Recovery of high-value components from Bauhinia variegata leaves using ultrasound-microwave-assisted extraction technique

Abstract

This research explored and compared different methods for extracting phyto compounds from Bauhinia variegata leaves. The study evaluated the performance of shaking water extraction (SWE), microwave-assisted extraction (MAE), and ultrasound-assisted extraction (UAE) to identify the most effective technique. UAE outperformed MAE and SWE, yielding the highest yield of total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity (measured via DPPH and FRAP assays). The optimal UAE conditions (300 W power, 30 min extraction, 1:15 solid-to-liquid ratio, pH 5.5) produced 69.97 ± 0.38 mg GAE/g TPC, 38.77 ± 0.20 mg QE/g TFC, and strong antioxidant activity (DPPH 29.44 ± 0.68 mg TE/g and FRAP 34.26 ± 0.24 mg TE/g). SEM confirmed superior cell disruption by UAE, enhancing extraction efficiency. HPLC identified key phenolic compounds, including caffeic acid (742.87 ± 6.85 ppm), quercetin (543.92 ± 18.14 ppm), and p-coumaric acid (498.36 ± 17.07 ppm), while GC-MS revealed α-methylmannofuranoside (41.65 % relative peak area) as the major volatile compound. These results highlight the UAE's effectiveness in extracting bioactive compounds from Bauhinia variegata leaves for food and industrial applications.