Subcritical water extraction of antioxidant compounds from Seabuckthorn (Hippophae rhamnoides) leaves for the comparative evaluation of antioxidant activity

A novel environmentally friendly technique, subcritical water extraction (SWE) was employed for the extraction of antioxidant compounds from Seabuckthorn leaves (SBT). Antioxidant activity of the extracts was evaluated using commonly accepted chemical assays. Also, present study reports the cytoprotective and antioxidant properties of SBT against tertiary-butyl hydroperoxide (tert-BOOH) induced oxidative stress in murine macrophages (Raw 264.7). Exposure of cells to tert-BOOH resulted, increase in cytotoxicity, reactive oxygen species (ROS) production and decrease in mitochondrial membrane potential, which is responsible for fall in intracellular antioxidant levels. Pretreatment of cells with SBT extracts inhibited cytotoxicity, ROS production and maintained antioxidants levels similar to that of control cells. The chemical composition of the SWE extracts studied showed total phenol content (76.07-93.72mg/g GAE) and total flavonoid content (47.06-66.03mg/g rutin). Further, some of its phenolic constituents; (1) Quercetin-3-galactoside, (2) Kaempferol and (3) Isorhamnetin were quantified by RP-HPLC.