Naphthoquinones from the leaves of Rhinacanthus nasutus having acetylcholinesterase inhibitory and cytotoxic activities.

Four new naphthoquinones ( 1 – 4 ), named rhinacanthins S ( 1 ), T ( 2 ), U ( 3 ) and V ( 4 ), together with 13 known naphthoquinones were isolated from the leaf extract of Rhinacanthus nasutus . The structures of isolated compounds were elucidated by spectroscopic methods, especially 1D and 2D NMR spectroscopy and mass spectrometry. Rhinacanthin S ( 1 ) exhibited acetylcholinesterase inhibition activity with a % inhibition value of 48.04 ± 3.25. The known rhinacanthin A ( 5 ) showed cytotoxicity against a MCF-7 cell line with an IC 50 value of 8.79 μM, while rhinacanthin N ( 15 ) was active against the NCI-H187 cell line with an IC 50 = 2.24 μM and Vero cells (IC 50 = 3.00 μM) [ABSTRACT FROM AUTHOR]