Bioactivity and phenolic characterization of different medicinal and aromatic plants

Abstract

Introduction: Plants are widely used to treat various diseases and have been widely recognized as a rich source of phytochemicals with antimicrobial potential. In fact, plants have received considerable attention by researchers being their biological properties widely explored. Hypothesis and aims: Medicinal and aromatic plants are known to have a wide range of uses and health benefits, and should be exploited concerning their bioactivity. Therefore, the antimicrobial activity of Satureja montana L., Origanum majorana L., Allium schoenoprasum L. and Anethum graveolens L. were evaluated and its phytochemical composition was profiled. Methodology: The antimicrobial susceptibility of Gram-positive and Gram-negative bacteria to four decoction and hydroethanolic (80:20, v/v) extracts, obtained from medicinal and aromatic plants (S. montana , O. majorana , A. schoenoprasum and A. graveolens ), was assessed aiming to identify the active extracts and the most effective were then tested against biofilms. Furthermore, the decoctions were characterized in terms of phenolic compounds by HPLC-DAD-ESI/MSn. Results: Overall, S. montana and O. majorana extracts were the most effective against Gram-positive (Staphylococcus aureus , Enterococcus faecalis and Streptococcus dysgalactiae ) and Gram-negative (Klebsiella pneumonia and Pseudomonas aeruginosa ) bacteria, with decoction presenting the most pronounced effects. O. majorana and S. montana decoction, at minimum inhibitory concentrations, were significantly effective against planktonic cells of S. aureus ATCC 25923. Concerning biofilm cells, S. montana promoted a slight antimicrobial activity against S. aureus ATCC 25923. A total of twentyfour phenolic compounds (9 phenolic acids and 15 flavonoids glycosides) were identified in S. montana and O. majorana decoctions, being rosmarinic acid the main molecule in the extracts. Conclusion: This study confirmed the bioactive potential of the medicinal and aromatic herbs, being S. montana and O. majorana decoction extracts those that showed the most promising applicability for the development of novel formulations with antimicrobial properties.