Exploring the Profiles of Phenolic Acids, Flavonoids, and Amino Acids and Their Associated Antioxidant Activities in the Leaves of Four Selected Zingiberaceae Species

Leaves of plants in the Zingiberaceae family are traditionally consumed as vegetables and used as herbal ingredients. However, the phytochemical composition and bioactive potential of Zingiberaceae leaves remain less investigated than those of rhizomes. This study evaluated the phytochemical composition, amino acid profiles, and antioxidant activities of leaves from four Zingiberaceae species, including Boesenbergia rotunda, Kaempferia marginata, Zingiber montanum, and Zingiber officinale. Total phenolics (TPC), total flavonoids (TFC), vitamin C, phenolic acids, flavonoids, and amino acids in the leaves were determined using HPLC and LC–MS/MS and associated with antioxidant activities (DPPH and FRAP assays). Significant differences among species were observed (p < 0.05). Z. montanum leaves exhibited the highest TPC (7.04 mg GAE/g DW), whereas Z. officinale leaves showed the highest vitamin C content (227.42 mg/100 g). The highest total phenolic acids were detected in K. marginata leaves (4830.36 µg/g DW), with caffeic acid as the dominant compound. In contrast, Z. officinale leaves contained the highest flavonoid content (16,255.10 µg/g DW), particularly rutin (15,123.09 µg/g DW). Amino acid analysis revealed that K. marginata leaves had the highest total amino acids (114.41 µg/g DW). Multivariate analyses demonstrated distinct phytochemical profiles among species, highlighting the chemical diversity and bioactive potential of Zingiberaceae leaves.