A new isoquinoline and ceramide from the stem barks of Discoglypremna caloneura (Pax) Prain (Euphorbiaceae) with antiproteinase and cytotoxic activities.

Two new compounds, an isoquinoline (1) and caloneuramide (2), a ceramide were isolated from the stem bark of Discoglypremna caloneura together with seven known compounds namely aurantiamide acetate (3), acetylaleuritolic acid (4), 3α-hydroxylaleuritolic acid 2α-p-hydroxybenzoate (5), mixture of stigmasterol (6) and β-sitosterol (7), mixture of 7-oxo-stigmasterol (8) and 7-oxo-β-sitosterol (9). Their structures were determined based on data from literature and spectroscopic methods. Derivatization reactions on the isoquinoline led to two new compounds, the methylated (10) and acetylated (11) derivatives. Some compounds and extracts were evaluated for their cytotoxic and antiproteinase activity. Antiproteinase effect of compounds 1, 10 and 11 exhibited IC50 values of 10.77, 1.19 and 3.61 μg/mL respectively; significantly low compared to the standard drug, acetyl salicylic acid (IC50 = 20.28 μg/mL). Ethyl acetate and methanol extract exhibited moderate cytotoxicity activity on Chang liver cells with CC50 values of 167.90 ± 2.20 and 106.30 ± 2.03 μg/mL compared to the reference drug cucurmin (CC50 = 11.05 ± 1.04 μg/mL).