Constituents from the leaves of Tricalysia oligoneura K. Schum (Rubiaceae) with antileishmanial and cytotoxic activities

Phytochemical investigation of the leaves of Tricalysia oligoneura K. Schum led to the isolation and characterization of a novel oleanane type triterpen (1), a phytosphingosine type ceramide (2) along with one known steroid (3), three previously identified triterpenoids (4−6), one ent-kauran type diterpene (7), two known flavonoids (8−9), and one sugar derivative (10). Structure elucidation was accomplished through spectroscopic analyses and comparison with previously reported data. To the best of our knowledge, this is the first comprehensive report describing metabolites from Tricalysia oligoneura, thereby enriching the chemical profile of the species and providing valuable insights into the chemotaxonic relationships within the genus Tricalysia. In addition, all isolated compounds were evaluated for their antileishmanial and cytotoxic activities against Leishmania donovani 1S (MHOM/SD/62/1S) promastigotes and on RAW 264.7 macrophage cells respectively. Compounds 1 and 2 exhibited moderate leishmanicidal activities with IC50 values of 33.51 and 35 μM respectively in comparison with the positive control, Amphotericin B (IC50 = 0.0017 μM). The crude extract exhibited good activity (IC50 value 13.62 μg/mL) against the parasite but relatively low selectivity (SI = 5.05). These findings suggest T. oligoneura may represent a promising source of new biologically active compounds further and support its chemotaxonomic placement within the Tricalysia genus.