Effect of whitening toothpaste on surface roughness and microhardness of human teeth: a systematic review and meta-analysis

Background: Whitening toothpastes exert a whitening effect on teeth through higher surface cleaning effectiveness resulting from the abrasive properties of the paste or specific chemical components. This systematic review and meta-analysis was conceptualized to examine the relationship between whitening toothpastes and surface roughness as well as microhardness of human teeth and to clarify the evidence base available around this relationship by conducting a systematic review and meta-analysis of studies in this topic area, looking at in vitro randomized control trials. Methods: Criteria for including studies in the review were done based on population, intervention, comparison, outcomes and study and studies were identified from electronic databases. Covidence® was used for data screening and data extraction. The CONSORT tool was used for checking relevant content and methodology used in each of the papers reviewed. Systematic review was done followed by meta-analysis, using Review Manager. Results: A total of 125 articles were obtained on key word search. After duplicate removal and title screening, 17 articles were eligible for full text review. Finally, 7 studies were included for systematic review and meta-analysis was conducted on 4 studies. The forest plot for surface roughness showed that that the meta-analytic effect was statistically significant with surface roughness value being higher in the intervention group. The forest plot for microhardness showed that the meta-analytic effect was statistically significant with the microhardness value being lesser in the intervention group. Conclusions: Although whitening toothpastes typically can lighten tooth color by about one or two shades, there is some evidence to show that these toothpastes also affect the mineral content of teeth by increasing surface roughness and reducing microhardness. More evidence and further research are needed to identify the type of whitening agent which will whiten the tooth effectively while maintaining the integrity of the tooth structure.

Use of Hydrogen as Fuel: A Trend of the 21st Century

The unbridled use of fossil fuels is a serious problem that has become increasingly evident over the years. As such fuels contribute considerably to environmental pollution, there is a need to find new, sustainable sources of energy with low emissions of greenhouse gases. Climate change poses a substantial challenge for the scientific community. Thus, the use of renewable energy through technologies that offer maximum efficiency with minimal pollution and carbon emissions has become a major goal. Technology related to the use of hydrogen as a fuel is one of the most promising solutions for future systems of clean energy. The aim of the present review was to provide an overview of elements related to the potential use of hydrogen as an alternative energy source, considering its specific chemical and physical characteristics as well as prospects for an increase in the participation of hydrogen fuel in the world energy matrix.

Master Key to Coinage Metal Nanoclusters Treasure Chest: 38-metal Clusters

Atomically precise metal nanoclusters with specific chemical compositions have become a popular research topic due to their precise structures, attractive properties and wide range of applications in various fields. Currently,...

The Effect of TIBA and NPA on Shoot Regeneration of Cannabis sativa L. Epicotyl Explants

Industrial hemp (Cannabis sativa L., family Cannabaceae) is a multi-purpose crop, used in the production of food, nutraceuticals, cosmetics and medicines. Therefore, development of new varieties with specific chemical profiles is necessary. In vitro culture methods could be complementary to conventional breeding and a useful tool for large-scale propagation. Strong apical dominance is considered as one of the factors contributing to the recalcitrance of industrial hemp in shoot proliferation. In this study, we tested the polar transport inhibitors N-1-naphtylphtalamic acid (NPA) and 2,3,5-triiodobenzoic acid (TIBA) to enhance shoot regeneration as the result of suppression of apical dominance and to develop in vitro protocols for Diana, Finola and Fedora 17 cultivars. Shoot tips derived from epicotyls were cultivated on Murashige and Skoog medium (MS) supplemented with meta-topolin (mT) and NPA, and also thidiazuron (TDZ) with a combination of TIBA and NPA. The results showed that the combination of TDZ with NPA (1–5 mg L−1) and TDZ with TIBA (0.5–2.5 mg L−1) increased the response of explants and the multiplication rate, but the effect was genotype-dependent and malformations were observed. To optimize the developed protocol, a two-step procedure with shortened time of exposure to inhibitors and reduced concentrations of them was applied. Shoots were rooted on media containing indole-3-butyric acid (IBA) and then successfully acclimatized. The obtained results will be useful in micropropagation of recalcitrant industrial hemp varieties.

Preclinical toxicity test results of a new antiviral–immune-modulator compound consisting of flavonoid molecules (COVID-19 clinical trial preliminary data)

Aim: Isolated specific glycone–aglycone conjugated flavonoids which are investigated for their effect of bioavailability and molecular concentrations. The specific formula is then tested via in vitro and in vivo cytotoxicity tests. Methods: Considering the higher affinity for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), quercetin, quercetin 3-sambubioside-3’-glucoside, luteolin, apigenin-7-4’alloside, kaempferol-7-O-glucoside, epicatechin-epigallocatechin-3-O-gallate, and hesperetin were selected to investigate the effects of a new combination of the formula. Specific chemical analyses, such as high-performance liquid chromatography (HPLC), liquid chromatography–mass spectrometry (LC–MS), quadrupole time of flight mass spectrometry (QTOF–MS) analysis and ultraviolet–visible (UV–VIS) spectrophotometry, were performed for molecular qualification and quantification. Results: In silico molecular docking analyses have shown that flavonoids can bind strongly to the spike protein and main protease of the SARS-CoV-2 virus. Flavonoids also have anti-inflammatory and immune-modulating activity by inhibiting cytokines. Although flavonoids may be a treatment alternative for coronavirus disease 2019 (COVID-19), an effective flavonoid compound has yet to be developed. The main problem here is that the absorption rate of flavonoids is very low (2–10%) in the intestines, and these compounds are metabolized rapidly. In contrast, according to recent literature, a conjugated flavonoid mixture is better absorbed in the small intestine, and its toxic effects are relatively fewer. Conclusions: It is found that the new formula has no cytotoxic or genotoxic effects. Furthermore, oral administrations of the new compound did not produce any toxicity symptoms or any mortality in male and female rats. The pre-clinical in vitro and in vivo toxicity test results indicated that the new flavonoid formula can be safely used for clinical trials.

In vivo and in silico Evaluation of Analgesic and Hypoglycemic Activities of Roots of Acacia nilotica, Azadirachta indica and Justica adhatoda

The present study focuses on the investigation of methanol extracts of roots of three indigenous plants of Bangladesh namely Acacia nilotica, Azadirachta indica and Justicia adhatoda to evaluate their analgesic and hypoglycemic activities in experimental animal model along with in silico modelling of several compounds present in the root extracts of these plants. Analgesic and hypoglycemic activities were evaluated in Swiss albino mice using acetic acid-induced writhing inhibition method and glucose tolerance test, respectively. In silico molecular docking and ADME study was conducted to assess the binding affinity with the target receptors and oral bioavailability of the compounds. The methanol extracts of A. nilotica, J. adhatoda and A. indica roots at a dose of 400 mg/kg body weight reduced the number of writhes by 61.53%, 54.61% and 47.69%, respectively compared to standard diclofenac sodium (70.77% at a dose of 50 mg/kg bw) (p<0.05). A. nilotica and A. indica root extracts showed significant hypoglycemic activity at a dose of 400 mg/kg bw (% reduction of blood glucose 43.66 and 37.55% respectively, p<0.001) and J. adhatoda root extract reduced the blood glucose level by 33.71% (p<0.001) compared to that of standard drug, glibenclamide (57.46% reduction of blood glucose) after 120 minutes of administration. Among the computationally tested compounds, flavan-3-ol showed the lowest binding energy (-8.7 kcal/mol) with both COX-1 and COX-2 compared to standard diclofenac sodium (-7.8 kcal/mol). On the other hand, quercetin demonstrated the lowest binding energy (-8.8 kcal/mol) with ATP-sensitive potassium channel with Sulfonylurea Receptor 1 subunit among the tested compounds compared to standard glibenclamide (-9.3 kcal/mol). All the compounds showed high oral bioavailability in ADME analysis. Among all the root extracts, A. nilotica exhibited the most promising analgesic and hypoglycemic activities and should be employed to future investigation for isolating specific chemical constituents. Dhaka Univ. J. Pharm. Sci. 20(2): 185-197, 2021 (December)

Development of “Quadrello di Ovino”, a Novel Fresh Ewe’s Cheese

This work was performed to produce a new soft ewe’s milk cheese, namely “Quadrello di ovino” (QdO) cheese, to enlarge ewe’s dairy product portfolio of South Italy, barely limited to Pecorino cheese typology. Cheese making was performed applying the technology for “Crescenza” cheese typology with some modifications. In particular, pasteurized ewes’ milk was inoculated with two commercial starter formulations (SF1 and SF2) of Streptococcus thermophilus to obtain two different productions (QdO-P1 and QdO-P2, respectively). Plate counts demonstrated the ability of both starter formulations to drive the fermentation process, since S. thermophilus counts reached 109 CFU/g in both productions. Generally, the two starter formulations did not affect the chemical composition of QdO cheeses that contained, on average, 64.08% dry matter of which approximately 54.99% were fats and 36.39% proteins. Among chemical parameters, significant differences were registered for secondary lipid oxidation state (significantly lower for QdO-P2), fatty acids and volatile organic compounds (VOCs). However, the differences registered among cheese VOCs from were not perceived by the panelists who recognized both cheese productions highly similar, although QdO-P2 cheeses were mostly appreciated by the judges. This study allowed to produce a novel fresh ovine cheese with specific chemical and sensorial characteristics well appreciated by consumers.

Physicochemical Characterization of Hyaluronic Acid and Chitosan Liposome Coatings

Hyaluronic acid (HA) and chitosan (CH) are biopolymers that are widely used in many biomedical applications and for cosmetic purposes. Their chemical properties are fundamental to them working as drug delivery systems and improving their synergistic effects. In this work, two different protocols were used to obtain zwitterionic liposomes coated with either hyaluronic acid or chitosan. Specifically, the methodologies used to perform vesicle preparation were chosen by taking into account the specific chemical properties of these two polysaccharides. In the case of chitosan, liposomes were first synthesized and then coated, whereas the coating of hyaluronic acid was achieved through lipidic film hydration in an HA aqueous solution. The size and the zeta-potential of the polysaccharide-coated liposomes were determined by dynamic light scattering (DLS). This approach allowed coated liposomes to be obtained with hydrodynamic diameters of 264.4 ± 12.5 and 450.3 ± 16.7 nm for HA- and CH-coated liposomes, respectively. The chemical characterization of the coated liposomal systems was obtained by surface infrared (ATR-FTIR) and nuclear magnetic resonance (NMR) spectroscopies. In particular, the presence of polysaccharides was confirmed by the bands assigned to amides and saccharides being in the 1500–1700 cm−1 and 800–1100 cm−1 regions, respectively. This approach allowed confirmation of the efficiency of the coating processes, evidencing the presence of HA or CH at the liposomal surface. These data were also supported by time-of-flight secondary ion mass spectrometry (ToF-SIMS), which provided specific assessments of surface (3–5 nm deep) composition and structure of the polysaccharide-coated liposomes. In this work, the synthesis and the physical chemistry characterization of coated liposomes with HA or CH represent an important step in improving the pharmacological properties of drug delivery systems.

Haze in Beer: Its Formation and Alleviating Strategies, from a Protein–Polyphenol Complex Angle

Beer is one of the oldest and most widely consumed alcoholic beverages. Haze formation in beer is a serious quality problem, as it largely shortens the shelf life and flavor of beer. This paper reviews the factors affecting haze formation and strategies for reducing haze. Haze formation is mainly associated with specific chemical components in malt barley grains, such as proteins. The main factor causing haze formation is a cross-linking of haze active (HA) proteins and HA polyphenols. Many HA proteins and their editing genes or loci have been identified by proteomics and quantitative trait locus (QTL) analysis, respectively. Although some technical approaches have been available for reducing haze formation in beer, including silica and polyvinylpolypyrrolidone (PVPP) adsorbent treatments, the cost of beer production will increase and some flavor will be lost due to reduced relevant polyphenols and proteins. Therefore, breeding the malt barley cultivar with lower HA protein and/or HA polyphenols is the most efficient approach for controlling haze formation. Owing to the completion of barley whole genome sequencing and the rapid development of modern molecular breeding technology, several candidate genes controlling haze formation have been identified, providing a new solution for reducing beer haze.

VDB Entropy Measures and Irregularity-Based Indices for the Rectangular Kekulene System

Theoretical chemists are fascinated by polycyclic aromatic hydrocarbons (PAHs) because of their unique electromagnetic and other significant properties, such as superaromaticity. The study of PAHs has been steadily increasing because of their wide-ranging applications in several fields, like steel manufacturing, shale oil extraction, coal gasification, production of coke, tar distillation, and nanosciences. Topological indices (TIs) are numerical quantities that give a mathematical expression for the chemical structures. They are useful and cost-effective tools for predicting the properties of chemical compounds theoretically. Entropic network measures are a type of TIs with a broad array of applications, involving quantitative characterization of molecular structures and the investigation of some specific chemical properties of molecular graphs. Irregularity indices are numerical parameters that quantify the irregularity of a molecular graph and are used to predict some of the chemical properties, including boiling points, resistance, enthalpy of vaporization, entropy, melting points, and toxicity. This study aims to determine analytical expressions for the VDB entropy and irregularity-based indices in the rectangular Kekulene system.