Assessment of Phytochemicals, Antioxidant and Antimicrobial Activities of Aqueous Ethanol Extract and Fractions of Azadirachta indica Stem Bark

Abstract

In this study, the aqueous ethanol extract of Azadirachta indica stem bark was obtained by Soxhlet extraction and partitioned into different solvents. The extract and fractions were then assessed for their phytochemical contents, antioxidant, and antimicrobial activities. The results showed that saponins, flavonoids, phenol, and tannins were present in all the samples. Also, the ethanol extract had the highest flavonoid (281.15 mgQE/g), phenolic (714.82 mgGAE/g), and tannin (156.54 mgTAE/g) contents, as well as the highest DPPH scavenging activity (95.71%) and total reducing power (1.27). However, among the fractions, butanol fraction showed the highest contents of flavonoids (235.20 mgQE/g), phenolics (413.42 mgGAE/g) and the highest DPPH scavenging activity (93.87 %) while the highest tannin content (86.90 mgTAE/g) and total reducing power (1.06) was observed in the ethyl acetate fraction. The lowest concentration of flavonoid (34.60 mgQE/g) and lowest antioxidant activity was obtained for the hexane fraction while lowest contents of phenolics (102.32 mgGAE/g) and tannins (41.21 mgTAE/g) were both observed in the water-soluble fraction. The most active fraction against both Staphylococcus aureus and Enterobacter cloacae was ethyl acetate. Meanwhile, the ethanol extract, hexane fraction, and water-soluble fractions showed the highest activity against Candida albicans, Salmonella typhi, and Escherichia coli, respectively. This research reveals that the stem bark of Azadirachta indica contains notable antioxidant and antimicrobial properties, making it a promising source for developing potent therapeutic drugs and functional foods.