High-performance liquid chromatography analysis of phenolics in <i>Casuarina cunninghamiana</i> : extraction, quantification and antioxidant evaluation

The study was carried out to evaluate the phenolic compounds and antioxidant activity in the aqueous extract from leaves, stems and flowers of <i>Casuarina cunninghamiana</i> Miq. subsp. <i>Cunninghamiana</i> through ultrasound-assisted and maceration extractions from Sfax, Tunisia. The leaves exhibited the highest total phenolic and flavonoid contents. HPLC analysis identified 14 phenolic compounds across all extracts, including caffeic acid, epicatechin and verbascoside. Remarkably, catechin was present at the highest concentration in <i>C. cunninghamiana</i> flowers extracts. The antioxidant activity was assessed using the DPPH radical scavenging assay and FRAP assay. The leaves extract exhibited the strongest antioxidant activity, with an IC<b>₅₀</b> value of 204.17 µg/mL in the DPPH assay and 197.5 µM BHT/g DW in the FRAP assay. These findings highlight the potential of <i>C. cunninghamiana</i> being studied for the first time in Tunisia as a natural source of bioactive compounds, with potential applications in biotechnology, pharmacology and natural product research.