Identification of Phenolic Compounds and Antioxidant Effects from the Exudate of Germinating Peanut (Arachis hypogaea)

Five phenolic compounds 1-5 were isolated for the first time from the exudate of geminating peanut (Arachis hypogaea). The structures were fully characterized by analysis of physical and spectral data. All isolated compounds were tested for antioxidant activities using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), and hydroxyl radical. Compounds 2, 3, and 5 exhibited a strong scavenging effect on DPPH (2: $IC_{50}\;=\;10.4\;{\um}M$, 3: $IC_{50}\;=\;45.2\;{\mu}M$, 5: $IC_{50}\;=\;5.0\;{\mu}M$), and ABTS (2: $IC_{50}\;=\;9.6\;{\mu}M$, 3: $IC_{50}\;=\;5.5\;{\mu}M$, 5: $IC_{50}\;=\;3.3\;{\mu}M$) radical activity, whereas these compounds had weak hydroxyl radical scavenging activity ($IC_{50}\;>\;200\;{\mu}M$). The total phenolic contents of the extracts using n-hexane, EtOAc, and n-BuOH were found to be 96.4-964.3 mg gallic acid equivalent per g dry material (GAE/g) and n-BuOH fraction showed the highest total phenolic content (964.3 mg GAE/g). These studies suggest that the exudate of geminating peanut may possess possible health related benefits to humans.