Chemical constituents of the egg cases of tenodera angustipennis (Mantidis ootheca) with intracellular reactive oxygen species scavenging activity

As a traditional medicine with potential antioxidant effects, Tenodera angustipennis egg cases (Mantidis ootheca) are a potential source of new bioactive substances. Herein, three new N-acetyldopamine derivatives, namely, (+)-tenoderin A (1a), (−)-tenoderin A (1b), and tenoderin B (2), along with thirteen known compounds (3–15), were isolated from a 70% EtOH extract of T. angustipennis egg cases. Compound 1 was isolated as a racemic mixture, and two enantiomers (1a and 1b) were successfully separated by chiral-phase preparative HPLC. The chemical structures of the new compounds were established by NMR spectroscopy and high-resolution electrospray ionization mass spectrometry, and the absolute configurations of enantiomers 1a and 1b were determined by electronic circular dichroism spectroscopy. All the new compounds exhibited antioxidant activities with IC₅₀ values of 19.45–81.98 µM, as evaluated using free-radical scavenging assays, with the highest activity observed for compound 2. In addition, compounds 1a, 1b, and 2 exhibited inhibitory activities on intracellular reactive oxygen species generation.