Unusual immuno-modulatory triterpene-caffeates in the skins of russeted varieties of apples and pears

Three triterpene-caffeates have been isolated from skins of a russeted apple cultivar "Merton Russet" and identified by LC-MS and NMR as betulinic acid-3-cis-caffeate, betulinic acid-3-trans-caffeate, and oleanolic acid-3-trans-caffeate. Betulinic acid-3-trans-caffeate and oleanolic acid-3-trans-caffeate were also found in russeted pear skins. These compounds have not been previously reported in apples or pears, or in any other foods. Their presence was related to suberized tissue as they were only found in russet portions of the partially russeted apple cultivar "Cox's Orange Pippin" and were not detected in the waxy apple cultivar "Royal Gala". High concentrations of betulinic acid-3-trans-caffeate were found in the bark of both "Merton Russet" and "Royal Gala" trees. The three triterpene-caffeates showed anti-inflammatory activity in vitro, inhibiting NF-κB activation with IC50's of 6-9 μM. Betulinic acid-3-trans-caffeate, the predominant compound in the apples, was immuno-modulatory at around 10 μM in the in vitro and ex vivo bioassays, boosting production of the pro-inflammatory cytokine TNFα in cells stimulated with bacterial lipopolysaccharides.

The aerial part of Taraxacum coreanum extract has an anti-inflammatory effect on peritoneal macrophages in vitro and increases survival in a mouse model of septic shock

ETHNOPHARMACOLOGICAL RELEVANCE

Taraxacum coreanum Nakaiis a dandelion native to Korea and is widely consumed as an edible and medicinal herb. The aerial part of Taraxacum coreanum (TC) has been used therapeutically as a diuretic and anti-inflammatory agent, but its mechanism of action has not yet been evaluated.

AIM OF THE STUDY

To investigate the anti-inflammatory potential of a Taraxacum coreanum chloroform fraction(TCC) and its mechanisms of action in vitro and in vivo.

MATERIALS AND METHODS

Isolated mouse peritoneal macrophages were stimulated in vitro with interferon-γ (IFN-γ) and lipopolysaccharide (LPS) in the presence or absence of TCC. The anti-inflammatory effects of TCC were assessed by measuring nitric oxide (NO) and prostaglandin E2 (PGE2) production, as well as expression of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), IκBα, phospho-IKK, mitogen-activated protein kinases (MAPKs), and signal transducer and activator of transcription (STAT1). The effects of TCC were tested in vivo by measuring cytokine production and survival in a mouse model of lethal septic shock. And the standard compounds of Taraxacum coreanum were analyzed by HPLC using a C18 column.

RESULTS

Treatment of primary macrophages with TCC in vitro significantly inhibited all of the inflammatory parameters measured, including LPS-induced NO and PGE2 production, iNOS and COX-2 expression, IκBα degradation, IKK phosphorylation, and MAPK and STAT1 activation. In a mouse model of LPS-induced septic shock, TCC inhibited the production of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, and increased survival by 83%.Standard compounds (gallic acid, syringic acid) of Taraxacum coreanum were qualified by HPLC analysis.

CONCLUSIONS

TCC possesses potent anti-inflammatory activity in vitro and in vivo, which occurs at least partly through inhibition of proinflammatory signaling and mediator release. These results strongly support the therapeutic potential of TCC as an anti-inflammatory agent in vivo.

Molecular characterization of the pentacyclic triterpenoid biosynthetic pathway in Catharanthus roseus

Catharanthus roseus is an important medicinal plant and the sole commercial source of monoterpenoid indole alkaloids (MIA), anticancer compounds. Recently, triterpenoids like ursolic acid and oleanolic acid have also been found in considerable amounts in C. roseus leaf cuticular wax layer. These simple pentacyclic triterpenoids exhibit various pharmacological activities such as anti-inflammatory, anti-tumor and anti-microbial properties. Using the EST collection from C. roseus leaf epidermome ( http://www.ncbi.nlm.nih.gov/dbEST ), we have successfully isolated a cDNA (CrAS) encoding 2,3-oxidosqualene cyclase (OSC) and a cDNA (CrAO) encoding amyrin C-28 oxidase from the leaves of C. roseus. The functions of CrAS and CrAO were analyzed in yeast (Saccharomyces cerevisiae) systems. CrAS was characterized as a novel multifunctional OSC producing α- and β-amyrin in a ratio of 2.5:1, whereas CrAO was a multifunctional C-28 oxidase converting α-amyrin, β-amyrin and lupeol to ursolic-, oleanolic- and betulinic acids, respectively, via a successive oxidation at the C-28 position of the substrates. In yeast co-expressing CrAO and CrAS, ursolic- and oleanolic acids were detected in the yeast cell extracts, while the yeast cells co-expressing CrAO and AtLUP1 from Arabidopsis thaliana produced betulinic acid. Both CrAS and CrAO genes show a high expression level in the leaf, which was consistent with the accumulation patterns of ursolic- and oleanolic acids in C. roseus. These results suggest that CrAS and CrAO are involved in the pentacyclic triterpene biosynthesis in C. roseus.

Anti-inflammatory procyanidins and triterpenes in 109 apple varieties

We evaluated the potential of apple to reduce inflammation. Phenolic compounds and triterpenes were analyzed in 109 apple cultivars. Total phenolics ranged from 29 to 7882 μg g(-1) of fresh weight (FW) in the flesh and from 733 to 4868 μg g(-1) FW in the skin, with flavanols including epicatechin and procyanidins as major components. Ursolic (44.7 to 3522 μg g(-1) FW) and oleanolic (47.2 to 838 μg g(-1) FW) acids dominated the skin triterpene profile. Five chemically contrasting cultivars were fractionated and their immune-modulating activity measured using two cell-based assays targeting key points in the inflammation process. Cultivars exhibiting high contents of procyanidins were the most potent at inhibiting NF-κB while triterpene-rich fractions reduced the promoter activity of the gene of TNFα. This study provides new insights into how apple genetic diversity could be used to alleviate inflammation.

Bioavailability, distribution, and antioxidative effects of selected triterpenes in mice

This study analyzed the content of eight triterpenes (oleanolic acid, ursolic acid, arjunolic acid, asiatic acid, boswellic acid, corosolic acid, madecassic acid, and maslinic acid) in ten vegetables and eight fruits. These compounds at 0.5% were supplied to mice for 4 or 8 weeks. The bioavailability, tissue distribution, and antioxidative protection of these triterpenes were examined. Results showed that triterpenes were detected in eight vegetables and six fruits. Basil and brown mustard contained seven test triterpenes, in the range of 14-102 mg/100 g dry weight. The level of each triterpene in plasma, brain, heart, liver, kidney, colon, and bladder increased as the feeding period was increased from 4 weeks to 8 weeks (P < 0.05). Renal homogenates from mice with triterpene intake had greater antioxidative effects against glucose-induced glutathione loss and malondialdehyde and oxidized glutathione production when compared with those from control groups (P < 0.05). These data support that these triterpenes were absorbed and deposited in their intact forms, which in turn exerted in vivo antioxidative protection.

In planta transient expression analysis of monoterpene synthases

In vitro-based analyses of monoterpene synthase (mono-TPS) enzymes have led to a wealth of knowledge regarding their catalytic behavior, the mechanistic principles governing their product specificity, and the molecular basis for their evolution. However, the efficient production of active enzymes in Escherichia coli or yeast can be challenging. Agrobacterium-mediated transient expression in tobacco leaves is increasingly being used as a viable alternative to in vitro-based approaches for the production and functional analysis of a wide range of plant proteins. Transient expression is well suited for qualitative and semiquantitative analyses of mono-TPS enzyme product specificity and, in conjunction with standard volatile analysis techniques, provides an efficient tool for screening mono-TPS function in planta. The primary advantages of this system for mono-TPS analysis are that both mono-TPS genomic clones and cDNAs can be cloned directly into plant expression vectors without modification and expressed enzymes can be analyzed without the need for purification or endogenous precursor addition. Here, we describe a simple and cost-effective method for the in planta functional analysis of plant mono-TPS enzymes. This method can accommodate both the analysis of single genes and the scaling for more high-throughput functional screening of mono-TPS gene families or mutant libraries.

Characterization of dandelion species using 1H NMR- and GC-MS-based metabolite profiling

Taraxacum, known as dandelion, is a large genus of plants in the family Asteraceae. Pharmacological studies have shown that these plants display a wide variety of medicinal properties because Taraxacum extracts contain many pharmacologically active metabolites that display anti-inflammatory, antinociceptive, antioxidant, and anticancer activity. Each plant species displays several different natural constituents, the majority of which have not been studied as no global metabolite screen of the diverse Taraxacum species has been performed. In this study, we investigated the metabolite difference in three species of Taraxacum (T. coreanum, T. officinale, and T. platycarpum) by (1)H NMR spectroscopy and gas chromatography-mass spectrometry (GC-MS) coupled with multivariate statistical analyses. The aim of this study was to identify the different chemical compositions of the polar and nonpolar extracts in these species. A partial least-squares discriminant analysis showed a significantly higher separation among nonpolar extracts (mainly fatty acids and sterols) compared to polar extracts (mainly amino acids, organic acids, and sugars) between these species. A one-way ANOVA was performed to statistically certify the metabolite differences of these nonpolar extracts. Taken together, these data suggest that a metabolomic approach using combined (1)H NMR and GC-MS analysis is an effective analytical method to differentiate biochemical compositions among different species in plants.