Anthocyanin incorporated dental copolymer: bacterial growth inhibition, mechanical properties, and compound release rates and stability by (1)h NMR

Reinforcement of Epoxidized Natural Rubber with High Antimicrobial Resistance Using Water Hyacinth Fibers and Chlorhexidine Gluconate

In this study, epoxidized natural rubber (ENR) was mixed using a two-roller mixer. Water hyacinth fiber (WHF) acted as a reinforcing agent in the preparation of the rubber composite at 10 phr (ENRC/WHF). Chlorhexidine gluconate (CHG) was added at different concentrations (1, 5, 10, and 20 phr) as an antimicrobial and coupling agent. The tensile strength increased with a CHG content of 1 phr (4.59 MPa). The ENRC/WHF/CHG20 blend offered high hardness (38) and good morphology owing to the reduction in cavities and fiber pull-out from the rubber matrix. The swelling of the sample blends in oil and toluene decreased as the CHG content increased. Reactions of -NH2/epoxy groups and -NH2/-OH groups occurred during the preparation of the ENRC/WHF/CHG blend. The FTIR spectroscopy peak at 1730 cm-1 confirmed the reaction between the -NH2 groups of CHG and epoxy groups of ENR. The ENRC/WHF/CHG blend at 10 phr and 20 phr exhibited zones of inhibition against three bacterial species (Staphylococcus aureus, Escherichia coli, and Bacillus cereus). CHG simultaneously acted as a crosslinking agent between ENR and WHF and as an antimicrobial additive for the blends. CHG also improved the tensile strength, hardness, swelling, and antimicrobial properties of ENR composites.

Vacuolar localisation of anthocyanin pigmentation in microgreen cotyledons of basil, cabbage and mustard greens does not impact on colonisation by Shiga-toxigenic Escherichia coli O157:H7

Microgreens, the immature plants harvested after a few weeks of growth, are perceived as a heathy, nutritious food ingredient but may be susceptible to colonisation by human pathogens including Shiga-toxigenic Escherichia coli (STEC). Some microgreen cultivars accumulate anthocyanins or secrete essential oils which, when extracted or purified, have been reported to inhibit bacterial growth. Therefore, the impact of anthocyanins on bacterial colonisation by STEC (Sakai) was compared for three species that have pigmented cultivars: basil (Ocimum basilicum L.), cabbage (Brassica oleracea L.) and mustard greens (Brassica juncea L.). Inoculation with low concentrations of STEC (Sakai) (3 log10 colony forming units/ml (CFU/ml)) during seed germination resulted in extensive colonisation at the point of harvest, accumulating to ∼ 8 log10 CFU/g FW in all cultivars. Bacterial colonies frequently aligned with anticlinal walls on the surface of epidermal cells of the cotyledons and, in basil, associated with peltate and capitate gland cells. Crude lysates of pigmented and non-pigmented basil cultivars had no impact on STEC (Sakai) growth rates, viability status or biofilm formation. Anthocyanins are located within plant vacuoles of these microgreen cultivars and did not affect colonisation by STEC (Sakai) and pigmentation therefore cannot be considered as a controlling factor in bacterial interactions.

Effect of chlorhexidine gluconate on mechanical and anti-microbial properties of thermoplastic cassava starch

Antimicrobial thermoplastic starch (TPS) was developed using cassava starch, glycerol, and chlorhexidine gluconate (CHG) blend. CHG was added at concentrations of 1%, 5%, 10%, and 20% (wt./wt.) as an antimicrobial additive. The tensile strength and hardness of the blended samples increased with the chlorhexidine gluconate content, especially for 1% CHG. wt./wt. (12.6 MPa and 94, respectively). The TPS/CHG20 blend exhibited a large phase of CHG and recrystallization of TPS. The water solubility decreased with the addition of CHG. Nuclear magnetic resonance data confirmed a reaction between the hydroxyl groups of TPS and the amino groups of CHG. The TPS/CHG20% exhibited an inhibition zone for three bacterial types (Staphylococcus aureus, Escherichia coli, and Bacillus cereus) and three fungal types (Rhizopus oligosporus, Aspergillus oryzae, and Candida albicans). CHG acted simultaneously as a chain extender and an antimicrobial additive for TPS, improving its tensile strength, hardness, and anti-microbial properties.

Sour cherry extract inhibits human salivary α-amylase and growth of Streptococcus mutans (a pilot clinical study)

The purpose of this study was to determine whether cherry extract has any effect on salivary α-amylase activity (sAA) or on the level of Streptococcus mutans in human saliva. 70 patients (45 females and 25 males) in three age groups (22 children, 25 young adults, and 23 adults) were examined. All participants completed a questionnaire to obtain information on their oral health behaviour and life style. Clinical examination was performed to record the number of decayed, missing and filled teeth (DMF-T). Saliva samples were collected for the measurement of sAA and the salivary S. mutans level before and after chewing a gum with or without cherry extract. Statistical evaluation of data was performed. S. mutans and the sAA level of unstimulated saliva samples did not depend on either age or gender. The basal sAA value of adult patients was in linear correlation with the dental caries status. Habitual chewing-gum use decreased the resting sAA and the mean of DMF-T. The number of S. mutans cells was significantly lower in the resting saliva of allergic patients. The applied mechanical and gustatory stimuli by chewing gum resulted in higher sAA and S. mutans levels and a slow decrease of values was observed in the control group for the next 30 min. Thereafter, sAA and S. mutans levels decreased earlier in the presence of sour cherry extract than those of control cases. Chewing gum with sour cherry extract may be useful for the prevention of dental caries.

Mechanical properties, water sorption characteristics, and compound release of grape seed extract-incorporated resins

Objective

This study evaluated the effect of grape seed extract (GSE) incorporation on the mechanical properties, water sorption, solubility, and GSE release from the experimental adhesive resins.

Material and Methods

An experimental comonomer mixture, consisting of 40% Bis-GMA, 30% Bis MP, 28% HEMA, 0.26% camphorquinone and 1% EDMAB, was used to prepare four GSE-incorporated adhesive resins at concentrations of 0.5, 1, 1.5, and 2 wt%. The neat resin without GSE was used as the control. Six resin beams (25 mm x 2 mm x 2 mm) per group were prepared for flexural strength and modulus of elasticity evaluations using a universal testing machine at a crosshead speed of 1 mm/min. Five disks (6 mm in diameter and 2 mm in thickness) per group were used for microhardness measurements using a Leitz micro-hardness tester with Leica Qgo software. Five disks (7 mm in diameter and 2 mm in thickness) per group were prepared and stored in deionized water for 28 days. Water sorption, solubility, and GSE release in deionized water were calculated for each GSE-incorporated adhesive at the end of 28th day. Data was evaluated using one-way ANOVA and Tukey multiple comparisons.

Results

Flexural strength, modulus of elasticity and microhardness of GSE-incorporated adhesive decreased significantly with incorporation of 1.5% of GSE (p<0.05). Addition of GSE had no effect on the water sorption of the adhesive resins (p=0.33). The solubility of the resin also increased significantly with incorporation of 1.5% of GSE (p<0.05). Quantities of GSE release increased with increased concentration of GSE in the adhesive resin.

Conclusion

Up to 1% of GSE can be incorporated into a dental adhesive resin without interfering with the mechanical properties or solubility of the resins.

Dual Role of Cyanidin-3-glucoside on the Differentiation of Bone Cells

Cyanidin-3-glucoside (C3G) is one of the major components of anthocyanin, a water-soluble phytochemical. Recent studies demonstrated the chemopreventive and chemotherapeutic activities of C3G in various conditions, including cancer, although the precise effects of C3G on osteoclast and osteoblast differentiation remain unclear. Here, we investigated the role of C3G in the differentiation of bone-associated cells and its underlying mechanism. C3G inhibited receptor activator of nuclear factor kappa-B ligand (RANKL)–mediated osteoclast differentiation and formation in a dose-dependent manner and downregulated the expression of osteoclast differentiation marker genes. Pretreatment with C3G considerably reduced the induction of extracellular signal–regulated kinase, c-Jun N-terminal kinase, and p38 mitogen-activated kinases activation by RANKL in osteoclast precursor cells. Furthermore, C3G dramatically inhibited the expression of c-Fos and nuclear factor of activated T-cells, cytoplasmic 1, which are important transcription factors for osteoclast differentiation and activation. The formation of osteoclasts in coculture of bone marrow cells and calvaria-derived osteoblasts was also inhibited by C3G treatment, although the expression of macrophage colony-stimulating factor and RANKL (master factors for osteoclast differentiation and formation) and osteoprotegerin (a decoy receptor for RANKL) on osteoblasts was unaffected. The inhibitory effect of C3G on osteoclastogenesis is therefore targeted specifically to osteoclasts but not osteoblasts. Moreover, analysis of the expression levels of osteoblast differentiation marker genes and alizarin red staining showed that osteoblast differentiation and matrix formation increased after C3G treatment. Taken together, these results strongly suggest that C3G has a dual role in bone metabolism, as an effective inhibitor of osteoclast differentiation but also as an activator of osteoblast differentiation. Therefore, C3G may be used as a potent preventive or therapeutic agent for bone-related diseases, such as osteoporosis, rheumatoid arthritis, and periodontitis.