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Polygonum hydropiperoides Michx. is an Asian native plant species that is also widely distributed in the Americas. Despite its traditional uses, P. hydropiperoides is scarcely scientifically exploited. This study aimed to chemically characterize and investigate the antioxidant and antibacterial activities of hexane (HE-Ph), ethyl acetate (EAE-Ph), and ethanolic (EE-Ph) extracts from aerial parts of P. hydropiperoides. The chemical characterization was performed through HPLC-DAD-ESI/MSn. The antioxidant activity was assessed by the phosphomolybdenum reducing power, nitric oxide inhibition, and the β-carotene bleaching assays. The antibacterial activity was determined by the minimal inhibitory concentration (MIC) and the minimal bactericidal concentration followed by the classification of the antibacterial effect. Chemical characterization revealed the expressive presence of phenolic acids and flavonoids in EAE-Ph. An increased antioxidant capacity was revealed in EAE-Ph. Regarding antibacterial activity, EAE-Ph showed weak to moderate property against 13 strains tested with MIC values ranging from 625 to 5000 µg/mL, with bactericidal or bacteriostatic effects. Glucogallin and gallic acid stand out as the most relevant bioactive compounds. These results suggest that P. hydropiperoides is a natural source of active substances, supporting this species' traditional use. [ABSTRACT FROM AUTHOR]

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. Coffea arabica L. leaves are considered a by‐product of the coffee industry however they are sources of several bioactive compounds. 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). The results of this research suggest that coffee leaves, a by‐product, contains compounds with antibacterial properties. Furthermore, this is the first time that caffeic acid‐O‐hexoside, (epi)catechin monoglucoside and procyanidin trimer have been detected in coffee leaves. [ABSTRACT FROM AUTHOR]