Triterpenoid glycosides from the leaves of Meliosma henryi

Triterpenoids

This review covers newly isolated triterpenoids that have been reported during 2015.

Triterpenoid saponins from Scabiosa stellata collected in North-eastern Algeria

Eight undescribed triterpenoid saponins, scabiostellatosides A-H, together with three known compounds were isolated from the whole plant of Scabiosa stellata L. Their structures were established by spectroscopic analyses (1D, 2D-NMR and HRESIMS) and chemical methods. Scabiostellatosides A-H were evaluated for their cytotoxicity against human fibrosarcoma cell line (HT1080). Scabiostellatoside F, a heptasaccharide derivative of oleanolic acid, exhibited moderate cytotoxicity against HT1080 cell line with IC₅₀ value of 12.0 μM.

Triterpene glycosides from the aerial parts of Gouania longipetala

Six previously undescribed triterpenoid saponins, gouaniaside I-VI, were isolated from the aerial parts of Gouania longipetala Hemsl. (Rhamnaceae), in addition to four known triterpenes. The structure elucidation of these compounds was based on analyses of spectroscopic data including 1D- and 2D-NMR and HR-ESI-MS techniques. The inhibitory activity of isolated compounds against promyelocytic leukemia HL60 and human erythromyeloblastoid leukemia K562 cell lines was evaluated and jujuboside I exhibited moderate cytotoxicity, with IC₅₀ values of 13.5 and 21.0 μM, respectively. Among the isolated triterpenes, alphitolic acid exhibited moderate antibacterial activity against Staphylococcus aureus, Enterococcus faecalis and Escherichia coli (MICs 32, 64 and 128 μg/mL, respectively).

Herbicidal and Cytotoxic Constituents from Aralia armata (Wall.) Seem

Two new triterpenoids, 3β-hydroxyoleana-11,13(18)-diene-28,30-dioic acid (1) and 3-oxooleana-11,13(18)-diene-28,30-dioic acid (2), one novel triterpenoid glycoside, 3β-O-(6'-O-methyl-β-D-glucuronopyranosyl)oleana-11,13(18)-dien-28-oic acid (3) along with six known compounds (4 - 9) were isolated from the stem bark of Aralia armata (Wall.) Seem. Their structures were elucidated through extensive spectroscopic methods. The herbicidal activities of these compounds against Bidens pilosa L., an invasive weed in P. R. China, were evaluated. Compounds 3, 5, and 6 exhibited more significant herbicidal activities on B. pilosa than the positive-control pendimethalin. Their possible use as herbicidal chemicals or model compounds deserved more attention. The effects of compounds 1 - 9 on Spodoptera litura cultured cell line Sl-1 cell proliferation and its morphology were also evaluated. The results indicated that compounds 1 - 5 affected Sl-1 cell proliferation. Compound 3 showed more obvious proliferation inhibition activities on Sl-1 cell than the positive-control rotenone. With regard to the effect on morphology, compound 2 significantly changed Sl-1 cell, resulting in cell blebbing and vacuole forming. Triterpenoids aremedicinally and agriculturally important, and cytotoxicity of the three new compounds 1 - 3 deserved further studies.

Cytotoxic triterpenoid saponins from Clematis tangutica

Eight previously undescribed oleanane-type triterpenoid saponins, clematangoticosides A-H, together with eight known saponins, were isolated from the whole plants of Clematis tangutica (Maxim.) Korsh. Their structures were elucidated by extensive spectroscopic analysis, in combination with chemical methods (acid hydrolysis and mild alkaline hydrolysis). Clematangoticosides D-G were found to be unusual 23, 28-bidesmosidic glycosides. The cytotoxic activities of all of the isolated saponins were evaluated against the four human cancer cell lines SGC-7901, HepG2, HL-60 and U251MG. Clematoside S, sapindoside B, kalopanax saponin A, and koelreuteria saponin A exhibited cytotoxicity against all of the test cancer cell lines with IC50 values in the range of 1.88-27.20 μM, while clematangoticoside D and F showed selective cytotoxicity against SGC-7901 with IC50 values of 24.22 and 21.35 μM, respectively.

Fast Identification of Radical Scavengers from Securigera varia by Combining 13C-NMR-Based Dereplication to Bioactivity-Guided Fractionation

Securigera varia (Fabaceae) is a common herbaceous perennial plant widely growing in Europe and Asia and purposely established for erosion control, roadside planting, and soil rehabilitation. The aim of this study was to determine the radical scavenging activity of a crude methanol extract of S. varia aerial parts by using the free radical DPPH (1,1-diphenyl-2-picrylhydrazyl) and to rapidly identify the compounds involved in this activity. The crude extract was initially separated in five fractions on Diaion HP20 resin and the most active part was fractionated by Centrifugal Partition Extraction (CPE). Known compounds were directly identified by a (13)C-NMR-based dereplication method. Semi-preparative high performance liquid chromatography purification experiments were further performed to identify unknown or minor active compounds. As a result, one new (13) and twelve known flavonoid glycosides together with three nitropropanoylglucopyranoses were isolated, including astragalin (1), kaempferol-3-O-(6-O-acetyl)-β-D-glucopyranoside (2), kaempferol-3,4'-di-O-β-D-glucopyranoside (3), trifolin (4), isoquercitrin (5), hyperoside (6), isovitexin (7), isoorientin (8), isovitexin 4'-O-β-D-glucopyranoside (9), apigenin 7-O-β-D-glucuronopyranoside (10), luteolin 7-O-β-D-glucuronopyranoside (11), apigenin 7-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucuronopyranoside (12), apigenin 7-O-β-D-glucopyranosyl-(1 → 2)-β-D-glucuronopyranoside (13), 6-O-(3-nitropropanoyl)-β-D-glucopyranoside (14), coronillin (16) and coronarian (15). 120 mg of the most active compound isoorientin against the free radical DPPH was recovered by CPE with an HPLC purity of 99%.