A syringic acid derivative and two iridoid glycosides from the roots of Stachys geobombycis and their antioxidant properties

Abstract

A new derivative of syringic acid, stageobester A (1) and two iridoid glycosides which including a new one, stageoboside A (2), were isolated from the roots of Stachys geobombycis. Their structures were elucidated on the basis of spectroscopic methods, including extensive NMR and MS spectra. In addition, all the isolates were tested for their antioxidant capacity. Compounds 1 and 2 showed moderate antioxidant activities against DPPH radical, with IC₅₀ values of 113.33 ± 1.53 and 40.33 ± 2.08 mg/L, respectively.

Keywords:

• Stachys geobombycis
• syringic acid derivative
• iridoid glycoside
• antioxidant