Chemical composition and antibacterial activity of essential oils of 3 Helichrysum species

Abstract

In Rwanda and Burundi, many species of the Helichrysum genus (Asteraceae) are used in traditional folk medicine for treating diarrhea diseases. Helichrysum forskahlii, Helichrysum panduratum and Helichrysum odoratissimum were selected on the basis of ethnobotanical data. The essential oils, obtained from fresh plants by steam distillation, were tested for antibacterial activity by a disc diffusion method against three gram-negative bacteria obtained from clinical isolates: Escherichia coli, Salmonella typhi and Shigella flexneri [1]. The chemical composition of the obtained essential oils was determined by GC and GC/MS [2–5]. The major constituents were identified as β-caryophyllene (26.3%), α-humulene (15.3%), δ-3-carene (13.7%), viridiflorene (5.1%) for Helichrysum froskahlii, α-humulene (13.5%), β-caryophyllene (12.6%), (Z)-β-ocimene (10.8%), α-pinene (5.7%), for Helichrysum odoratissimum and germacrene-D (53.2%), β-Caryophyllene (13.29%) for Helichrysum panduratum. The in vitro screening for antibacterial activity showed that only the essential oil from Helichrysum forskahlii presents activity against all tested bacteria (MIC between 0.2 and 0.8mg/ml) whereas the essential oils from Helichrysum panduratum and Helichrysum odoratissimum did not show any activity on tested bacteria.