Ana Cláudia Dantas de Medeiros

Study Bioprospecting of Medicinal Plant Extracts of the Semiarid Northeast: Contribution to the Control of Oral Microorganisms

Dental pathologies can be caused by plaque-forming bacteria and yeast, which reside in the oral cavity. The bacteria growing in dental plaque, a naturally occurring biofilm, display increased resistance to antimicrobial agents. The objective was the evaluation of a preclinical assay of medicinal plants of the semiarid region from the northeast against oral pathogenic microorganism, aiming at bioprospecting a new product. The selection of plant material for this study was based on the ethnobotanical data on the traditional use of plants from the semiarid region. The thirty extracts were subjected to the determination of antibiofilm activity against gram-positive, gram-negative bacteria and yeast. The hydroalcoholic extract which showed positive antibiofilm activity against most of the microorganisms tested in agar diffusion assay was further tested for the determination of minimum inhibitory concentration (MIC) and Bioassay with Artemia salina. Plant samples tested in this study exhibited good antibiofilm activity for the treatment of oral problems. The Schinopsis brasiliensis showed greater activity for Pseudomonas aeruginosa and Staphylococcus aureus, but toxicity against Artemia salina.

In vitro evaluation of the root canal cleaning ability of plant extracts and their antimicrobial action

This in vitro study evaluated both the antimicrobial activity and the root canal cleaning ability of plant extracts used in irrigation solutions. The antimicrobial activities of the aroeira-da-praia (Schinus terebintifolius Raddi) and the quixabeira (Syderoxylum obtusifolium Roem & Schult) hydroalcoholic extracts, of 2.5% sodium hypochlorite (NaOCl) and of 0.12% chlorhexidine (positive control) against Enterococcus faecalis were tested with the agar well diffusion method. The level of root canal cleanliness was examined by scanning electron microscopy (SEM). Twenty one single-rooted human teeth were divided into three groups according to the irrigation solution applied: 1) 50% aroeira-da-praia; 2) 50% quixabeira and 3) a combination of 2.5% sodium hypochlorite + 17% EDTA. All solutions tested demonstrated antimicrobial activity against Enterococcus faecalis. The SEM analysis revealed that higher and lower degrees of surface cleaning were observed, in the three groups, respectively for the coronal and apical thirds, in that quixabeira showed the greatest efficiency in removing the smear layer in the apical third. All the agents tested presented antimicrobial activity against E. faecalis. None, however, was able to completely remove the smear layer of the dentinal surface in the different thirds of the root canal. The results suggest that the analyzed plant extracts may represent a new therapeutic option in the list of alternative agents available for endodontic treatment.

Sideroxylon obtusifolium herbal medicine characterization using pyrolysis GC/MS, SEM and different thermoanalytical techniques

This study aimed to characterize by analytical techniques Sideroxylon obtusifolium herbal medicine raw material derived from the leaves in different particle sizes, using scanning electron microscopy (SEM), thermoanalytical techniques [thermogravimetry (TG) and analysis differential thermal (DTA)] and pyrolysis coupled to gas chromatography/mass spectrometry (PYR-GC/MS). The different particle surface area among the samples was differentiated by the techniques. SEM distinguished the particles by its volumetric size, DTA and TG by the thermal and kinetic parameters and the PYR-GC/MS by degradation products chromatographic identification through the pyrograms.

Compatibility study between lipoic acid with polymers used in controlled drug release systems

Lipoic acid is derived from octanoic acid and is considered a universal antioxidant for combating free radicals and regeneration of endogenous antioxidant, as well as acting like an essential cofactor in multienzyme mitochondrial complex. In the pharmaceutical field, the polymers are among used excipients in pharmaceutical technology, especially in therapies controlled release of drugs. The aim of this study was to evaluate the drug–excipient compatibility between the AL and excipients used in controlled release drug delivery systems. To investigate the possible interactions between substances, was initially performed one screening with differential scanning calorimetry (DSC) to detect possible interactions, and analyses were performed by infrared spectroscopy (FTIR) to confirm the possible interactions. Based on the results of DSC and FTIR was found to be incompatible only with PVP-K30. Based on these results, we can conclude that the analytical tools used in this study are effective for defining incompatibilities between drugs and pharmaceutical excipients in order to ensure a new formulation with well-defined parameters of quality control and stability.

Antimicrobial and Antiproliferative Potential of Anadenanthera colubrina (Vell.) Brenan

The aim of the present study was to perform an in vitro analysis of the antimicrobial and antiproliferative potential of an extract from Anadenanthera colubrina (Vell.) Brenan (angico) and chemically characterize the crude extract. Antimicrobial action was evaluated based on the minimum inhibitory concentration (MIC), minimum bactericidal/fungicidal concentration, and the inhibition of formation to oral biofilm. Cell morphology was determined through scanning electron microscopy (SEM). Six strains of tumor cells were used for the determination of antiproliferative potential. The extract demonstrated strong antifungal activity against Candida albicans ATCC 18804 (MIC = 0.031 mg/mL), with similar activity found regarding the ethyl acetate fraction. The extract and active fraction also demonstrated the capacity to inhibit the formation of Candida albicans to oral biofilm after 48 hours, with median values equal to or greater than the control group, but the difference did not achieve statistical significance (P > 0.05). SEM revealed alterations in the cell morphology of the yeast. Regarding antiproliferative activity, the extract demonstrated cytostatic potential in all strains tested. The present findings suggest strong antifungal potential for Anadenanthera colubrina (Vell.) Brenan as well as a tendency toward diminishing the growth of human tumor cells.

Antifungal Activity, Phytochemical Characterization and Thermal Profile of Anadenanthera colubrina (Vell.) Brenan

Objective: To investigate the antifungal potential of A. colubrina , and its phytochemical characteristics, thermal profile and toxicity. Material and Methods: To assess potential antifungal activity, the technique of microdilution was used with the determination of the Minimum Inhibitory Concentration and Minimum Fungicidal Concentration, using standard species of Candida and recent clinical isolates of Candida albicans . Analyses of action of the extract were performed on the wall and cell morphology of C. albicans , of the interactive effect between the plant extract and nystatin on C. albicans through the checkerboard method, and of growth kinetics. The phytochemical screening was determined by spectrophotometry. The thermal profile was traced with the determination of thermogravimetric curves (TG) and differential scanning calorimetry (DSC). The toxicity was evaluated by the method of hemolysis. Results: The extract of A. colubrina showed a fungistatic potential against all bacteria tested and it acted by modifying the cellular morphology of C. albicans . There was a synergism between nystatin and the plant extract (FIC=0.375), and 53.18% of total polyphenols were determined. The TG curve showed the occurrence of three steps of thermal decomposition. None of the tested concentrations became the effective cytotoxic concentration. Conclusion: Further studies should be conducted to understand the efficacy and the mechanisms of action involved in the antifungal activity of the plant extract of A. colubrina in order to produce a new drug for the treatment of oral candidiasis.