Chemical Composition and Antibacterial Activity of the Essential Oil of <em>Mesosphaerum suaveolens</em> (Lamiaceae)

Mesosphaerum suaveolens (Lamiaceae) is a medicinal plant commonly used in Brazil for the treatment of diseases related to the digestive tract and respiratory diseases, so we hypothesized that the essential oil of this species may have antibacterial activity. Thus, we aimed to evaluate the in vitro antibacterial and modulatory activity of the essential oil of M. suaveolens as well as to characterize its chemical composition. The identification of the constituents was performed by gas chromatography-flame ionization detector (GC-FID) and the antibacterial and modulating activity by the plate microdilution method. We found the oil had sesquiterpene β-caryophyllene as the major component. This compound may account for the antibacterial activity against Staphylococcus aureus strains, since the essential oil had a MIC of 64 μg/mL for the standard strain and 256 μg/mL for the multiresistant strain, demonstrated that the oil does not exhibit drug modulating activity. Thus, M. suaveolens oil has bioactive compounds which can be used in the preparation of drugs

Phytochemical Analysis, Antibacterial Activity and Modulating Effect of Essential Oil from Syzygium cumini (L.) Skeels

One of the main global problems that affect human health is the development of bacterial resistance to different drugs. As a result, the growing number of multidrug-resistant pathogens has contributed to an increase in resistant infections and represents a public health problem. The present work seeks to investigate the chemical composition and antibacterial activity of the essential oil of Syzygium cumini leaves. To identify its chemical composition, gas chromatography coupled to mass spectrometry was used. The antibacterial activity test was performed with the standard strains Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 25853 and Staphylococcus aureus ATCC 25923 and multidrug-resistant clinical isolates E. coli 06, P. aeruginosa 24 and S. aureus 10. The minimum inhibitory concentration (MIC) was determined by serial microdilution as well as the verification of the modulating effect of the antibiotic effect. In this test, the oil was used in a subinhibitory concentration. The test reading was performed after 24 h of incubation at 37 &deg;C. The results show that the major chemical constituent is &alpha;-pinene (53.21%). The oil showed moderate activity against E. coli ATCC 25922, with the MIC of 512 &micro;g/mL; there was no activity against the other strains. The oil potentiated the effect of antibiotics demonstrating possible synergism when associated with gentamicin, erythromycin and norfloxacin against E. coli 06 and S. aureus 10