Abstract
Phytochemical investigation of the leaves of Pittosporum angustifolium
resulted in the isolation and structural elucidation of nine new triterpene
saponins, named pittangretosides A-I (1–9), together with a
known compound (10). Mainly by NMR and HRESIMS experiments, eight
compounds were identified as A1-barrigenol glycosides
(1–7, 10), whereas two compounds exhibited an unusual
17,22-seco-backbone of oleanolic acid (8, 9). All compounds were
evaluated for their in vitro cytotoxicities against human urinary
bladder carcinoma cells (5637). Only compounds with an angeloyl-residue at
C-22 of the aglycone (1–4 and 10) showed
antiproliferative effects with IC50 values of 4.1, 5.2, 2.1,
17.9, and 2.4 µM, respectively.
Key words
Pittosporum angustifolium
- Pittosporaceae - A
1-barrigenol - seco-glycosides - pittangretosides