Isolation and characterization of secondary metabolites from <i>eucalyptus camaldulensis</i> var. <i>obtusa</i>

Two new acylated chromone glucosides eucamalduside D (<b>1</b>) and eucamalduside E (<b>2</b>) together with twelve known compounds were isolated from the leaves of <i>Eucalyptus camaldulensis</i> var. <i>obtusa.</i> The structures of new compounds <b>1</b> and <b>2</b> were established through 1D and 2D NMR, and HRESI-MS and their stereochemistry was established by measuring optical rotation of methyl esters and sugars obtained by methanolysis and hydrolysis respectively. Ursolic acid lactone (<b>5</b>) showed good immunosuppressant activity in luminol-based chemiluminescence assay performed on whole blood, neutrophils and macrophages with IC₅₀ values of 1.74 ± 0.4, 3.1 ± 0.2 and 6.53 ± 1.59 <i>µ</i>g/mL, respectively, while cypellocarpin C_a (<b>13</b>) exhibited moderate decrease in T-lymphocyte proliferation with IC₅₀ of 6.2 ± 0.8 <i>µ</i>g/mL.