Lupane-type Triterpenoids from the Leaves of Heteropanax fragrans

Abstract

Lupane-type triterpenoids, a very large and interesting family of compounds, are widely distributed in food, herbs, and other plants throughout the world. This class of compounds possess a wide range of biological properties including cytotoxic, antitumor, antiviral, anti-inflammatory effects and the ability to induce apoptosis in the most prevalent cancer cell lines, such as HepG2, Hep3B and MCF7 cells. The betulinic acid, one of the known lupanetype triterpenoids, showed the selective cytotoxic activity toward melanoma cell lines and is being examined in Phase I trials as a cancer chemoprevention agent. For their various pharmacological and medicinal properties, these pentacyclic triterpenes of the lupane-type have recently been investigated by the scientific community. Heteropanax fragrans (Roxb.) Seem (Araliaceae), an ornamental plant and important source of herb, is distributed in the southern China. The rhizomes of H. fragrans have been used for acesodyne, hemostasia and detumescence by local people. Previous studies reported that four lupane-type triterpenoids and glycosides were isolated from the rhizomes of H. fragrans. However, chemical constituents of the leaves of H. fragrans have not been studied. In this paper, we report the isolation and structure elucidation of one new lupanetype triterpenoid, 3β-hydroxylup-20(29)-ene-23,27,28-trioic acid (1), as well as four known lupane-type derivatives, melaleucic acid (2), 3-oxolup-20(29)-ene-27,28-dioic acid (3), cylicodiscic acid (4), and 3β,23-dihydroxylup-20(29)ene-27,28-dioic acid (5) from the leaves of the title plant (Fig. 1). All the compounds were tested for the cytotoxic activity against KB cell. Compound 1 was obtained as a white amorphous powder. Its molecular formula was assigned as C30H44O7 based on HRESIMS ([M-H]−, m/z 515.2996), C NMR and DEPT data, indicating nine degrees of unsaturation. The IR spectrum of 1 indicated the existence of hydroxyl (3399 cm) and carboxyl groups (1696 cm). Analysis of the H NMR data (Table 1) and the correlations observed in the HSQC experiment showed that the molecule contained four methyl singlets [δH 0.97 (3H, s), 1.18 (3H, s), 1.62 (3H, s), 1.96 (3H,