Chemical compositions and biological activities of Scutellaria pinnatifida A. Hamilt aerial parts

Phytochemical analysis of the methanolic and dichloromethane extracts of the aerial parts of Scutellaria pinnatifida led to the isolation of a phenylpropanoid, 1-o-feruloyl-β-D-glucose (1), two known flavonoids including luteolin-7-o-glucoside (2) and apigenin-7-o-glucoside (3), three known phenylethanoid glycosides composed of phlomisethanoside (4), syringalide A (5), and verbascoside (6), and oleic acid (7). Isolation and structural elucidation of compounds were accomplished by HPLC and spectroscopic methods (UV, 1H-NMR, 13C-NMR). The extracts were also evaluated for their radical scavenging activity and insecticidal property by 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay and contact toxicity method, respectively. Among the extracts, the methanol extract showed the most potent free radical scavenging activity with a RC50 value of 0.044 ± 0.350 mg/mL which could be attributed to the presence of the isolated phenolic compounds. In the case of insecticidal activity, the n-hexane extract displayed the most potent activity and caused 10%, 15%, and 40% mortality to Oryzaephilus mercator at the concentration of 5, 10, and 15 mg/mL after 4 h of exposure.