Libyan Thymus capitatus essential oil: antioxidant, antimicrobial, cytotoxic and colon pathogen adhesion-inhibition properties.

AIMS: In the present work, the Libyan wild-growing Thymus capitatus essential oil (EO) was evaluated for its biological properties. METHODS AND RESULTS: Carvacrol (68.19%) and thymol (12.29%) were found to be the main compounds of the oil. Antioxidant properties, determined by 2,2-diphenylpicrylhydrazyl (DPPH) assay, revealed that IC50 values were 119, 403 and 105 µg ml(-1) for oil, thymol and carvacrol respectively. Microdilution method showed strong antibacterial and especially antifungal potential. Tetrazolium (MTT) colorimetric assay indicated moderate cytotoxicity towards human cell lines MRC-5, HCT 116 and HT-29 (IC50 = 30-150 µg ml(-1)). In adhesion-inhibition assay oil and main compounds reduced adhesion of Escherichia coli and Listeria monocytogenes on colon cells HT-29 (51 and 39% of inhibition against L. monocytogenes and E. coli respectively). CONCLUSIONS: Essential oil of Th. capitatus showed moderate cytotoxic activity, together with excellent antimicrobial effect, in particular against fungi, and significant potential to reduce pathogen colonization in colon. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report that EO of Th. capitatus could protect against colonization of pathogens to colon epithelium. Thymus capitatus from Libya should be recognized as possible new source of natural antioxidants, antimicrobials as well as possible source of new chemotherapeutics.

Biocompatibility of new nanostructural materials based on active silicate systems and hydroxyapatite: in vitro and in vivo study.

AIM: To evaluate in vitro cytotoxicity and in vivo inflammatory response to new nanostructural materials based on active calcium silicate systems (CS) and hydroxyapatite (HA-CS). METHODOLOGY: Cytotoxicity of eluates of new nanostructural noncommercial materials CS and HA-CS, and MTA (White MTA, Angelus(®) Soluções Odontológicas, Londrina, Brazil) as a control, were tested using the MTT assay on MRC-5 cells. Eluates of set materials were tested in 100% and 50% concentrations, 24 h, 7 days and 21 days post-elution. The pH values were determined for undiluted eluates of set materials. Polyethylene tubes containing the test materials (CS, HA-CS, MTA) were implanted in subcutaneous tissue of Wistar rats. Histopathological examinations were conducted at 7, 15, 30 and 60 days after the implantation. Data were statistically analyzed using three-way and one-way anova Tukey's post hoc test as well as Kruskall-Wallis test with Dunn's post hoc test at α = 0.05. RESULTS: All materials significantly reduced cell viability; especially when undiluted eluates were used (P < 0.001). After 24 h elution, cell viability was 10 ± 1.8%, 49.5 ± 4.2% and 61 ± 7.4%, for MTA, and HA-CS, respectively. However, CS and HA-CS were significantly less toxic than the control material MTA (P < 0.05). Cytotoxicity could be at least partially attributed to pH kinetics over time. Dilution of eluates of all tested materials resulted in better cell survival. Histopathological examination indicated similar inflammatory reaction, vascular congestion and connective tissue integrity associated with CS, HA-CS and MTA at each observation period (P > 0.05). The only significant difference was found for capsule thickness, that is thicker capsule was associated with HA-CS compared to MTA at 60 days (P = 0.0039). HA-CS induced moderately thick capsules (median score 3, score range 2-3), whereas MTA resulted in thin capsule formation (median score 2, score range 1-3). CONCLUSIONS: Evaluation of cytotoxicity and inflammatory response indicated better biocompatibility of CS and HA-CS, in comparison with MTA (White MTA, Angelus(®) Soluções Odontológicas, Londrina, Brazil).

New nanostructural biomaterials based on active silicate systems and hydroxyapatite: characterization and genotoxicity in human peripheral blood lymphocytes.

AIM: To characterize and investigate the genotoxic effect of a new endodontic cement based on dicalcium- and tricalcium-silicate (CS) with hydroxyapatite (HA) on human lymphocytes. METHODOLOGY: Hydrothermal treatment was applied for synthesis of CS and HA. The final mixture HA-CS, with potential to be used in endodontic practice, is composed of CS (34%) and HA (66%). Human lymphocytes were incubated with HA, HA-CS and CS for 1 h, at 37 °C and 5% CO2. Cell viability was determined using the trypan blue exclusion assay. To evaluate the level of DNA damage comet assay (single cell gel electrophoresis) was performed. For the statistical analysis anova and Duncan's Post Hoc Test were used. RESULTS: The SEM analysis indicated that CS consisted mostly of agglomerates of several micrometers in size, built up from smaller particles, with dimensions between 117 and 477 nm. This is promising because dimensions of agglomerates are not comparable with channels inside the cell membranes, whereas their nano-elements provide evident activity, important for faster setting of these mixtures compared to MTA. Values of DNA damage obtained in the comet assay indicated low genotoxic risk of the new endodontic materials. CONCLUSIONS: The significantly improved setting characteristics and low genotoxic risk of the new material support further research.

Protective effect of linalool, myrcene and eucalyptol against t-butyl hydroperoxide induced genotoxicity in bacteria and cultured human cells.

We studied the protective effect of monoterpenes myrcene, eucalyptol and linalool against t-butyl hydroperoxide (t-BOOH) induced genotoxicity in reverse mutation assay with Escherichia coli WP2 IC185 strain and its oxyR mutant IC202, and with the comet assay in human hepatoma HepG2 and human B lymphoid NC-NC cells. The monoterpenes were tested in concentration ranges 0.05-1.5 mg/plate and 0.01-1.0 microg/ml in bacteria and mammalian cells, respectively. Suppression of t-BOOH induced mutagenesis was detected only in IC202 strain, and correlated with the observed inhibition of lipid peroxidation by the three monoterpenes. Linalool and myrcene strongly suppressed t-BOOH induced mutagenesis. Eucalyptol, in addition to moderate suppression of t-BOOH induced mutagenesis, suppressed also spontaneous mutagenesis. In NC-NC cells linalool and myrcene reduced t-BOOH induced DNA damage by about 50% at 0.01 microg/ml, while eucalyptol was less efficient (about 50% reduction at 1.0 microg/ml). In HepG2 cells linalool and eucalyptol reduced DNA damage by 30% and 40%, respectively, while myrcene was ineffective. The repair of t-BOOH induced DNA damage, studied in HepG2 cells, was not affected by monoterpenes. The results indicate that linalool, eucalyptol and myrcene have substantial protective effect against oxidant induced genotoxicity, which is predominately mediated by their radical scavenging activity.