ABSTRACT
Four undescribed alkaloids, 7-ethoxy-6-methoxy-2-methylisoquinolin-1(2H)-one, 7,8-dihydroxy-6-methoxy-2-methylisoquinolin-1(2H)-one, N-formylhernagine, and 5,6-dihydroxy-N-methylphthalimide, were obtained from the root bark of Hernanadia nymphaeifolia, along with fourteen known compounds. The structures of these compounds were determined through spectroscopic and MS analyses. 7,8-Dihydroxy-6-methoxy-2-methylisoquinolin-1(2H)-one, N-formylhernagine, 5,6-dihydroxy-N-methylphthalimide, oxohernagine, hernandonine, and N-trans-feruloylmethoxytyramine inhibited the superoxide anion (O2-) production (IC50 values ≤ 6.23 µg/mL) by neutrophils stimulated with formyl-L-methionyl-L-leuckyl-L-phenyl-alanine/cytochalasin B (fMLP/CB). Furthermore, 7,8-dihydroxy-6-methoxy-2-methylisoquinolin-1(2H)-one, N-formylhernagine, 5,6-dihydroxy-N-methylphthalimide, oxohernagine, and N-trans-feruloylmethoxytyramine inhibited fMLP/CB-induced elastase release with IC50 values ≤ 7.41 µg/mL. In addition, 7,8-dihydroxy-6-methoxy-2-methylisoquinolin-1(2H)-one, N-formylhernagine, oxohernagine, and N-trans-feruloylmethoxytyramine showed potent inhibition with IC50 values ≤ 28.55 µM, against lipopolysaccharide (LPS)-induced nitric oxide (NO) generation.
