Triterpene Glycosides from the Leaves of Pittosporum angustifolium

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.

A Contemporary Introduction to Essential Oils: Chemistry, Bioactivity and Prospects for Australian Agriculture

“…Previous studies have supported potential anticancer activity [118][119][120], as well as possible antiviral activity (using the older name P. phylliraeoides), particularly the Ross River Fever virus [121].…”

Inhibition of DNA–Topoisomerase I by Acylated Triterpene Saponins from Pittosporum angustifolium Lodd.

“…for the treatment of skin diseases and cough and, furthermore, as a supportive agent for complementary therapy strategies [ 1 , 2 ]. Recently, we have extensively investigated the phytochemistry of the seeds and leafs of P. angustifolium , resulting in the isolation and structural elucidation of five known polyphenols (quercetin glycosides and dicaffeoylquinic acids) and 33 mono- and bisdesmosidic triterpene saponins, of which 29 were reported for the first time, possessing oleanane, rare 17,22-seco-oleanolic acid and taraxastane aglycones [ 3 – 7 ]. Since the biological activities of triterpene saponins are described as manifold as their number of possible structures [ 8 ], often a generalized cytotoxic activity but also detailed modes of action, as well, are published [ 9 ].…”

“…Since the biological activities of triterpene saponins are described as manifold as their number of possible structures [ 8 ], often a generalized cytotoxic activity but also detailed modes of action, as well, are published [ 9 ]. In recent studies we have screened isolated compounds of P. angustifolium for their cytotoxic potential against three tumorigenic cell lines (MCF7—human breast cancer, 5637—human urinary bladder carcinoma, LN18—human glioblastoma) and one non-tumorigenic cell line (HaCaT—human keratinocyte) [ 3 , 5 , 7 , 10 ]. We found, that monodesmosidic saponins of the oleanane-type, featuring acyl-substituents like acetyl (Ac), 2-acetoxy-2-methylbutyroyl (AcOMebu), angeloyl (Ang) or 2-methylbutyroyl (Mebu) groups at C-21/C-22 of the aglycone backbone showed cytotoxic activity up to the low µM-range [ 3 , 5 , 10 ].…”

“…In recent studies we have screened isolated compounds of P. angustifolium for their cytotoxic potential against three tumorigenic cell lines (MCF7—human breast cancer, 5637—human urinary bladder carcinoma, LN18—human glioblastoma) and one non-tumorigenic cell line (HaCaT—human keratinocyte) [ 3 , 5 , 7 , 10 ]. We found, that monodesmosidic saponins of the oleanane-type, featuring acyl-substituents like acetyl (Ac), 2-acetoxy-2-methylbutyroyl (AcOMebu), angeloyl (Ang) or 2-methylbutyroyl (Mebu) groups at C-21/C-22 of the aglycone backbone showed cytotoxic activity up to the low µM-range [ 3 , 5 , 10 ]. Similar results concerning those structural elements of investigated saponins combined with a linked cytotoxicity have also been described in the past [ 11 – 15 ].…”

“…Instead, an inhibition of topoisomerase I has been observed, while the aglycones of active glycosides were without discernible impact. Encouraged by these outcomes, herewith we report the results of an investigation of 10 acylated triterpene saponins (Table 1 ) isolated from P. angustifolium ( 1 - 10 ) [ 3 , 5 , 6 ] and partially from other Pittosporum species before ( 4 , 8 , 9 ) [ 21 , 22 ] for their potential to inhibit the human topoisomerase I via gel based relaxation assay. We further present computational predictions of the binding mode of the active compounds within the topoisomerase I–DNA complex.…”