Five new diterpenoids from Pseudolarix kaempferi

3,4-Secocycloartane Triterpenoids from the Cones of Pseudolarix amabilis

Four new 3,4-secocycloartane triterpenoids, pseudolactones A-D (1-4), were isolated from the ethanol extract of the cones of Pseudol arixamabilis. Their structures were established by extensive 1D- and 2D-NMR experiments. The cones of P. arixamabilis are enriched in the ring-expanded or cleaved cycloartane triterpenoids. This work provides new insight into cycloartane triterpenoids from the cones of P. arixamabilis.

Cycloartane triterpenoids from Pseudolarix amabilis and their antiviral activity

Seven undescribed cycloartane triterpenoids, pseudolarnoids A-G, together with ten known ones, were isolated from the seeds of Pseudolarix amabilis (J. Nelson) Rehder. Their structures were elucidated on the basis of spectroscopic analysis, X-ray crystallography, and ECD data. Pseudolarnoids A-C are cycloartane triterpenoids with a unique 16S, 23R-spirolactone moiety. Pseudolarnoids F, G, and pseudolarolide C demonstrated potent antiviral effects on HSV-1 in vitro.

New triterpenoids and PTP1B inhibitory constituents of Pseudolarix amabilis

Six new triterpenoids, pseudolarins A-F (1-6), were isolated from the twigs of Pseudolarix amabilis, together with four known triterpenoids (7-10) and five known diterpenoids (11-15). Their structures were determined by extensive spectroscopic analysis, and the absolute configuration of 1 was assigned by single-crystal X-ray diffraction. Compound 1 is a 3,4:9,10-diseco-cycloartane triterpenoid possessing an unprecedented 5/5/7/6/5/6/5 ring system. Compounds 1, 5, 7, 9-11, and 13 showed inhibition against protein tyrosine phosphatase 1B (PTP1B) in vitro.

Domino enyne metathesis en route to skeletally diverse, privileged scaffolds: synthesis of the tricyclic core of pseudolaric acid F

A domino enyne metathesis strategy for the efficient synthesis of skeletally diverse, privileged scaffolds has been developed.

Pseudolarenone, an unusual nortriterpenoid lactone with a fused 5/11/5/6/5 ring system featuring an unprecedented bicyclo[8.2.1]tridecane core from Pseudolarix amabilis

A phytochemical investigation of the cone of Pseudolarix amabilis led to the isolation of pseudolarenone (), a structurally novel pentacyclic (5/11/5/6/5) nortriterpenoid lactone with an unprecedented carbon skeleton featuring a unique bicyclo[8.2.1]tridecane core. Its structure and absolute configurations were elucidated by spectroscopic analysis and single crystal X-ray diffraction (CuK(α)).

Discovery of structurally diverse and bioactive compounds from plant resources in China

This review describes the major discoveries of structurally diverse and/or biologically significant compounds from plant resources in China, mainly from the traditional Chinese medicines (TCMs) since the establishment of our research group in 1999. In the past decade, a large array of biologically significant and novel structures has been identified from plant resources (or TCM) in our laboratory. The structural modification of several biologically important compounds led to more than 400 derivatives, some of which exhibited significantly improved activities and provided opportunities to elucidate the structure-activity relationship of the related compound class. These findings are important for drug discovery and help us understand the biological basis for the traditional applications of these plants in TCM.

In vitro synergy of pseudolaric acid B and fluconazole against clinical isolates of Candida albicans

Candida albicans is the most common fungal pathogen in humans. The emergence of resistance to azole antifungals has raised the issue of using such antifungals in combination to optimise therapeutic outcome. The objective of this study was to evaluate in vitro synergy of pseudolaric acid B (PAB) and fluconazole (FLC) against clinical isolates of C. albicans. The in vitro antifungal activity of PAB, a diterpene acid from Pseudolarix kaempferi Gordon, was evaluated alone and in combination with FLC against 22 FLC-resistant (FLC-R) and 12 FLC-susceptible (FLC-S) C. albicans using the chequerboard microdilution method and time-killing test assays. Synergism was observed in all 22 (100%) FLC-R strains tested as determined by both fractional inhibitory concentration index (FICI) with values ranging from 0.02 to 0.13 and bliss independence (BI) models. Synergism was observed in two of 12 (17%) FLC-S strains as determined by FICI model with values ranging from 0.25 to 0.5 and in three of 12 (18%) FLC-S strains as determined by BI model. For FLC-R strains, the drug concentrations of FLC and PAB, where synergistic interactions were found, ranged from 0.06 to 4 μg ml(-1) and 0.5 to 4 μg ml(-1) respectively. For FLC-S strains, the drug concentrations of FLC and PAB were 1-8 μg ml(-1) and 0.5-4 μg ml(-1) respectively. The BI model gave results consistent with FICI, but no antagonistic activity was observed in any of the strains tested. These interactions between PAB and FLC were confirmed using the time-killing test for the selected strains. Fluconazole and PAB exhibited a good synergism against azole-R isolates of C. albicans.

Rapid separation and identification of major constituents in Pseudolarix kaempferi by ultra-performance liquid chromatography coupled with electrospray and quadrupole time-of-flight tandem mass spectrometry

A rapid and reliable method based on ultra-performance liquid chromatography (UPLC) coupled with photodiode-array detection (PDA) and electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-Q-TOF-MS/MS) has been developed for separation and identification of major constituents in extracts of root bark of Pseudolarix kaempferi Gordon (PKG). Identification of the constituents was carried out by interpretation of their retention times, UV absorption spectra, MS and MS/MS spectra, as well as the data provided by authentic standards and literatures. A total of 20 components were separated in only 8.0 min on a small particle size C18 column (1.7 microm). These components included nine diterpene acids, seven glycosides and four triterpenoids, among which pseudolaric acid C-O-beta-D-glucopyranoside and pseudolaric acid C2-O-beta-D-glucopyranoside were separated and identified for the first time in this study. Furthermore, the fragmentation patterns of the three types of compounds were elucidated for the first time. This established UPLC-PDA/Q-TOF-MS/MS method is reliable and effective for the separation and identification of the 20 compounds and will be useful for quality control of the crude materials of Pseudolarix kaempferi Gordon and their related preparations.

Effects of osthole on apoptosis and TGF-beta1 of hypertrophic scar fibroblasts

Osthole, 7-methoxy-8-[3-methylpent-2-enyl]coumarin (1), was extracted from a Chinese herb Cnidium monnieri (L.) Cuss. It showed immunity strengthening, anti-tumor, anti-hepatitis, and anti-osteoporosis activities in previous studies. Our goals are to study the effects of 1 on cell proliferation and TGF-beta of hypertrophic scar fibroblasts. Our results showed that 1 induced apoptosis and inhibited cell proliferation in hypertrophic scar fibroblasts. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that its IC(50) value toward hypertrophic scar fibroblasts was 15.5 +/- 2.2 micromol/l. Furthermore, the results of cell growth curve matched with the above results. Inducing apoptosis by 1 in hypertrophic scar fibroblasts was assessed by various morphological and biochemical characteristics, including cell shrinkage, chromatin condensation, membrane blebbing, formation of apoptotic bodies, and DNA ladder formation. A typical 'Sub-G(1) peak' was also checked through flow cytometry. We used immunohistochemistry to observe the expression of TGF-beta(1). Also, we found that 1 could obviously inhibit the expression of TGF-beta(1) of fibroblasts derived from hypertrophic scar compared with the control group (P < 0.05). These results suggest that 1 inhibits the growth of hypertrophic scar fibroblasts through apoptosis and decreases the expression of TGF-beta(1).

Effects of PLAB on apoptosis and Smad signal pathway of hypertrophic scar fibroblasts

Pseudolaric acid-B (PLAB), a diterpene acid, was isolated from the root and trunk barks of Pseudolarix kaempferi. It has shown antifungal and anti-fertility effects and cytotoxic activities in previous studies. Our goals are to study the effects of PLAB on cell proliferation and Smad signal pathway of hypertrophic scar fibroblasts. Our results showed that PLAB induced apoptosis in hypertrophic scar fibroblasts and inhibited cell proliferation of hypertrophic scar fibroblast. MTT assay showed that its IC(50) value toward hypertrophic scar fibroblasts was 12.9+/-1.20 micromol/L. Furthermore, the results of cell growth curve matched with the above results. Inducing apoptosis by PLAB in hypertrophic scar fibroblast was assessed by various morphological and biochemical characteristics, including cell shrinkage, chromatin condensation, membrane blebbing, formation of apoptotic bodies, and DNA ladder formation. A typical "Sub-G1 peak" was also checked through flow cytometry. The Smad2 and Smad7 mRNA levels of 48-h PLAB treatment were determined by reverse transcription-polymerase chain reaction (RT-PCR) 48 h later. RT-PCR showed that Smad7 mRNA level increased and significant differences were observed between control group and experimental group (P<0.05); While there is no significant difference in Smad2 mRNA between the two groups. Our results showed that PLAB interfered with the microtubule dynamics of tubulin polymerisation and depolymerisation, which results in the inhibition of chromosomal segregation in mitosis and consequently the inhibition of cell division. These results suggest that PLAB inhibits hypertrophic scar fibroblast growth through apoptosis and Smad signal pathway.

Studies on anti-tumour activities of pseudolaric acid-B (PLAB) and its mechanism of action

Pseudolaric acid-B (PLAB), a diterpene acid, was isolated from the root and trunk barks of Pseudolarix kaempferi. It showed antifungal and anti-fertility effects as well as cytotoxic activities in previous studies. The present study investigates cytotoxic activity on cultured human cancer cells, inhibition on the growth of transplantable tumours in mice and the mechanism of these actions. The experimental results showed that PLAB had potent cytotoxic effects on cancer cells derived from different tissues. MTT assay showed that its IC50 towards these tumour cells was 0.17 to 5.20 micromol/L, and towards one normal human kidney proximal tubular epithelial cell (HKC) was 5.77 micromol/L. Furthermore, the results of cell growth curve and colony formation of cancer cells matched the above results. The results in vivo demonstrated that PLAB significantly inhibited the growth of transplantable tumours, such as Lewis lung cancer and hepatocarcinoma 22 (H22) in mice. The inhibitory rate to H22 was 14.4% and 40.1%, and to Lewis lung cancer reached 39.1% and 47.0%, when PLAB was given by intraperitoneal injection (i.p.) at a dose of 30 mg/kg/day and 60 mg/kg/day for 10 days, respectively. It is suggested that PLAB also showed obvious anticancer activity in vivo. Inducing apoptosis by PLAB in HeLa cells was assessed by various morphological and biochemical characteristics, including cell shrinkage, chromatin condensation, membrane blebbing, formation of apoptotic bodies, and internucleosomal DNA fragmentation. A typical 'sub-G1 peak' was also checked through flow cytometry. These results were accompanied by up-regulating P53, down-regulating Bcl-2 and activating Caspase-3, which was revealed by Western blotting. PLAB also caused cell cycle arrest to G2/M phase in a dose-dependent manner. The experiments suggest that PLAB is a new potent anti-tumour agent.

Chemical constituents fromPseudolarix Kaempferi

A novel degraded triterpenoid isopseudolaritone A (1) and one new oligosaccharide, 1-O-isopropyl-6-O-[2-O-methyl-alpha-L-rhamnopyranosyl(1 --> 6)]-beta-D-glucopyranose (2), two new artefacts, 9-O-formacyl cedrusin (5) and 9,9'-O-diformacyl cedrusin (6), as well as 12 known phenolic Compounds (3-4, 7 16), were isolated from the root bark of Pseudolarix kaempferi. Their structures were elucidated mainly by spectroscopic methods.

Antifungal diterpenoids of Pseudolarix kaempferi, and their structure-activity relationship study

The in vitro antifungal activities of 19 structurally diversified analogues of pseudolaric acids tested against the major pathogenic fungus Candida albicans has led to the establishment of a very clear structure-activity relationship of pseudolaric acids derivatives. Pseudolaric acid A was first found to be a potent antifungal component comparable with pseudolaric acid B. Among the tested 19 diterpenoids, pseudolaric acids A2 (1), B2 (3), B3 (4) and methyl pseudolarate A2 (2) are new isolates of the root bark of Pseudolarix kaempferi, and their structures were elucidated mainly by 2D-NMR techniques and chemical methods. Compounds 12-19 were first semi-synthesized by efficient routines from pseudolaric acid B.