SVU-International Journal of Agricultural Sciences Volume 6 Issue (1) pp.: 88-97, 2024 Print ISSN 2636-3801 | Online ISSN 2636-381X Doi: 10.21608/svuijas.2024.268955.1343 RESEARCH ARTICLE 88 *Corresponding author: Ghadir A. El-Chaghaby ghadiraly@yahoo.com Email: Received: February 9, 2023; Accepted: March 11, 2024; Published online: March 13, 2024. ©Published by South Valley University. This is an open access article licensed under Antioxidant and antimicrobial activities of diverse parts of Acacia nilotica plant extracted by different solvents Ghadir A. El-Chaghaby 1 *, S. Rashad 1 , H.G.M. El-Sayed 1 and A.A.A. Abdel-Wareth 2 1 Regional Center for Food and Feed (RCFF), Agricultural Research Center, 12619 Giza, Egypt 2 Department of Animal and Poultry Production, Faculty of Agriculture, South Valley University, 83523 Qena, Egypt Abstract The present study investigates the effect of three different extraction solvents on the antioxidant and antibacterial activities of Acacia nilotica fruits, bark, and leaves. The solvents used included ethanol, acetic acid, and distilled water. The extraction was done by ultrasonication for 2 hours at 25°C. The total antioxidant capacity was determined by the colorimetric “phosphomolebdenum method”. The total phenolic content of plant parts used in the present investigation was measured using the Folin–Ciocalteau assay and the total flavonoids were determined by aluminum chloride assay. The antibacterial activities of plant extracts against Bacillus subtilis, Escherichia Coli, Staphylococcus aureus, and Pseudomonas aeruginosa were determined by the disc diffusion method. The data revealed that for all plant parts the highest values of total antioxidant capacity, total phenolic compounds, total flavonoids, and potent inhibitory effects against the tested bacteria were achieved using ethanol as extraction solvent followed by acetic acid, whereas, the lowest values were recorded for water extracts. The results also revealed that Acacia bark ethanolic extract recorded significantly higher total antioxidant capacity (14293 mgAAE/100g), total phenolics (14053.98 mgGAE/100g) , and total flavonoids (218.33 mgQE/Kg) as compared to all other extracts. All ethanolic extracts exerted high inhibition percentages ranging from 46-71% for fruits, 42-62% for bark, and 50-62% for leaves. The study also revealed that the bacterial inhibition of the extracts is positively correlated with their phenolic contents. Based on the results obtained during the present work, Acacia extract could be further investigated as a natural animal feed or food additive alternative to synthetic ones. Keywords: Acacia extracts; bioactivity; Acetic acid; Ethanol; Water. 1. Introduction Plants offer a wide variety of opportunities for several applications owing to their natural bioactive constituents such as vitamins, phenolic compounds, flavonoids and many other plant- derived compounds (El-Chaghaby et al., 2019). Significant physiological activity and commercial worth are possessed by these bioactive components found in plants. Therefore, it is crucial to extract these bioactive components from plants, especially for sectors like food processing, animal production, pharmaceutical engineering, and bioengineering (Shen et al., 2023). Synthetic antioxidants have been used extensively as food additives to prevent or postpone food oxidation and to extend food shelf life. Nowadays, the scientific community is becoming more interested in recovering safer antioxidants from natural sources as alternatives to chemical ones that are potentially harmful.