Evaluation of Total Phenolic, Flavonoid Contents, Antioxidant Activities and Antibacterial Activities of Moringa oleifera Seed Meal Extracts

Abstract

Moringa seeds are used in various forms in the food, cosmetic, and pharmaceutical industries. This research aimed to study the total phenolic content, total flavonoid content, antioxidant activity, and antibacterial activity of moringa seed meal, a byproduct of cold-pressed oil extraction plants. The moringa seed meal was extracted using the Soxhlet method with 30%, 60%, and 95% ethanol as a solvent. The total phenolic content of the extracts was determined using Folin-Ciocalteu reagents. The method was used to analyze the total phenolic content using gallic acid as a standard (y = 0.0143x + 0.0082, R² = 0.9983). The total flavonoid content was analyzed using the aluminium chloride colorimetric assay with quercetin as a standard (y = 0.0011x - 0.1111, R² = 0.9976). Antioxidant activity was evaluated using DPPH radical scavenging. Antibacterial activity against Bacillus cereus, Staphylococcus aureus, Salmonella Typhi, and Escherichia coli was assessed using the agar well spread method at a concentration of 200 mg/mL. The total phenolic and total flavonoid content of the 60% ethanol extract was found to be highest, at 10.30±0.19 mg GAE/g E and 41.97±4.78 mg QE/g E, respectively, and exhibited DPPH radical scavenging activity of equal to 75.06% when tested at a concentration of 10 mg/mL, which is higher than the 30% and 95% ethanol extracts. Furthermore, the 60% ethanol extract can inhibit the growth of Bacillus cereus, Staphylococcus aureus, and Salmonella Typhi bacteria with inhibitory zone sizes of 0.13±0.06, 0.27±0.06 และ 0.20±0.10 mm, respectively. The experimental results show that Moringa seed cake still contains active compounds that can be further studied for beneficial applications.