Jun-Shan Yang

Spirobisnaphthalene Analogues from the Endophytic Fungus Preussia sp.

A study on the chemical constituents of the endophytic fungus Preussia sp. led to the isolation of three new spirobisnaphthalene analogues, spiropreussione A (1), spiropreussione B (2), and spiropreussomerin A (3). Compound 2 is a spirobisnaphthalene analogue with a cyclopenteno-naphthoindene fragment bridged to a 1,8-dioxygenated naphthalene fragment, and compound 1 is the second compound in this series with a spiro-nonadiene skeleton. The structures of 1-3 were elucidated using spectroscopic data interpretation. Compound 1 showed cytotoxicity toward A2780 and BEL-7404 cells with IC(50) values of 2.4 and 3.0 microM, respectively, and weak activity against Staphylococcus aureus (CMCC B26003) with a MIC value of 25 microM.

Daphniphyllum Alkaloids: Recent Findings on Chemistry and Pharmacology

The unique polycyclic fused ring systems of Daphniphyllum alkaloids, along with their extensive bioactivities, make this family of alkaloids especially attractive targets for total synthesis and biogenetic studies. Successive discoveries of new alkaloids with unprecedented skeletons have made a great contribution to structural diversities of alkaloids elaborated by plants of the genus Daphniphyllum. By the end of 2008, more than 200 alkaloids belonging to 14 different skeletal types have been isolated from different parts of plants of thirteen Daphniphyllum species. These alkaloids show cytotoxic, antioxidant, vasorelaxant, and antiplatelet activating factor effects. The plausible biosynthetic pathways for Daphniphyllum alkaloids have been proposed and biomimetic total syntheses of some alkaloids completed. To provide an update of the previous reviews published in 2009, new structures, synthesis, and bioactivity of Daphniphyllum alkaloids reported in recent years are presented in this article. In the meantime, an additional 54 novel alkaloids have been isolated and identified. Among them, some possess unprecedented frameworks. Several inspired organic syntheses were completed.

Caesalpins A-H, bioactive cassane-type diterpenes from the seeds of Caesalpinia minax.

Eight new cassane-type diterpenes, caesalpins A-H (1-8), were isolated from the ethyl acetate extract of Caesalpinia minax. Compound 1 displayed significant antiproliferative activity against HepG-2 (IC50 4.7 μM) and MCF-7 (IC50 2.1 μM) cells, and compounds 2 and 4 exhibited selective cytotoxic activities against MCF-7 (IC50 7.9 μM) and AGS (IC50 6.5 μM) cells.

Biotransformation of ursolic acid by Syncephalastrum racemosum CGMCC 3.2500 and anti-HCV activity.

Microbial transformation of ursolic acid (UA, 3β-hydroxy-urs-12-en-28-oic acid, 1) by filamentous fungus Syncephalastrum racemosum CGMCC 3.2500 was conducted. Five metabolites 3β, 7β, 21β-trihydroxy-urs-12-en-28-oic acid (2); 3β, 21β-dihydroxy-urs-11-en-28-oic acid-13-lactone (3); 1β, 3β, 21β-trihydroxy-urs-12-en-28-oic acid (4); 3β, 7β, 21β-trihydroxy-urs-1-en-28-oic acid-13-lactone (5); and 21-oxo-1β, 3β-dihydroxy-urs-12-en-28-oic acid (6) were afforded. Elucidation of the structures of these metabolites was primarily based on 1D and 2D NMR and HR-MS data. Metabolite 2 was a new compound. In addition, the anti-HCV activity of compounds 1-6 was evaluated.

Cassane-type Diterpenes from the Seeds of Caesalpinia minax with Their Antineoplastic Activity

Five new cassane-type diterpenes, neocaesalpin AA (1), neocaesalpin AB (2), neocaesalpin AC (3), neocaesalpin AD (4) and neocaesalpin AE (5), were isolated from Caesalpinia minax together with three known compounds, 12α-methoxyl,5α,14β-dihydroxy-1α,6α,7β-triacetoxycass-13(15)-en-16,12-olide (6), spirocaesalmin (7) and magnicaesalpin (8). Their structures were elucidated based on 1D and 2D NMR, MS and CD analyses. Compounds 1-6 were tested against Hela, HCT-8, HepG-2, MCF-7 and A549 cancer cells and showed moderate cytotoxicity with IC₅₀ values from 18.4 to 83.9 µM.

Characterization of aromatic glycosides in the extracts of Trollius species by ultra high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry

Ultra high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UHPLC/ESI-Q-TOF MS/MS) was used to investigate the MS fragmentation behaviors of flavone C-glycosides present in the extracts of five Trollius species. In this study, the primary MS fragmentation pathways and key diagnostic fragment ions of flavone C-glycosides were systematically investigated and summarized to distinguish different types of derivatives and to trace other analogs in Trollius species. This method was useful, rapid, efficient and sensitive and allowed the simultaneous identification of different types of flavone C-glycosides present in other medicinal plants. The features of the MS fragmentation of these compounds indicated that the product ions were primarily the result of cleavage in the saccharide moiety, followed by hydrogen rearrangement and dehydration. In this study, thirty-six components including thirty-two flavone C-glycosides, two flavone O-glycosides and two phenylethanoid glycosides, were identified in the extracts of five Trollius species. Eleven of the flavone C-glycosides were identified by comparison with reference standards, and twenty-one flavone C-glycosides were tentatively identified based on their retention times, exact mass information and fragment ions. Two potentially new flavone C-glycosides (2″-O-vanilloylorientin and 2″-O-feruloylvitexin) were successfully characterized based on the summarized fragmentation pathways, and six known flavone C-glycosides (2″-O-glucosylvitexin, 2″-O-acetylorientin, 2″-O-acetylvitexin, 3″-O-acetylorientin, 3″-O-acetylvitexin and 6″-O-acetylvitexin) were identified in these plant species for the first time. In conclusion, the fragmentation pathways proposed in this paper were helpful for the identification of different types of flavone C-glycosides when no reference standards were available.

Antimalarial and Antiproliferative Cassane Diterpenes of Caesalpinia sappan.

Bioassay-guided fractionation of a methanol extract of the seeds of Caesalpinia sappan led to the isolation of 12 new cassane-type diterpenes, caesalsappanins A-L (1-12). Their structures were elucidated on the basis of NMR and HRESIMS analysis, and the absolute configuration of compound 1 was determined by single-crystal X-ray crystallography. All isolated compounds were tested against a chloroquine-resistant Plasmodium falciparum strain for antiplasmodial activities and against a small panel of human cancer cell lines for antiproliferative activities. Compounds 7 and 8 displayed antimalarial activity against the chloroquine-resistant K1 strain of P. falciparum with IC50 values of 0.78 and 0.52 μM and selectivity indices of 17.6 and 16.4, respectively. Compound 10 showed antiproliferative activity against the KB cancer cell line with an IC50 value of 7.4 μM.

Antimalarial diterpene alkaloids from the seeds of Caesalpinia minax

Two new diterpene alkaloids, caesalminines A (1) and B (2), possessing a tetracyclic cassane-type furanoditerpenoid skeleton with γ-lactam ring, were isolated from the seeds of Caesalpinia minax. Their structures were determined by different spectroscopic methods and ECD calculation. The plausible biosynthetic pathway of caesalminines A and B was proposed. The anti-malarial activity of compounds 1 and 2 is presented with IC50 values of 0.42 and 0.79 μM, respectively.

Triterpene saponins from Tabellae Clinopodii.

Three new triterpene saponins, named Clinoposaponin A, Clinoposaponin B, and Clinoposaponin C along with three known triterpene saponins were isolated from the Tabellae Clinopodii. The structures of these compounds were elucidated by means of various spectroscopic analyses. All of the isolated compounds were tested against Hela, HCT-8, AGS, and MCF-7 human cancer cell lines and showed moderate cytotoxic activities with IC₅₀ values between 4.1 and 19.7 μM.

A new triterpene from the plant of uncaria macrophylla.

Our ongoing investigations on the stem bark of Uncaria macrophylla afforded a new ursolic triterpene, 3β,6β,19α-trihydroxy-urs-12-en-28-oic acid-24-carboxylic acid methyl ester (1), named uncariursanic acid, and three known ursolic triterpenes including 3β,6β,19α-trihydroxy-23-oxo-urs-12-en-28-oic acid (2), 3β,6β,19α-trihydroxy-urs-12-en-28-oic acid (3) and ursolic acid (4). Their structures were elucidated by extensive spectral methods, including 1D and 2D NMR and HR-ESI-MS. The cytotoxicities of the four compounds were evaluated against two cancer cell lines (MCF-7 and HepG2) by the MTT method, and only compound 4 exhibited potent activity.