Brazil has the greatest plant diversity in the world. Many species exhibit a wide range of phytochemical compounds which can be exploited in food, agronomic, pharmacological and medicinal plant industries. Therefore, the chemical composition and in vitro bioactivities of volatile oil from Psidium firmum fresh leaves (PfVO) were investigated for the first time. GC-FID and GC-MS analyses revealed 28 compounds in PfVO. The major ones were α-selinene (20.8%), β-caryophyllene (16.5%) and nerolidol (10.4%). Results showed that PfVO affected the growth of Leishmania amazonensis promastigote forms in a dose-dependent manner; its IC50 value was 14.05 µg/mL. PfVO also exhibited antibacterial activity against Salmonella enteritidis, Yersinia enterocolitica, Staphylococcus aureus, Pseudomonas aeruginosa and Listeria monocytogenes; MIC values ranged from 25 μg/mL to 250 μg/mL. Moreover, PfVO promoted normal cell growth inhibition at 61.02 ± 1.97 µg/mL. Antiproliferative activity was observed against human tumor cell lines; IC50 values of MCF-7 cells, HeLa cells and M059J cells were 47.91 µg/mL, 73.78 µg/mL and 41.94 µg/mL, respectively. Results provided strong evidence of the promising potential of PfVO as a nature-based antileishmanial, antibacterial and antiproliferative agent.

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.