaporous hinokitiol with zinc oxide did not show synergistic effects. These results showed that the liquid and vapor phases of hinokitiol have strong anti-oral bacteria abilities. Hinokitiol has the potential to be applied in oral health care products, dental materials, and infection controls to exert antimicrobial activity.

Protective Role of Hinokitiol Against H2O2-Induced Injury in Human Corneal Epithelium

PURPOSE

We recently found that hinokitiol has anti-inflammatory activity in human corneal epithelial (HCE) cells. Herein, we investigated the protective role of hinokitiol against H₂O₂-induced injury in HCE cells and the mechanisms that underlie its action.

METHODS

HCE cells were incubated with different concentrations of hinokitiol or dimethylsulfoxide (DMSO), which served as a vehicle control, before H₂O₂ stimulus. The cell viability was evaluated using a cell counting kit-8 (CCK-8) assay. TUNEL, phosphorylated histone γH2A.X, cleaved caspase-3 expression analyses, and location of cytochrome c were conducted to detect cell injury and apoptosis. Reactive oxygen species (ROS), catalase (CAT), superoxide dismutase (SOD), methane dicarboxylic aldehyde (MDA), and total antioxidative capacity (T-AOC) were used to determine oxidative stress. Bcl-2 and Bax protein expressions were measured by western blotting.

RESULTS

Hinokitiol significantly improved the cell viability, decreased the apoptosis rate, inhibited DNA damage, and reduced cleaved caspase-3 expression and the leakage of cytochrome c from mimitochondrion to cytoplasm of HCE cells against the oxidative stress induced by H₂O₂. Generation of ROS and MDA and decreased activity of CAT, SOD, and T-AOC were also ameliorated by hinokitiol administration. Moreover, Bcl-2 expression was down-regulated while Bax was up-regulated by H₂O₂ stimulus, which were reversed by hinokitiol application.

CONCLUSION

Hinokitiol protects HCE cells against H₂O₂-induced injury likely by its antioxidant activity and modulating the Bcl-2 signaling pathway.

Hinokitiol-Loaded Mesoporous Calcium Silicate Nanoparticles Induce Apoptotic Cell Death through Regulation of the Function of MDR1 in Lung Adenocarcinoma Cells

Hinokitiol is a tropolone-related compound found in heartwood cupressaceous plants. Hinokitiol slows the growth of a variety of cancers through inhibition of cell proliferation. The low water solubility of hinokitiol leads to less bioavailability. This has been highlighted as a major limiting factor. In this study, mesoporous calcium silicate (MCS) nanoparticles, both pure and hinokitiol-loaded, were synthesized and their effects on A549 cells were analyzed. The results indicate that Hino-MCS nanoparticles induce apoptosis in higher concentration loads (>12.5 μg/mL) for A549 cells. Hino-MCS nanoparticles suppress gene and protein expression levels of multiple drug resistance protein 1 (MDR1). In addition, both the activity and the expression levels of caspase-3/-9 were measured in Hino-MCS nanoparticle-treated A549 cells. The Hino-MCS nanoparticles-triggered apoptosis was blocked by inhibitors of pan-caspase, caspase-3/-9, and antioxidant agents (N-acetylcysteine; NAC). The Hino-MCS nanoparticles enhance reactive oxygen species production and the protein expression levels of caspase-3/-9. Our data suggest that Hino-MCS nanoparticles trigger an intrinsic apoptotic pathway through regulating the function of MDR1 and the production of reactive oxygen species in A549 cells. Therefore, we believe that Hino-MCS nanoparticles may be efficacious in the treatment of drug-resistant human lung cancer in the future.

Hinokitiol inhibits vasculogenic mimicry activity of breast cancer stem/progenitor cells through proteasome-mediated degradation of epidermal growth factor receptor

Hinokitiol, alternatively known as β-thujaplicin, is a tropolone-associated natural compound with antimicrobial, anti-inflammatory and antitumor activity. Breast cancer stem/progenitor cells (BCSCs) are a subpopulation of breast cancer cells associated with tumor initiation, chemoresistance and metastatic behavior, and may be enriched by mammosphere cultivation. Previous studies have demonstrated that BCSCs exhibit vasculogenic mimicry (VM) activity via the epidermal growth factor receptor (EGFR) signaling pathway. The present study investigated the anti-VM activity of hinokitiol in BCSCs. At a concentration below the half maximal inhibitory concentration, hinokitiol inhibited VM formation of mammosphere cells derived from two human breast cancer cell lines. Hinokitiol was additionally indicated to downregulate EGFR protein expression in mammosphere-forming BCSCs without affecting the expression of messenger RNA. The protein stability of EGFR in BCSCs was also decreased by hinokitiol. The EGFR protein expression and VM formation capability of hinokitiol-treated BCSCs were restored by co-treatment with MG132, a proteasome inhibitor. In conclusion, the present study indicated that hinokitiol may inhibit the VM activity of BCSCs through stimulating proteasome-mediated EGFR degradation. Hinokitiol may act as an anti-VM agent, and may be useful for the development of novel breast cancer therapeutic agents.

Hinokitiol induces autophagy in murine breast and colorectal cancer cells

Hinokitiol is found in the heartwood of cupressaceous plants and possesses several biological activities. Hinokitiol may play an important role in anti-inflammation and antioxidant processes, making it potentially useful in therapies for inflammatory-mediated disease. Previously, the suppression of tumor growth by hinokitiol has been shown to occur through apoptosis. Programmed cell death can also occur through autophagy, but the mechanism of hinokitiol-induced autophagy in tumor cells is poorly defined. We used an autophagy inhibitor (3-methyladenine) to demonstrate that hinokitiol can induce cell death via an autophagic pathway. Further, we suggest that hinokitiol induces autophagy in a dose-dependent manner. Markers of autophagy were increased after tumor cells were treated with hinokitiol. In addition, immunoblotting revealed that the levels of phosphoprotein kinase B (P-AKT), phosphomammalian target of rapamycin (P-mTOR), and phospho-p70 ribosomal s6 kinase (P-p70S6K) in tumor cells were decreased after hinokitiol treatment. In conclusion, our results indicate that hinokitiol induces the autophagic signaling pathway via downregulation of the AKT/mTOR pathway. Therefore, our findings show that hinokitiol may control tumor growth by inducing autophagic signaling.

Isoliquiritigenin as a cause of DNA damage and inhibitor of ataxia-telangiectasia mutated expression leading to G2/M phase arrest and apoptosis in oral squamous cell carcinoma

BACKGROUND

Isoliquiritigenin (ISL), a natural compound extracted from licorice, has chemopreventive and antitumor activities. The purpose of this study was to investigate the anticancer effect of ISL on human oral squamous cell carcinoma (OSCC).

METHODS

The anti-OSCC effects of ISL were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test, flow cytometry, reverse transcription-polymerase chain reaction, Western blotting, promoter activity, terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, malignant phenotype analysis, microRNA, and xenografting.

RESULTS

ISL induced OSCC cell cycle G2/M phase arrest, apoptosis, and DNA damage. However, the DNA repair-associated ataxia telangiectasia mutated (ATM) and phospho-ATM were downregulated, ATM mRNA remained unchanged, and the downstream signals were inhibited. ATM recovered when the caspase activity was blocked by Z-DVED-FMK. A low dose of ISL inhibited OSCC malignancy in vitro and reduced the tumor size in vivo.

CONCLUSION

ATM was cleaved by ISL-activated caspase, thus inhibiting DNA repair in OSCC cells. Therefore, ISL is a promising chemopreventive agent against oral cancer. © 2015 Wiley Periodicals, Inc. Head Neck 38: E360-E371, 2016.

Anti-inflammatory effects of hinokitiol on human corneal epithelial cells: an in vitro study

PURPOSE

This study assessed the anti-inflammatory effect and mechanism of action of hinokitiol in human corneal epithelial (HCE) cells.

METHODS

HCE cells were incubated with different concentrations of hinokitiol or dimethylsulfoxide (DMSO), which served as a vehicle control. Cell viability was evaluated using Cell Counting Kit-8 (CCK-8) assay. After polyriboinosinic:polyribocytidylic acid (poly(I:C)) stimulus, cells with or without hinokitiol were evaluated for the mRNA and protein levels of interleukin-8 (IL-8), interleukin-6 (IL-6), and interleukin-1β (IL-1β) using real-time PCR analysis and an enzyme-linked immunosorbent assay (ELISA), respectively. Nuclear and cytoplasmic levels of nuclear factor kappa B (NF-κB) p65 protein and an inhibitor of NF-κB α (IκBα) were evaluated using western blotting.

RESULTS

There were no significant differences among the treatment concentrations of hinokitiol compared with cells incubated in medium only. Incubating with 100 μM hinokitiol significantly decreased the mRNA levels of IL-8 to 58.77±10.41% (P<0.01), IL-6 to 64.64±12.71% (P<0.01), and IL-1β to 54.19±8.10% (P<0.01) compared with cells stimulated with poly(I:C) alone. The protein levels of IL-8, IL-6, and IL-1β had similar trend. Further analysis revealed that hinokitiol maintained the levels of IκBα and significantly reduced NF-κB p65 subunit translocation to the nucleus which significantly inhibiting the activation of the NF-κB signal pathway.

CONCLUSION

Hinokitiol showed a significant protective effect against ocular surface inflammation through inhibiting the NF-κB pathway, which may indicate the possibility to relieve the ocular surface inflammation of dry eye syndrome (DES).