Evaluation of <i style="">in vitro</i> antioxidant activity of Indian bay leaf, <i style="">Cinnamomum tamala </i>(Buch. -Ham.) T. Nees & Eberm<i style=""> </i>using rat brain synaptosomes as model system

Abstract

The study investigated the perturbation of oxidant-antioxidant balance in brain synaptosomes of diabetic rats and determined the antioxidant and free radical-scavenging property of the Indian bay leaf. Brain synaptosomes were isolated from control and streptozotocin-induced diabetic animals and oxidative stress parameters were assayed. A methanolic extract of bay leaf (BLE) was tested for the polyphenolic content and antioxidant activity by <i style="">in vitro</i> assays. A significant increase in the levels of lipids and lipid peroxidation products and a decline in antioxidant potential were observed in diabetic rat brain synaptosomes. The total polyphenolic content of BLE was found to be 6.7mg gallic acid equivalents (GAE)/100g. BLE displayed scavenging activity against superoxide and hydroxyl radicals in a concentration-dependent manner. Further, BLE showed inhibition of Fe²⁺-ascorbate induced lipid peroxidation in both control and diabetic rat brain synaptosomes. Maximum inhibition of lipid peroxidation, radical scavenging action and reducing power of BLE were observed at a concentration of 220 <img src='/image/spc_char/micro.gif'> g GAE. These effects of BLE <i style="">in vitro</i> were comparable with that of butylated hydroxyl toluene (BHT), a synthetic antioxidant. It can be concluded that synaptosomes from diabetic rats are susceptible to oxidative damage and the positive effects of bay leaf <i style="">in vitro</i>, could be attributed to the presence of antioxidant phytochemicals.