Geraniol and linalool anticandidal activity, genotoxic potential and embryotoxic effect on zebrafish.

AIM: Geraniol and linalool are major constituents of the essential oils of medicinal plants. MATERIALS & METHODS: Antifungal activity of geraniol and linalool were evaluated against five Candida species. The genotoxicity of these compounds was evaluated by the cytokinesis-block micronucleus test, and the embryotoxic assays use zebrafish model. RESULTS: Geraniol and linalool inhibited Candida growth, but geraniol was more effective. The geraniol at concentration of 800 µg/ml and the linalool at concentration of 125 µg/ml significantly increased chromosome damage. Geraniol was more toxic to zebrafish embryo than linalool: LC50 values were 31.3 and 193.3 µg/ml, respectively. CONCLUSION: Geraniol and linalool have anticandidal activity, but they also exert genotoxic and embryotoxic effects at the highest tested concentrations.

Kaurenoic acid and its sodium salt derivative: antibacterial activity against Porphyromonas gingivalis and their mechanism of action.

AIM: To evaluate the antibacterial activity of 12 kaurane-type diterpenes against a panel of bacteria that cause endodontic infection. METHODS & MATERIALS: We conducted tests against bacteria in the planktonic or in the sessile mode, cytotoxic assays for the most promising compounds against human normal lung fibroblast cells, and Porphyromonas gingivalis (ATCC 33277) proteomic analysis. RESULTS & CONCLUSION: Kaurenoic acid and its salt exhibited satisfactory antibacterial action against the evaluated bacteria. Proteomic analysis suggested that these compounds might interfere in bacterial metabolism and virulence factor expression. Kaurane-type diterpenes are an important class of natural products and should be considered in the search for new irrigating solutions to treat endodontic infections.

Bioassay-guided fractionation and antimicrobial and cytotoxic activities of Cassia bakeriana extracts

ABSTRACT The antimicrobial potential of extracts of bark and leaves of Cassia bakeriana Craib, Fabaceae, against aerobic and anaerobic oral bacteria was evaluated by the microdilution broth method. For crude ethanol extracts and organic fractions tested, the bark dichloromethane phase showed a significant antibacterial effect, with MIC values ranging from 12.5 to 100 µg/ml for most of the microorganisms tested. Thus, a bioassay-guided fractionation of this fraction was performed. This fractionation led to isolation of the 1,8-dihydroxy-anthraquinone-3-carboxylic acid, also known as cassic acid or rhein. It is the first time that this bioactive anthraquinone has been isolated from this plant. Rhein exhibited good selectivity and high activity against anaerobic microorganisms, with MIC values ranging between 3.12 µg/ml (11.0 µM) and 25 µg/ml (88.0 µM). These results were considered very promising since the most active samples and rhein showed greater selectivity against oral microorganisms than toxicity to Vero cells.

Antibacterial activity of (-)-cubebin isolated from Piper cubeba and its semisynthetic derivatives against microorganisms that cause endodontic infections

Abstract Recent publications have highlighted the numerous biological activities attributed to the lignan (-)-cubebin (1), Piper cubeba L. f., Piperaceae, and ongoing studies have focused on its structural optimization, in order to obtain derivatives with greater pharmacological potential. The aim of this study was the obtainment of (1), its semisynthetic derivatives and evaluation of antibacterial activity. The extract of the seeds of P. cubeba was chromatographed, subjected to recrystallization and was analyzed by HPLC and spectrometric techniques. It was used for the synthesis of: (-)-O-methylcubebin (2), (-)-O-benzylcubebin (3), (-)-O-acetylcubebin (4), (-)-O-(N, N-dimethylamino-ethyl)-cubebin (5), (-)-hinokinin (6) and (-)-6.6'-dinitrohinokinin (7). The evaluation of the antibacterial activity has been done by broth microdilution technique for determination of the minimum inhibitory concentration and the minimum bactericidal concentration against Porphyromonas gingivalis, Prevotella nigrescens, Actinomyces naeslundii, Bacteroides fragilis and Fusobacterium nucleatum. It was possible to make an analysis regarding the relationship between structure and antimicrobial activity of derivatives against microorganisms that cause endodontic infections. The most promising were minimum inhibitory concentration =50 µg/ml against P. gingivalis by (2) and (3), and minimum inhibitory concentration =100 µg/ml against B. fragilis by (6). Cytotoxicity assays demonstrated that (1) and its derivatives do not display toxicity.

RP-HPLC analysis of manool-rich Salvia officinalis extract and its antimicrobial activity against bacteria associated with dental caries

In this paper we screened the dichloromethane extract from the aerial parts of Salvia officinalis L., Lamiaceae, against a representative panel of microorganisms that cause caries, conducted a bioassay-guided fractionation to establish themselves the most active metabolite (manool) and determined the Salvia officinalis fraction with the manool highest concentration to be used to activate an ingredient in oral care products such as toothpastes and mouthwashes. Both manool and S. officinalis extract showed very promising minimal inhibitory concentration values (between 6.24 and 31.36 µg.ml-1) and time kill curves against the primary causative agents of dental caries (Streptococcus mutans) revealed that, at twice its minimal bactericidal concentration (12.48 µg.ml-1), manool required 6 h to completely kill the bacteria. Salvia officinalis extract at twice its minimal bactericidal concentration (31.36 µg.ml-1 ) needed 12 h. The results achieved with Salvia officinalis extract motivated us to develop and validate an analytical RP-HPLC method to detect and determine manool in this extract. The validation parameters were satisfactorily met and evaluated allows us to consider the developed method suitable for use in different labs. In conclusion, our results evidenced that the manool-rich S. officinalis extract can be considered an analytically validated alternative to develop novel and effective antimicrobial agents against the main bacteria responsible for dental caries.