Essential Oil from Psidium cattleianum Sabine (Myrtaceae) Fresh Leaves: Chemical Characterization and in vitro Antibacterial Activity Against Endodontic Pathogens

Abstract Endodontic infections result from oral pathogenic bacteria which reach and infect dental pulp, as well as surrounding tissues, through cracks, unrepaired caries and failed caries restorations. This study aims to determine the chemical composition of essential oil from Psidium cattleianum leaves (PC-EO) and to assess its antibacterial activity against endodontic bacteria. Antibacterial activity of PC-EO was evaluated in terms of its minimum inhibitory concentration (MIC) values by the broth microdilution method on 96-well microplates. Bacteria Porphyromonas gingivalis (MIC = 20 µg/mL), Prevotella nigrescens (MIC = 62.5 µg/mL), Fusobacterium nucleatum (MIC = 12.5 µg/mL), Actinomyces naeslundii (MIC = 50 µg/mL), Bacteroides fragilis (MIC = 12.5 µg/mL), Aggregatibacter actinomycetemcomitans (MIC = 6.25 µg/mL) and Peptostreptococcus anaerobius (MIC = 62.5 µg/mL) were evaluated and compared to chlorhexidine dihydrochloride (CDH), the positive control. PC-EO was obtained by hydrodistillation with the use of a Clevenger-type apparatus whereas its chemical composition was analyzed by gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Viridiflorol (17.9%), β-caryophyllene (11.8%), 1,8-cineole (10.8%) and β-selinene (8.6%) were the major constituents found in PC-EO, which exhibited high antibacterial activity against all endodontic pathogens under investigation. Therefore, PC-EO, a promising source of bioactive compounds, may provide therapeutic solutions for the field of endodontics.

Phytochemical screening of extracts from Spiranthera odoratissima A. St.-Hil. (Rutaceae) leaves and their in vitroantioxidant and anti-Listeria monocytogenes activities

Spiranthera odoratissima A. St.-Hil (Rutaceae), a shrub whose common name is manacá do Cerrado in Brazilian Portuguese, is about 1-m high and has been used by folk medicine to treat stomachache, kidney and liver infections, headache, rheumatism and as a blood purifier. This study aimed at preparing hexane, ethyl acetate, methanolic, hydroethanolic and aqueous extracts from S. odoratissima leaves, at carrying out preliminary phytochemical screening and at evaluating their in vitroantioxidant and anti-Listeria monocytogenesactivities. Antioxidant activity was evaluated by the DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2-azinobis-3-ethybenzothiazoline-6-sulfonate) and FRAP (ferric reducing antioxidant power) methods. Antibacterial activity was investigated against L. monocytogenesand Minimum Inhibitory Concentration (MIC) values of plant extracts were calculated by the broth microdilution method with the use of 96-well plates. In aqueous, methanolic, hydroethanolic, ethyl acetate and hexane extracts from S. odoratissima leaves, the following classes of compounds were investigated: organic acids, reducing sugars, flavonoids, saponin compounds, coumarin compounds, phenolics, tannins, purine compounds, catechins, flavonol derivatives, sesquiterpene lactonesand anthraquinones. All plant extracts, except the hexane one, exhibited high antioxidant activity. Regarding antibacterial activity, the most polar extracts showed high activity against L. monocytogenes; their MIC values ranged between 12.5 and 62.5 μg mL-1, while the hexane one exhibited low activity (MIC = 1000 μgmL-1). In short, extracts from S. odoratissima leaves may be consideredpromising sources of secondary metabolites with relevant antioxidant and antibacterial activities.