Xiang-Rong Tian

New antioxidant and antiglycation active triterpenoid saponins from the root bark of Aralia taibaiensis

Four new oleanane type triterpenoid saponins (1-4) and a known saponin (5) were isolated from the root bark of Aralia taibaiensis Z.Z. Wang et H.C. Zheng. The structures of the four new compounds were elucidated as 3-O-{β-D-glucopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucurono-pyranosyl}-olean-11,13(18)-diene-28-oic acid 28-O-β-D-glucopyranosyl ester (1), 3-O-{β-D-gluco-pyranosyl-(1→3)-[α-l-arabinofuranosyl-(1→4)]-β-D-glucuronopyranosyl}-olean-11,13(18)-diene-28-oic acid 28-O-β-D-glucopyranosyl ester (2), 3-O-{β-d-glucopyranosyl-(1→2)-[α-l-arabinofuranosyl-(1→4)]-β-D-glucuronopyranosyl}-oleanolic acid 28-O-β-D-glucopyranosyl ester (3) and 3-O-{β-D-glucopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucuronopyranosyl}-oleanolic acid 28-O-β-D-glucopyranosyl ester (4), on the basis of extensive spectral analysis and chemical evidence. Compounds 1-5 exhibited moderate effects on antioxidant and antiglycation activities, which correlated with treatment of diabetes mellitus.

Saponins: the Potential Chemotherapeutic Agents in Pursuing New Anti-glioblastoma Drugs

Saponins are natural glycosides consisting of a triterpene or steroid aglycone with a range of pharmacological properties such as significant anti-tumor activity. In this article, we review our recent progress in the studies of the saponins possessing anticancer effects, especially anti-glioblastoma effects from twelve species of marine organisms and terrestrial plants. The anti-glioblastoma active saponins discovered by other researchers in recent decades are also reviewed and compared. Systematic extraction, isolation and structural elucidation on the saponin constituents from three species of starfishes, five species of sea cucumbers and four species of medicinal plants led to the identification of more than 129 saponins, among which 76 saponins are new compounds. Most of the new compounds were found to possess relatively rare structural features showing in vitro cytotoxicity against tumor cells, especially glioblastoma cells. Several saponins exhibited significant anti-glioblastoma effects in vivo by in situ administration (interstitial chemotherapy) and their haemolytic side effects were avoided in the tests. Multiple mechanisms of action, such as interfering with cell cycle progression, inducing apoptosis, promoting stabilization of microtubule, as well as several signal transduction pathways, were involved in their anticancer effects. The review provided valuable leads for pursuing new anti-glioblastoma drugs, and established a new viewpoint for further development of these marine and terrestrial organisms. The successful approach to administrate saponins in situ conquered the bottleneck in the development of saponins as new drugs- haemolytic effects. It means that saponins may be developed as potential chemotherapeutic agents in pursuing new antiglioblastoma drugs.

Cytotoxic triterpenoid saponins from the rhizomes of Anemone taipaiensis.

Two new oleanane-type triterpenoid saponins, 1 and 2, and a new natural product, 3, together with five known saponins, 4- 8, were isolated from the rhizomes of ANEMONE TAIPAIENSIS. Their structures were elucidated by extensive spectroscopic analysis and chemical evidences. Six saponins, 1, 2, 4- 7, which possessed a free carboxylic group at C-28, exhibited significant cytotoxicity against human leukemia HL-60 cells and human hepatocellular carcinoma Hep-G2 cells with IC (50) values in the range of 1.31-10.12 µM.

Two new cytotoxic triterpenoid saponins from the roots of Clematis argentilucida

Bioassay-guided fractionation of the n-BuOH extract of the roots of Clematis argentilucida led to the isolation of two new triterpenoid saponins along with a known one, cussonside B (3). By extensive spectral analysis and chemical evidences, the structures of the two new saponins were determined to be 3β-O-[β-D-ribopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl] hederagenin-11,13-dien-28-oic acid (1) and 3β-O-{β-D-ribopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→4)]-β-D-xylopyranosyl} oleanolic acid (2), respectively. Saponin 1 is the first example of triterpenoid saponins with two double bonds located at C-11 and C-13 in the aglycone from the genus Clematis. The two new saponins exhibited significant cytotoxicity against human leukemia HL-60 cell lines, human hepatocellular carcinoma Hep-G2 cell lines and human glioblastoma U251MG cell lines with a range of IC(50) values from 2.74 to 25.40μM, while 3 showed inactivity against all of the three cancer cell lines.

New Cytotoxic Oxygenated Sterols from the Marine Bryozoan Cryptosula pallasiana

Six new sterols (1-6), together with seven known sterols (7-13), were isolated from the CCl4 extract of the marine bryozoan Cryptosula pallasiana, four (3-6) of which have already been reported as synthetic sterols. This is the first time that these compounds (3-6) are reported as natural sterols. The structures of the new compounds were determined on the basis of the extensive spectroscopic analysis, including two-dimensional (2D) NMR and HR-ESI-MS data. Compounds 1-4, 7 and 10-13 were evaluated for their cytotoxicity against HL-60 human myeloid leukemia cell line, and all of the evaluated compounds exhibited moderate cytotoxicity to HL-60 cells with a range of IC50 values from 14.73 to 22.11 µg/mL except for compounds 12 and 13.

New cytotoxic triterpenoid saponins from the whole plant of Clematis lasiandra Maxim

Four new oleanane type triterpenoid saponins (1-4) and three known saponins (5-7) were isolated from the whole plant of Clematis lasiandra Maxim. The structures of the four new compounds were elucidated as 3-O-β-D-ribopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-[β-D-glucopyranosyl-(1 → 4)]-β-D-xylopyranosyl hederagenin (1), 3-O-β-D-ribopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1→2)-β-D-xylopyranosyl oleanolic acid 28-O-β-D-glucopyranosyl ester (2), 3-O-β-D-ribopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-β-D-xylopyranosyl hederagenin (3) and 3-O-β-D-ribopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-[β-D-glucopyranosyl-(1→4)]-α-L-arabinopyranosyl hederagenin (4) on the basis of extensive spectroscopic analysis and chemical evidence. Compounds 1-7 were evaluated for their cytotoxicity against human tumor cell lines HL-60, Hep-G2 and SGC-7901, and all of the evaluated saponins showed significant cytotoxicity to those three tumor cell lines with IC₅₀ in the range from 1.40 to 19.50 μmol/L except for compounds 2 and 6.

Triterpenoid saponins from the roots of Clematis argentilucida.

Reinvestigation of the n-BuOH extract of the roots of Clematis argentilucida led to the isolation of a new ursane-type triterpenoid saponin 1 and a new taraxerane-type saponin 2, four known saponins 3-6 first isolated from the species, together with seven saponins 7-13 reported in the previous papers. The structures of saponins 1-6 were elucidated by extensive spectroscopic analysis and chemical evidences. The ursane-type and taraxerane-type triterpenoid saponins were obtained from genus Clematis for the first time, and the aglycone of saponin 1, 3β,28-dihydroxy-18αH-ursan-20-en was first encountered. The cytotoxicity of all the saponins was evaluated against human glioblastoma U251MG cell lines. The monodesmosidic saponins 1, 2 and 4-8 exhibited cytotoxic activity against the cells with IC50 values ranging from 6.95 to 38.51 μM.

Triterpenoid Saponins with Anti-Myocardial Ischemia Activity from the Whole Plants of Clematis tangutica

Four new triterpenoid saponins named clematangosides A-D (1-4) along with six known saponins (5-10) were isolated from the whole plants of Clematis tangutica. Their structures were determined by extensive spectral analysis and chemical evidences. All saponins were evaluated for their protective effects in hypoxia-induced myocardial injury model. Compounds 2-4, 6, and 10 exhibited anti-myocardial ischemia activities with ED50 values in the range of 75.77-127.22 µM.

Triterpenoid saponins from the root of Anemone tomentosa

Three new triterpenoid saponins, tomentoside A (1), B (2) and C (3), along with four known saponins (4–7) were isolated from the root of Anemone tomentosa. The structures of the new compounds were elucidated as 3-O-β-d-ribopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-[β-d-glucopyranosyl-(1→4)]-α-l-arabinopyranosyl hederagenin 28-O-α-l-rhamnopyranosyl-(1→4)-β-d-glucopyranosyl-(1→6)-β-d-glucopyranoside (1), 3-O-β-d-ribopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-[β-d-glucopyranosyl-(1→4)]-β-d-xylopyranosyl hederagenin 28-O-α-l-rhamnopyranosyl-(1→4)-β-d-glucopyranosyl-(1→6)-β-d-glucopyranoside (2) and 3-O-β-d-galactopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-β-d-xylopyranosyl oleanolic acid 28-O-α-l-rhamnopyranosyl-(1→4)-β-d-glucopyranosyl-(1→6)-β-d-glucopyranoside (3) on the basis of chemical and spectral evidence. In the oligosaccharide chains of compound 3, the characteristic d-galactose residue is a rare structural feature and secondly encountered among triterpenoid saponins from Anemone.

Neritinaceramides A–E, New Ceramides from the Marine Bryozoan Bugula neritina Inhabiting South China Sea and Their Cytotoxicity

Five new ceramides, neritinaceramides A (1), B (2), C (3), D (4) and E (5), together with six known ceramides (6–11), two known alkyl glycerylethers (12 and 13) and a known nucleoside (14), were isolated from marine bryozoan Bugula neritina, which inhabits the South China Sea. The structures of the new compounds were elucidated as (2S,3R,3′S,4E,8E,10E)-2-(hexadecanoylamino)-4,8,10-octadecatriene-l,3,3′-triol (1), (2S,3R,2′R,4E,8E,10E)-2-(hexadecanoylamino)-4,8,10-octadecatriene-l,3,2′-triol (2), (2S,3R,2′R,4E,8E,10E)-2-(octadecanoylamino)-4,8,10-octadecatriene-l,3,2′-triol (3), (2S,3R,3′S,4E,8E)-2-(hexadecanoylamino)-4,8-octadecadiene-l,3,3′-triol (4) and (2S,3R,3′S,4E)-2-(hexadecanoylamino)-4-octadecene-l,3,3′-triol (5) on the basis of extensive spectral analysis and chemical evidences. The characteristic C-3′S hydroxyl group in the fatty acid moiety in compounds 1, 4 and 5, was a novel structural feature of ceramides. The rare 4E,8E,10E-triene structure in the sphingoid base of compounds 1–3, was found from marine bryozoans for the first time. The new ceramides 1–5 were evaluated for their cytotoxicity against HepG2, NCI-H460 and SGC7901 tumor cell lines, and all of them exhibited selective cytotoxicity against HepG2 and SGC7901 cells with a range of IC50 values from 47.3 μM to 58.1 μM. These chemical and cytotoxic studies on the new neritinaceramides A–E (1–5) added to the chemical diversity of B. neritina and expanded our knowledge of the chemical modifications and biological activity of ceramides.