Investigation of Microwave-Assisted Extraction Method on Chemical Profiling and Anti-Tyrosinase Activities of Equisetum ramosissimum Desf. subsp. debile (Roxb. ex Vaucher) Hauk for Potential Cosmetic Applications by LC-MS/MS and Molecular Docking Analysis

Equisetum ramosissimum Desf. Subsp. debile (Roxb. ex Vaucher) Hauk (E. ramosissimum), exhibits anti-tyrosinase and antioxidant activities. However, identifying the key compounds exhibiting anti-tyrosinase effects and establishing effective protocols for their extraction have not been accomplished. Herein, we investigate and establish an effective extraction method and identify the key bioactive compounds responsible for tyrosinase inhibition. E. ramosissimum was extracted using the microwave-assisted extraction (MAE) method. The MCW4 extract exhibited the highest antioxidant activity (IC₅₀: 90.96 ± 0.515 µg/mL) and TPC (27.23 ± 1.180 mg of GAE/g-crude extract), while the MCW5 extract showed the strongest anti-tyrosinase activity (IC₅₀: 126.48 ± 6.668 µg/mL). LC-MS/MS analysis identified resveratrol isomers, protocatechuic acid, cis-ETRA acid, KF-3-GBS, 1-16:0-lysoPC, and 1-16:0-lysoPE as potential anti-tyrosinase compounds, detected only in MCW4 and MCW5 under the applied extraction and analytical conditions. Molecular docking indicated favorable predicted binding toward human tyrosinase (hTyr) for resveratrol isomers, KF-3-GBS, and 1-16:0-lysoPE. KF-3-GBS was uniquely detected in MCW5. These results suggest that MAE using a solid-to-solvent ratio of 1:16 at 40 °C for 15 min produced an E. ramosissimum extract that exhibited strong tyrosinase inhibitory activity. Kaempferol-3-gentiobioside (KF-3-GBS) demonstrated favorable binding to hTyr in molecular docking analysis, supporting its potential role as a direct tyrosinase inhibitor.