Cui-Xian Zhang

New triterpene saponins from the root of Ilex pubescens.

Two new triterpene glycosides named ilexpublesnin A (1) and ilexpublesnin B (2) were isolated from the root of Ilex pubescens. Their structures were determined as 3-O-(β-D-xylopyranosyl)-28-O-(β-D-glucopyranosyl)-3β, 19α-dihydroxyurs-23-oxo-12-en-28-oic acid (1) and 28-O-(β-D-xylopyranosyl-(2→1)-β-D-glucopyranosyl)-3β, 19α-dihydroxyurs-23-oxo-12-en-28-oic acid (2) on the basis of chemical and spectroscopic methods.

Acerinol, a cyclolanstane triterpenoid from Cimicifuga acerina, reverses ABCB1-mediated multidrug resistance in HepG2/ADM and MCF-7/ADR cells.

Persistent cancer chemotherapy can lead to multidrug resistance which is one of the most common reasons for failure of chemotherapy. The ABCB1 transporter is a member of the ATP-binding cassette superfamily and it is frequently over-expressed in multidrug resistant cancer cells. Active ingredients derived from traditional Chinese medicinal herbs have been reported to reverse multidrug resistance mediated by ATP-binding cassette transporters. In this study, acerinol, isolated from Cimicifuga acerina, was tested for its potential to modulate the ABCB1 transporter. Our results demonstrated that acerinol could increase the chemosensitivity of ABCB1-overexpressing HepG2/ADM and MCF-7/ADR cells to chemotherapeutic drugs, doxorubicin, vincristine and paclitaxel. Furthermore, it could also increase the retention of ABCB1 substrates doxorubicin and rhodamine 123 in HepG2/ADM and MCF-7/ADR cells. A mechanistic study showed that acerinol significantly stimulated the activity of ABCB1 ATPase without affecting the expression of ABCB1 on neither mRNA nor protein level. Acerinol was also found to reverse the resistance of MCF-7/ADR cells to vincristine, dependent partly on ABCB1. In addition, acerinol׳s action was reversible, suggesting that acerinol may act as a competitive inhibitor of ABCB1 by competing with other drug substrates like doxorubicin. Indeed, docking analysis indicated that acerinol would most likely bind to the sites on ABCB1 that partly overlapped with that of verapamil. In conclusion, the present study is the first to show that acerinol from C. acerina significantly enhances the cytotoxicity of chemotherapeutic drugs by modulating the function of ABCB1. It is hopeful to develop acerinol as a new multidrug resistance reversal agent.

New precursor of tetraterpenoids from the soft coral Sarcophyton glaucum

One new precursor of tetraterpenoids, Sarglaucol (1), along with eight known compounds have been isolated from the soft coral Sarcophyton glaucum collected from the Sanya Bay, Hainan Island, China. Their structures were elucidated through spectroscopic techniques including 1D- and 2D-NMR, and their relative configurations were also assigned by NMR and NOESY analysis. Compounds 1 showed weak antitumour activities.

New cyclic tetrapeptide from the coral-derived endophytic bacteria Brevibacterium sp. L-4 collected from the South China Sea

One new cyclic tetrapeptide cyclic-(Tyr-Ala-Leu-Ser) (1) along with four natural compounds firstly obtained 3H-imidazole-4-carboxylic acid (2), 2-methyl-3H-imidazole-4-carboxylic acid (3), 3-ethylidene-6-isopropyl-piperazine-2,5-dione (4), and 3-isobutylidene-6-methyl piperazine-2,5-dione (5) have been isolated from the coral derived endophytic bacteria Brevibacterium sp. L-4 collected from the South China Sea. Their structures were elucidated through spectroscopic techniques including NMR (1D and 2D), MS, and EA, and their relative configurations were also assigned by NMR analysis.

Gerardianin A, a new abietane diterpenoid from Isodon lophanthoides var. gerardianus

A new abietane diterpenoid, gerardianin A (1), along with a known compound 6,7-dehydroroyleanone (2), has been isolated from the aerial parts of Isodon lophanthoides var. gerardianus [Bentham] H. Hara. The structure of 1 was determined on the basis of spectroscopic methods and X-ray single-crystal diffraction analysis.

Antiproliferative Triterpenoid Saponins from the Stem of Psychotria sp.

Six new triterpenoid saponins, psychotrianosides A-F (1-6), and two known triterpenoid saponins, psychotrianoside G (7) and ardisianoside D (8), were isolated from Psychotria sp. Their structures were determined mainly by spectroscopic methods. The cytotoxic activities of 1-8 against five human cancer cell lines (MDA-MB-231, MCF-7, MCF-7/ADM, HepG2, and HepG2/ADM) are reported for the first time. Psychotrianoside C (3) showed the most potent antiproliferative activity among these saponins, and the IC50 value of 3 against MDA-MB-231 was 2.391 ± 0.161 µM. Compound 3 was also found to induce apoptosis.

Pelopuradazole, a new imidazole derivative alkaloid from the marine bacteria Pelomonas puraquae sp. nov.

One new imidazole derivative alkaloid pelopuradazole (1), together with three known alkaloids as in 3H-imidazole-4-carboxylic acid (2), 1H-pyrrole-2-carboxylic acid (3) and 2-methyl-3H-imidazole-4-carboxylic acid (4) and two known cyclo-dipeptides pelopurin A (5) and pelopurin B (6), has been isolated from the marine bacterium Pelomonas puraquae sp. nov. Pelopuradazole (1) was a new imidazole derivative alkaloid, while compounds 2, 3, 5 and 6 were firstly obtained as natural products. Compounds 1–6 were isolated from P. puraquae sp. nov. for the first time.

New sphingolipid psychotramide A–D from the stem of Psychotria sp.

Chemical study of the Psychotria sp. led to the isolation of a new type of ceramide named psychotramide (1). HR-FAB–MS analysis revealed that psychotramide consists of four new sphingolipids. Their structures were determined on the basis of the spectroscopic data and chemical methods to be psychotramide A (1-a), psychotramide B (1-b), psychotramide C (1-c) and psychotramide D (1-d).