TỐI ƯU HÓA QUÁ TRÌNH THU NHẬN VÀ ĐÁNH GIÁ KHẢ NĂNG KHÁNG KHUẨN CỦA SAPONIN TỪ CÂY KIM TIỀN THẢO Desmodium styracifolium

Desmodium styracifolium is a medicinal plant containing a high level of valuable bioactive compounds, particularly saponins — a class of natural substances with diverse biological activities and wide application potential. This study investigated the influence of key parameters on saponin extraction efficiency using Solid–Liquid Extraction (SLE) and Microwave-Assisted Extraction (MAE). The extraction conditions were then optimized using Response Surface Methodology (RSM), and the antibacterial activity of the saponin-rich extract was evaluated. The MAE method exhibited higher efficiency than SLE; therefore, optimization focused on MAE conditions, including a material-to-solvent ratio of 1:21.47 (w/v), microwave power of 318.92 W, and irradiation time of 65.76 seconds, yielding 79.32 mg OAE/g DW of saponins. The saponin-rich extract from D. styracifolium showed significant antibacterial activity against Staphylococcus aureus and Escherichia coli, as determined by the agar diffusion method. Increasing the extract concentration from 100 µg/mL to 300 µg/mL resulted in inhibition zones of 20.48 ± 0.39 mm, 22.92 ± 0.06 mm, and 24.36 ± 0.10 mm for S. aureus, and 16.33 ± 0.28 mm, 18.40 ± 0.25 mm, and 19.94 ± 0.32 mm for E. coli. These results indicate the potential application of D. styracifolium saponin extract in the development of functional food and pharmaceutical products.