Direct assessment of the antioxidant property of salivary histatin

Human Salivary Histatin-1 Attenuates Osteoarthritis through Promoting M1/M2 Macrophage Transition

Osteoarthritis (OA) is an inflammation-driven degenerative joint disease. Human salivary peptide histatin-1 (Hst1) shows pro-healing and immunomodulatory properties. but its role in OA treatment is not fully understood. In this study, we investigated the efficacy of Hst1 in the inflammation modulation-mediated attenuation of bone and cartilage damage in OA. Hst1 was intra-articularly injected into a rat knee joint in a monosodium iodoacetate (MIA)-induced OA model. Micro-CT, histological, and immunohistochemical analyses showed that Hst1 significantly attenuates cartilage and bone deconstruction as well as macrophage infiltration. In the lipopolysaccharide-induced air pouch model, Hst1 significantly reduced inflammatory cell infiltration and inflammation. Enzyme-linked immunosorbent assay (ELISA), RT-qPCR, Western blot, immunofluorescence staining, flow cytometry (FCM), metabolic energy analysis, and high-throughput gene sequencing showed that Hst1 significantly triggers M1-to-M2 macrophage phenotype switching, during which it significantly downregulated nuclear factor kappa-B (NF-κB) and mitogen-activated protein kinases (MAPK) signaling pathways. Furthermore, cell migration assay, Alcian blue, Safranin O staining, RT-qPCR, Western blot, and FCM showed that Hst1 not only attenuates M1-macrophage-CM-induced apoptosis and matrix metalloproteinase expression in chondrogenic cells, but it also restores their metabolic activity, migration, and chondrogenic differentiation. These findings show the promising potential of Hst1 in treating OA.

Efficient enrichment of total flavonoids from kale (Brassica oleracea L. var. acephala L.) extracts by NKA-9 resin and antioxidant activities of flavonoids extract in vitro

This work established an effective method for kale flavonoids enrichment by resins. Resin screening, adsorption kinetics and isotherms, dynamic adsorption and desorption tests were conducted to optimize the appropriate resins and enrichment conditions. The results showed that NKA-9 was the optimum resin. The best adsorption conditions were 0.2 mg/mL flavonoids concentration, 12.5 bed volume (BV) sample volume and 2 BV/h adsorption rate. The desorption conditions were 3 BV of 80% ethanol at 2 BV/h elution rate. Under these conditions, the product purity was 31.16%. The purified flavonoids extract was mainly comprised of Kaempferol-3-O-sophoroside-7-O-diglucoside, Kaempferol-3,7,4'-O-d-triglucoside, Kaempferol-3-O-feruloyl-sophoroside-7-O-d-glucoside, and Kaempferol-3-O-sinapoyl-sophoroside. Moreover, it presented higher scavenging ability against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and hydroxyl (OH) radical than crude extract. In conclusion, kale flavonoids can be well concentrated by NKA-9 resin and the purified flavonoids extract has good antioxidant activity which can be potentially applied in food, cosmetic or pharmacy industries.

Ergothioneine in a peptide: Substitution of histidine with 2-thiohistidine in bioactive peptides

Ergothioneine (EGT) is the betaine of 2-thiohistidine (2-thioHis) and may be the last undiscovered vitamin. EGT cannot be incorporated into a peptide because the α-nitrogen is trimethylated, although this would be advantageous as an EGT-like moiety in a peptide would impart unique antioxidant and metal chelation properties. The amino acid 2-thioHis is an analogue of EGT and can be incorporated into a peptide, although there is only one reported occurrence of this in the literature. A likely reason is the harsh conditions reported for protection of the thione, with similarly harsh conditions used in order to achieve deprotection after synthesis. Here, we report a novel strategy for the incorporation of 2-thioHis into peptides in which we decided to leave the thione unprotected. This decision was based upon the reported low reactivity of EGT with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), a very electrophilic disulfide. This strategy was successful, and we report here the synthesis of 2-thioHis analogues of carnosine (βAH), GHK-tripeptide, and HGPLGPL. Each of these peptides contain a histidine (His) residue and possesses biological activity. Our results show that substitution of His with 2-thioHis imparts strong antioxidant, radical scavenging, and copper binding properties to the peptide. Notably, we found that the 2-thioHis analogue of GHK-tripeptide was able to completely quench the hydroxyl and ABTS radicals in our assays, and its antioxidant capacity was significantly greater than would be expected based on the antioxidant capacity of free 2-thioHis. Our work makes possible greater future use of 2-thioHis in peptides.

The Relationship Between Salivary Redox, Diet, and Food Flavor Perception

The mouth is the gateway for entrance of food and microorganisms into the organism. The oral cavity is bathed by saliva, which is thus the first fluid that food and microorganisms will face after their entrance. As a result, saliva plays different functions, including lubrication, predigestion, protection, detoxification, and even transport of taste compounds to chemoreceptors located in the taste buds. To ensure its function of protection, saliva contains reactive harmful compounds such as reactive oxygen species that are controlled and neutralized by the antioxidant activity of saliva. Several antioxidant molecules control the production of molecules such as reactive oxygen compounds, neutralize them and/or repair the damage they have caused. Therefore, a balance between reactive oxidant species and antioxidant compounds exists. At the same time, food can also contain antioxidant compounds, which can participate in the equilibrium of this balance. Numerous studies have investigated the effects of different food components on the antioxidant capacity of saliva that correspond to the ability of saliva to neutralize reactive oxygen species. Contradictory results have sometimes been obtained. Moreover, some antioxidant compounds are also cofactors of enzymatic reactions that affect flavor compounds. Recent studies have considered the salivary antioxidant capacity to explain the release of flavor compounds ex vivo or in vivo. This article aims to review the effect of food on the antioxidant capacity of saliva and the impact of salivary antioxidant capacity on flavor perception after a brief presentation of the different molecules involved.

Beneficial effect of aged garlic extract on periodontitis: a randomized controlled double-blind clinical study

The purpose of this study is to assess the long-term efficacy of aged garlic extract to improve periodontitis. Two hundred and one participants were randomly stratified and assigned equally to the regimen group or the control group. At the start, 12 month, and 18 month subjects received dental examination and periodontal evaluation. Probing Pocket Depth and Gingival Recession were examined. For each efficacy parameter, the mean value of examination was calculated and assessed using paired-difference t tests. Statistical tests were two-sided using a 5% significance level. The mean value of pocket depth for the aged garlic extract group at 18 month was 1.06 ± 0.49 as compared to the baseline value of 1.89 ± 0.74 (p<0.001) and the corresponding value of 1.50 ± 0.46 for the placebo group (p<0.001), indicating the beneficial effect of aged garlic extract on periodontitis. According to a Multiple linear regression analysis the only three variables which reached statistical significance as predictors of PPD level were the baseline PPD scores (p<0.001), smoking (p = 0.020), and consumption of daily dose of aged garlic extract (p<0.001). These results demonstrated that aged garlic extract is an effective supplement for preventing or improving periodontal disease. The well demonstrated benefits of aged garlic extract for the oral disease may also be used as a means to improve general health because of the close relationship between periodontitis and some systemic diseases such as diabetes, hypertension, atherosclerosis, and others.

Direct evaluation of the antioxidant properties of salivary proline-rich proteins

Proline-rich proteins are associated with the formation of an acquired protein layer overlying the tooth enamel surface. Previous studies have described the antioxidant activity of salivary histatin against the hydroxyl radical from Fenton’s reaction, acting as the critical reactive oxygen species. However, the role of proline-rich proteins in mitigating the oxidative stress caused by reactive oxygen species in the oral cavity remains unclear. In this study, we investigated the antioxidant effects of proline-rich proteins 2 on direct reactive oxygen species using electron spin resonance spectroscopy. For the first time, we demonstrated that proline-rich proteins 2 exhibits antioxidant activity directly against the hydroxyl radical produced by hydrogen peroxide with ultraviolet. Considering that identical results were obtained when assaying 30 residues of proline-rich proteins 2, the direct antioxidant effects against the hydroxyl radical by proline-rich proteins 2 may be related to these specific 30 residues.