The effect of active components from citrus fruits on dentin MMPs

The activity, distribution, and colocalization of cathepsin K and matrix metalloproteases in intact and eroded dentin

OBJECTIVES

This study aimed to assess the activity, distribution, and colocalization of cathepsin K (catK) and matrix metalloproteases (MMPs) in both intact and eroded dentin in vitro.

MATERIALS AND METHODS

Eroded dentin was obtained by consecutive treatment with 5% citric acid (pH = 2.3) for 7 days, while intact dentin remained untreated. Pulverized dentin powder (1.0 g) was extracted from both intact and eroded dentin using 5 mL of 50 mM Tris-HCl buffer (0.2 g/1 mL, pH = 7.4) for 60 h to measure the activity of catK and MMPs spectrofluorometrically. In addition, three 200-μm-thick dentin slices were prepared from intact and eroded dentin for double-labeling immunofluorescence to evaluate the distribution and colocalization of catK and MMPs (MMP-2 and MMP-9). The distribution and colocalization of enzymes were analyzed using inverted confocal laser scanning microscopy (CLSM), with colocalization rates quantified using Leica Application Suite Advanced Fluorescent (LAS AF) software. One-way analysis of variance (ANOVA) was used to analyze the fluorescence data related to enzyme activity (α = 0.05).

RESULTS

The activity of catK and MMPs was significantly increased in eroded dentin compared with intact dentin. After erosive attacks, catK, MMP-2, and MMP-9 were prominently localized in the eroded regions. The colocalization rates of catK with MMP-2 and MMP-9 were 13- and 26-fold higher in eroded dentin, respectively, than in intact dentin.

CONCLUSIONS

Erosive attacks amplified the activity of catK and MMPs in dentin while also altering their distribution patterns. Colocalization between catK and MMPs increased following erosive attacks.

CLINICAL RELEVANCE

CatK, MMP-2, and MMP-9 likely play synergistic roles in the pathophysiology of dentin erosion.

Biological Properties and Antimicrobial Potential of Cocoa and Its Effects on Systemic and Oral Health

Cocoa is considered a functional food because it is a natural source of macro- and micronutrients. Thus, cocoa is rich in vitamins, minerals, fiber, fatty acids, methylxanthines and flavonoids. In addition to favoring the metabolism of lipids and carbohydrates, the bioactive components of cocoa can have an antioxidant, anti-inflammatory and antimicrobial effect, providing numerous benefits for health. This literature review presents an overview of the effects of cocoa, fruit of the Theobroma cacao tree, on systemic and oral health. Several studies report that cocoa intake may contribute to the prevention of cardiovascular, neurodegenerative, immunological, inflammatory, metabolic and bone diseases, in addition to reducing the risk of vascular alterations and cognitive dysfunctions. On oral health, in vitro studies have shown that cocoa extract exerted an inhibitory effect on the growth, adherence and metabolism of cariogenic and periodontopathogenic bacteria, also inhibiting acid production, glycosyltransferase enzyme activity and the synthesis of insoluble polysaccharides. Additionally, administration of cocoa extract reduced biofilm accumulation and caries development in animals infected with cariogenic species. Clinical studies also reported that the use of mouthwashes containing cocoa extract reduced Streptococcus mutans counts in saliva and dental biofilm formation. In short, these studies highlight the nutritional value of cocoa, considering its clinical applicability, stability and economic accessibility.

The Role of Selected Flavonoids from Bajakah Tampala (Spatholobus littoralis Hassk.) Stem on Cosmetic Properties: A Review

Cosmetics made from natural ingredients are increasingly popular because they contain bioactive compounds which can provide many health benefits, more environmentally friendly and sustainable. The health benefits obtained from natural-based ingredients include anti-aging, photoprotective, antioxidant, and anti-inflammatory. This article reviewed the potential of selected flavonoids from bajakah tampala (Spatholobus littoralis Hassk.) as the native plant in Indonesia. We present in silico, in vitro, in vivo, and clinical research data on the use of selected flavonoids that have been reported in other extracts.

Dual function of quercetin as an MMP inhibitor and crosslinker in preventing dentin erosion and abrasion: An in situ/in vivo study

OBJECTIVE

The aim of the present study was to evaluate the in situ/in vivo effect of quercetin on dentin erosion and abrasion.

METHODS

Human dentin blocks (2 × 2 × 2 mm) were embedded and assigned to 6 groups: 75 μg/mL, 150 μg/mL and 300 μg/mL quercetin (Q75, Q150, Q300); 120 μg/mL chlorhexidine (CHX, positive control); and deionized water and ethanol (the negative controls). The specimens were treated with the respective solutions for 2 min and then subjected to in situ/in vivo erosive/abrasive challenge for 7 d as follows: in vivo erosion 4 times a day and then in vivo toothbrush abrasion after the first and last erosive challenges of each day. Dentin loss was assessed by profilometry. An additional dentin specimen was used to evaluate the penetration depth of quercetin into dentin by tracking the spatial distribution of its characteristic Raman peak. Moreover, dentin blocks (7 × 1.7 × 0.7 mm) were used to detect the impact of quercetin on dentin-derived matrix metalloproteinase (MMP) inhibition by in situ zymography, and the inhibition percentage (%) was calculated. Additionally, the potential collagen crosslinking interactions with quercetin were detected by Raman spectroscopy, and the crosslinking degree was determined with a ninhydrin assay. Fully demineralized dentin beams (0.5 × 0.5 × 10 mm) were used to evaluate the impact of quercetin on the mechanical properties of dentin collagen fibre by the ultimate micro-tensile strength test (μUTS). The data were analysed by one-way analysis of variance and Tukey's test (α = 0.05).

RESULTS

Compared to the negative controls, all treatment solutions significantly reduced dentin loss. The dentin loss of Q150 and Q300 was significantly less than that of CHX (all P < 0.05). The amount of quercetin decreased with increasing dentin depth, and the maximum penetration depth was approximately 25-30 µm. In situ zymography showed that quercetin significantly inhibited the activities of dentin-derived MMPs. The inhibitory percentages of Q75 and Q150 were significantly lower than that of CHX (all P < 0.05), but no significant difference was found between Q300 and CHX (P = 0.58). The collagen crosslinking interactions with quercetin primarily involved hydrogen bonding and the degree of crosslinking increased in a concentration-dependent manner. Statistically significant increases in μUTS values were observed for demineralized dentin beams after quercetin treatment compared with those of the control treatments (all P < 0.05).

SIGNIFICANCE

This study provides the first direct evidence that quercetin could penetrate approximately 25-30 µm into dentin and further prevent dentin erosion and abrasion by inhibiting dentin-derived MMP activity as well as crosslinking collagen of the demineralized organic matrix.

Inhibitory activity of S-PRG filler on collagen-bound MMPs and dentin matrix degradation

OBJECTIVES

To evaluate the inhibitory activity of an ion-releasing filler (S-PRG) eluate on dentin collagen-bound metalloproteinases (MMPs) and dentin matrix degradation.

METHODS

Dentin beams (5 × 2 × 0.5 mm) from human molars were completely demineralized to produce dentin matrix specimens. The dry mass was measured, and a colorimetric assay (Sensolyte) determined the initial total MMP activity to allocate the beams into four treatment groups (n = 10/group): 1) water for 1 min (negative control); 2) 2% chlorhexidine digluconate (CHX - inhibitor control) for 1 min; 3) S-PRG eluate for 1 min; 4) S-PRG eluate for 30 min. After the treatments, the total MMP activity was reassessed. The specimens were stored in simulated body fluid (SBF) at 37 °C for up to 21 days. The dry mass was reassessed weekly. On day 7, the dentin matrix degradation was analyzed for the presence of collagen fragments (CF; Sirius Red) and hydroxyproline (Hyp) in the SBF. Statistical analyses were performed with ANOVA/Tukey, paired t-tests, and RM-ANOVA/Sidak (α = 5%).

RESULTS

S-PRG eluate exposure for 1 and 30 min reduced (p < 0.0001) MMP activity. S-PRG exposure for 30 min presented MMP activity inhibition equivalent to CHX (p = 0.061). S-PRG and CHX decreased CF (p ≤ 0.007) and Hyp (p < 0.046) release. After 21 days of storage, S-PRG-treated beams, regardless of exposure time, presented a reduced (p ≤ 0.017) mass loss, intermediate between CHX and control.

CONCLUSION

Treating demineralized dentin with S-PRG eluate for 1 or 30 min reduced matrix-bound MMP activity and dentin matrix degradation for up to 21 days.

CLINICAL SIGNIFICANCE

S-PRG filler may hinder the progression of dentin carious/erosive lesions and enhance the stabilization of dentin bonding interfaces.

Therapeutic Effects of Citrus Flavonoids Neohesperidin, Hesperidin and Its Aglycone, Hesperetin, on Bone Health

Flavonoids are natural phytochemicals that have therapeutic effects and act in the prevention of several pathologies. These phytochemicals can be found in seeds, grains, tea, coffee, wine, chocolate, cocoa, vegetables and, mainly, in citrus fruits. Neohesperidin, hesperidin and hesperetin are citrus flavonoids from the flavanones subclass that have anti-inflammatory and antioxidant potential. Neohesperidin, in the form of neohesperidin dihydrochalcone (NHDC), also has dietary properties as a sweetener. In general, these flavanones have been investigated as a strategy to control bone diseases, such as osteoporosis and osteoarthritis. In this literature review, we compiled studies that investigated the effects of neohesperidin, hesperidin and its aglycone, hesperetin, on bone health. In vitro studies showed that these flavanones exerted an antiosteoclastic and anti- inflammatory effects, inhibiting the expression of osteoclastic markers and reducing the levels of reactive oxygen species, proinflammatory cytokines and matrix metalloproteinase levels. Similarly, such studies favored the osteogenic potential of preosteoblastic cells and induced the overexpression of osteogenic markers. In vivo, these flavanones favored the regeneration of bone defects and minimized inflammation in arthritis- and periodontitis-induced models. Additionally, they exerted a significant anticatabolic effect in ovariectomy models, reducing trabecular bone loss and increasing bone mineral density. Although research should advance to the clinical field, these flavanones may have therapeutic potential for controlling the progression of metabolic, autoimmune or inflammatory bone diseases.

Hesperidin reduces dentin wear after erosion and erosion/abrasion cycling in vitro

OBJECTIVE

To evaluate the action of hesperidin (HPN) at different concentrations to prevent dentin erosive wear, associated or not to abrasion.

METHODS

A study with 6 experimental groups (n = 10) for erosion (experiment 1) and another 6 for erosion + abrasion (experiment 2). The treatments were: distilled water (DW), DW with collagenase (DW + Col), 0.46% epigallocatechin-3-gallate (EGCG) and 0.1%, 0.5% or 1% HPN. The specimens were submitted to a cycle (3x/day) for 5 days that consisted of immersion on 1% citric acid (5 min), artificial saliva (60 min), treatment (5 min), brushing (150 movements only in experiment 2), and artificial saliva (60 min / overnight). Collagenase was added in artificial saliva for all groups except DW-group. Dentin changes were assessed with optical profilometry and scanning electron microscopy. Data were submitted to one-way analysis of variance and Tukey tests (α = 0.05).

RESULTS

For experiment 1, DW showed the lowest wear and did not significantly differ from EGCG. DW + Col showed the highest wear, being significantly different from HPN at 1%. In experiment 2, DW showed the lowest wear and DW + Col the highest. EGCG showed less wear than the three groups treated with HPN. In addition, for both cycling models, there were no significant differences among the three concentrations of HPN analyzed. In micrographs of HPN-treated groups, it could be observed the formation of a barrier on the dentin that promoted the obliteration of the tubules.

CONCLUSIONS

HPN was able to preserve the demineralized organic matrix layer but did not overcome the effect of EGCG.

Antioxidants and Collagen-Crosslinking: Benefit on Bond Strength and Clinical Applicability

Antioxidants are known for their potential of strengthening the collagen network when applied to dentin. They establish new intra-/intermolecular bonds in the collagen, rendering it less perceptive to enzymatic hydrolysis. The study evaluated the benefit on shear bond strength (SBS) of a resin–composite to dentin when antioxidants with different biomolecular mechanisms or a known inhibitor of enzymatic activity are introduced to the bonding process in a clinically inspired protocol. Specimens (900) were prepared consistent with the requirements for a macro SBS-test. Four agents (Epigallocatechingallate (EGCG), Chlorhexidindigluconate (CHX), Proanthocyanidin (PA), and Hesperidin (HPN)) were applied on dentin, either incorporated in the primer of a two-step self-etch adhesive or as an aqueous solution before applying the adhesive. Bonding protocol executed according to the manufacturer’s information served as control. Groups (n = 20) were tested after one week, one month, three months, six months, or one year immersion times (37 °C, distilled water). After six-month immersion, superior SBS were identified in PA compared to all other agents (p < 0.01) and a higher reliability in both primer and solution application when compared to control. After one year, both PA incorporated test groups demonstrated the most reliable outcome. SBS can benefit from the application of antioxidants. The use of PA in clinics might help extending the lifespan of resin-based restorations.

3,5,6,7,8,3',4'-Heptamethoxyflavone, a Citrus Flavonoid, Inhibits Collagenase Activity and Induces Type I Procollagen Synthesis in HDFn Cells

Citrus fruits contain various types of flavonoids with powerful anti-aging and photoprotective effects on the skin, and have thus been attracting attention as potential, efficacious skincare agents. Here, we aimed to investigate the chemical composition of Citrus unshiu and its protective effects on photoaging. We isolated and identified a bioactive compound, 3,5,6,7,8,3',4'-heptamethoxyflavone (HMF), from C. unshiu peels using ethanol extraction and hexane fractionation. HMF inhibited collagenase activity and increased type I procollagen content in UV-induced human dermal fibroblast neonatal (HDFn) cells. HMF also suppressed the expression of matrix metalloproteinases 1 (MMP-1) and induced the expression of type I procollagen protein in UV-induced HDFn cells. Additionally, HMF inhibited ultraviolet B (UVB)-induced phosphorylation of the mitogen-activated protein kinases (MAPK) cascade signaling components-ERK, JNK, and c-Jun-which are involved in the induction of MMP-1 expression. Furthermore, HMF affected the TGF-β/Smad signaling pathway, which is involved in the regulation of type I procollagen expression. In particular, HMF induced Smad3 protein expression and suppressed Smad7 protein expression in UV-induced HDFn cells in a dose-dependent manner. These findings suggest a role for Citrusunshiu in the preparation of skincare products in future.