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Introduction: Coffea arabica L. leaves are considered a by-product of the coffee industry however they are sources of several bioactive compounds., Objectives: This study aimed to evaluate the chemical composition and the in vitro antibacterial activity of the lyophilised ethanol extract of arabica coffee leaves (EE-CaL)., Material and Methods: The chemical characterisation of EE-CaL was performed using ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-ToF-MS/MS). The in vitro antibacterial effect of EE-CaL was evaluated using the broth microdilution method and the adapted drop plate agar method to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC), respectively., Results: The chemical analysis of EE-CaL revealed the presence of compounds from the alkaloid class, such as trigonelline and caffeine, in addition to the phenolic compounds such as quinic acid, 5-caffeoylquinic acid, caffeic acid-O-hexoside, mangiferin, (epi)catechin, (epi)catechin monoglucoside and procyanidin trimer. Regarding the antibacterial potential, EE-CaL was active against Gram-positive and Gram-negative bacteria, being more effective against Escherichia coli (ATCC 25922) (MIC = 2500 μg/mL and bactericidal effect)., Conclusion: The results of this research suggest that coffee leaves, a by-product, possess compounds with antibacterial properties. Thus, further studies with coffee leaf extracts must be carried out to relate the compounds present in the extract with the antibacterial activity and find the mechanisms of action of this extract against bacteria., (© 2022 John Wiley & Sons Ltd.)

Kalanchoe brasiliensis Cambess. is a native Brazilian plant popularly known as "saião", and the juice of its fresh leaves is traditionally used to treat several disorders, including inflammatory and infectious processes such as dysentery. The goals of this study were to characterize the phytochemical composition and investigate the antioxidant activity, the antibiotic effect, and the mode of action against Salmonella of the hydroethanolic extracts from K. brasiliensis leaves collected in the summer and spring Brazilian seasons. These extracts had their chemical composition established by high-performance liquid chromatography with diode-array detection. Total phenolic and flavonoid contents were spectrophotometrically determined. 2,2-Diphenyl-1-picryl-hydrazyl radical scavenging, phosphomolybdenum reducing power and β -carotene bleaching assays were carried out to evaluate the antioxidant capacity. Antibiotic potential was assessed by minimal inhibitory concentration against 8 bacterial ATCC® and 5 methicillin-resistant Staphylococcus aureus and 5 Salmonella clinical strains. The mode of action was investigated by time-kill, bacterial cell viability, and leakage of compounds absorbing at 280 nm assays against Salmonella . Chromatographic profile and UV spectrum analyses suggested the significant presence of flavonoid type patuletin and eupafolin derivatives, and no difference between both periods of collection was noted. Significant amounts of total phenolic and flavonoid contents and a promising antioxidant capacity were observed. Hydroethanolic extracts (70%, summer and spring) were the most active against the tested Gram-positive and Gram-negative bacterial strains, showing the bacteriostatic action of 5000 μ g/mL. Time-kill data demonstrated that these extracts were able to reduce the Salmonella growth rate. Cell number was reduced with release of the bacterial content. Together, these results suggest that K. brasiliensis is a natural source of antioxidant and antibacterial agents that can be applied in the research and development of new antibiotics for the treatment of Salmonella gastroenteritis because they are able to interfere in the Salmonella growth, probably due to cell membrane damage., Competing Interests: The authors declare that they have no conflict of interest regarding the publication of this research article., (Copyright © 2019 Oscar Alejandro Santos Mayorga et al.)