Analysis of Free Amino Acids in Different Extracts of Leaves by High-Performance Liquid Chromatography Combined with Solid-Phase Extraction.

Background: (OS) Benth is a medicinal plant and native in Southeast Asia. Previous studies have shown that OS leaves possess antioxidant, cytotoxic, diuretic, antihypertensive, and uricosuric effects. These beneficial effects have been attributed to the presence of primary and secondary metabolites such as polyphenols, amino acids, and flavonoids.