Antifungal response of oral-associated candidal reference strains (American Type Culture Collection) by supercritical fluid extract of nutmeg seeds for geriatric denture wearers: An in vitro screening study

A Temporary Acrylic Soft Denture Lining Material Enriched with Silver-Releasing Filler-Cytotoxicity, Mechanical and Antifungal Properties

Colonization of temporary denture soft linings and underlying tissues by yeast-like fungi is an important clinical problem due to the negative influence on the process of prosthetic treatment. Typical hygienic procedures are often insufficient to prevent fungal infections, so in this study, an antimicrobial filler (silver sodium hydrogen zirconium phosphate) was introduced into acrylic soft liner at concentrations of 1, 2, 4, 6, 8 and 10% (w/w). The effect of this modification on antifungal properties against Candida albicans, cytotoxicity, Shore A hardness, tensile strength and tensile bond strength, sorption and solubility was investigated, considering the recommended 30-day period of temporary soft lining use. The most favorable compilation of properties was obtained at a 1 to 6% filler content, for which nearly a total reduction in Candida albicans was registered even after 30 days of sample storing. The tensile and bond strength of these composites was at the desired and stable level and did not differ from the results for the control material. Hardness increased with the increasing concentration in filler but were within the range typical for soft lining materials and their changes during the experiment were similar to the control material. The materials were not cytotoxic and sorption and solubility levels were stable.

In Vitro Activity of Caffeic Acid Phenethyl Ester against Different Oral Microorganisms

This was an in vitro study that aimed to evaluate the antimicrobial effect of the propolis extract caffeic acid phenethyl ester (CAPE) on four different oral microorganisms. Seven different concentrations of CAPE (0.2, 0.5, 1, 1.5, 2, 3, and 4 mg/mL) for use against Staphylococcus aureus, Streptococcus mutans, Streptococcus oralis, and Streptococcus salivarius were determined using minimum inhibition concentration (MIC), minimum bactericidal concentration (MBC), broth microdilution, and well diffusion tests over 1, 3, 6, 12, and 24 h, while NaF at 0.05 percent was used as a positive control. Staphylococcus aureus was most affected by CAPE’s inhibitory effect on bacterial growth, whereas S. mutans was the least affected. S. mutans and S. oralis had similar CAPE MIC and MBC values of 1 mg/mL and 1.5 mg/mL, respectively. The most resistant bacteria to CAPE were S. salivarius and S. aureus, with MIC and MBC values of 3 mg/mL and 4 mg/mL, respectively. S. oralis, followed by S. salivarius, S. mutans, and S. aureus, had the highest viable count following exposure to CAPE’s MBC values, while S. aureus had the lowest. The current results of the inhibitory effect of CAPE on bacterial growth are promising, and the values of both CAPE MBC and MIC against the related four cariogenic bacterial organisms are significant. CAPE can be employed as an adjunct dental hygiene substance for maintaining good oral hygiene, and has a potential therapeutic effect in the field of oral health care.

Evaluation of the Antimicrobial Effect of Thymoquinone against Different Dental Pathogens: An In Vitro Study

This study aimed to evaluate the antimicrobial effect of Thymoquinone (TQ) on four different oral microorganisms. Minimum Bactericidal Concentration (MBC), Minimum Inhibition Concentration (MIC), Broth microdilution, and Well diffusion tests were used to determine the optimum antimicrobial concentrations of TQ against Streptococcus salivarius, Streptococcus oralis, Streptococcus mutans, and Staphylococcus aureus over 1, 3, 6, 12 and 24 h. Chlorhexidine 0.12% was selected as a positive control. The inhibitory effect of TQ on bacterial growth was most noticeable with S. salivarius, while the least affected was S. aureus. TQ’s MBC and MIC for S. oralis and S. aureus were comparable 2 mg/mL and 3 mg/mL, respectively. S. salivarius was most resistant to TQ and displayed a value of 5 mg/mL and 4 mg/mL for MIC and MBC, respectively. The viable count of different strains after exposure to TQ’s MBC values was most noticeable with S. aureus followed by S. oralis and S. mutans, while S. salivarius was least affected. This study emphasized the promising antimicrobial effect of TQ against the four main oral microorganisms. It has a potential preventive effect against dental caries as well as other oral diseases.

Anti-melanogenic activity of Myristica fragrans extract against Aspergillus fumigatus using phenotypic based screening

Background

Aspergillus fumigatus, an opportunistic fungal pathogen is associated with a wide array of diseases. It produces 1, 8-dihydroxy naphthalene (DHN) melanin that imparts greenish grey color to conidia and is an important virulence factor. It masks various molecular patterns associated with A. fumigatus and protects the fungus from host immune system. Myristica fragrans, enriched with secondary metabolites has been traditionally used for the treatment of infectious and inflammatory diseases. The present study was aimed to explore the anti-melanogenic effect of M. fragrans extracts on A. fumigatus.

Methods

M. fragrans extracts (hexane, chloroform, methanol and ethanol) were prepared through polarity guided extraction. Phytochemical analysis was performed to detect the chemical constituents of the extracts. The minimum effective concentration (MEC) of the extracts against A. fumigatus melanin was determined by broth micro-dilution assay. Various virulence factors were assayed by spectrophotometric methods. Electron microscopic studies were performed to evaluate the effect of the hexane extract of M. fragrans on A. fumigatus cell surface morphology. The major active compounds of the extract were detected by gas chromatography-mass spectrometry (GC-MS). Docking was performed to study the interaction between the major identified compounds and the ketosynthase domain of polyketide synthase protein.

Results

The results indicated that the hexane extract of M. fragrans inhibited melanin production (76.09%), reduced ergosterol content (83.63%) and hydrophobicity of the cell (72.2%) at the MEC of 0.078 mg/mL. Altered conidial surface, disappearance of protrusions and absence of melanin layer on outer cell surface was observed in electron microscopy. Forty-two compounds were identified by GC-MS. The main constituents were identified as sabinene (12.2%), linoleic acid (11.7%), hexadecanoic acid (10.5%), safrole (8.1%) and elemicin (7.8%). Docking studies revealed that hexadecanoic acid, its derivative compound cis-9-hexadecenal and isoeugenol have lower binding energy forming proper hydrogen bond with ketosynthase domain of polyketide synthase protein.

Conclusion

The study concludes that the extract of M. fragrans has potential antifungal properties that can be explored in combination with available antifungals. This combination approach may be helpful for large number of patients suffering with A. fumigatus infections.

Effect of Silver-Emitting Filler on Antimicrobial and Mechanical Properties of Soft Denture Lining Material

Colonization of silicone-based soft lining materials by pathogenic yeast-type fungi is a common problem associated with the use of dentures. In this study, silver sodium hydrogen zirconium phosphate (SSHZP) was introduced into polydimethylsiloxane-based material as an antimicrobial filler at concentrations of 0.25, 0.5, 1, 2, 4, 6, 8, 10, 12, and 14% (w/w). The in vitro antimicrobial efficacy was investigated. Candida albicans was used as a characteristic representative of pathogenic oral microflora. Staphylococcus aureus and Escherichia coli were used as the typical Gram-positive and Gram-negative bacterial strains, respectively. The effect of filler addition on the Shore A hardness, tensile strength, tensile bond strength, sorption, and solubility was investigated. An increase in the filler concentration resulted in an increase in hardness, sorption, and solubility, and for the highest concentration, a decrease in bond strength. The favorable combination of antimicrobial efficacy with other properties was achieved at filler concentrations ranging from 2% to 10%. These composites exhibited mechanical properties similar to the material without the antimicrobial filler and enhanced in vitro antimicrobial efficiency.