Phytochemical Analysis and Biological Activity of the Leaf Extracts of Polyalthia longifolia (Masquerade Tree)

The serious global health concern of antimicrobial resistance has prompted the search for new antimicrobials. Plants are considered a rich source of potent anti-infective agents. This study aimed to assess the phytochemical constituents of the Nigerian Polyalthia longifolia and its antimicrobial potency, based on its ethno-medicinal use. The crude extract was obtained by extracting the powdered air-dried leaf of Polyalthia longifolia with methanol. Standard chemical procedures were used to screen the extract for phytochemicals. Solvent-solvent extraction was used to separate the crude extract into hexane, neutral, acid, and base fractions. The crude extract and fractions were tested for activity against Salmonella typhi, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albicans, and Aspergillus niger. FT-IR and GC-MS analyses were employed to identify functional groups and specific bioactive compounds in the crude extract. Phytochemical analysis revealed that terpenoids, alkaloids, saponins, tannins, flavonoids, steroids, and volatile oils were present. The neutral and base fractions exhibited notable antibacterial efficacy, particularly against Salmonella typhi and Staphylococcus aureus, with inhibition zones comparable to standard antibiotics. The fungi Aspergillus niger and Candida albicans were not inhibited by the crude extract or its fractions. Major compounds such as diisooctyl phthalate, oleic acid, palmitic acid, farnesol formate, n-hexadecanoic acid, octadecanoic acid, and methyl kolavenate were identified by comparing the crude extract’s GC-MS analysis with reference library computer mass spectrometry data. These compounds may be responsible for the observed bioactivity. The findings support the traditional use of P. longifolia which is a potential source of antibacterial agents for novel drugs.