Insights into Arbutin Effects on Bone Cells: Towards the Development of Antioxidant Titanium Implants

Molecular analysis of dUTPase of Helicobacter pylori for identification of novel inhibitors using in silico studies

The human gastric pathogen Helicobacter pylori chronically affects the gastric mucosal layer of approximately half of world's population. The emergence of resistant strains urges the need for identification of novel and selective drug against new molecular targets. A ubiquitous enzyme, Deoxyuridine 5'-triphosphate nucleotidohydrolase (dUTPase), is considered as first line of defense against uracil mis-incorporation into DNA, and essential for genome integrity. Lack of dUTPase triggers an elevated recombination frequency, DNA breaks and ultimately cell death. Hence, dUTPase can be considered as a promising target for development of novel lead inhibitor compounds in H. pylori treatment. Herein, we report the generation of three-dimensional model of the target protein using comparative modelling and its validation. To identify dUTPase inhibitors, a high throughput virtual screening approach utilizing Knowledge-based inhibitors and DrugBank database was implemented. Top ranked compounds were scrutinized based on investigations of the protein-ligand interaction fingerprints, molecular interaction maps and binding affinities and the drug potentiality. The best ligands were studied further for complex stability and intermolecular interaction profiling with respect to time under 100 ns classical molecular dynamic stimulation, establishing significant stability in dynamic states as observed from RMSD and RMSF parameters and interactions with the catalytic site residues. The binding free energy calculation computed using MM-GBSA method from the MD simulation trajectories demonstrated that our molecules possess strong binding affinity towards the Helicobacter pylori dUTPase protein. We conclude that our proposed molecules may be potential lead molecules for effective inhibition against the H. pylori dUTPase protein subject to experimental validation.Communicated by Ramaswamy H. Sarma.

Temporary alleviation of MAPK by arbutin alleviates oxidative damage in the retina and ARPE-19 cells

Dry age-related macular degeneration (AMD) is one of the main diseases that causes blindness in humans, and the number of cases is increasing yearly. However, effective treatments are unavailable, and arbutin (ARB) has been reported to have antioxidant, anti-inflammatory, and anti-aging effects in other age-related diseases. However, whether ARB can be used to treat dry AMD remains unknown. To explore the therapeutic potential and molecular mechanism of arbutin in the treatment of dry AMD. MTT assays, reactive oxygen species (ROS) production assays, flow cytometry assays, qPCR and western blotting were used to assess the impact of ARB on human RPECs induced by H2O2. A transcriptome sequencing assay was used to further explore how ARB acts on human RPECs treated with H2O2. Hematoxylin and eosin (H&E) staining and total antioxidant capacity (T-AOC) assays were used to observe the impact of ARB on mouse retina induced by sodium iodate. ARB counteracted the H2O2-induced reduction in human RPECs viability, ARB reversed H2O2-induced cellular ROS production by increasing the expression of antioxidant-related genes and proteins, ARB also reversed H2O2-induced cell apoptosis by altering the expression of apoptosis-related genes and proteins. Transcriptome sequencing and western blotting showed that ARB reduced ERK1/2 and P-38 phosphorylation to prevent H2O2-induced oxidation damage. The in vivo experiments demonstrated that ARB protected against retinal morphology injury in mice, increased serum T-AOC levels and increased antioxidant oxidase gene expression levels in the mouse retina induced by sodium iodate. We concluded that ARB reversed the H2O2-induced decrease in human RPECs viability through the inhibition of ROS production and apoptosis. The ERK1/2 and P38 MAPK signaling pathways may mediate this process. ARB maintained retinal morphology, increased serum T-AOC level and improved the expression of antioxidant oxidase genes in mice.

Electrospun PCL/gelatin/arbutin nanofiber membranes as potent reactive oxygen species scavengers to accelerate cutaneous wound healing

The presence of excessive reactive oxygen species (ROS) at a skin wound site is an important factor affecting wound healing. ROS scavenging, which regulates the ROS microenvironment, is essential for wound healing. In this study, we used novel electrospun PCL/gelatin/arbutin (PCL/G/A) nanofibrous membranes as wound dressings, with PCL/gelatin (PCL/G) as the backbone, and plant-derived arbutin (hydroquinone-β-d-glucopyranoside, ARB) as an effective antioxidant that scavenges ROS and inhibits bacterial infection in wounds. The loading of ARB increased the mechanical strength of the nanofibres, with a water vapour transmission rate of more than 2500 g/(m2 × 24 h), and the water contact angle decreased, indicating that hydrophilicity and air permeability were significantly improved. Drug release and degradation experiments showed that the nanofibre membrane controlled the drug release and exhibited favourable degradability. Haemolysis experiments showed that the PCL/G/A nanofibre membranes were biocompatible, and DPPH and ABTS+ radical scavenging experiments indicated that PCL/G/A could effectively scavenge ROS to reflect the antioxidant activity. In addition, haemostasis experiments showed that PCL/G/A had good haemostatic effects in vitro and in vivo. In vivo animal wound closure and histological staining experiments demonstrated that PCL/G/A increased collagen deposition and remodelled epithelial tissue regeneration while showing good in vivo biocompatibility and non-toxicity. In conclusion, we successfully prepared a multifunctional wound dressing, PCL/G/A, for skin wound healing and investigated its potential role in wound healing, which is beneficial for the clinical translational application of phytomedicines.

The combined toxicity of silver nanoparticles and typical personal care products in diatom Navicula sp

Toxicity of silver nanoparticles (AgNPs) at environmentally relevant concentrations has been received an increasing attention, and their influence on the bioavailability of personal care products has been seldom studied. Here, the toxicity of AgNPs in typical diatom Navicula sp. was explored, and their influence on the bioavailability of typical personal care products such as triclosan (TCS) and galaxolide (HHCB) was also investigated. The underlying toxicity mechanisms were explored using liquid chromatography-mass spectrometry (LC-MS)-based metabolomics. Low concentrations of AgNPs (10 and 50 μg L-1) induced no observable responses of Navicula sp., in terms of growth rate, chlorophyll contents, and malondialdehyde accumulation. Furthermore, low doses of AgNPs could attenuate TCS or HHCB toxicity to Navicula sp., which was mainly attributed to the reduced oxidative stress. Metabolomics revealed that the disruption of DNA or RNA synthesis and instability of cytokinin-like substances may be also the reasons for the toxicity of AgNPs and TCS to Navicula sp. The damaged algal photosynthesis exposed to HHCB may be recovered by AgNPs, and the presence of signal chemicals (dehydrophytosphingosine and cardamonin) also showed a recovered algal growth. These results emphasize the potential of metabolomics to reveal toxicity mechanism, providing a new perspective on the aquatic risk assessment of nanoparticles and emerging organic pollutants.

Efficient Whole-Cell Biotransformation for α-Arbutin Production through the Engineering of Sucrose Phosphorylase Combined with Engineered Cell Modification

α-Arbutin is extensively used in cosmetic industries. The lack of highly active enzymes and the cytotoxicity of hydroquinone limit the biosynthesis of α-arbutin. In this study, a whole-cell biocatalytic approach based on enzyme engineering and engineered cell modification was identified as effective in enhancing α-arbutin production. First, a sucrose phosphorylase (SPase) mutant with higher enzyme activity was obtained by experimental screening. Next, to avoid the oxidation of hydroquinone, we established an anaerobic process to improve the robustness of the cells by knocking out lytC, sdpC, and skfA in Bacillus subtilis and overcoming the inhibitory effect of a high concentration of hydroquinone. Finally, the engineered strain was used for biotransformation in a 5 L fermenter with batch feeding for 24 h. The final yield of α-arbutin achieved was 129.6 g/L, which may provide a basis for the large-scale industrial production of α-arbutin.

In Vitro Antibacterial and Anti-Inflammatory Activity of Arctostaphylos uva-ursi Leaf Extract against Cutibacterium acnes

Cutibacterium acnes (C. acnes) is the main causative agent of acne vulgaris. The study aims to evaluate the antimicrobial activity of a natural product, Arctostaphylos uva-ursi leaf extract, against C. acnes. Preliminary chemical–physical characterization of the extract was carried out by means of FT-IR, TGA and XPS analyses. Skin permeation kinetics of the extract conveyed by a toning lotion was studied in vitro by Franz diffusion cell, monitoring the permeated arbutin (as the target component of the extract) and the total phenols by HPLC and UV-visible spectrophotometry, respectively. Antimicrobial activity and time-killing assays were performed to evaluate the effects of Arctostaphylos uva-ursi leaf extract against planktonic C. acnes. The influence of different Arctostaphylos uva-ursi leaf extract concentrations on the biofilm biomass inhibition and degradation was evaluated by the crystal violet (CV) method. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) test was used to determine the viability of immortalized human keratinocytes (HaCaT) after exposure to Arctostaphylos uva-ursi leaf extract for 24 and 48 h. Levels of interleukin (IL)-1β, IL-6, IL-8 and tumour necrosis factor (TNF)-α were quantified after HaCaT cells cotreatment with Arctostaphylos uva-ursi leaf extract and heat-killed C. acnes. The minimum inhibitory concentration (MIC) which exerted a bacteriostatic action on 90% of planktonic C. acnes (MIC₉₀) was 0.6 mg/mL. Furthermore, MIC and sub-MIC concentrations influenced the biofilm formation phases, recording a percentage of inhibition that exceeded 50 and 40% at 0.6 and 0.3 mg/mL. Arctostaphylos uva-ursi leaf extract disrupted biofilm biomass of 57 and 45% at the same concentrations mentioned above. Active Arctostaphylos uva-ursi leaf extract doses did not affect the viability of HaCaT cells. On the other hand, at 1.25 and 0.6 mg/mL, complete inhibition of the secretion of pro-inflammatory cytokines was recorded. Taken together, these results indicate that Arctostaphylos uva-ursi leaf extract could represent a natural product to counter the virulence of C. acnes, representing a new alternative therapeutic option for the treatment of acne vulgaris.

Arbutin improves gut development and serum lipids via Lactobacillus intestinalis

Arbutin has been widely studied in whitening, anti-inflammatory, and antioxidant. However, the interaction between arbutin and intestinal microbes has been rarely studied. Thus, mice were treated with arbutin concentrations of 0, 0.1, 0.2, 0.4, and 1 mg/ml. We found that arbutin promoted gut development such as villus length, villus areas, and villus length/crypt depth (L/D). Total cholesterol (TC), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) were significantly reduced by low concentrations of arbutin. Importantly, we analyzed the microbial composition in the control and 0.4 mg/ml arbutin group and found that the abundance of Lactobacillus intestinalis (L. intestinalis) was highest and enhanced in arbutin. Further, mice were fed with oral antibiotics and antibiotics + 0.4 mg/ml arbutin and then we transplanted fecal microbes from oral 0.4 mg/ml arbutin mice to mice pretreated with antibiotics. Our results showed that arbutin improves gut development, such as villus width, villus length, L/D, and villus areas. In addition, L. intestinalis monocolonization was carried out after a week of oral antibiotics and increased villus length, crypt depth, and villus areas. Finally, in vitro arbutin and L. intestinalis co-culture showed that arbutin promoted the growth and proliferation of L. intestinalis. Taken together, our results suggest that arbutin improves gut development and health of L. intestinalis. Future studies are needed to explore the function and mechanism of L. intestinalis affecting gut development.

The Importance of Antioxidant Biomaterials in Human Health and Technological Innovation: A Review

Biomaterials come from natural sources such as animals, plants, fungi, algae, and bacteria, composed mainly of protein, lipid, and carbohydrate molecules. The great diversity of biomaterials makes these compounds promising for developing new products for technological applications. In this sense, antioxidant biomaterials have been developed to exert biological and active functions in the human body and industrial formulations. Furthermore, antioxidant biomaterials come from natural sources, whose components can inhibit reactive oxygen species (ROS). Thus, these materials incorporated with antioxidants, mainly from plant sources, have important effects, such as anti-inflammatory, wound healing, antitumor, and anti-aging, in addition to increasing the shelf-life of products. Aiming at the importance of antioxidant biomaterials in different technological segments as biodegradable, economic, and promising sources, this review presents the main available biomaterials, antioxidant sources, and assigned biological activities. In addition, potential applications in the biomedical and industrial fields are described with a focus on innovative publications found in the literature in the last five years.

Exploring the Potential of Myrothamnus flabellifolius Welw. (Resurrection Tree) as a Phytogenic Feed Additive in Animal Nutrition

Simple Summary

The unregulated use of in-feed antibiotic growth promoters has received widespread condemnation due to an increase in cases of antibiotic-resistant microbes. This has fueled an ever-growing demand for new sources of natural and safe alternative products with minimal impacts on the environment and human health in animal production. Myrothamnus flabellifolius, as a phytogenic feed additive, fits this description, as it is a natural plant containing high amounts of secondary metabolites necessary for cell function, regulation, and protection for improved animal growth, performance, and health. With some limitations towards its use, several processing and combination strategies are available to unlock nutrients and explore its potential in animal production, as described in this review.

Abstract

Myrothamnus flabellifolius (Welw.) is used in African traditional medicine for the treatment of depression and mental disorder, asthma, infectious diseases, respiratory, inflammation, epilepsy, heart, wound, backaches, diabetes, kidney ailments, hypertension, hemorrhoids, gingivitis, shingles, stroke, and skins conditions. The effectiveness of M. flabellifolius is due to the presence of several secondary metabolites that have demonstrated efficacy in other cell and animal models. These metabolites are key in cell regulation and function and have potential use in animal production due to antimicrobial and antioxidant properties, for an improvement in growth performance, feed quality and palatability, gut microbial environment, function, and animal health. The purpose of this review is to provide a detailed account on the potential use of M. flabellifolius in animal nutrition. Limitations towards the use of this plant in animal nutrition, including toxicity, economic, and financial issues are discussed. Finally, novel strategies and technologies, e.g., microencapsulation, microbial fermentation, and essential oil extraction, used to unlock and improve nutrient bioaccessibility and bioavailability are clearly discussed towards the potential use of M. flabellifolius as a phytogenic additive in animal diets.

Osteogenic Effect of Fisetin Doping in Bioactive Glass/Poly(caprolactone) Hybrid Scaffolds

Treating large bone defects or fragile patients may require enhancing the bone regeneration rate to overcome a weak contribution from the body. This work investigates the osteogenic potential of nutrient fisetin, a flavonoid found in fruits and vegetables, as a doping agent inside the structure of a SiO₂-CaO bioactive glass-poly(caprolactone) (BG-PCL) hybrid scaffold. Embedded in the full mass of the BG-PCL hybrid during one-pot synthesis, we demonstrate fisetin to be delivered sustainably; the release follows a first-order kinetics with active fisetin concentration being delivered for more than 1 month (36 days). The biological effect of BG-PCL-fisetin-doped scaffolds (BG-PCL-Fis) has been highlighted by in vitro and in vivo studies. A positive impact is demonstrated on the adhesion and the differentiation of rat primary osteoblasts, without an adverse cytotoxic effect. Implantation in critical-size mouse calvaria defects shows bone remodeling characteristics and remarkable enhancement of bone regeneration for fisetin-doped scaffolds, with the regenerated bone volume being twofold that of nondoped scaffolds and fourfold that of a commercial trabecular bovine bone substitute. Such highly bioactive materials could stand as competitive alternative strategies involving biomaterials loaded with growth factors, the use of the latter being the subject of growing concerns.

Innovative Surface Modification Procedures to Achieve Micro/Nano-Graded Ti-Based Biomedical Alloys and Implants

Due to the growing aging population of the world, and as a result of the increasing need for dental implants and prostheses, the use of titanium and its alloys as implant materials has spread rapidly. Although titanium and its alloys are considered the best metallic materials for biomedical applications, the need for innovative technologies is necessary due to the sensitivity of medical applications and to eliminate any potentially harmful reactions, enhancing the implant-to-bone integration and preventing infection. In this regard, the implant’s surface as the substrate for any reaction is of crucial importance, and it is accurately addressed in this review paper. For constructing this review paper, an internet search was performed on the web of science with these keywords: surface modification techniques, titanium implant, biomedical applications, surface functionalization, etc. Numerous recent papers about titanium and its alloys were selected and reviewed, except for the section on forthcoming modern implants, in which extended research was performed. This review paper aimed to briefly introduce the necessary surface characteristics for biomedical applications and the numerous surface treatment techniques. Specific emphasis was given to micro/nano-structured topographies, biocompatibility, osteogenesis, and bactericidal effects. Additionally, gradient, multi-scale, and hierarchical surfaces with multifunctional properties were discussed. Finally, special attention was paid to modern implants and forthcoming surface modification strategies such as four-dimensional printing, metamaterials, and metasurfaces. This review paper, including traditional and novel surface modification strategies, will pave the way toward designing the next generation of more efficient implants.

A comprehensive review of the therapeutic potential of α-arbutin

Cosmetic dermatology preparations such as bleaching agents are ingredients with skin-related biological activities for increasing and improving skin beauty. The possibility of controlling skin hyperpigmentation disorders is one of the most important research goals in cosmetic preparations. Recently, cosmetics containing herbal and botanical ingredients have attracted many interests for consumers of cosmetic products because these preparations are found safer than other preparations with synthetic components. However, high-quality trial studies in larger samples are needed to confirm safety and clinical efficacy of phytotherapeutic agents with high therapeutic index. Arbutin (p-hydroxyphenyl-β-d-glucopyranoside) is a bioactive hydrophilic polyphenol with two isomers including alpha-arbutin (4-hydroxyphenyl-α-glucopyranoside) and β-arbutin (4-hydroxyphenyl-β-glucopyranoside). It is used as a medicinal plant in phytopharmacy. Studies have shown that alpha-arbutin is 10 times more effective than natural arbutin. A comparison of IC50 values showed that α-arbutin (with concentration 2.0 mM) has a more potent inhibitory activity on human tyrosinase against natural arbutin (with higher concentration than 30 mM). A review of recent studies showed that arbutin could be beneficial in treatment of various diseases such as hyperpigmentation disorders, types of cancers, central nervous system disorders, osteoporosis, diabetes, etc. This study was designed to describe the therapeutic efficiencies of arbutin.

Effects of titanium with different micro/nano structures on the ability of osteoblasts to resist oxidative stress

Excessive accumulation of oxidative intermediates in the elderly significantly aggravates bone degradation and hinders the osseointegration of topological titanium (Ti) implants. Thus, it is of great significance to evaluate the antioxidant and osteoinduction capabilities of various nano, micro or micro/nano-composite structures under oxidative stress (OS) microenvironment. In this study, we discovered that 110 nm titania nanotubes (TNTs) enhanced the adsorption of fibronectin (FN) proteins onto smooth and rough titanium surfaces to varying degrees. Compared with Ti and 30 nm TNTs (T₃₀) groups, cells on 110 nm TNTs (T₁₁₀), microstructure/30 nm TNTs (M₃₀) and microstructure/110 nm TNTs (M₁₁₀) had smaller area, lower reactive oxygen species (ROS), and better proliferation/osteogenic differentiation abilities under OS condition, but there was no significant difference among the three groups. In addition, combined with our previous study, we suggested that T₁₁₀, M₃₀ and M₁₁₀ resistance to OS was also strongly associated with the high expression of FN-receptor integrin α5 or β1. All the findings indicated that the micro/nano-composed structures (M₃₀ & M₁₁₀) had similar anti-oxidation and osteogenesis abilities to T₁₁₀, which provided guidance for the application of different titanium implants with different topologies in the elderly.