Haifeng Wu

Recent developments in qualitative and quantitative analysis of phytochemical constituents and their metabolites using liquid chromatography–mass spectrometry

Over the past few years, the applications of liquid chromatography coupled with mass spectrometry (LC-MS) in natural product analysis have been dramatically growing because of the increasingly improved separation and detection capabilities of LC-MS instruments. In particular, novel high-resolution hybrid instruments linked to ultra-high-performance LC and the hyphenations of LC-MS with other separation or analytical techniques greatly aid unequivocal identification and highly sensitive quantification of natural products at trace concentrations in complex matrices. With the aim of providing an up-to-date overview of LC-MS applications on the analysis of plant-derived compounds, papers published within the latest years (2007-2012) involving qualitative and quantitative analysis of phytochemical constituents and their metabolites are summarized in the present review. After briefly describing the general characteristics of natural products analysis, the most remarkable features of LC-MS and sample preparation techniques, the present paper mainly focuses on screening and characterization of phenols (including flavonoids), alkaloids, terpenoids, steroids, coumarins, lignans, and miscellaneous compounds in respective herbs and biological samples, as well as traditional Chinese medicine (TCM) prescriptions using tandem mass spectrometer. Chemical fingerprinting analysis using LC-MS is also described. Meanwhile, instrumental peculiarities and methodological details are accentuated.

Anti-Hyperlipidemic Effects and Potential Mechanisms of Action of the Caffeoylquinic Acid-Rich Pandanus tectorius Fruit Extract in Hamsters Fed a High Fat-Diet

Hyperlipidemia is considered to be one of the greatest risk factors contributing to the prevalence and severity of cardiovascular diseases. In this work, we investigated the anti-hyperlipidemic effect and potential mechanism of action of the Pandanus tectorius fruit extract in hamsters fed a high fat-diet (HFD). The n-butanol fraction of the P. tectorius fruit ethanol extract (PTF-b) was rich in caffeoylquinic acids (CQAs). Administration of PTF-b for 4 weeks effectively decreased retroperitoneal fat and the serum levels of total cholesterol (TC), triglycerides (TG) and low density lipoprotein–cholesterol (LDL-c) and hepatic TC and TG. The lipid signals (fatty acids, and cholesterol) in the liver as determined by nuclear magnetic resonance (NMR) were correspondingly reduced. Realtime quantitative PCR showed that the mRNA levels of PPARα and PPARα-regulated genes such as ACO, CPT1, LPL and HSL were largely enhanced by PTF-b. The transcription of LDLR, CYP7A1, and PPARγ was also upregulated. Treatment with PTF-b significantly stimulated the activation of AMP-activated protein kinase (AMPK) as well as the activity of serum and hepatic lipoprotein lipase (LPL). Together, these results suggest that administration of the PTF-b enriched in CQAs moderates hyperlipidemia and improves the liver lipid profile. These effects may be caused, at least in part, by increasing the expression of PPARα and its downstream genes and by upregulation of LPL and AMPK activities.

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.

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.

A new labdane diterpene from the rhizomes of Alpinia officinarum

A new labdane diterpene, (Z)-12,14-labdadien-15(16)-olide-17-oic acid (1), and a new natural cadinane sesquiterpene, 4-isopropyl-6-methyl-1-naphthalenemethanol (2), were isolated from the ethanolic extract of the rhizomes of Alpinia officinarum, together with three other products, galangin (3), kaempferol (4) and quercetin (5). Their structures were elucidated by using extensive spectroscopic methods. Compounds 1 and 2 showed no remarkable cytotoxic activity against HeLa and HepG2 cancer cell lines with IC50>50 μg mL− 1.

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.

The dichloromethane fraction from Mahonia bealei (Fort.) Carr. leaves exerts an anti-inflammatory effect both in vitro and in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE Mahonia bealei has a long history of medical use in traditional Chinese medicine for the treatment of inflammatory-associated diseases. Despite numerous phytochemical and pharmacological studies, there is a lack of systematic studies to understand the cellular and molecular mechanisms of the anti-inflammatory activity of this plant. AIM OF STUDY This study aimed to evaluate the anti-inflammatory activity of the dichloromethane fraction from M. bealei leaves (MBL-CH). MATERIALS AND METHODS RAW 264.7 cells were pretreated with different concentrations of MBL-CH for 30min prior to treatment with 1μg/ml of lipopolysaccharide (LPS). The nuclear factor κB (NF-κB) pathway and subsequent production of inflammatory mediators, such as nitric oxide (NO), prostaglandin E2 (PGE2), and tumour necrosis factor (TNF)-α were investigated. Furthermore, the in vivo mouse model of LPS-induced acute lung injury (ALI) was employed to study the anti-inflammatory effects of MBL-CH. RESULTS Pre-treatment with MBL-CH significantly inhibited the LPS-stimulated secretion of NO, PGE2, and TNF-α into the culture medium, as well as the mRNA levels of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and TNF-α, which were associated with a reduction in the phosphorylation of IκBα, Akt, and PI3K and inhibition of the transcriptional activity of NF-κB. Furthermore, in vivo experiments revealed that MBL-CH attenuated LPS-stimulated lung inflammation in mice. CONCLUSION Taken together, our findings indicate that MBL-CH attenuates LPS-stimulated inflammatory responses in macrophages by blocking NF-κB activation through interference with activation of the PI3K/Akt pathway, providing scientific evidence that the plant can be employed in traditional remedies.

A new diterpene from Clinopodium chinense

A new abietane diterpene, named as 3β-hydroxy-12-O-β-d-glucopyranosyl-8,11,13-abietatrien-7-one (1), together with four known flavonoids, was isolated from the hot water extract of the aerial parts of Clinopodium chinense. Their structures were determined by analysing the spectroscopic data including 1D, 2D NMR and HR-ESI-MS. Compound 1 tested against HepG-2 and A549 cancer cell lines expressed weak cytotoxicity. Cardioprotective effects of compounds 2–5 against H2O2-induced apoptosis in H9c2 cells were also evaluated; compounds 2 and 3 exhibited moderate cardioprotective effect.

Clerodendranoic acid, a new phenolic acid from Clerodendranthus spicatus.

Phenolic acid derivatives are typical constituents of Clerodendranthus spicatus which were considered to the active principles of this medicinal plant. These chemical constituents with their interesting frameworks and biological significance attracted our attention. As part of our ongoing chemical investigation of C. spicatus using various column chromatography techniques, a new phenolic compound, named clerodendranoic acid (1), was isolated from the aerial parts of C. spicatus together with five known ones, including rosmarinic acid (2), methyl rosmarinate (3), caffeic acid (4), methyl caffeate (5), ethyl caffeate (6). Their structures, including stereochemical configurations, were completely established by extensive spectroscopic methods, mainly inclvolving 1D, 2D NMR, as well as HRESIMS.