Identification and quantification of a major anti-oxidant and anti-inflammatory phenolic compound found in basil, lemon thyme, mint, oregano, rosemary, sage, and thyme

Major phenolic compounds from basil, lemon thyme, mint, oregano, rosemary, sage, and thyme were investigated using a high-performance liquid chromatography (HPLC) profiling technique in combination with DPPH-radical scavenging, xanthine oxidase and cyclooxygenase assays. For the present study, 15 plant-derived phenolic compounds (gallic, protocatechuic, vanillic, syringic, chlorogenic, rosmarinic, caffeic, ferulic, and sinapic acids, protocatechualdehyde, vanillin, N-coumaroyltyramine, N-caffeoyltyramine, N-feruloyltyramine, and N-sinapoyltyramine) were selected and their DPPH-radical scavenging activities were first determined. Then, a standard HPLC profiling of these phenolics was constructed using an HPLC method to isolate anti-oxidant and anti-inflammatory phenolic compounds from MeOH extracts of the plants. Rosmarinic acid was identified as a major anti-oxidant compound (0.22-0.97%) in all seven herbs, confirmed by nuclear magnetic resonance. Rosmarinic acid from the plants quenched superoxide radicals from xanthine oxidase and inhibited cyclooxygenase I and II enzymes. In this study, the rosmarinic acid content of perilla was also determined and compared with those of the seven herbs.