Optimization of rosmarinic acid extraction from <i>Heliotropium foertherianum</i> leaves and evaluation of biological activity

Abstract The recovery efficiency of rosmarinic acid (RA) from Heliotropium foertherianum leaves collected in Truong Sa, Vietnam was investigated through the optimization of solvent-to-leaf ratio, solvent composition, and the application of microwave-ultrasonic-assisted extraction (MUAE). Phenolic (including RA), flavonoid, and alkaloid groups of compounds were found in the LC-HRMS spectral analysis data. Quantification of RA using high-performance liquid chromatography (HPLC) revealed a significantly high yield of 8.3525 mg/g under optimal conditions: a 50:50 (v/v) ethanol–water solvent acidified with 10% (v/v) acetic acid, a solvent-to-leaf ratio of 15:1 (v/w), and a 24 h extraction time. The MUAE method demonstrated clear advantages in extraction efficiency, notably reducing processing time while enhancing yield. The biological activity of the extract was assessed in vitro, showing strong DPPH radical scavenging activity and notable antibacterial properties. These findings highlight the potential of H. foertherianum leaves as a promising natural source of RA for applications in pharmaceuticals and healthcare.