Optimization of Ultrasound-Assisted Methanolic Extraction of Terminalia arjuna Bark Using Response Surface Methodology and Characterization of the Extract.

Terminalia arjuna's bark is a renowned medicinal plant material within the Indian subcontinent. Ultrasound-assisted extraction (UAE) of Terminalia arjuna bark was optimized using response surface methodology (RSM) with methanol as the extraction solvent. Methanol was selected for its ability to efficiently solubilize phenolic and flavonoid compounds, which are major contributors to the bark's bioactivity. A Box-Behnken design was followed to model the effects of temperature, solvent-to-solid ratio, extraction time and sonication power on the yield. The optimized UAE conditions produced an extract with a yield of 12.09%, which was highly enriched in phenolic (442.2 ± 16.2 mg GAE/g) and flavonoid (294.6 ± 8.1 mg QE/g) compounds, demonstrating the method's efficiency for targeted phytochemical recovery. Proximate and mineral analysis revealed the bark's nutritional composition and its content of essential minerals like calcium (86.27 ± 1.43 mg/kg) and iron (16.03 ± 1.21 mg/kg). The extract exhibited significant in vitro antioxidant activity, with an IC₅₀ of 186.4 μg/mL in the DPPH assay and 24.4 μM Fe (II) equivalents in the FRAP assay. The study demonstrates that UAE is an efficient technique for obtaining a phytochemically rich extract from T. arjuna bark, which shows antioxidant potential.