Quantification of Phenolics, Flavonoids, and In Vitro Antioxidant Activity in Rosella and Breadfruit Leaf Extracts

Indonesia is a country rich in biodiversity, with numerous plant species traditionally used in medicine. One such plant is breadfruit (Artocarpus altilis), whose leaves contain bioactive compounds such as flavonoids, saponins, tannins, quercetin, artocarpanone, and artoindonesianin. Another plant with high medicinal value is roselle (Hibiscus sabdariffa L.), a tropical plant from the Malvaceae family known for its rich phenolic content. Both plants are widely found across Indonesia and have potential as natural antioxidants. In this study, the dry extracts were prepared using the decoction method followed by spray drying. Phytochemical screening, total phenolic and flavonoid content analysis, and antioxidant activity tests were performed using standard in vitro methods. The DE2C extract (a combination of breadfruit leaves and roselle flowers) exhibited high total phenol content at 0.953 ± 0.005 g GAE/100 g and flavonoid content at 136.97 ± 5.050 μg QE/100 g. Meanwhile, the DE3C extract showed an IC_₅₀ value of 540.55 ppm in the DPPH assay. Pearson correlation analysis showed a strong positive correlation between total phenolic content and antioxidant activity (R = 0.956, p < 0.05), while flavonoids also showed a moderate correlation (R = 0.502, p < 0.05). These results confirm that phenolic compounds play a key role in the antioxidant potential of the extract.