Phytochemical Profiling and Bioactivity Correlation of Acacia nilotica and Acacia seyal Using HPLC-DAD Analysis

This study provides a comprehensive phytochemical and biological evaluation of Acacia nilotica and Acacia seyal samples collected from Khartoum State, Sudan. Methanolic extracts of A. nilotica leaves (SN), A. seyal leaves (TL), and A. nilotica seeds (S) were evaluated for total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (DPPH radical scavenging and reducing power), and antimicrobial activity against selected pathogenic microorganisms. High-performance liquid chromatography coupled with diode array detection (HPLC-DAD) was used to identify and quantify individual phenolic compounds. The SN sample exhibited the highest TPC (287.527 mg GAE/g), DPPH scavenging activity (96.815%), and reducing power (2.356), whereas TL showed the highest flavonoid content (155.296 mg QE/g). All samples demonstrated considerable antifungal activity against Candida albicans, while antibacterial activity varied according to species and extract type. HPLC-DAD analysis revealed the presence of major phenolic compounds, including naringenin, gallic acid, catechin, and methyl gallate, with notable variations among the investigated samples. In addition, several unidentified peaks were observed in the chromatographic profiles, suggesting the presence of additional phytochemical constituents under the applied analytical conditions. A strong positive correlation was observed between total phenolic content and antioxidant activity (R2 > 0.97), indicating the possible contribution of phenolic compounds to the observed bioactivity. Overall, this study provides further insight into the relationship between phenolic composition and biological activity in Acacia species and highlights their potential as natural sources of bioactive compounds for pharmaceutical and food applications.