Separation and Identification of phenolic compounds from the flowers of Hibiscus sabdariffa L.and study its effect on two types of Bacteria

Abstract

The current study focused on the phytochemical screening and antibacterial activity of two bacterial species Acinetobacter baumannii and Streptococcus pneumoniae, where we were able to isolate and identify some active compounds from the flowers of the Iraqi plant, Hibiscus sabdariffa L. This was achieved by preparing some plant extracts using the continuous extraction apparatus, Soxhlet, according to the successive solvent system which relies mainly on the difference in polarity, including petroleum ether (60-80) °C (HS1), chloroform (HS2), acetone(HS3), IMS(HS4), in addition to using hot water (HS5).Acid hydrolysis was performed on the raw extracts of acetone (HS3), IMS(HS4) and hot water (HS5) to obtain some free phenolic compounds, including ( Chlorogenic acid,Caffeic acid,Rutin,Gallic acid, Quercetin, Ferulic acid)  using high-performance liquid chromatographic (HPLC) technique. Ferulic acid appeared at the highest concentration in the IMS (HS4) extract compared to other extracts, while Rutin appeared at the lowest concentration in the acetone extract (HS3).Hibiscus sabdariffa Flowers were also tested for their effect on two types of bacteria, Streptococcus pneumoniae (G+) and Acinetobacter baumannii (G-), commonly found in human infections.Phenolic compounds were identified in the extracts, with the highest inhibition (43.65 mm) caused by the hot water extract (HS5) at 100% concentration, and the lowest inhibition (14.54 mm) caused by the IMS extract (HS4) at 25% concentration in A. baumannii.In S. pneumoniae, the highest inhibition (38.63 mm) was caused by the hot water extract (HS5) at 100% concentration and the lowest inhibition (10.36 mm) was caused by the acetone extract (HS3) at 25% concentration.