Chemical profile and biological properties of the Piper corcovadense C.DC. essential oil.

The essential oil from Piper corcovadense D.DC. (EOPc), an important plant belonging to the Piperaceae family, which is commonly found in the northern region of Brazil and poorly explored scientifically, was used in this study. Thus, the EOPc was characterized chemically by Gas Chromatography/Mass Spectrometry (GC/MS) and the antioxidant and antimicrobial activities and their potential effects on cutaneous melanoma (SK-MEL-28) and healthy peripheral blood mononuclear (PBMC) cells were determined. The major compounds identified in the EOPc were: trans-sesquisabinene hydrate, trans-caryophyllene, ß-pinene, trans-ß-farnesene, 14-hydroxycaryophyllene, limonene and p-cymene. The EOPc demonstrated antioxidant activity as evaluated by Folin-Ciocalteu reagent (FC) reducing capacity, DPPH, and ABTS methods. The values found were respectively 5.41 ± 0.17 mg GAE mL-1 (GAE: Gallic acid equivalent), 2.88 ± 0.17 µmol TE mL-1 (TE: Trolox equivalent) and 6.26 ± 0.02 µmol TE mL-1. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for different bacterial strains. The EOPc at a concentration of 2.61 µg mL-1 exhibited both bactericidal and bacteriostatic properties against Escherichia coli. The EOPc showed potential antitumor activity as it reduced the cell viability of human cutaneous melanoma cells SK-MEL-28. Besides, the EOPc did not exhibit cytotoxic activity against healthy PBMCs, indicating that it does not harm healthy cells at the tested concentrations. The EOPc increased the levels of ROS at concentrations of 250 µg mL-1. The EOPc also did not stimulate the mobilization of endogenous antioxidant defenses, as assessed by total thiol (PSH) and non-protein thiols (NPSH). Thus, the study suggests that the EOPc has antioxidant and antimicrobial properties due to the presence of specific compounds. It also exhibits antitumor potential against cutaneous melanoma cells while showing no cytotoxicity to healthy PBMCs. It directly influenced ROS levels at the highest tested concentration in the cells, suggesting an antitumor effect related to the intrinsic apoptosis pathway. Nevertheless, while the study has initial findings, the results are promising and indicate an attractive biological potential of P. corcovadense, mainly in human cutaneous melanoma cells.

Chemical Characterization, Antioxidant Capacity and Antimicrobial Potential of Essential Oil from the Leaves of Baccharis oreophila Malme.

This is the first time that composition, antimicrobial potential and antioxidant ability of essential oil from the leaves of Baccharis oreophila are reported. Essential oil was obtained by hydrodistillation and analyzed by GC/MS. Antimicrobial potential was evaluated by diffusion disk and broth microdilution methods. ABTS.+ , DPPH. and FRAP methods were employed for antioxidant activity evaluation. Essential oil yield was 0.47 %. Sixty-five compounds were identified, representing 88.53 % of the total essential oil, which showed to be rich in oxygenated (37.88 %) and hydrocarbons sesquiterpenes (34.84 %). The main constituents were khusimone (16.37 %) and spathulenol (16.12 %). Antimicrobial activity was verified against S. aureus (10.33±0.5 mm, MIC: 1250 µg mL-1 ) and C. albicans (8.66±0.5 mm, MIC: >2500 µg mL.1 ). Antioxidant ability was evidenced by FRAP (4.09 µmol FeSO4 E mL-1 ), ABTS.+ (1.45 µmol TE mL-1 ) and DPPH. (1.04 µmol TE mL-1 ) scavenging capacity. Results showed that this essential oil has interesting biological potential, encouraging further investigations especially in relation to action mechanisms of antimicrobial and antioxidant activity.