Determination of gallic, p-coumaric and ferulic acids in Solanum indicum L. extract using high-performance liquid chromatography

Bitter eggplant (Solanum indicum L.), locally known in Laos as Mak Khaeng Khom, is a medicinal plant commonly used in traditional medicine. It contains phenolic compounds such as gallic acid, p-coumaric acid, and ferulic acid, which are well-known for their important biological and pharmacological activities. The objective of this study was to determine the content of gallic acid, p-coumaric acid and ferulic acid in S. indicum extracts using HPLC. Plant material was extracted using ethanol maceration and Supercritical Fluid Extraction (SFE). HPLC analysis showed that ethanol maceration contained 224.00 ± 0.8 µg/g of gallic acid, 56.25 ± 0.57 µg/g of p-coumaric acid, and 131.68 ± 0.18 µg/g of ferulic acid. SFE with 3% ethanol contained 209.55 ± 1.23 µg/g of gallic acid, 13.30 ± 0.04 µg/g of p-coumaric acid, and 275.18 ± 0.79 µg/g of ferulic acid. SFE with 5% ethanol contained 219.32 ± 1.60 µg/g of gallic acid, 15.06 ± 1.06 µg/g of p-coumaric acid, and 277.14 ± 1.09 µg/g of ferulic acid. The findings indicate maceration provides higher p-coumaric acid, while SFE enhances ferulic acid extraction.