A comparison of antioxidant activities and tyrosinase inhibitions in fresh white radish, garlic and ginger

Thailand has a diversity of plant foods, e.g. fruits and vegetables, which contain a significant amount of biologically active components and biochemical functions that may benefit human health. In particular, they contain the phenolic compound constitute natural sources of antioxidants. In fact, vegetables have formed a major part of daily consumptions in either healthy or sick people, including a provision of variety pleasant and attractive flavors. Furthermore, a generous consumption prefers fresh ones, including white radish (Raphanus sativus), garlic (Allium sativum) and ginger (Zingiber officinale). The current study aims at determining antioxidants, e.g. flavonoids, total phenolic content (TPC) and tyrosinase inhibition, in these fresh vegetables. Data are gathered from three representative markets in Bangkok, and further analyzed for discovering any antioxidant activity by observing DPPH radical scavenging, flavonoids, TPC and tyrosinase inhibition activity. The results show that DPPH radical scavenging activities of white radish, garlic and ginger are 30.42%, 11.39% and 75.24% in Bangrak, Bangrak and Ratchathewi, respectively. The highest flavonoids of white radish, garlic and ginger are 2.9mg/100g, 8.38 mg/100g and 9.81mg/100g in these regions, respectively. Meanwhile, the TPC of garlic, ginger and white radish are 1.94mg/100g, 1.82mg/100g and 0.57mg/100g in the same places, respectively. Then, the highest tyrosinase inhibition activity of white radish, garlic and ginger are 137.35%, 114.25%, 518.72% in Prathumwan, Ratchathewi and Ratchathewi, respectively. Therefore, they appear to be a good candidate for being an intermediary between fresh and salt-processed due to their capabilities to inhibit tyrosinase and oxidation.Keywords:2,2-diphenyl-1-picrylhydrazyl; Total Phenolic Content; Flavonoid; Tyrosinase; White radish; Garlic; Ginger