Phenolic content, antioxidant and antimicrobial activity of Moringa oleifera leaves

Abstract

Moringa oleifera is a medicinal plant that is a source of nutrients. It is rich in protein, fatty acids, minerals, relatively high polyphenol compound, and has antioxidant activity. This study investigates the extraction yield, phytochemical content, antioxidant, and antimicrobial activities of Moringa oleifera leaves using two different extraction methods: maceration with methanol and aqueous decoction. The methanolic extract showed a higher yield (11.82%) compared to the aqueous extract (8.35%). Phytochemical screening revealed the presence of polyphenols, tannins, flavonoids and quinones in both extracts, while saponins, anthraquinones, and terpenoids were absent. Quantitative analysis indicated that the methanolic extract contained significantly higher total phenolic content (100.11±10.24 μg GAE/mg) and flavonoid content (52.85±0.46 μg QE/mg) than the aqueous extract (30.47±7.74 μg GAE/mg and 15.16±2.16 μg QE/mg, respectively). The antioxidant activities were assessed using DPPH radical scavenging assay, total antioxidant capacity (TAC), and ferric reducing antioxidant power (FRAP). The methanolic extract exhibited a superior DPPH scavenging activity (IC50 = 70.24 μg/ml) compared to the aqueous extract (IC50 = 103.71 μg/ml), and higher TAC (50.42%) and FRAP (EC50 = 815.5 μg/ml).Despite the promising antioxidant potential, neither extract demonstrated antimicrobial activity against Escherichia coli, Bacillus subtilis, Staphylococcus aureus, or Pseudomonas aeruginosa, which were tested using standard inhibition zone assays. These findings highlight the influence of extraction methods on the phytochemical and antioxidant profiles of M.oleifera leaves, suggesting that methanol is a more effective solvent than water for extracting bioactive compounds.