Phytochemical profiling, antioxidant potential, and antimicrobial assessment of the essential oil extracted from Moringa oleifera

Abstract

Since antibiotic resistance is still on the rise, the search for safe plant-based bioactives keeps growing in importance. The "Miracle Tree," Moringa oleifera, also has immense potential since it contains a vast pool of compounds and is also said to be capable of curing a vast pool of diseases as well. Phytochemical content, antioxidant activity, and antibacterial activity of Moringa oleifera leaf extracts in ethanol, ethyl acetate, and chloroform solvents were investigated comprehensively in this study. Four fractions: crude ethanol, non-partitioned ethyl acetate, organic chloroform, and aqueous chloroform, were subjected to Thin Layer Chromatography (TLC), DPPH antioxidant assay, and Kirby-Bauer antibacterial test. Thin Layer Chromatography (TLC) of Moringa oleifera leaf extracts exhibited solvent-dependent variation in bioactive compound profiles. The most compositionally rich was ethanol extract, with several flavonoid bands (Rf ≈ 0.55–0.93), alkaloid bands (Rf ≈ 0.51–0.88), anthraquinone bands (Rf ≈ 0.57–0.64), phenolics, and proteins, showing efficient extraction of mid-polar and polar compounds. Moderate alkaloids, flavonoids, and anthraquinones bands (Rf ≈ 0.24–0.75) were shown by the organic chloroform fraction, while the ethyl acetate extract showed weak bands of phenolics and alkaloids (Rf ≈ 0.78–0.93). No bands were seen by aqueous chloroform extract, showing low yield of phytochemicals. Overall, ethanol was the most suitable solvent since it had extracted the broadest range of bioactive compounds for the antimicrobial and antioxidant activity of Moringa oleifera leaves. DPPH assay for antioxidant assay showed that extracts had dose-dependent radical scavenging activity. Ethanol extract was superior, with an IC₅₀ value of 56.54 μg/mL. Ethyl acetate, aqueous chloroform, and organic chloroform extracts were inferior with IC₅₀ values 159.40 μg/mL, 300.52 μg/mL, and 580.25 μg/mL, respectively. 5 Compared to the control ascorbic acid (IC₅₀ = 6.1–10.47 μg/mL), the ethanol extract was around 5–9-fold lower. Yet it was greater than 90% scavenging activity at 1000 μg/mL and therefore was highly active against antioxidants owing to the presence of flavonoids and phenolics. No zone of inhibition was found in well diffusion and disk diffusion antibacterial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhi, Shigella flexneri, Vibrio cholerae, and Enterococcus faecalis. Inhibition of activity because of small quantity of the extract (30 mg/disc), inability of lipophilic molecules to diffuse via agar, and ultimate break-down of heat labile molecules. Moringa oleifera leaf extracts, particularly the ethanol fraction, were rich in phytochemicals and showed vigorous antioxidant activity with poor antibacterial inhibition under the assay conditions. The research highlights the solvent polarity as a driving force for phytochemical recovery and antioxidant activity and as a foundation for its future optimization and for improved nano-formulation approaches to antimicrobial delivery.