Antioxidant and enzyme inhibition activities of Spartium junceum with HPLC-DAD profiling

Spartium junceum L., a Fabaceae plant, is commonly known as Spanish broom and cultivated in the Mediterranean regions. This study aimed to investigate the chemical profiles and antioxidant and different enzyme inhibitory activities of methanol, ethanol and aqueous extracts obtained from flowers and stems of S. junceum. Also, their phenolic compositions were analyzed by high-performance liquid chromatography with a diode-array detector (HPLC-DAD). The aqueous extract of stems showed the highest phenolic content (63.94 mg gallic acid equivalents/g), while the aqueous extract of stems contained the highest flavonoid content (61.33 mg quercetin equivalents/g). The stem water extract demonstrated the highest 2,2′-diphenyl-1-picrylhydrazyl radical-scavenging activity (IC₅₀: 2327 μg/ml), while the stem water extract exhibited a strong 2,2′-azino-di(3-ethylbenzothiazoline-6-sulfonic acid) radical-scavenging activity (IC₅₀: 91.80 ± 0.90 μg/ml). The tested extracts differed greatly in terms of enzyme inhibition activity. The stem water extract showed the highest anti-acetylcholinesterase activity (IC₅₀: 46.69 ± 1.66 μg/ml); however, the stem methanol extract exhibited a strong anti-butyrylcholinesterase activity (IC₅₀: 76.39 ± 0.27 μg/ml). The flower methanol extract was the most active against the α-glucosidase enzyme (IC₅₀: 296.7 ± 3.77 μg/ml). All extracts showed low activities against α-amylase and tyrosinase enzymes. The evaluation of the biological activity results provides evidence for bioactivity-guided isolation studies on the active extracts of this plant.