The reductive capacity index of saliva obtained from donors of various ages

Evaluation of Antimicrobial Activity of Aqueous Extract of “Ocimum Sanctum–Queen of Herb” on Dental Caries Microorganisms: An In Vitro Study

Aim

To evaluate the efficacy of three different concentrations of Ocimum sanctum aqueous extract against various caries causing microorganisms, Streptococcus mutans, Streptococcus mitis, Streptococcus sanguis, and Lactobacillus acidophilus.

Materials and methods

Aqueous extract of Ocimum sanctum was prepared by the cold extraction method. The extract was diluted with milli Q water, to obtain 3 different concentrations [2%, 3%, and 4%] of the extract. Glycerol 6%v/v and tween-80, 0.1%v/v were also added to get a stable suspension. About 0.2% chlorhexidine was used as a positive control and milli Q water was used as a negative control. The extract, along with the controls, was then subjected to microbiological investigation to determine which concentration among the three different concentrations of extract gave a wider inhibition zone against Streptococcus mutans, Streptococcus mitis, Streptococcus sanguis, and Lactobacillus acidophilus. The zones of inhibition were measured in millimeters.

Results

Ocimum sanctum aqueous extract demonstrated maximum antimicrobial activity against microorganisms responsible for dental caries at the 4% concentration level although 3% and 2% were also effective. Maximum activity was seen against S. mutans and S. sanguis with 4% extract.

Conclusion

Ocimum sanctum aqueous extract was effective against all caries causing the microorganisms.

Clinical significance

Dental caries is still a major oral disease in children which affects their quality of life. It is important to come up with an alternative oral hygiene aid which is easily available and with lesser side effects and maximum benefits by acting against caries causing microbes. Thus aqueous extract of commonly available tulsi is studied to know its effect on caries causing microorganisms.

How to cite this article

Pai KR, Pallavi LK, Bhat SS, et al. Evaluation of Antimicrobial Activity of Aqueous Extract of “Ocimum Sanctum-Queen of Herb” on Dental Caries Microorganisms: An In Vitro Study. Int J Clin Pediatr Dent 2022;15(S-2):S176-S179.

Cyclic Voltammetry in Biological Samples: A Systematic Review of Methods and Techniques Applicable to Clinical Settings

Oxidative stress plays a pivotal role in the pathogenesis of many diseases, but there is no accurate measurement of oxidative stress or antioxidants that has utility in the clinical setting. Cyclic Voltammetry is an electrochemical technique that has been widely used for analyzing redox status in industrial and research settings. It has also recently been applied to assess the antioxidant status of in vivo biological samples. This systematic review identified 38 studies that used cyclic voltammetry to determine the change in antioxidant status in humans and animals. It focusses on the methods for sample preparation, processing and storage, experimental setup and techniques used to identify the antioxidants responsible for the voltammetric peaks. The aim is to provide key information to those intending to use cyclic voltammetry to measure antioxidants in biological samples in a clinical setting.

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.

Does interindividual variability of saliva affect the release and metabolization of aroma compounds ex vivo? The particular case of elderly suffering or not from hyposalivation

The aim of this work was to study the effects of interindividual variability of human elderly saliva on aroma release and metabolization by ex vivo approaches. Thirty individuals suffering or not from hyposalivation were selected from a panel formed by 110 elderly people (aged >65 years old) that were matched by age and sex. Then, their stimulated saliva samples were independently incubated in presence of three aroma compounds (ethyl hexanoate, octanal, 2-nonanone) to perform headspace-gas chromatography and liquid/liquid extraction-gas chromatography mass spectrometry analyses. These assays revealed that the extent of saliva effect on the release and metabolization of aroma compounds was highly dependent on the chemical family of the compounds (octanal>ethyl hexanoate>2-nonanone). Moreover, salivas from the hyposalivator (HPS) group exerted a significant lower release and/or higher metabolization than those of the control group for the three assayed compounds. Regarding the biochemical characterization of the saliva samples, no significant differences were found in the total protein content between the two groups. This does not preclude the involvement of specific proteins on the observed results that need to be clarified in further experiments. Saliva from the HPS group presented a significantly higher total antioxidant capacity than that of the control group, which suggests that this parameter could be related to the metabolization of aroma compounds by saliva. Such effects might alter aroma perception in individuals suffering from hyposalivation. PRACTICAL APPLICATIONS: The world population is getting older so fast that most countries are not prepared to handle this demographic challenge, characterized by an increasing prevalence of noncommunicable chronic diseases (e.g., diabetes, gastrointestinal disorders) associated to inadequate eating patterns. Thus, supporting a balanced diet is one of the most cost-effective strategies to maintain a good quality of life. A suitable diet needs to take into account both, specific sensory and nutritional individual needs. However, aging is often accompanied by deterioration in oral health (e.g., low salivary secretions), which could alter the capacities to taste and smell. Results from this work contribute to a better understanding of the role of human saliva in aroma release and metabolization, a first step to comprehend retronasal aroma release and perception. This knowledge will help to propose innovative solutions for the reformulation of food products better adapted to the elderly's needs, thus allowing delayed onset of dependency.

Altered Salivary Profile in Heavy Smokers and its Possible Connection to Oral Cancer

Saliva is the first biological fluid to encounter inhaled cigarette smoke, whose numerous carcinogens and oxidants are responsible for the oral cancer so prevalent among smokers. Whole saliva, collected from 25 consenting heavy smokers and from a control group of 25 age- and gender-matched non-smokers, was subjected to sialochemical, biochemical, immunological and oxidative analyses. The mean flow rate was significantly higher in smokers than in non-smokers, as were the median activity value of superoxide dismutase (SOD) and the total salivary antioxidant capacity (ImAnOx) (by 32% and 12%, respectively, p=0.05). The salivary carbonyl concentration (an oxidative stress indicator) was significantly higher by 126% (p=0.0006) among smokers, while lactate dehydrogenase, albumin, total immunoglobulin G, and the metalloproteinases MMP-2 and MMP-9 concentrations were significantly lower in the smokers, by 86% (p=0.003), 65% (p=0.003), 61% (p=0.048), 35% (p=0.005) and 55% (p=0.035), respectively. Apparently, the oral cavity's salivary antioxidant system fails to cope with the severe attack of reactive oxygen species originating in cigarette smoke. Moreover, various other salivary functional and protective parameters also decreased among the smokers. Hence, further research aimed at examining the possibility of administration of agents as antioxidants or saliva substitutes to the oral cavity of smokers should be considered.

Understanding the release and metabolism of aroma compounds using micro-volume saliva samples by ex vivo approaches

This study investigated the behaviour of key aroma compounds in the presence of human saliva (200μL) from different individuals (n=3) submitted or not to centrifugation (whole vs clarified saliva). HS-GC results showed that human saliva strongly decreased the release of carbonyl compounds (aldehydes and ketones). This effect was dependent on i) the structure of the aroma compounds and ii) the saliva composition. Whole saliva exerted a higher effect than clarified saliva on aroma compounds. Moreover, this effect was individual-dependent and related to the total protein content and the total antioxidant capacity of saliva. HS-SPME and LLE-GC/MS analyses revealed that metabolism of the compounds by salivary enzymes was involved. This observation indicates that some aroma compounds could be metabolized in the oral cavity in an individual manner, which could have implications for aroma perception (e.g., formation of new metabolites with different odor thresholds and qualities) and/or organisms' health status (e.g., compound detoxification).

Salivary and Urinary Total Antioxidant Capacity as Biomarkers of Oxidative Stress in Humans

Total Antioxidant Capacity (TAC) is a biomarker often used in order to investigate oxidative stress in many pathological conditions. Saliva and urine can be collected noninvasively and represent attractive diagnostic fluids for detecting biomarkers of various pathological conditions. The reviewed case-control and intervention studies that measured salivary or urinary TAC revealed that diseases, antioxidant foods, or supplements and age, gender, and lifestyle factors influenced salivary or urinary TAC. Salivary and urinary TAC were particularly affected by oral or renal status, respectively, as well as by infection; therefore these factors must be taken into account in both case-control and intervention studies. Furthermore, some considerations on sample collection and normalization strategies could be made. In particular, unstimulated saliva could be the better approach to measure salivary TAC, whereas 24 h or spontaneous urine collection should be chosen on the basis of the study outcome and of the creatinine clearance. Finally, the uric acid-independent TAC could be the better approach to evaluate red-ox status of body, in particular after nutritional interventions and in diseases associated with hyperuricaemia.

Alternations of salivary antioxidant enzymes in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with chronic systemic inflammation. Oxidative stress may play a role in the pathogenesis of SLE. An increase in free radicals or an impaired antioxidant defense system in SLE causes oxidative stress. Therefore, oxidative damage plays an important role in the pathogenesis of SLE. Variations in antioxidant activity have been previously studied in serum of patients with this disease. However, salivary factors have not been evaluated. Considering that saliva, the noninvasive biological fluid, could be a reflection of the state of health, the purpose of this study was evaluation of peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) activity in the saliva of patients with SLE. During the course of the practical part of the project, 30 patients with SLE and 30 healthy controls were selected to donate their saliva samples. After centrifugation of un-stimulated saliva, biological activity of POD, CAT and SOD were evaluated on their appropriate substrates using spectrophotometric methods and the results were statistically analyzed. The results showed that activities of antioxidant enzymes SOD and CAT were significantly reduced in saliva of SLE patients as compared to controls. The results suggest that antioxidant status was impaired in the saliva of SLE patients, and antioxidant status of saliva could be one of the non-invasive markers for SLE.

Selenium effect on ischemia-reperfusion injury of gastrocnemius muscle in adult rats

Selenium is a trace element that has antioxidant and neuroprotective effects. The aim of this study is to investigate the effects of selenium in reducing ischemia-reperfusion injury of the gastrocnemius muscle. In this experimental study, 80 adult male Wistar rats weighing 250-300 g were divided into ten groups (N = 8 per group). Group 1 is control group (without ischemia-reperfusion). Group 2 received 0.2 mg/kg selenium. Group 3 received ischemia + 3 d reperfusion + 0.2 mg/kg selenium, group 4 received ischemia + 3 d reperfusion + 0.2 mg/kg placebo, group 5 received ischemia + 7 d reperfusion + 0.2 mg/kg selenium, group 6 received ischemia + 7 d reperfusion + 0.2 mg/kg placebo, group 7 received ischemia + 14 d reperfusion + 0.2 mg/kg selenium, group 8 received ischemia + 14 d reperfusion + 0.2 mg/kg placebo, group 9 received ischemia + 28 d reperfusion + 0.2 mg/kg selenium and group 10 received ischemia + 3 d reperfusion + 0.2 mg/kg placebo. External iliac artery blocked for 3 h. After reperfusion, rats killed and gastrocnemius muscle removed, fixed, and tissue processing performed. Samples stained with hematoxylin-eosin for edema evaluation, toluidine blue for mast cell infiltration evaluation and immunohistochemistry for detection TNF-alpha and NF-kappa B proteins. Comparison of mast cell infiltration, edema of the interstitial fluid on the tissue, expression of TNF-alpha protein, and expression of NF-kappa B protein in the groups that received selenium with corresponding placebo group showed that selenium can reduce edema, mast cell infiltration, and TNF-alpha expression and inactivated NF-kappa B. The use of selenium simultaneously with creating ischemia can reduce ischemia-reperfusion injury of the gastrocnemius muscle.

Mucositis and salivary antioxidants in patients undergoing bone marrow transplantation (BMT)

OBJECTIVES

High doses of chemotherapy generate DNA damage in patients undergoing bone marrow transplantation (BMT), due to the production of reactive oxygen species (ROS). In order to evaluate the local defensive effectiveness of the patient undergoing BMT, the concentrations of the antioxidants superoxide dismutase (SOD) and uric acid (UA) were measured in saliva.

STUDY DESIGN

Basal saliva samples were collected from 20 patients undergoing BMT at the Oncology Department, Sanatorio Allende (Córdoba), in the stages: initial, prior to conditioning therapy (I); middle: 7 to 10 days after BMT (M) and final stage, 30 days after discharge from isolation (F). SOD levels were determined using a RANDOX kit (RANSOD superoxide dismutase manual), and for uric acid enzymatic UOD / PAP spectrophotometric method, ( Trinder Color Kit , Wiener Lab) was used.

RESULTS

85% of the patients developed oral mucositis. SOD concentration in the M stage was significantly higher (p<0.01) compared with stage I, and it reversed in stage F. UA concentration was significantly lower (p<0.001) in stage M compared with stage I, and in stage F it recovered the initial values.

CONCLUSIONS

SOD increase in stage M coincided with the appearance of mucositis, which could be interpreted as a defensive mechanism of saliva against oxidative stress produced by chemotherapy. UA decrease in stage M would favour the development of higher degrees of mucositis.

Total antioxidant capacity of saliva and dental caries

OBJECTIVE

Dental caries is one of the most common infectious diseases worldwide. Saliva has many functions in the oral cavity and is the first line defense against dental caries. Oxidative stress can affect initiation and progression of many inflammatory and infectious diseases such as dental caries. Thus the aim of this study was to evaluate the relationship between total antioxidant capacity (TAC) of saliva and dental caries.

STUDY DESIGN

100 healthy high school students (50 female and 50 male) with age range of 15 -17 years were randomly selected, divided to four groups. Unstimulated whole saliva specimens were collected at the morning. TAC of saliva was evaluated by spectrophotometric assay. Statistical comparisons were performed using Student's t-test, by SPSS 13.

RESULTS

The level of TAC was significantly higher in the saliva of caries active group relative to the caries free subjects. Statistical analysis for male and female groups showed a statistically significant reduction of TAC level in female group.

CONCLUSION

TAC was higher in caries active group. Thus this result showed that total antioxidant capacity may influence in dental caries and activity can be measured by salivary factors and this may be helpful in preventive dentistry.

Salivary defense system alters in vegetarian

PURPOSE

The aim of this research was investigating antimicrobial and enzymatic antioxidant activities in salivary fluids of vegetarians as compared to normal subjects.

MATERIAL & METHODS

Antimicrobial activity of the saliva samples was evaluated against four clinically important bacteria. The biological activities of three of the main antioxidant enzymes of saliva were measured using appropriate methods of enzyme assay in both groups.

RESULTS

According to the results, saliva obtained from vegetarians showed a reduced inhibitory effect on growth of Staphylococcus aureus, Klebsiella oxytoca, Pseudomonas aeruginosa and Escherichia coli as compared to those obtained from the non-vegetarian subjects. The activity of salivary peroxidase, catalase and superoxide dismutase showed a statistically marked decrease in vegetarian group.

CONCLUSIONS

According to our literature survey, this is the first report on the antibacterial and antioxidant capacity in saliva of vegetarians. Results obtained from the present study have opened a new line of research with the basis of saliva as a research tool.

Salivary markers of oxidative stress are related to age and oral health in adult non-smokers

BACKGROUND

Salivary concentrations of thiobarbituric acid-reacting substances (TBARS) are associated with the periodontal status assessed as papillary bleeding index (PBI). Whether this association is age independent is currently unclear. Salivary concentrations of advanced oxidation protein products (AOPPs) and advanced glycation end products (AGEs) have not been assessed in relation to age or oral health yet. The aim of our study was to analyse salivary markers of oxidative stress in dental patients in relation to age, gender and oral health.

METHODS

Consecutive adult non-smoking dental patients were enrolled (n = 204; aged 19-83 years). PBI and the caries index (CI) were assessed. Markers of oxidative stress, such as TBARS, AOPPs and AGEs, and the total antioxidant capacity (TAC) were measured in saliva samples taken before clinical examination.

RESULTS

Linear regression showed that salivary TBARS, AGEs and TAC significantly increase with age (r squared = 5.3%, 2.1% and 5%, respectively). PBI is an independent predictor of salivary TBARS (r squared = 5.5%), and the CI negatively affected AOPPs (r = 3.2%) and positively affected TBARS (r = 2.5%). Gender did not affect any of the analysed parameters.

CONCLUSIONS

Age as a significant contributor to the variance should be taken into account in studies focusing on salivary markers of oxidative stress. The relationship between PBI and salivary TBARS confirms results from previous studies. In addition, our results show that the association is age independent. Negative association between the CI and AOPPs might be related to recent findings that AOPP might be actually a marker of non-enzymatic antioxidant status.

Age-related changes in salivary antioxidant profile: possible implications for oral cancer

Oral cancer's much higher prevalence among older people may be due to an age-related reduction in protective salivary antioxidant mechanisms and/or an age-related increase in the magnitude of oral carcinogen attack, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS), causing DNA aberrations. This study found a significantly reduced total value of salivary antioxidant capacity in elderly persons (as measured by overall antioxidant capacity [ImAnOx] assay), (46% of healthy individuals, p =.004), increased oxidative stress (86% increase in carbonyl concentrations--indicators of enhanced ROS attack, p =.001), and increased salivary concentrations and total values of RNS (7-fold and 3-fold higher respectively, p =.001), all contributing to increased DNA oxidation of oral epithelial cells. Salivary oxidative stress-related changes in the intimately related saliva and oral epithelium compounded with higher viscosity of saliva may explain the higher prevalence of oral cancer in the elderly population. Administration of local therapeutic agents (i.e., antioxidants) to the oral cavity should be considered.

Saliva plays a dual role in oxidation process in stomach medium

The aim of this study was to evaluate the role of saliva in the oxidation process under the acidic condition of the stomach. Saliva specimens played varied roles in the lipid peroxidation process of heated muscle tissue in simulated gastric fluid: pro-oxidant effects, no effects, and antioxidant effects. To elucidate these differences, selected saliva components were examined. The pseudoperoxidase activity of lactoperoxidase increased lipid peroxidation, while thiocyanate and nitrite-reduced lipid peroxidation. The effect of a saliva specimen on lipid peroxidation was correlated with the concentration of nitrite in the specimen, but not with that of other saliva components. The inhibitory effect of nitrite may be due to its conversion to NO. Elucidation of the antioxidant effect of saliva on co-oxidation of d-alpha-tocopherol in gastric fluid, demonstrated that saliva alone cannot protect d-alpha-tocopherol from co-oxidation, although it partially protected against lipid peroxidation. The presence of red wine polyphenols in stomach medium totally inhibits food lipid peroxidation and d-alpha-tocopherol co-oxidation.

Effects of cigarette smoking on the antioxidant defence in young healthy male volunteers

Cigarette smoking induces a significant oxidant effect related to variety of free radical-related diseases often affecting the upper respiratory tract, unless it is effectively compensated by the antioxidant barriers of the humans. In the present study, the evaluation of the antioxidant compensatory mechanisms, by estimating the antioxidant capacity of extracellular defence (saliva and plasma) and the intracellular resistance of peripheral lymphocytes to oxidative stress in young healthy smokers, was investigated. Twenty young healthy male smokers and 20 age-matched non-smokers with similar dietary profiles were enrolled in the study. Total saliva and plasma samples were collected from both groups, and total antioxidant capacity (TAC) and lag time were estimated. The latter was also repeated in smokers just after a cigarette smoking. Peripheral lymphocytes isolated from the subjects of both groups were also tested for their inherent DNA damage as well as for their ability to resist H2O2-induced DNA damage by using the comet assay. TAC of plasma was found significantly higher in smokers compared to non-smokers (p <0.004), whereas no difference was recorded in plasma lag time values. Lymphocytes of smokers manifested a significantly decreased oxidant resistance (increased DNA fragmentation) to H2O2, in comparison to non-smokers. Our results indicate that young smokers do not manifest different salivary antioxidant defence than non-smokers. They exhibit, however, a higher plasma antioxidant capacity, but a significantly reduced ability of blood lymphocytes, to resist to H2O2-induced DNA damage.

[Variations of salivary dismutase superoxide in tonsillar infection]

The antioxidant effect of superoxido dismutase in saliva was measured in children bearing of tonsillar hypertrophy, recidivant tonsillitis or peritonsillar abscess. These levels were compared to those detected on tonsillar tissue obtained from tonsillectomy (p < 0.001). Although salivary SOD concentration in children with tonsillar infection was higher than hypertrophy, there was not a significative correlation to tonsillar value of the enzyme (R2 = 0.2276), so we can not accept a predictive value for salivary SOD of tonsillar suffering and, eventually, of tonsillectomy.

Influence of amalgam fillings on Hg levels and total antioxidant activity in plasma of healthy donors

In order to evaluate the influence of specific factors on mercury (P-Hg) levels and antioxidant power (P-FRAP) in human plasma, 26 healthy donors were examined by a dentist, their plasma analyzed for Hg by atomic absorption spectrometry and for total antioxidant activity by FRAP method. Hg plasma concentration was found to be correlated with the number of amalgam fillings, suggesting that Hg released from fillings is a source of Hg in non-occupational exposed subjects. P-FRAP correlated negatively with P-Hg suggesting a pro-oxidant role of the Hg released from amalgam fillings. Though age by itself was not significantly correlated with P-FRAP, when considered together with P-Hg in multivariate analysis, it was found to be a major related cofactor. Multivariate analysis showed no influence of fish consumption or cigarette smoking on P-FRAP.

Influence of human saliva on odorant concentrations. 2. aldehydes, alcohols, 3-alkyl-2-methoxypyrazines, methoxyphenols, and 3-hydroxy-4,5-dimethyl-2(5H)-furanone

The influence of human whole saliva on selected alcohols, aldehydes, 3-alkyl-2-methoxypyrazines, and phenols in food-relevant concentrations was investigated. At pH 7.5-8 it was found that the alcohols, methoxyphenols, methoxypyrazines, and 3-hydroxy-4,5-dimethyl-2(5H)-furanone remained unmodified by saliva, whereas aldehydes were reduced to their corresponding alcohols. Generally, the processes were found to be dependent on the salivary activity of the panelists as well as on the concentration of the applied odorants. Reduction of the aldehydes did not occur after thermal treatment of the saliva. These investigations are aimed at finding an explanation for longer lasting aftertaste in humans, as it is induced by some odor-active compounds after the consumption of food materials.

Redox analysis of human plasma allows separation of pro-oxidant events of aging from decline in antioxidant defenses

Oxidative stress is a component of diseases and degenerative processes associated with aging. However, no means are available to assess causative oxidative events separately from decline in function of protective antioxidant systems. Previous studies show that ongoing oxidative processes maintain plasma cysteine/cystine redox at a value that is more oxidized than the antioxidant glutathione/glutathione disulfide (GSH/GSSG) system, suggesting that redox analysis of these plasma thiols could allow separate evaluation of an increase in oxidative events from a decline in antioxidant function. The present study uses measurement of cysteine/cystine and GSH/GSSG redox in plasma of 122 healthy individuals aged 19-85 years to determine whether thiol-disulfide redox changes occur with age. The results show a linear oxidation of cysteine/cystine redox state with age at a rate of 0.16 mV/year over the entire age span. In contrast, GSH/GSSG redox was not oxidized prior to 45 years and subsequently was oxidized at a nearly linear rate of 0.7 mV/year. These data suggest that there is a continuous, linear increase in oxidative events throughout adult life but that the capacity of the GSH antioxidant system is maintained until 45 years and then declines rapidly. The data further suggest that redox states of cysteine/cystine and GSH/GSSG provide an approach to clinically distinguish between increased causative oxidative events and decreased GSH antioxidant function. In principle, such analyses can be used to assess efficacy of intervention strategies against oxidative stress prior to or early after onset of clinical symptoms in aging and age-related disease.

Release of mercury from dental amalgam and its influence on salivary antioxidant activity

Dental amalgam fillings are known to release significant amounts of mercury (Hg) in saliva which could represent a continuous source of oxidative damage to mouth tissues. The present investigation was aimed at verifying this hypothesis by determining a possible correlation between salivary Hg levels and salivary total antioxidant activity (TAA), which is used as an index of oxidative stress. Samples of saliva from 34 healthy donors were analyzed for Hg content, by vapor atomic absorption spectrometry, and for TAA, by determining the ferric reducing ability ('FRAP' method). A significant correlation between Hg and the number of amalgam restorations or total amalgam surface was evident in both the male and female subjects. A significant negative correlation between TAA and Hg levels or number of amalgam restorations or amalgam surface was evident in females, indicating that small increases in salivary Hg were sufficient to produce a decrease in salivary TAA. On the other hand, no significant correlation was found in the males. The present study provides, for the first time, evidence of a pro-oxidant role of the amalgam Hg chronically released in saliva.

Characterization of the differentiated antioxidant profile of human saliva

Saliva is armed with various defense mechanisms, such as the immunological and enzymatic defense systems. In addition, saliva has the ability to protect the mucosa against mechanical insults and to promote its healing via the activity of epidermal growth factor. However, another defense mechanism, the antioxidant system, exists in saliva and seems to be of paramount importance. The most interesting finding of the present study was the demonstration of the existence of much higher concentrations of the various salivary molecular and enzymatic antioxidant parameters in the parotid saliva compared with the submandibular/sublingual saliva. For example, peroxidase, superoxide dismutase, uric acid, and total antioxidant status were higher in resting parotid saliva compared with resting submandibular/sublingual saliva by 2405, 235, 245, and 147%, respectively. Another important finding was the distinction between the salivary antioxidant system and the immunological and enzymatic protective systems, as represented by the salivary concentrations of secretory IgA and lysozyme, respectively. These findings suggest that the profound antioxidant capacity of saliva secreted from parotid glands is related either to the different physiological demands related to eating (parotid predominance), to oral integrity maintenance (submandibular/sublingual predominance), or to the high content of deleterious redox-active transitional metal ions present in parotid saliva. This also may signify that our oral cavity environment is only partially protected against oxidative stress during most of the day and night.

Vitamins C and E improve rat embryonic antioxidant defense mechanism in diabetic culture medium

BACKGROUND

Diabetes teratogenicity seems to be related to embryonic oxidative stress and the extent of the embryonic damage can apparently be reduced by antioxidants. We have studied the mechanism by which antioxidants, such as vitamins C and E, reduce diabetes-induced embryonic damage. We therefore compared the antioxidant capacity of 10.5-day-old rat embryos and their yolk sacs cultured for 28h in diabetic culture medium with or without vitamins C and E.

METHODS

The embryos were cultured in 90% rat serum to which 2mg/ml glucose, 2mg/ml beta hydroxy butyrate (BHOB) and 10 microg/ml of acetoacetate were added. Rat embryos were also cultured in a diabetic medium with 25 microg/ml of vitamin E and 50 microg/ml of vitamin C. Control embryos were cultured in normal rat serum with or without vitamins C and E.

RESULTS

Decreased activity of Cu/Zn superoxide dismutase (SOD) and of catalase (CAT) in the "diabetic" embryos and their yolk sacs, and reduced concentrations of low molecular weight antioxidant (LMWA) were found. Under these conditions we also found a decrease in vitamin C and vitamin E concentrations in the embryos, as measured by HPLC. In situ hybridization for SOD mRNA showed a marked reduction of SOD mRNA in the brain, spinal cord, heart and liver of embryos cultured in diabetic medium in comparison to controls. Following the addition of vitamins C and E to the diabetic culture medium, SOD and CAT activity, the concentrations of LMWA, the levels of vitamin C and E and the expression of SOD mRNA in the embryos and yolk sacs returned to normal.

CONCLUSIONS

Diabetic metabolic factors seem to have a direct effect on embryonic SOD gene and perhaps genes of other antioxidant enzymes, reducing embryonic endogenous antioxidant defense mechanism. This in turn may cause a depletion of the LMWA, such as vitamins C and E. The addition of these vitamins normalizes the embryonic antioxidant defense mechanism, reducing the damage caused by the diabetic environment.

Exercise and oxidative stress methodology: a critique

Historically, exercise physiologists' interest in oxygen has primarily centered on the problem of oxygen consumption. However, the interest of the general scientific community in oxygen-centered radicals has raised awareness of the oxygen paradox and has motivated investigators to question whether exercise-stimulated "overconsumption" of oxygen might induce an oxidative stress and pose some risk to biological systems. In recent years, a considerable amount of research has demonstrated that radicals are capable of damaging a vast array of biological targets. Unfortunately, the work related to oxidative stress and antioxidants subsequent to exercise has been narrow in scope. This paper provides a brief review of the shortcomings of the present state of knowledge in this discipline and outlines topics requiring attention.

Antioxidant status and human health. Use of cyclic voltammetry for the evaluation of the antioxidant capacity of plasma and of edible plants

The low molecular weight antioxidants (LMWA) play a major role in protecting biological systems against reactive oxygen-derived species (ROS), and reflect the antioxidant capacity of the system. The cyclic voltammetry (CV) has been conveniently used and validated for the quantitation of the antioxidant capacity of the LMWA of blood plasma, tissue homogenates, and plant extracts. The CV tracing provides the biological oxidation potential (E and E1/2 which relate to the nature of the molecule(s)), the intensity of the anodic current wave (Ia), and its area S (both relate to the concentration of the molecule(s)). The components of the first anodic wave of plasma were identified by comparison with HPLC-electrochemical detection. CV together with another plasma parameter R, which reflects the level of oxidized ascorbate, were used for the evaluation of the antioxidant status and the oxidative stress in healthy subjects and in chronic (diabetes mellitus) and acute patients (subjected to total body irradiation prior to bone marrow transplantation). These methodologies could be widely employed for rapid evaluation of subjects, in health and disease, for monitoring of their response to treatment and nutritional supplementation, and for screening of specific populations.

Effect of cigarette smoke on salivary proteins and enzyme activities

Exposure of human plasma in vitro to gas-phase cigarette smoke (CS) causes a marked modification of plasma proteins as measured by protein carbonyl assay. Aldehydes present in CS may cause this elevation of protein carbonyls by reacting with sulfhydryl groups of proteins. Saliva is the first body fluid to confront the inhaled CS. Thus, in vitro exposure of saliva to nine "puffs" of CS also showed a distinct increase in protein carbonyls. Ascorbate and desferrioxamine mesylate had little effect on protein carbonyl formation, while GSH and N-acetylcysteine considerably inhibited the accumulation of protein carbonyls due to CS exposure. Following the exposure to CS, the activities of several salivary enzymes-amylase, lactic dehydrogenase (LDH), and acid phosphatase-were found to be significantly reduced (34, 57, and 77%, respectively). However, CS had no effect on the activities of aspartate aminotransferase and alkaline phosphatase. Addition of 1 mM of GSH and N-acetylcysteine considerably protected LDH and amylase activities, suggesting that sulfhydryl groups are affected in LDH and amylase. On the other hand, addition of 1 mM ascorbate caused a further loss of LDH and amylase activities, which could be partially prevented by the addition of desferrioxamine mesylate, implicating metal-catalyzed oxidation processes. Finally, loss of acid phosphatase activity was completely unaffected by any of the above antioxidants. It is concluded that the loss of salivary enzyme activities may be due to various agents in the CS that affect the enzyme activities via different mechanisms.

The use of cyclic voltammetry for the evaluation of antioxidant capacity

Low-molecular weight antioxidants (LMWAs) play a major role in protecting biological systems against reactive oxygen-derived species and reflect the antioxidant capacity of the system. Cyclic voltammetry (CV), shown to be convenient methodology, has been validated for quantitation of the LMWA capacity of blood plasma, tissue homogenates, and plant extracts. Analysis of the CV tracing yields the values of (i) the biological oxidation potential, E and E(1/2), which relate to the nature of the specific molecule(s); (ii) the intensity (Ia) of the anodic current; and (iii) the area of the anodic wave (S). Both Ia and S relate to the concentration of the molecule(s). LMWA components of human plasma and animal tissues were identified and further validated by reconstruction of the CV tracing and by high-performance liquid chromatography-electrochemical detection. To reflect the oxidative stress status, the use of an additional parameter, R, has been proposed. R represents the level (%) of oxidized ascorbate (compared with total ascorbate) and is measured by high-performance liquid chromatography-electrochemical detection. All these parameters were monitored in healthy human subjects as well as in chronic (diabetes mellitus) and acute care patients (subjected to total body irradiation before bone marrow transplantation). The electroanalytical methodologies presented here could be widely employed for rapid evaluation of the status of subjects (in health and disease) for monitoring of their response to treatment and/or nutritional supplementation as well as for screening of specific populations.

Role of reactive oxygen species (ROS) in the diabetes-induced anomalies in rat embryos in vitro: reduction in antioxidant enzymes and low-molecular-weight antioxidants (LMWA) may be the causative factor for increased anomalies

A disturbed embryonic antioxidant defense mechanism may play a major role in diabetes-induced teratogenesis. We therefore studied the antioxidant capacity of 10.5-day-old rat embryos and their yolk sacs after culture for 28 hr in vitro under diabetic conditions (3 mg/ml glucose, 2 mg/ml beta-hydroxybutyrate (BHOB) and 10 microg/ml of acetoacetate), as compared with control embryos in vitro. We found a high rate of congenital anomalies, decreased growth and protein content, and a decrease in the activity of both superoxide dismutase (SOD) and catalase (CAT) under diabetic conditions, as compared with controls. The reducing power, which reflects the concentration and type of water-soluble and of lipid-soluble low-molecular-weight antioxidants (LMWA), was measured by cyclic voltammetry. Generally, LMWA were reduced in the embryos and yolk sacs under diabetic conditions. In the water-soluble fraction of control embryos and yolk sacs, two peak potentials were found, indicating two major groups of LMWA, while only one peak potential was found under diabetic conditions, indicating that an entire group of LMWA is missing. HPLC studies have demonstrated a decrease in vitamin C (water-soluble fraction) and in vitamin E (lipid-soluble fraction) under diabetic culture conditions, and an increase in uric acid. Generally, the concentration of LMWA was higher in the embryos than in the yolk sac. LMWA concentration, protein content, and antioxidant enzyme activity were lower in the malformed experimental embryos than in experimental embryos without anomalies. The addition of vitamins C and E to the diabetic culture medium abolished the deleterious effects of the diabetic serum on the embryos. The disturbed antioxidant defense mechanism under diabetic conditions may be explained, at least in part, by a direct effect of diabetic metabolic factors on the activity of antioxidant enzymes and on the concentration of reducing equivalents. This, in turn, may be embryotoxic.

Reducing equivalents in the aging process

Reducing equivalents may play a major role in the aging process. These metabolites are responsible for the endogenous redox potential in the living cell which is kept under tight regulation. Among their various roles is the ability to donate electrons to reactive oxygen species and by doing so to scavenge them. Most of the reducing equivalents in the cell are molecules with low molecular weights, such as glutathione and NADH which are synthesized by the cell. Other members of this group, such as uric acid are produced as waste products, while others, such as ascorbic acid and tocopherol, are derived from the diet. We studied the role of these equivalents in the aging process in various rat tissues. We demonstrated that the reducing power of a tissue may reflect its antioxidant activity. We used cyclic voltammeter methodology in order to evaluate the overall reducing power of tissue homogenates and other biological fluids. It was found that reducing power changes during the aging process in a bell-shaped manner in liver, lungs and kidneys, but not in heart and brain. We also showed that skin possesses strong reducing power which decreases dramatically with age. A non-invasive procedure to evaluate the oxidation status and the antioxidant activity of skin was developed. Using this method we demonstrated that there is an accumulation of organic peroxide in old skin compared to young skin, supporting the free radical hypothesis of aging.

Changes of biological reducing activity in rat brain following closed head injury: a cyclic voltammetry study in normal and heat-acclimated rats

Reactive oxygen species (ROS) are normally generated in the brain during metabolism, and their production is enhanced by various insults. Low molecular weight antioxidants (LMWA) are one of the defense mechanisms of the living cell against ROS. The reducing capacity of brain tissue (total LMWA) was measured by cyclic voltammetry (CV), which records biological oxidation potential specific to the type of scavenger(s) present and anodic current intensity (Ia), which depends on scavenger concentration. In the present study, the reducing capacity of rat brain following closed head injury (CHI) was measured. In addition, CV of heat-acclimated traumatized rats was used to correlate endogenous cerebroprotection after CHI with LMWA activity. Sham-injured rat brains displayed two anodic potentials: at 350 +/- 50 mV (Ia = 0.75 +/- 0.06 microA/mg protein) and at 750 +/- 50 mV (Ia = 1.00 +/- 0.05 microA/mg protein). Following CHI, the anodic waves appeared at the same potentials as in the sham animals. However, within 5 min of CHI, the total reducing capacity was transiently decreased by 40% (p < 0.01). A second dip was detected at 24 h (60%, p < 0.005). By 48 h and at 7 days, the Ia levels normalized. The acclimated rats displayed anodic potentials identical to those of normothermic rats. However, the Ia of both potentials was lower (60% of control, p < 0.001). The Ia profile after CHI was the direct opposite of the normothermic Ia profile: no immediate decrease of Ia and an increase from 4 h and up to 7 days (40-50%, p < 0.001). We suggest that the lowered levels of LMWA in the post-CHI period reflect their consumption due to overproduction of free radicals. The augmented concentration of LMWA found in the brain of the heat-acclimated rats suggests that these rats are better able to cope with these harmful radicals, resulting in a more favorable outcome following CHI.

Evaluation of plasma low molecular weight antioxidant capacity by cyclic voltammetry

The low molecular weight antioxidants (LMWA) of biological samples include many compounds and contribute to the total antioxidant capacity of the system. They act as direct chemical scavengers neutralizing, reactive oxygen-derived species (ROS), and contribute to the ability of the sample to cope with oxidative stress. We propose cyclic voltammetry (CV) as a new method for evaluating the antioxidant capacity of plasma-LMWA and the severity of oxidative stress exerted on the plasma. It is based on the reducing properties of these molecules. CV has been proven to be a simple, sensitive and reliable method. Its tracing does not change during storage of frozen plasma for up to six months. We analyzed the CV tracings by the oxidation potential E1/2, and the current heights Ia of its anodic wave(s). E1/2 indicates the specific component of the LMWA and its ability to donate electron(s); Ia indicates the concentration of this component. Two anodic waves have been identified in human plasma, at E1/2 = 420 +/- 25 and 920 +/- 25 mV. Ascorbate (AA) and urate (UA) were identified as major LMWA components of the first anodic wave, and were confirmed by HPLC-electrochemical detection. Ia was shown to depend linearly on the concentration of either of these LMWA, both in buffer and in plasma. Oxidative stress exerted by exposure to peroxyl radicals, copper ions and ionizing irradiation caused marked changes in the CV tracing. These changes represent corresponding alterations particularly in la, rather than in E1/2. The Ia and E1/2 values reflect the antioxidant capacity of the plasma, while the change of Ia value represents the severity of the oxidative stress induced.

Neuroprotective and antioxidant activities of HU-211, a novel NMDA receptor antagonist

This study examines the ability of (+)-(3S,4S)-7-hydroxy-delta 6-tetrahydrocannabinol-1,1-dimethylheptyl (HU-211), a non-competitive NMDA receptor antagonist to: (1) rescue neurons in culture from injury evoked by sodium nitroprusside, hydrogen peroxide (H2O2) and oxygen glucose deprivation; and (2) scavenge reactive oxygen species in vitro. Qualitative and quantitative assessments of cell survival have indicated that: (1) Neuronal cell injury produced following deprivation of oxygen and glucose was significantly attenuated by 5 microM HU-211. (2) Glial and neuronal cell damage induced by sodium nitroprusside was markedly ameliorated by 10 microM HU-211. (3) HU-211 reduced protein oxidation initiated by gamma irradiation, and scavenged peroxyl radicals. (4) HU-211 carries an oxidation potential of 550 mV. These findings suggest that HU-211 holds a unique position among putative neuroprotectant agents in that it combines NMDA receptor antagonistic activity and free radical scavenging abilities in a single molecule.

Hydrogen peroxide: a review of its use in dentistry

Several dentifrices that contain hydrogen peroxide are currently being marketed. The increased use of bleaching agents containing (or generating) H2O2 prompted this review of the safety of H2O2 when used in oral hygiene. Daily exposure to the low levels of H2O2 present in dentifrices is much lower than that of bleaching agents that contain or produce high levels of H2O2 for an extended period of time. Hydrogen peroxide has been used in dentistry alone or in combination with salts for over 70 years. Studies in which 3% H2O2 or less were used daily for up to 6 years showed occasional transitory irritant effects only in a small number of subjects with preexisting ulceration, or when high levels of salt solutions were concurrently administered. In contrast, bleaching agents that employ or generate high levels of H2O2 or organic peroxides can produce localized oral toxicity following sustained exposure if mishandled. Potential health concerns related to prolonged hydrogen peroxide use have been raised, based on animal studies. From a single study using the hamster cheek pouch model, 30% H2O2 was referred to as a cocarcinogen in the oral mucosa. This (and later) studies have shown that at 3% or less, no cocarcinogenic activity or adverse effects were observed in the hamster cheek pouch following lengthy exposure to H2O2. In patients, prolonged use of hydrogen peroxide decreased plaque and gingivitis indices. However, therapeutic delivery of H2O2 to prevent periodontal disease required mechanical access to subgingival pockets. Furthermore, wound healing following gingival surgery was enhanced due to the antimicrobial effects of topically administered hydrogen peroxide. For most subjects, beneficial effects were seen with H2O2 levels above 1%.

The biological reductive capacity of tissues is decreased following exposure to oxidative stress: a cyclic voltammetry study of irradiated rats

The reductive capacity of rat tissue homogenates and body fluids was determined by cyclic voltammetric measurements. The reductive capacity of rat lung, liver and kidney homogenates was significantly reduced four days after total body gamma-ray irradiation with 5.5 Gy as compared to controls. In parallel, reduced ability of the irradiated organ homogenates to scavenge hydroxyl radicals and to destroy hydrogen peroxide was recorded. However, no difference in their superoxide dismutase activity was found. The possible use of cyclic voltammetry as a method for qualitative evaluation of the ability of biological tissues to cope with oxidative stress is discussed.