Phytochemical Screening of Bioactive Compounds and Antimicrobial Activity of Different Extracts of Syzygium samarangense Leaves

Syzygium samarangense is a plant well known for its various medicinal and therapeutic properties. In this research work, the phytochemical constituents or bioactive compounds present in different extracts of the leaves of this plant, as well as the anti-microbial activity of these leave extracts were studied in three different solvents (aqueous, ethanolic, and hexane) of varying polarity. The dried Syzygium samarangense leaves were employed and the extracts were obtained via cold maceration technique at room temperature. Preliminary phytochemical screening of the leave extracts unearthed the presence of some bioactive components such as alkaloids, flavonoids, phenols, saponins, and tannins. The UV-Visible and the FT-IR spectroscopic analysis of the three crude extracts indicated the presence of alcohols, aldehydes, alkanes, alkenes, alkynes, amines, aromatic compounds, carboxylic acids, nitro-containing compounds, and phenols. The total phenolic and flavonoids contents were found to be 162.03±0.05–90.42±0.28 ppm and 148.24±0.07–99.64±0.08 ppm, respectively. The extracts were subjected to anti-microbial activities in order to ascertain the medicinal and therapeutic properties. The antibacterial activity of Syzygium samarangense leaves extract was determined by disc diffusion method with slight modification. The crude extracts of Syzygium samarangense (hexane, ethanol, and aqueous, with Ciprofloxacin as control) were tested against 4 pathogenic bacteria species: Klebsiella pneumoniae, Escherichia coli, Salmonella paratyphi A, and Pseudomonas aeruginosa. The antibacterial activity expressed as inhibition zone diameters of the Syzygium samarangense extracts (hexane, ethanolic, and aqueous) at concentrations 1 mg disc-1 against Klebsiella pneumoniae, Salmonella paratyphi A, Pseudomonas aeruginosa, and Escherichia coli. It was observed that the ethanol extract of Syzygium samarangense offered a maximum inhibition zone of 22.03±0.096 mm and 17±0.182 mm against the E. coli and Klebsiella pneumoniae respectively. These results indicate that the crude extracts from Syzygium samarangense leaves have the potential to act as natural antimicrobial agents against pathogenic bacteria.