Phytochemistry, Antimicrobial, and Antibiofilm Properties of Malagasy Helichrysum manopappoides Essential Oil

: Helichrysum Mill. is one of the largest genera in the Asteraceae family, and in Madagascar, a plant paradise with ca 14,000 species, 111 Helichrysum species are known, 110 of which are endemic. In this work, the essential oil of endemic Helichrysum manopappoides Humbert, obtained by steam distillation, was investigated chemically and biologically. The spectrometric data obtained by GC-MS (Gas Chromatography-Mass Spectrometry) analysis highlighted the presence of three major compounds, such as eucalyptol (7.38 ± 0.36%), α-humulene (14.75 ± 0.79%), and β-caryophyllene (19.78 ± 0.89%), which were also structurally confirmed by NMR (Nuclear Magnetic Resonance) spectroscopic investigation. Biological results showed potential antimicrobial, antioxidant, and antibiofilm effects of both the H manopappoides essential oil and the main components identified by GC-MS, enhancing an interesting approach for intestinal infections, being active against Escherichia coli, Listeria monocytogenes, Shigella sonnei, and Salmonella enterica ser. typhimurium strains.