Stability of Bioactive Compounds and Antioxidant Activity of Thai Cruciferous Vegetables during In Vitro Digestion

Abstract

Raphanus sativus (L.) var. caudatus Alef (Thai rat-tailed radish), Brassica juncea (L.) Czern. (leaf mustard) and Brassica juncea (L.) Coss. var. sareptana Sinskaja (mustard green) are cruciferous vegetable commonly consumed in Thailand and Asian countries. The vegetables were extracted with different solvents namely methanol, hexane and water prior to total phenolic content (TPC), phenethyl isothiocyanate (PEITC) content and antioxidant activity by ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay were determined. Effects of gastrointestinal digestion on stability of these characteristics were investigated. It was found that the order of extraction efficiency for high bioactive compounds and antioxidant activity was water> methanol> hexane. Among vegetables, mustard green showed the highest TPC, PEITC, FRAP and DPPH values being 19.78±0.01 g GAE, 9.65 ± 1.08 µmol, 8.18±0.01 µM FeSO4 and 7.75±0.31 µM TE per 100g, respectively. Decreases in DPPH (30.6-53.5%), FRAP (49.0-88.0%) and PEITC (27.2-56.7%) values were slightly higher than TPC (27.9-41.6%) after in vitro digestion. It can be said that Thai cruciferous vegetables contain substantial chemical property and this may promote their health protection but the stability through digestive system should be warranted.