Goyangamins A–C, Three Pairs of Enantiomeric 2(1 H )-Quinolinone Alkaloid Dimers with Antisenescent Activity from Tetradium daniellii

Goyangamins A–C ( 1 – 3 ), three 2(1 H )-quinolinone alkaloid dimers, were isolated from the roots of Tetradium daniellii . The structures of these dimers were elucidated by HRESIMS, 1D and 2D NMR spectroscopy, and ECD analysis. Compounds 1 and 2 feature an sp 3 –sp 2 chiral axis, whereas compound 3 contains an sp 2 –sp 2 chiral axis, giving rise to a pair of interconverting atropisomers. Variable-temperature NMR (VT NMR), in conjunction with computational potential energy surface (PES) scans, indicated that compounds 1 – 3 belong to class I atropisomers that can readily interconvert at room temperature. Compound 3 exhibited the most potent antisenescence activity, with an IC 50 value of 7.8 ± 2.2 μM and showed a dual mode of action involving inhibition of senescence-associated secretory phenotype (SASP) markers (IL-6, IL-8, IL-1α, and IL-1β) and suppression of senescence-associated β-galactosidase (SA-β-gal) activity.