New lipoxygenase and cholinesterase inhibitory sphingolipids from <i>Carthamus oxyacantha</i>

<p>Two new sphingolipids: oxyacanthin A [(2<i>S</i>,3<i>S</i>,4<i>R</i>)-2-{[(2<i>R</i>,5<i>E</i>)-2-hydroxyoctadec-5-enoyl]amino}hexaeicosane-1,3,4-triol; <b>1</b>] and B [(2<i>S</i>,3<i>S</i>,4<i>R</i>)-2-{[(2<i>R</i>,5<i>E</i>)-2-hydroxyoctadec-5-enoyl]amino}hexaeicosane-1,3,4-triol-1-<i>O</i>-<i>β</i>-D-glucopyranoside; <b>2</b>], together with 1-octacosanol, <i>β</i>-sitosterol, <i>β</i>-sitosterol 3-<i>O</i>-<i>β</i>-D-glucopyranoside and luteolin 7-<i>O</i>-<i>β</i>-glucopyranoside were isolated from the methanolic extract of the whole plant of <i>Carthamus oxyacantha</i>. Their structures were elucidated using ¹H and ¹³C NMR spectra and 2D NMR analyses (HMQC, HMBC and COSY) in combination with mass spectrometry (EI-MS, HR-EI-MS, FAB-MS and HR-FAB-MS) experiments and in comparison with the literature data of the related compounds. Both the compounds <b>1</b> and <b>2</b> showed inhibitory potential against lipoxygenase (LOX) in a concentration-dependent manner with IC₅₀ values 83.3 ± 1.3 and 245.7 ± 1.1 µM, whereas compound <b>2</b> showed inhibition against enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with IC₅₀ values 65.3 ± 0.1 and 93.6 ± 0.1 µM, respectively.</p