Anti-Oxidative Stress Activities of Silibinin on α-Amanitin In Vitro

Abstract

Alpha amanitin (α-amanitin) is the mainly toxic substance in Amanita mushrooms in Thailand. Toxicity of α-amanitin is directly on the liver organ leading to body systemic failure. Silibinin is an antioxidant and only one medication that can help reduce the toxicity of α-amanitin, but its mechanism of action is still unclear. The antioxidant activities of silibinin in scavenging free radicals, i.e. superoxide radical, hydroxyl radical, and H₂O₂ as well as the direct trapping between silibinin and α-amanitin were evaluated in vitro. The scavenging free radicals of silibinin in this study were demonstrated in XO-HX, Ribose- and H₂O₂- ABT/HRP systems by comparing to the standard antioxidants; gallic acid, N-acetylcysteine (NAC), and quercetin. Anti-toxicity was studied in human blood from α-amanitin oxidation, then the whole blood glutathione (GSH) and plasma malondialdehyde (MDA) levels were detected with DTNB and TBARs . The results showed that silibinin scavenged superoxide radicals lower than quercetin but higher than gallic acid and NAC. It scavenged hydroxyl radicals better than quercetin, NAC and gallic acid, respectively. However, the scavenging activity on H₂O₂ of silibinin was lowest among the compared antioxidants. Interestingly, silibinin protected the GSH and inhibited MDA production in blood from α-amanitin oxidation in a dose response manner. The study revealed that silibinin had scavenging activity directly on free radicals, especially superoxide, hydroxyl radicals, and H₂O₂. It also protected the GSH and inhibited MDA production in human blood from α-amanitin oxidation.