Antioxidant and α-Glucosidase Inhibitory Activities of Different Solvent Extracts of Skullcap (Scutellaria baicalensis)

In this study, different solvent extracts of skullcap (Scutellaria baicalensis) were assayed for their total phenol content (TPC), antioxidant activity [determined as DPPH radical scavenging activity, superoxide dismutase (SOD)-like activity, oxygen radical absorbance capacity (ORAC) assay, and comet assay], and a-glucosidase-inhibitory activity. The TPC of skullcap ranged from 9.06 mg/g gallic acid equivalents (GAE) for acetone extract (AE) to 91.8 mg/g GAE for methanol extract (ME). AE, which had a low TPC, exhibited the highest DPPH radical scavenging activity and SOD-like activity. TPC positively correlated with the ORAC assay (r=0.96, p<0.001). All skullcap extracts significantly reduced the hydrogen peroxide-induced DNA damage in human leukocytes. ME with a high TPC and ORAC value showed the highest alpha-glucosidase inhibition. The difference in the biological activities of the extracts may be due to the differences in their chemical structure or polarity. Therefore, the results obtained indicate that might be a potential source of compounds with health-protective effects. ME, in particular, might be a prospective therapeutic agent for diabetes.