In vitro antimicrobial and anticancer potential of hinokitiol against oral pathogens and oral cancer cell lines

Searching for the role of membrane lipids in the mechanism of antibacterial effect of hinokitiol

The aim of this work was to investigate the effect of monoterpenoid hinokitiol (β-thujaplicin) on the monolayers and bilayers composed of lipids typical for bacteria membranes and gain insight into the potential role of the lipids in antibacterial activity and selectivity of this compound. To explore this issue, the in vitro studies were performed on different bacterial strains to verify antibacterial potency of hinokitiol. Then, the experiments on E. coli and S. aureus bacteria membrane models (i.e. multicomponent lipid monolayers and bilayers) were done. Finally, the effect of hinokitiol on one component lipid monolayers was investigated. The lipids used in the experiments included Phosphatidylethanolamines (PEs), Phosphatidylglycerols (PGs) and Cardiolipins differing in the structure of the polar head and/or the hydrophobic chains. This choice allowed the analysis of correlations between the lipid structure and the effect of hinokitiol. In vitro tests confirmed the antimicrobial activity of hinokitiol against most of the strains tested. In addition, the in vitro tests showed that E. coli bacteria were more sensitive to hinokitiol than S. aureus bacteria. Interestingly, the studies on model systems evidenced that hinokitiol molecules are of stronger effect on E.coli film and they are able to insert into these systems even at membrane-related surface pressures. Moreover, the structure of the lipid and its content in the model system correlated with the effect exerted by hinokitiol on the monolayer properties. It was found that hinokitiol differs in the affinity to particular lipids and additionally hinokitiol/lipid interactions may occur according to different mechanisms. Namely, depending on the lipid structure, hinokitiol may incorporate into the lipid film (Cardiolipins and PEs) or interact preferentially with the lipid polar head (PGs) and form hydrogen bonds. The effect of hinokitiol on the lipids was determined by the charge and size of the polar head as well as by the spatial size of the lipid molecule. Moreover, comparing the lipids of the same polar heads, hinokitiol caused stronger expansion of the film formed from the lipid having unsaturated chains. The results obtained may explain the difference in the effect of hinokitiol on particular bacterial strains. In conclusions, it can be suggested that the lipids should be considered as the bacteria membrane structural elements of a possible role in the mechanism of action of hinokitiol.

Evidence for the O-H⋅⋅⋅O=C Resonance-Assisted Hydrogen Bond in Tropolones and Quantification of its σ- and π-Components Using Molecular Tailoring Approach

For a series of tropolones, the nature of the intramolecular O-H⋅⋅⋅O=C hydrogen bond closing the five-membered quasi-cycle was studied. Enhancement of conjugation in the hydrogen-bonded rotamer was revealed. Quantification of hydrogen bond energy in tropolones via the molecular tailoring approach yields values in the range from 15 to 20 kcal/mol suggesting that the intramolecular interaction in tropolones has nature of the resonance-assisted hydrogen bond. The total resonance-assisted hydrogen bond energy in the tropolones was divided into σ- and π-components. The magnitudes of total energy of resonance-assisted hydrogen bond in the substituted tropolones can be controlled by the electronic properties of the substituents at the tropone ring. In 3-, 4-, and 5-substituted tropolones, the resonance-assisted hydrogen bond energy is raised due to electron-donating substituents and lowered due to electron-withdrawing ones. The opposite trend is observed in 7-substituted tropolones. The size of the π-shares plays a crucial role in establishing the total energy of resonance-assisted hydrogen bond. The reason for the occurrence of a resonance-assisted hydrogen bond in the tropolones is the molecular backbone aromaticity, since, in accordance with the Hückel rule, 10 π-electrons are delocalized.

Therapeutic Effects of Hinokitiol through Regulating the SIRT1/NOX4 against Ligature-Induced Experimental Periodontitis

Hinokitiol (HKT) is one of the essential oil components found in the heartwood of Cupressaceae plants, and has been reported to have various bioactive effects, including anti-inflammatory effects. However, the improving effect of HKT on periodontitis, which is characterized by periodontal tissue inflammation and alveolar bone loss, has not been clearly revealed. Therefore, we investigated the periodontitis-alleviating effect of HKT and the related molecular mechanisms in human periodontal ligament cells. According to the study results, HKT downregulated SIRT1 and NOX4, which were increased by Porphyromonas gingivalis Lipopolysaccharide (PG-LPS) stimulation and were found to regulate pro-inflammatory mediators and oxidative stress through SIRT1/NOX4 signals. Additionally, by increasing the expression of osteogenic makers such as alkaline phosphatase, osteogenic induction of human periodontal ligament (HPDL) cells, which had been reduced by PG-LPS, was restored. Furthermore, we confirmed that NOX4 expression was regulated through regulation of SIRT1 expression with HKT. The in vitro effect of HKT on improving periodontitis was proven using the periodontal inflammation model, which induces periodontal inflammation using ligature, a representative in vivo model. According to in vivo results, HKT alleviated periodontal inflammation and restored damaged alveolar bone in a concentration-dependent manner in the periodontal inflammation model. Through this experiment, the positive effects of HKT on relieving periodontal tissue inflammation and recovering damaged alveolar bone, which are important treatment strategies for periodontitis, were confirmed. Therefore, these results suggest that HKT has potential in the treatment of periodontitis.

Hinokitiol Inhibits Breast Cancer Cells In Vitro Stemness-Progression and Self-Renewal with Apoptosis and Autophagy Modulation via the CD44/Nanog/SOX2/Oct4 Pathway

Breast cancer (BC) represents one of the most prevalent malignant threats to women globally. Tumor relapse or metastasis is facilitated by BC stemness progression, contributing to tumorigenicity. Therefore, comprehending the characteristics of stemness progression and the underlying molecular mechanisms is pivotal for BC advancement. Hinokitiol (β-thujaplicin), a tropolone-related compound abundant in the heartwood of cupressaceous plants, exhibits antimicrobial activity. In our study, we employed three BC cell lines (MDA-MB-231, MCF-7, and T47D) to assess the expression of stemness-, apoptosis-, and autophagy-related proteins. Hinokitiol significantly reduced the viability of cancer cells in a dose-dependent manner. Furthermore, we observed that hinokitiol enhances apoptosis by increasing the levels of cleaved poly-ADP-ribose polymerase (PARP) and phospho-p53. It also induces dysfunction in autophagy through the upregulation of LC3B and p62 protein expression. Additionally, hinokitiol significantly suppressed the number and diameter of cancer cell line spheres by reducing the expression of cluster of differentiation44 (CD44) and key transcription factors. These findings underscore hinokitiol's potential as a therapeutic agent for breast cancer, particularly as a stemness-progression inhibitor. Further research and clinical studies are warranted to explore the full therapeutic potential of hinokitiol in the treatment of breast cancer.

Static Magnetic Field Reduces the Anticancer Effect of Hinokitiol on Melanoma Malignant Cells-Gene Expression and Redox Homeostasis Studies

BACKGROUND

Melanoma malignant is characterized by a high mortality rate, accounting for as much as 65% of deaths caused by skin cancer. A potential strategy in cancer treatment may be the use of natural compounds, which include hinokitiol (β-Thujaplicin), a phenolic component of essential oils extracted from cypress trees. Many studies confirm that a high-induction SMF (static magnetic field) has anticancer effects and can be used as a non-invasive anticancer therapy in combination with or without drugs.

AIM

The aim of this experiment was to evaluate the effect of a static magnetic field on melanoma cell cultures (C32 and COLO 829) treated with hinokitiol.

METHODS AND RESULTS

Melanoma cells were exposed to a static magnetic field of moderate induction and hinokitiol. The research included determining the activity of the antioxidant enzymes (SOD, GPx, and CAT) and MDA concentration as well as the gene expression profile.

CONCLUSION

Hinokitiol disturbs the redox homeostasis of C32 and COLO 829 melanoma malignant cells. Moreover, a static magnetic field has a protective effect on melanoma malignant cells and abolishes the anticancer effect of hinokitiol.

Hinokitiol as a modulator of TLR4 signaling and apoptotic pathways in atopic dermatitis

Atopic dermatitis (AD) poses a significant global health challenge, characterized by dysregulated inflammation and apoptotic processes. This study explores the therapeutic efficacy of hinokitiol, employing a comprehensive in vivo and in vitro approach. Assessment of inflammation-related markers in the animal model included observation of physical appearance, Western blotting, ELISA, and H&E staining. Additionally, the cell culture model enabled the evaluation of apoptosis and ROS levels using MTT assay, crystal violet staining, Western blot, and DCFDA assays. The results revealed hinokitiol's proficiency in ameliorating ear and skin morphology in the DNCB-induced AD model, mediated through the TLR4/MyD88 pathway. Notably, hinokitiol intervention led to a reduction in both M1 and M2 macrophage phenotypes. In vitro investigations demonstrated hinokitiol's ability to enhance cell viability and morphology under TNF-α and IFN-γ induction. Mechanistically, hinokitiol exhibited regulatory effects on apoptosis-related proteins, including Bax, Cytochrome c, Caspase-3, and PARP, thereby averting cellular damage. These findings suggest that hinokitiol is a promising natural compound with significant potential for alleviating inflammation and apoptosis in AD, indicating potential avenues for future therapeutic developments.

Natural Compounds with Antifungal Properties against Candida albicans and Identification of Hinokitiol as a Promising Antifungal Drug

Candida albicans is an opportunistic yeast that causes most fungal infections. C. albicans has become increasingly resistant to antifungal drugs over the past decade. Our study focused on the identification of pure natural compounds for the development of antifungal medicines. A total of 15 natural compounds from different chemical families (cinnamic derivatives, aromatic phenols, mono- and sesquiterpenols, and unclassified compounds) were screened in this study. Among these groups, hinokitiol (Hi), a natural monoterpenoid extracted from the wood of the cypress family, showed excellent anti-C. albicans activity, with a MIC value of 8.21 µg/mL. Hi was selected from this panel for further investigation to assess its antifungal and anti-inflammatory properties. Hi exhibited significant antifungal activity against clinically isolated fluconazole- or caspofungin-resistant C. albicans strains. It also reduced biofilm formation and hyphal growth. Treatment with Hi protected Caenorhabditis elegans against infection with C. albicans and enhanced the expression of antimicrobial genes in worms infected with C. albicans. Aside from its antifungal activities against C. albicans, Hi challenge attenuated the LPS-induced expression of pro-inflammatory cytokines (IL-6, IL-1β, and CCL-2) in macrophages. Overall, Hi is a natural compound with antifungal and anti-inflammatory properties, making Hi a promising platform with which to fight against fungal infections.

Current and Potential Applications of Monoterpenes and Their Derivatives in Oral Health Care

Plant products have been employed in medicine for centuries. As the world becomes more health-conscious, there is a growing interest in natural and minimally processed products for oral health care. This has led to an increase in research into the bioactive compounds found in plant products, particularly monoterpenes. Monoterpenes are known to have beneficial biological properties, but the specific mechanisms by which they exert their effects are not yet fully understood. Despite this, some monoterpenes are already being used in oral health care. For example, thymol, which has antibacterial properties, is an ingredient in varnish used for caries prevention. In addition to this, monoterpenes have also demonstrated antifungal, antiviral, and anti-inflammatory properties, making them versatile for various applications. As research continues, there is potential for even more discoveries regarding the benefits of monoterpenes in oral health care. This narrative literature review gives an overview of the biological properties and current and potential applications of selected monoterpenes and their derivatives in oral health care. These compounds demonstrate promising potential for future medical development, and their applications in future research are expected to expand.

Antifungal Activity of Plant Secondary Metabolites on Candida albicans: An Updated Review

Fungal infections have been increasing continuously worldwide, especially in immunocompromised individuals. Fungi, regarded as eukaryotic pathogens, have many similarities to the host cells, which inhibit anti-fungal drug development progress. Various fungal model systems have been studied, and it was concluded that Candida spp. is the most common disease-causing fungus. Candida species are well known to cause infections not only in our mouth, skin, and vagina, but they are also a frequent cause of life-threatening hospital bloodstream infections. The morphological and developmental pathways of Candida have been studied extensively, providing insight into the fungus development. Candida albicans is known to be the most pathogenic species responsible for a variety of infections in humans. Conventional anti-fungal drugs, mainly azoles drugs available in the market, have been used for years developing resistance in C. albicans. Hence, the production of new anti-fungal drugs, which require detailed molecular knowledge of fungal pathogenesis, needs to be encouraged. Therefore, this review targets the new approach of "Green Medicines" or the phytochemicals and their secondary metabolites as a source of novel anti-fungal agents to overcome the drug resistance of C. albicans, their mechanism of action, and their combined effects with the available anti-fungal drugs.

The radiosensitizing effect of β-Thujaplicin, a tropolone derivative inducing S-phase cell cycle arrest, in head and neck squamous cell carcinoma-derived cell lines

Background

Resistance to radiotherapy is a common cause of treatment failure in advanced head and neck squamous cell carcinoma (HNSCC). ß-Thujaplicin, a natural tropolone derivative, acts as an anti-cancer agent and has recently been shown to radiosensitize non-HNSCC cancer cells. However, no data is currently available on its radiosensitizing potential in HNSCC.

Methods

To investigate the effect of ß-Thujaplicin and irradiation in HNSCC cell lines CAL27 and FADU, we performed a cell viability assay, colony forming assay, flow cytometry for cell cycle analysis and a wound healing assay. Drug-irradiation interaction was analyzed using a zero-interaction potency model.

Results

Treatment with ß-Thujaplicin led to a dose-dependent decrease in cell viability and enhanced the effect of irradiation. Clonogenic survival was inhibited with synergistic drug-irradiation interaction. ß-Thujaplicin further led to S-phase arrest and increased the sub-G1 population. Moreover, combined ß-Thujaplicin and irradiation treatment had a higher anti-migratory effect compared to irradiation alone.

Conclusions

ß-Thujaplicin acts as a radiosensitizer in HNSCC cell lines. Further evaluation of its use in HNSCC therapy is warranted.

Hinokitiol Dysregulates Metabolism of Carcinoma Cell Lines and Induces Downregulation of HPV16E6 and E7 Oncogenes and p21 Upregulation in HPV Positive Cell Lines

Background: Hinokitiol (β-thujaplicin), isolated from the wood of Chamaecyparis taiwanensis, has a wide variety of biological properties including anti-inflammatory, anti-microbial, and anti-tumor effects. Therefore, hinokitiol has become a frequent additive in oral and other healthcare products. Objectives: Our goal was to determine the anti-tumor activity of hinokitiol on human papillomavirus (HPV) positive (n = 3) and negative (n = 2) cell lines derived from cervical or head and neck squamous cell carcinoma (HNSCC) and keratinocyte cell lines (n = 3) transformed spontaneously or with HPV16E6 and E7 oncogenes. Methods: The cell-lines were exposed to hinokitiol at different concentrations (0–200 µM) for 24 h. Cell metabolism, proliferation, and the cell cycle distribution were assessed by MTT- and 3H-thymidine incorporation and flow cytometry. Expressions of p21 and on HPV16E6 and E7 oncogenes were assessed by qPCR. Results: In all carcinoma cell lines, hinokitiol treatment declined the metabolic activity irrespective of the HPV status. This decline was statistically significant, however, only in HPV-positive cell lines CaSki and UD-SCC-2 when exposed to hinokitiol concentrations at 100 and 200 µM, respectively (p < 0.05). Immortalized cell lines, HMK and HPV-positive IHGK, were more sensitive as a similar metabolic effect was achieved at lower hinokitiol concentrations of 3.1, 6.25, and 50 µM, respectively. Hinokitiol blocked DNA synthesis of all carcinoma cell lines without evident association with HPV status. G1 cell cycle arrest and p21 upregulation was found in all cell lines after hinokitiol treatment at higher concentration. However, when the p21 results of all HPV-positive cells were pooled together, the increase in p21 expression was statistically significantly higher in HPV-positive than in HPV-negative cell lines (p = 0.03), but only at the highest hinokitiol concentration (200 µM). In HPV-positive cell lines hinokitiol declined the expression of HPV16E7 and E6 along the increase of p21 expression. The dose-dependent inverse correlation between p21 and E7 was statistically significant in SiHa cells (r = −0.975, p-value = 0.03) and borderline in UD-SCC-2 cells (r = −0.944, p-value = 0.06), in which p21 and E6 were also inversely correlated (r = −0.989). Conclusions: Our results indicate that hinokitiol might have potential in preventing the progress of immortalized cells toward malignancy and the growth of malignant lesions. Hinokitiol can also influence on the progression of HPV-associated lesions by downregulating the E6 and E7 expression.

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.

Hinokitiol Protects Cardiomyocyte from Oxidative Damage by Inhibiting GSK3β-Mediated Autophagy

More and more attention has been paid to the use of traditional phytochemicals. Here, we first verified the therapeutic potential of a natural bioactive compound called Hinokitiol in myocardial ischemia reperfusion injury. Hinokitiol exerts cardioprotective effect through inhibition of GSK-3β and subsequent elimination of excessive autophagy, tuning autophagic activity in moderate extent for remedial profit in acute myocardial infarction and myocardial ischemia reperfusion injury. Overall, our study establishes Hinokitiol as a novel available interventional treatment for myocardial ischemia reperfusion injury.

Thallium(I) Tropolonates: Synthesis, Structure, Spectral Characteristics, and Antimicrobial Activity Compared to Lead(II) and Bismuth(III) Analogues

Synthesis, single-crystal X-ray determination diffraction and FT-IR, NMR (¹H, ¹³C, ¹⁹F and ²⁰⁵Tl), UV–vis, and luminescence spectra characteristics were described for series of thallium(I) compounds: thallium(I) triflate (Tl(OTf)), 1:1 co-crystals of thallium(I) triflate and tropolone (Htrop), Tl(OTf)·Htrop, as well as simple thallium(I) chelates: Tl(trop) (1), Tl(5-metrop) (2), Tl(hino) (3), with Htrop, 5-methyltropolone (5-meHtrop), 4-isopropyltropolone (hinokitiol, Hhino), respectively, and additionally more complex {Tl@[Tl(hino)]₆}(OTf) (4) compound. Comparison of their antimicrobial activity with selected lead(II) and bismuth(III) analogs and free ligands showed that only bismuth(III) complexes demonstrated significant antimicrobial activity, from two- to fivefold larger than the free ligands.

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.

Polymer Vesicles for Antimicrobial Applications

Polymer vesicles, hollow nanostructures with hydrophilic cavity and hydrophobic membrane, have shown significant potentials in biomedical applications including drug delivery, gene therapy, cancer theranostics, and so forth, due to their unique cell membrane-like structure. Incorporation with antibacterial active components like antimicrobial peptides, etc., polymer vesicles exhibited enhanced antimicrobial activity, extended circulation time, and reduced cell toxicity. Furthermore, antibacterial, and anticancer can be achieved simultaneously, opening a new avenue of the antimicrobial applications of polymer vesicles. This review seeks to highlight the state-of-the-art of antimicrobial polymer vesicles, including the design strategies and potential applications in the field of antibacterial. The structural features of polymer vesicles, preparation methods, and the combination principles with antimicrobial active components, as well as the advantages of antimicrobial polymer vesicles, will be discussed. Then, the diverse applications of antimicrobial polymer vesicles such as wide spectrum antibacterial, anti-biofilm, wound healing, and tissue engineering associated with their structure features are presented. Finally, future perspectives of polymer vesicles in the field of antibacterial is also proposed.

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.

Hinokitiol Exhibits Antitumor Properties through Induction of ROS-Mediated Apoptosis and p53-Driven Cell-Cycle Arrest in Endometrial Cancer Cell Lines (Ishikawa, HEC-1A, KLE)

Hinokitiol is a natural tropolone derivative that is present in the heartwood of cupressaceous plants, and has been extensively investigated for its anti-inflammatory, antioxidant, and antitumor properties in the context of various diseases. To date, the effects of hinokitiol on endometrial cancer (EC) has not been explored. The purpose of our study was to investigate the anti-proliferative effects of hinokitiol on EC cells. Cell viability was determined with an MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and the quantification of apoptosis and reactive oxygen species (ROSs) was performed by using flow cytometry, while protein expression was measured with the Western blotting technique. Hinokitiol significantly suppressed cell proliferation through the inhibition of the expression of cell-cycle mediators, such as cyclin D1 and cyclin-dependent kinase 4 (CDK4), as well as the induction of the tumor suppressor protein p53. In addition, hinokitiol increased the number of apoptotic cells and increased the protein expression of cleaved-poly-ADP-ribose polymerase (PARP) and active cleaved-caspase-3, as well as the ratio of Bcl-2-associated X protein (Bax) to B-cell lymphoma 2 (Bcl-2). Interestingly, except for KLE cells, hinokitiol induced autophagy by promoting the accumulation of the microtubule-associated protein light chain 3B (LC3B) and reducing the sequestosome-1 (p62/SQSTM1) protein level. Furthermore, hinokitiol triggered ROS production and upregulated the phosphorylation of extracellular-signal-regulated kinase (p-ERK1/2) in EC cells. These results demonstrate that hinokitiol has potential anti-proliferative and pro-apoptotic benefits in the treatment of endometrial cancer cell lines (Ishikawa, HEC-1A, and KLE).

β-Thujaplicin Enhances TRAIL-Induced Apoptosis via the Dual Effects of XIAP Inhibition and Degradation in NCI-H460 Human Lung Cancer Cells

Background: β-thujaplicin, a natural tropolone derivative, has anticancer effects on various cancer cells via apoptosis. However, the apoptosis regulatory proteins involved in this process have yet to be revealed. Methods: Trypan blue staining, a WST-8 assay, and a caspase-3/7 activity assay were used to investigate whether β-thujaplicin sensitizes cancer cells to TNF-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis. Additionally, western blotting was performed to clarify the effects of β-thujaplicin on X-linked inhibitor of apoptosis protein (XIAP) in NCI-H460 cells and a fluorescence polarization binding assay was used to evaluate the binding-inhibitory activity of β-thujaplicin against XIAP-BIR3. Results: β- and γ-thujaplicins decreased the viability of NCI-H460 cells in a dose-dependent manner; they also sensitized the cells to TRAIL-induced cell growth inhibition and apoptosis. β-thujaplicin significantly potentiated the apoptosis induction effect of TRAIL on NCI-H460 cells, which was accompanied by enhanced caspase-3/7 activity. Interestingly, β-thujaplicin treatment in NCI-H460 cells decreased XIAP levels. Furthermore, β-thujaplicin was able to bind XIAP-BIR3 at the Smac binding site. Conclusions: These findings indicate that β-thujaplicin could enhance TRAIL-induced apoptosis in NCI-H460 cells via XIAP inhibition and degradation. Thus, the tropolone scaffold may be useful for designing novel nonpeptidic small-molecule inhibitors of XIAP and developing new types of anticancer drugs.

Design, synthesis and biological evaluation of 2-quinolyl-1,3-tropolone derivatives as new anti-cancer agents

Tropolones are promising organic compounds that can have important biologic effects. We developed a series of new 2-quinolyl-1,3-tropolones derivatives that were prepared by the acid-catalyzed reaction of 4,7-dichloro-2-methylquinolines with 1,2-benzoquinones. 2-Quinolyl-1,3-tropolones have been synthesized and tested for their anti-proliferative activity against several human cancer cell lines. Two compounds (3d and mixture B of 3i-k) showed excellent activity against six cancer cell lines of different tissue of origin. The promising compounds 3d and mixture B of 3i-k also demonstrated induction of apoptotic cell death of ovarian cancer (OVCAR-3, OVCAR-8) and colon cancer (HCT 116) cell lines and affected ERK signaling. In summary, 2-quinolyl-1,3-tropolones are promising compounds for development of effective anticancer agents.

Mycogenic Synthesis of Extracellular Zinc Oxide Nanoparticles from Xylaria acuta and Its Nanoantibiotic Potential

Purpose

The study aimed to find an effective method for fungal-mediated synthesis of zinc oxide nanoparticles using endophytic fungal extracts and to evaluate the efficiency of synthesized ZnO NPs as antimicrobial and anticancerous agents.

Methods

Zinc oxide nanoparticles (ZnO NPs) were produced from zinc nitrate hexahydrate with fungal filtrate by the combustion method. The spectroscopy and microscopy techniques, such as ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), and transmission electron microscopy (TEM) with selected area electron diffraction (SAED), were used to characterize the obtained product. Antibacterial activity on Gram-positive (Staphylococcus aureus and Bacillus cereus) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) samples was tested by broth microplate dilution technique. ZnO NPs antifungal activity was determined against plant pathogenic and regular contaminating fungi using the food-poison method. The anticancerous assay of the synthesized ZnO NPs was also investigated by cell uptake, MTT assay, and apoptosis assay.

Results

The fungal synthesized ZnO NPs were pure, mainly hexagonal in shape and size range of 34–55 nm. The biosynthesized ZnO NPs could proficiently inhibit both Gram-positive and Gram-negative bacteria. ZnO NPs synthesized from fungal extract exhibited antifungal activity in a dose-dependent manner with a high percentage of mycelial inhibition. The cell uptake analysis of ZnO NPs suggests that a significant amount of ZnO NPs (1 μg/mL) was internalized without disturbing cancer cells’ morphology. As a result, the synthesized ZnO NPs showed significant anticancer activity against cancer cells at 1 μg/mL concentration.

Conclusion

This fungus-mediated synthesis of ZnO NPs is a simple, eco-friendly, and non-toxic method. Our results show that the synthesized ZnO NPs are an excellent novel antimicrobial and anticancer agent. Further studies are required to understand the mechanism of the antimicrobial, anticancerous action of ZnO NPs and their possible genotoxicity.

Treatment of severe pneumonia by hinokitiol in a murine antimicrobial-resistant pneumococcal pneumonia model

Streptococcus pneumoniae is often isolated from patients with community-acquired pneumonia. Antibiotics are the primary line of treatment for pneumococcal pneumonia; however, rising antimicrobial resistance is becoming more prevalent. Hinokitiol, which is isolated from trees in the cypress family, has been demonstrated to exert antibacterial activity against S. pneumoniae in vitro regardless of antimicrobial resistance. In this study, the efficacy of hinokitiol was investigated in a mouse pneumonia model. Male 8-week-old BALB/c mice were intratracheally infected with S. pneumoniae strains D39 (antimicrobial susceptible) and NU4471 (macrolide resistant). After 1 h, hinokitiol was injected via the tracheal route. Hinokitiol significantly decreased the number of S. pneumoniae in the bronchoalveolar lavage fluid (BALF) and the concentration of pneumococcal DNA in the serum, regardless of whether bacteria were resistant or susceptible to macrolides. In addition, hinokitiol decreased the infiltration of neutrophils in the lungs, as well as the concentration of inflammatory cytokines in the BALF and serum. Repeated hinokitiol injection at 18 h intervals showed downward trend in the number of S. pneumoniae in the BALF and the concentration of S. pneumoniae DNA in the serum with the number of hinokitiol administrations. These findings suggest that hinokitiol reduced bacterial load and suppressed excessive host immune response in the pneumonia mouse model. Accordingly, hinokitiol warrants further exploration as a potential candidate for the treatment of pneumococcal pneumonia.

A possible application of hinokitiol as a natural zinc ionophore and anti-infective agent for the prevention and treatment of COVID-19 and viral infections

Zinc and the combination with zinc ionophore have been reported in basic research and several clinical investigations as a potentially viable and economical preventive and therapeutic options for COVID-19 treatment. Zinc is a vital microelement that actively supports respiratory epithelium barrier integrity, innate and adaptive immune functions, and inflammatory regulations. Moreover, zinc may also prevent viral entry, suppress viral replication, and mitigate the damages due to oxidative stress and hyperinflammatory reaction in patients with respiratory infections. Hinokitiol (β-thujaplicin) is a natural monoterpenoid and is considered as a safe zinc ionophore to help zinc transport into cells. It has been widely used in skin and oral care, and therapeutic products for its potent antiviral, antimicrobial, antifungal, anti-inflammatory, and anticancer applications. The ongoing COVID-19 pandemic and the significant morbidity and mortality exist in the high-risk group of patients associated with other respiratory infections such as influenza, respiratory syncytial virus, and dengue fever. There is an urgent need for the development of inexpensive, safe, and effective therapeutics to prevent and treat these viral infections. Considering that hydroxychloroquine (HCQ), the most studied zinc ionophore drug for COVID-19, is linked to potentially serious side effects, we propose the implementation of hinokitiol as a zinc ionophore and anti-infective agent for the prevention and treatment of COVID-19 and other viral infections.

Chemical cross-linking on gelatin-hyaluronan loaded with hinokitiol for the preparation of guided tissue regeneration hydrogel membranes with antibacterial and biocompatible properties

The mechanical properties and structural stability of hydrogels and their performance in antidegradation can be enhanced by cross-linking them with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC). However, residual EDC compromises the biocompatibility of cross-linked hydrogels and the formability of un-cross-linked hydrogels. In this study, a facile process for preparing hydrogel regenerative membranes exerting antibacterial effects and containing gelatin/hyaluronic acid (G/HA) through solution casting was proposed. The membranes were cross-linked with EDC (G/HA-Ec-0H) and impregnated with two concentrations of the antibacterial agent of hinokitiol (G/HA-Ec-2H and G/HA-Ec-4H). Amide bonds formed, and the rate of active amino acid fixation was higher than 90%, which was directly proportional to the degree of cross-linking. The G/HA-Ec-2H and G/HA-Ec-4H groups with hinokitiol showed good antibacterial properties. The rate of hydrogel degradation decreased, and the integrity of sample morphology was maintained at more than 80% for over 3 days in the immersion. Then, the hydrogel structures relaxed and disintegrated through a rapid degradation reaction within 24 h. The biocompatibility results showed that low concentrations of hinokitiol did not affect cell viability. Moreover, hydrogel membranes after 14 days of cell incubation showed good cell adhesion and proliferation. In summary, the membrane biostability of the cross-linked gelatin/hyaluronan hydrogels was enhanced by EDC at a biocompatible concentration, and the functionalized group of G/HA-Ec-2H shows potential as a biodegradable material for biocompatible tissue-guarded regeneration membranes with antibacterial properties.

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.

Cellular senescence and cancer: Focusing on traditional Chinese medicine and natural products

Cancer is the principal cause of death and a dominant public health problem which seriously threatening human life. Among various ways to treat cancer, traditional Chinese medicine (TCM) and natural products have outstanding anti‐cancer effects with their unique advantages of high efficiency and minimal side effects. Cell senescence is a physiological process of cell growth stagnation triggered by stress, which is an important line of defence against tumour development. In recent years, active ingredients of TCM and natural products, as an interesting research hotspot, can induce cell senescence to suppress the occurrence and development of tumours, by inhibiting telomerase activity, triggering DNA damage, inducing SASP, and activating or inactivating oncogenes. In this paper, the recent research progress on the main compounds derived from TCM and natural products that play anti‐cancer roles by inducing cell senescence is systematically reviewed, aiming to provide a reference for the clinical treatment of pro‐senescent cancer.

The hydroxyl moiety on carbon one (C1) in the monoterpene nucleus of thymol is indispensable for anti-bacterial effect of thymol

Background

Thymol, a natural monoterpene phenol is not only relevant clinically as an anti-microbial, anti-oxidant and anti-inflammatory agent but also holds the prospect as a natural template for pharmaceutical semi-synthesis of therapeutic agents. It is a major component of essential oils from many plants. Evidence abound linking overall bioactivity of thymol to its monoterpene nucleus, specifically, the hydroxyl (-OH) substituent on carbon number one (C1) on the monoterpene nucleus. Other studies have posited that the overall bioactivity of thymol is not substantially altered by chemical modification of - OH on the C1 of the monoterpene nucleus. In view of this, it is still unclear as to whether removal or modification of the –OH on C1 of the monoterpene nucleus relates generally or context-dependently to bioactivity of thymol.

Objective

The present study investigated anti-bacterial effects of ester-and-ether substituted derivatives of thymol on S. aureus, P. aeruginosa and E. coli.

Materials and methods

twelve ester-and-ether substituted derivatives of thymol (6TM1s and 6TM2s) were synthesized and characterized by using HPLC, Mass spectrometry, and IR techniques. Anti-bacterial activity of the 12 thymol derivatives was evaluated using broth macrodilution and turbidimetric methods against pure clinical isolates (S. aureus, P. aeruginosa and E. coli). Standard anti-biotics used were Thymol Streptomycin and flucloxacillin, while DMSO was used as vehicle for thymol derivatives. MIC and MBC were determined.

Results

Thymol produced broad-spectrum growth inhibition on all isolates. At equimolar concentrations, thymol and reference drugs produced concentration-dependent growth inhibition against the isolates (Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli) compared to DMSO. Although the growth inhibitory effects of the ester-and-ether derivatives of thymol was significant (P ≤ 0.05) compared to DMSO, it was however insignificant (P ≥ 0.05) compared to thymol and reference antibiotics. Comparatively, at equimolar concentrations, ester-substituted derivatives of thymol, particularly the branched chain derivative (TM1C) produced more effective growth inhibition on the isolates than the ether-substituted derivatives of thymol. Thymol was twice as potent (MIC and MBC, 500 μg/ml) than both ester-and-ether substituted derivatives of thymol (MIC and MBC, > 1000 μg/ml) on all the three clinical isolates. Increase in side chain bulkiness of –OH moiety on the monoterpene nucleus of thymol decreased growth inhibition on isolates.

Conclusion

Thymol has demonstrated broad-spectrum anti-bacterial effects attributable to the hydroxyl moiety on C1 of the monoterpene nucleus. Structural modification of the hydroxyl moiety on C1 of the monoterpene nucleus of thymol with either ether-or-ester substitutions yielded no significant anti-bacterial effects.

Protective effect of hinokitiol against periodontal bone loss in ligature-induced experimental periodontitis in mice

OBJECTIVE

The overall objective of this study was to investigate the effects of hinokitiol on periodontal bone loss in a murine model of experimental periodontitis and evaluate the anti-inflammatory activity of hinokitiol in vitro.

DESIGN

Periodontitis was induced by tying a silk ligature around the maxillary second molar of mice for 8 days. Hinokitiol was injected once a day for 7 days into the palatal gingiva of the ligated molar. Periodontal bone loss was then assessed morphometrically in the maxillary second molar, and the number of tartrate-resistant acid phosphatase positive multinucleated giant cells around the molar was quantified. The bacterial load of the silk ligature was calculated by counting the number of colony-forming units, while the transcription levels of proinflammatory cytokine-related genes in the palatal gingiva were evaluated by real-time qPCR. The activity of hinokitiol against LPS-induced transcription of proinflammatory genes in RAW 264.7 macrophages was also examined.

RESULTS

Local treatment with hinokitiol significantly inhibited the alveolar bone loss and osteoclast differentiation induced by tooth ligation. In addition, hinokitiol treatment decreased the oral bacterial load of the silk ligature and downregulated the mRNA levels of inflammatory cytokine-related genes, both in vitro and in vivo.

CONCLUSION

The results indicated that hinokitiol exhibits antibacterial and anti-inflammatory activity and exerts a protective effect against periodontitis.

Antibacterial activity of hinokitiol against both antibiotic-resistant and -susceptible pathogenic bacteria that predominate in the oral cavity and upper airways

Hinokitiol, a component of the essential oil isolated from Cupressaceae, possesses antibacterial and antifungal activities and has been used in oral care products. In this study, the antibacterial activities of hinokitiol toward various oral, nasal and nasopharyngeal pathogenic bacteria, including Streptococcus mutans, Streptococcus sobrinus, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Prevotella intermedia, Fusobacterium nucleatum, methicillin-resistant and -susceptible Staphylococcus aureus, antibiotic-resistant and -susceptible Streptococcus pneumoniae, and Streptococcus pyogenes were examined. Growth of all these bacterial strains was significantly inhibited by hinokitiol, minimal inhibitory concentrations of hinokitiol against S. mutans, S. sobrinus, P. gingivalis, P. intermedia, A. actinomycetemcomitans, F. nucleatum, methicillin-resistant S. aureus, methicillin-susceptible S. aureus, antibiotic-resistant S. pneumoniae isolates, antibiotic-susceptible S. pneumoniae, and S. pyogenes being 0.3, 1.0, 1.0, 30, 0.5, 50, 50, 30, 0.3-1.0, 0.5, and 0.3 μg/mL, respectively. Additionally, with the exception of P. gingivalis, hinokitiol exerted bactericidal effects against all bacterial strains 1 hr after exposure. Hinokitiol did not display any significant cytotoxicity toward the human gingival epithelial cell line Ca9-22, pharyngeal epithelial cell line Detroit 562, human umbilical vein endothelial cells, or human gingival fibroblasts, with the exception of treatment with 500 μg/mL hinokitiol, which decreased numbers of viable Ca9-22 cells and gingival fibroblasts by 13% and 12%, respectively. These results suggest that hinokitiol exhibits antibacterial activity against a broad spectrum of pathogenic bacteria and has low cytotoxicity towards human epithelial cells.

β-Thujaplicin induces autophagic cell death, apoptosis, and cell cycle arrest through ROS-mediated Akt and p38/ERK MAPK signaling in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC), a common liver malignancy worldwide, has high morbidity and mortality. β-Thujaplicin, a tropolone derivative, has been used in some health-care products and clinical adjuvant drugs, but its use for HCC is unknown. In this study, we found that β-Thujaplicin inhibits the growth of HCC cells, but not normal liver cells, with nanomolar potency. Mechanistically, we found that β-Thujaplicin could induce autophagy, as judged by western blot, confocal microscopy, and transmission electron microscopy. Further using β-Thujaplicin combined with an autophagy blocker or agonist treatment HepG2 cells, we found that β-Thujaplicin induced autophagic cell death (ACD) mediated by ROS caused inhibition of the Akt-mTOR signaling pathway. Moreover, β-Thujaplicin triggered HepG2 apoptosis and increased cleaved PARP1, cleaved caspase-3, and Bax/Bcl-2 ratio, which indicated that β-Thujaplicin induced apoptosis mediated by the mitochondrial-dependent pathway. We also found that increased expression of p21 and decreased expression of CDK7, Cyclin D1, and Cyclin A2 participating in β-Thujaplicin caused the S-phase arrest. It seems that β-Thujaplicin exerts these functions by ROS-mediated p38/ERK MAPK but not by JNK signaling pathway activation. Consistent with in vitro findings, our in vivo study verified that β-Thujaplicin treatment significantly reduced HepG2 tumor xenograft growth. Taken together these findings suggest that β-Thujaplicin have an ability of anti-HCC cells and may conducively promote the development of novel anti-cancer agents.

Synergistic Anticancer Effects of Curcumin and Hinokitiol on Gefitinib Resistant Non-Small Cell Lung Cancer Cells

This study evaluated the synergistic effect of curcumin (diferuloylmethane) and hinokitiol (β-thujaplicin), natural product derived phytochemicals, on gefitinib (Iressa) resistant non-small cell lung cancer (NSCLC) cells. Gefitinib, a tyrosine kinase inhibitor targeting epidermal growth factor receptor (EGFR), is widely used for lung cancer treatment. However, gefitinib resistance is easily acquired by NSCLC and followed by the development of progressive disease. Curcumin and hinokitiol are well-known bioactive compounds demonstrating anti-inflammation, anti-bacteria and anticancer effects. However, the effects of co-treatment of curcumin and hinokitiol on cancer cells have not been reported. Here, we postulated, for the first time, the possibility of combination therapy with curcumin and hinokitiol for treatment of gefitinib resistant NSCLC via increment of apoptosis and lysosomal enlargement.

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.

Antibacterial potential of secondary metabolites produced by Aspergillus sp., an endophyte of Mitrephora wangii

Mitrephora wangii, an ethnomedicinal plant, has been used as a natural antibiotic and immunity booster in Thailand. A total of 22 fungi were isolated from M. wangii flowers. The fungal isolates were categorized into six genera including Agrocybe, Aspergillus, Colletotrichum, Nigrospora, Puccinia and Ustilago. Most extracts exhibited antibacterial activity against at least one of the test bacteria. Aspergillus sp. MFLUCC16-0845 was identified as the most bioactive fungus. Chemical composition of Aspergillus sp. MFLUCC16-0845 investigated using gas chromatography-mass spectrometry indicated that the major antibacterial compound was β-thujaplicin. Moreover, the newly isolated Aspergillus sp. MFLUCC16-0845 could be exploited as a potential source of bioactive compounds and plant defense activators. In addition, it is the first time that strain of Aspergillus sp. isolated and cultured from M. wangii flowers could produce β-thujaplicin at high yield with strong antimicrobial spectrum, which may lead to wide utilization in producing cosmetics and clinical products.

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.

Synthesis, Self-Assembly, and Biomedical Applications of Antimicrobial Peptide-Polymer Conjugates

Antimicrobial peptides (AMPs) have been attracting much attention due to their excellent antimicrobial efficiency and low rate in driving antimicrobial resistance (AMR), which has been increasing globally to alarming levels. Conjugation of AMPs into functional polymers not only preserves excellent antimicrobial activities but reduces the toxicity and offers more functionalities, which brings new insight toward developing multifunctional biomedical materials such as hydrogels, polymer vesicles, polymer micelles, and so forth. These nanomaterials have been exhibiting excellent antimicrobial activity against a broad spectrum of bacteria including multidrug-resistant (MDR) ones, high selectivity, and low cytotoxicity, suggesting promising potentials in wound dressing, implant coating, antibiofilm, tissue engineering, and so forth. This Perspective seeks to highlight the state-of-the-art strategy for the synthesis, self-assembly, and biomedical applications of AMP-polymer conjugates and explore the promising directions for future research ranging from synthetic strategies, multistage and stimuli-responsive antibacterial activities, antifungi applications, and potentials in elimination of inflammation during medical treatment. It also will provide perspectives on how to stem the remaining challenges and unresolved problems in combating bacteria, including MDR ones.

Stimulation of cell responses and bone ingrowth into macro-microporous implants of nano-bioglass/polyetheretherketone composite and enhanced antibacterial activity by release of hinokitiol

Poor osteogenesis and bacterial infection lead to the failure of implants, thus enhancements of osteogenic activity and antibacterial activity of the implants have significances in orthopedic applications. In this study, macro-microporous bone implants of nano-bioglass (nBG) and polyetheretherketone (PK) composite (mBPC) were fabricated. The results indicated that the mBPC with the porosity of around 70% exhibited interconnected macropores (sizes of about 400 μm) and micropores (sizes of about 10 μm). The apatite mineralization ability of mBPC in simulated body fluid (SBF) was significantly improved compared with macroporous nBG/PK composite (BPC) without micropores and macroporous PK (mPK). Drug of hinokitiol (HK) was loaded into mBPC (dmBPC), which displayed excellent in vitro antibacterial activity against Staphylococcus aureus. The MC3T3-E1 cells proliferation and ALP activity were significantly promoted by mBPC and dmBPC as compared with BPC and mPK. The micro-CT and histological evaluation showed that both mBPC and dmBPC containing nBG and micropores induced higher new bone formation into porous implants than mPK and BPC. The immunohistochemistry analysis indicated that the expression of BMP-2 in mBPC and dmBPC exhibited obviously higher level than mPK and BPC. The results suggested that the incorporation of nBG and micropores in mBPC obviously improved the osteogenic activity, and mBPC load with HK also promoted osteogenesis, indicating good biocompatibility. The dmBPC with HK significantly enhanced osteogenesis and antibacterial activity, which had great potential as bone implant for hard tissue repair.

[Suppressive Effects of Extract of Cedar Wood on Heat-induced Expression of Cellular Heat Shock Protein]

 In recent years, highly antimicrobial properties of cedar heartwood essential oil against the wood-rotting fungi and pathogenic fungi have been reported in several papers. Antimicrobial properties against oral bacteria by hinokitiol contained in Thujopsis have been also extensively studied. The relation of naturally derived components and human immune system has been studied in some previous papers. In the present study, we focused on Japanese cedar, which has the widest artificial afforestation site in the country among various tree species. Extract oil was obtained from mixture of sapwood and heartwood of about 40-year cedar grown in Oguni, Kumamoto, Japan. We examined the influence of extract components from Japanese cedar woods on the expression of heat shock protein 70 (Hsp70) during heating, and on the micronucleus formation induced by the treatment of bleomycin as a DNA damaging agent. Cell lines used in this study were human fetal glial cells (SVGp12) and human glioma cells (MO54). Remarkable suppression of the Hsp70 expression induced by heating at 43°C was detected by the treatment of cedar extract in both SVGp12 and MO54 cells. We also found that cedar extract had an inhibitory tendency to reduce the micronucleus formation induced by bleomycin. From these results, the extract components from Japanese cedar woods would have an inhibitory effect of the stress response as a suppression of the heat-induced Hsp70 expression, and might have a reductive effect on carcinogenicity.

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.

Natural product β-thujaplicin inhibits homologous recombination repair and sensitizes cancer cells to radiation therapy

Investigation of natural products is an attractive strategy to identify novel compounds for cancer prevention and treatment. Numerous studies have shown the efficacy and safety of natural products, and they have been widely used as alternative treatments for a wide range of illnesses, including cancers. However, it remains unknown whether natural products affect homologous recombination (HR)-mediated DNA repair and whether these compounds can be used as sensitizers with minimal toxicity to improve patients' responses to radiation therapy, a mainstay of treatment for many human cancers. In this study, in order to systematically identify natural products with an inhibitory effect on HR repair, we developed a high-throughput image-based HR repair screening assay and screened a chemical library containing natural products. Among the most interesting of the candidate compounds identified from the screen was β-thujaplicin, a bioactive compound isolated from the heart wood of plants in the Cupressaceae family, can significantly inhibit HR repair. We further demonstrated that β-thujaplicin inhibits HR repair by reducing the recruitment of a key HR repair protein, Rad51, to DNA double-strand breaks. More importantly, our results showed that β-thujaplicin can radiosensitize cancer cells. Additionally, β-thujaplicin sensitizes cancer cells to PARP inhibitor in different cancer cell lines. Collectively, our findings for the first time identify natural compound β-thujaplicin, which has a good biosafety profile, as a novel HR repair inhibitor with great potential to be translated into clinical applications as a sensitizer to DNA-damage-inducing treatment such as radiation and PARP inhibitor. In addition, our study provides proof of the principle that our robust high-throughput functional HR repair assay can be used for a large-scale screening system to identify novel natural products that regulate DNA repair and cellular responses to DNA damage-inducing treatments such as radiation therapy.

A review on influencing factors on the minimum inhibitory concentration of essential oils

With growing interest in essential oils as natural preservatives in the food industry, the literature is expanding enormously. To understand the antimicrobial activity of essential oils, the antimicrobial mechanism of individual essential oil (EO) compounds, and their minimum inhibitory concentrations (MICs), are interesting starting points for research. Therefore, and to get insight into the factors influencing their antimicrobial activities, the Web of Science was searched for MICs of EO compounds (1995-2016). Many MICs for individual EO compounds have already been reported in the literature, but there is large variability in these data, even for the MIC of the same compound against the same species. No correlation was found between the tested structural parameters of EO compounds (polarity, water solubility, dissociation constant, molecular weight and molecular complexity) and their MICs against all microorganisms, Gram-negative bacteria, Gram-positive bacteria and fungi. Few clear differences in sensitivity between microorganisms could be found. Based on this review it is clear that different incubation conditions, culture media and the use of emulsifiers/solvents have an influence on the MIC, causing big variance. This review points out the need for a good international standard method to assess the antimicrobial activity of EO compounds for better comparability between studies.

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 induces DNA demethylation via DNMT1 and UHRF1 inhibition in colon cancer cells

BACKGROUND

DNA hypermethylation is a key epigenetic mechanism for the silencing of many genes in cancer. Hinokitiol, a tropolone-related natural compound, is known to induce apoptosis and cell cycle arrest and has anti-inflammatory and anti-tumor activities. However, the relationship between hinokitiol and DNA methylation is not clear. The aim of our study was to explore whether hinokitiol has an inhibitory ability on the DNA methylation in colon cancer cells.

RESULTS

MTT data showed that hinokitiol had higher sensitivity in colon cancer cells, HCT-116 and SW480, than in normal colon cells, CCD18Co. Hinokitiol reduced DNA methyltransferase 1 (DNMT1) and ubiquitin-like plant homeodomain and RING finger domain 1 (UHRF1) expression in HCT-116 cells. In addition, the expression of ten-eleven translocation protein 1 (TET1), a known DNA demethylation initiator, was increased by hinokitiol treatment. ELISA and FACS data showed that hinokitiol increased the 5-hydroxymethylcytosine (5hmC) level in the both colon cancer cells, but 5-methylcytosine (5mC) level was not changed. Furthermore, hinokitiol significantly restored mRNA expression of O⁶-methylguanine DNA methyltransferase (MGMT), carbohydrate sulfotransferase 10 (CHST10), and B-cell translocation gene 4 (BTG4) concomitant with reduction of methylation status in HCT-116 cells.

CONCLUSIONS

These results indicate that hinokitiol may exert DNA demethylation by inhibiting the expression of DNMT1 and UHRF1 in colon cancer cells.

Antifungal effects of phytocompounds on Candida species alone and in combination with fluconazole

Invasive fungal infections caused by Candida spp. remain the most predominant nosocomial fungal infections. Owing to the increased use of antifungal agents, resistance of Candida spp. to antimycotics has emerged frequently, especially to fluconazole (FLC). To cope with this issue, new efforts have been dedicated to discovering novel antimycotics or new agents that can enhance the susceptibility of Candida spp. to existing antimycotics. The secondary metabolites of plants represent a large library of compounds that are important sources for new drugs or compounds suitable for further modification. Research on the anti-Candida activities of phytocompounds has been carried out in recent years and the results showed that a series of phytocompounds have anti-Candida properties, such as phenylpropanoids, flavonoids, terpenoids and alkaloids. Among these phytocompounds, some displayed potent antifungal activity, with minimum inhibitory concentrations (MICs) of ≤8 µg/mL, and several compounds were even more effective against drug-resistant Candida spp. than FLC or itraconazole (e.g. honokiol, magnolol and shikonin). Interestingly, quite a few phytocompounds not only displayed anti-Candida activity alone but also synergised with FLC against Candida spp., even leading to a reversal of FLC resistance. This review focuses on summarising the anti-Candida activities of phytocompounds as well as the interactions of phytocompounds with FLC. In addition, we briefly overview the synergistic mechanisms and present the structure of the antimycotic phytocompounds. Hopefully, this analysis will provide insight into antifungal agent discovery and new approaches against antifungal drug resistance.

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.

Antimicrobial/Antibiofilm Activity and Cytotoxic Studies of β-Thujaplicin Derivatives

Natural β-thujaplicin displays a remarkable array of biological activities for the prevention or treatment of various disorders while its tropolone scaffold inspired the synthesis of new analogs. The main goal of the current study was to evaluate the influence of 4-substituted piperazine moieties at position 7 of the β-thujaplicin scaffold, on the antimicrobial activity. In order to determine the biological activity of the β-thujaplicin derivatives, a microdilution method was used against a wide variety of bacteria and fungi. Pseudomonas aeruginosa PAO 1 was used for testing antiquorum and antibiofilm effects. Four human tumor cell lines (MCF-7, NCI-H460, HeLa, and HepG2) and a porcine liver derived cell line (PLP2) were used for testing antitumor and cytotoxic activity. The compounds present better antibacterial and antifungal activity in comparison with approved antimicrobials used as control agents. β-Thujaplicin showed strong antibacterial and antifungal activities against all tested species. Further studies of their antibacterial activity revealed that all compounds presented good antibiofilm and antiquorum effects. Fungi were more susceptible than bacteria to the tested compounds, with the exception of MK150, which possessed the best antibacterial effect. None of the tested compounds, at the GI50 values obtained for the tumor cell lines, have shown toxicity for non-tumor liver cells (PLP2). The prediction of physicochemical properties of the compounds was performed to further explain the structure-activity relationship. Finally, in order to explore a possible mechanism of action of the synthesized compounds, molecular docking studies were performed on CYP51 (14-a lanosterol demethylase), an important component of the fungal cell membrane.

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.

Impact of Type and Duration of Application of Commercially Available Oral Moisturizers on Their Antifungal Effects

PURPOSE

To examine the impact of oral moisturizer type and application time on antifungal effects.

MATERIALS AND METHODS

Seventeen oral moisturizers (7 liquids, 10 gels) and amphotericin B (AMPH-B) were tested. Antifungal effects were evaluated with newly opened moisturizer samples (0 hour) and with samples incubated for 8 hours to simulate contact during sleep. Candida albicans samples (10⁸ cells/ml) were placed into cylindrical holes in 50% trypticase soy agar plates. Antifungal effects were evaluated based on growth-inhibitory zones after 24 hours. Equal quantities of moisturizers showing growth-inhibitory zones were mixed as additional samples. The effects of moisturizer type and application time on growth-inhibitory zones were evaluated with ANOVA. Growth-inhibitory zone sizes were compared with multiple comparisons.

RESULTS

Growth-inhibitory zones were found with two liquids, one gel, moisturizer mixtures, and AMPH-B. Significant differences in antifungal effects were found among different moisturizer types and between the 0- and 8-hour groups. The growth-inhibitory zones of the 8-hour group were significantly smaller than those of the 0-hour group. In both the 0- and 8-hour groups, the growth-inhibitory zones of the liquid-gel mixtures were significantly larger than those of other moisturizer types, and were the same size as those of AMPH-B at two concentrations (1.25 and 2.5 μg/ml). Growth-inhibitory zones of individual moisturizers and liquid-liquid mixtures were the same size as those of lower AMPH-B concentrations (0.16, 0.31, and 0.63 μg/ml).

CONCLUSION

Our findings suggest that mixing liquid and gel moisturizers improves their antifungal efficiency.