TLC bioautography-guided isolation of antioxidants from fruit of Perilla frutescens var. acuta

Guided isolation through bioautography on TLC using 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH) as a detection reagent led to the isolation of four antioxidant compounds from fruit of Perilla frutescens var. acuta. These compounds were identified as rosmarinic acid (1), luteolin (2), apigenin (3), and chrysoeriol (4), by means of UV, NMR, and ESI MS. All the compounds were isolated for the first time from the fruit of the plant. Compounds 1 and 2 showed significant DPPH scavenging capacities, with IC50 values of 8.61 and 7.50 μM, respectively. Further quantitative HPLC analysis confirmed that compounds 1–4 are the predominant contributors to the free radical scavenging activity of the extract of P. frutescens var. acuta.