Assessment and comparison of phytochemicals and antioxidant properties from various parts of the Australian maroon bush (Scaevola spinescens)

Scaevola spinescens is endemic to Australia and traditionally used as a medicinal plant. While its bioactive compounds have been studied, their concentrations in different parts of the plant have not been reported. This study compared total phenolic content (TPC), flavonoids, saponins and antioxidant properties, as well as major individual phytochemical compounds in the whole root, root bark, root wood, whole stem, stem bark, stem wood, and leaf of S. spinescens. The results showed the leaf had significantly highest concentrations of TPC followed by the root bark and stem bark (47.34, 12.24 and 10.20 mg GAE/g, respectively). Flavonoids concentrations were also significantly higher in the leaf compared to the root bark and stem bark (20.95, 6.22 and 4.19 mg CE/g, respectively). For saponins, the root bark contained significantly highest concentrations (112.58 mg EE/g). Luteolin 7-glucoside was isolated and identified in the leaf of S. spinescens. Eight major compounds were identified with the leaf displaying the highest diversity of major compounds, and in higher concentrations, compared to the other plant constituents. As the leaf and root bark contained the highest concentrations of phytochemicals, these plant parts are recommended as starting material for future studies, to further isolate and identify the major compounds from S. spinescens and investigate their biological properties for use in pharmaceutical and food applications.