Showing papers on "Triterpene published in 2014"

Triterpene Biosynthesis in Plants

Abstract: The triterpenes are one of the most numerous and diverse groups of plant natural products. They are complex molecules that are, for the most part, beyond the reach of chemical synthesis. Simple triterpenes are components of surface waxes and specialized membranes and may potentially act as signaling molecules, whereas complex glycosylated triterpenes (saponins) provide protection against pathogens and pests. Simple and conjugated triterpenes have a wide range of applications in the food, health, and industrial biotechnology sectors. Here, we review recent developments in the field of triterpene biosynthesis, give an overview of the genes and enzymes that have been identified to date, and discuss strategies for discovering new triterpene biosynthetic pathways.

Combinatorial biosynthesis of sapogenins and saponins in Saccharomyces cerevisiae using a C-16α hydroxylase from Bupleurum falcatum

Abstract: The saikosaponins comprise oleanane- and ursane-type triterpene saponins that are abundantly present in the roots of the genus Bupleurum widely used in Asian traditional medicine. Here we identified a gene, designated CYP716Y1, encoding a cytochrome P450 monooxygenase from Bupleurum falcatum that catalyzes the C-16α hydroxylation of oleanane- and ursane-type triterpenes. Exploiting this hitherto unavailable enzymatic activity, we launched a combinatorial synthetic biology program in which we combined CYP716Y1 with oxidosqualene cyclase, P450, and glycosyltransferase genes available from other plant species and reconstituted the synthesis of monoglycosylated saponins in yeast. Additionally, we established a culturing strategy in which applying methylated β-cyclodextrin to the culture medium allows the sequestration of heterologous nonvolatile hydrophobic terpenes, such as triterpene sapogenins, from engineered yeast cells into the growth medium, thereby greatly enhancing productivity. Together, our findings provide a sound base for the development of a synthetic biology platform for the production of bioactive triterpene sapo(ge)nins.

Functional Analysis of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Encoding Genes in Triterpene Saponin-Producing Ginseng

Abstract: Ginsenosides are glycosylated triterpenes that are considered to be important pharmaceutically active components of the ginseng (Panax ginseng ‘Meyer’) plant, which is known as an adaptogenic herb. However, the regulatory mechanism underlying the biosynthesis of triterpene saponin through the mevalonate pathway in ginseng remains unclear. In this study, we characterized the role of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) concerning ginsenoside biosynthesis. Through analysis of full-length complementary DNA, two forms of ginseng HMGR (PgHMGR1 and PgHMGR2) were identified as showing high sequence identity. The steady-state mRNA expression patterns of PgHMGR1 and PgHMGR2 are relatively low in seed, leaf, stem, and flower, but stronger in the petiole of seedling and root. The transcripts of PgHMGR1 were relatively constant in 3- and 6-year-old ginseng roots. However, PgHMGR2 was increased five times in the 6-year-old ginseng roots compared with the 3-year-old ginseng roots, which indicates that HMGRs have constant and specific roles in the accumulation of ginsenosides in roots. Competitive inhibition of HMGR by mevinolin caused a significant reduction of total ginsenoside in ginseng adventitious roots. Moreover, continuous dark exposure for 2 to 3 d increased the total ginsenosides content in 3-year-old ginseng after the dark-induced activity of PgHMGR1. These results suggest that PgHMGR1 is associated with the dark-dependent promotion of ginsenoside biosynthesis. We also observed that the PgHMGR1 can complement Arabidopsis (Arabidopsis thaliana) hmgr1-1 and that the overexpression of PgHMGR1 enhanced the production of sterols and triterpenes in Arabidopsis and ginseng. Overall, this finding suggests that ginseng HMGRs play a regulatory role in triterpene ginsenoside biosynthesis.

Investigation of triterpene synthesis and regulation in oats reveals a role for β-amyrin in determining root epidermal cell patterning

Abstract: Sterols have important functions in membranes and signaling. Plant sterols are synthesized via the isoprenoid pathway by cyclization of 2,3-oxidosqualene to cycloartenol. Plants also convert 2,3-oxidosqualene to other sterol-like cyclization products, including the simple triterpene β-amyrin. The function of β-amyrin per se is unknown, but this molecule can serve as an intermediate in the synthesis of more complex triterpene glycosides associated with plant defense. β-Amyrin is present at low levels in the roots of diploid oat (Avena strigosa). Oat roots also synthesize the β-amyrin–derived triterpene glycoside avenacin A-1, which provides protection against soil-borne diseases. The genes for the early steps in avenacin A-1 synthesis [saponin-deficient 1 and 2 (Sad1 and Sad2)] have been recruited from the sterol pathway by gene duplication and neofunctionalization. Here we show that Sad1 and Sad2 are regulated by an ancient root developmental process that is conserved across diverse species. Sad1 promoter activity is dependent on an L1 box motif, implicating sterol/lipid-binding class IV homeodomain leucine zipper transcription factors as potential regulators. The metabolism of β-amyrin is blocked in sad2 mutants, which therefore accumulate abnormally high levels of this triterpene. The accumulation of elevated levels of β-amyrin in these mutants triggers a “superhairy” root phenotype. Importantly, this effect is manifested very early in the establishment of the root epidermis, causing a greater proportion of epidermal cells to be specified as root hair cells rather than nonhair cells. Together these findings suggest that simple triterpenes may have widespread and as yet largely unrecognized functions in plant growth and development.

Tetra- and pentacyclic triterpene acids from the ancient anti-inflammatory remedy frankincense as inhibitors of microsomal prostaglandin E(2) synthase-1.

Abstract: The microsomal prostaglandin E2 synthase (mPGES)-1 is the terminal enzyme in the biosynthesis of prostaglandin (PG)E2 from cyclooxygenase (COX)-derived PGH2. We previously found that mPGES-1 is inhibited by boswellic acids (IC50 = 3-30 μM), which are bioactive triterpene acids present in the anti-inflammatory remedy frankincense. Here we show that besides boswellic acids, additional known triterpene acids (i.e., tircuallic, lupeolic, and roburic acids) isolated from frankincense suppress mPGES-1 with increased potencies. In particular, 3α-acetoxy-8,24-dienetirucallic acid (6) and 3α-acetoxy-7,24-dienetirucallic acid (10) inhibited mPGES-1 activity in a cell-free assay with IC50 = 0.4 μM, each. Structure-activity relationship studies and docking simulations revealed concrete structure-related interactions with mPGES-1 and its cosubstrate glutathione. COX-1 and -2 were hardly affected by the triterpene acids (IC50 > 10 μM). Given the crucial role of mPGES-1 in inflammation and the abundance of highly active triterpene acids in frankincence extracts, our findings provide further evidence of the anti-inflammatory potential of frankincense preparations and reveal novel, potent bioactivities of tirucallic acids, roburic acids, and lupeolic acids.

Review on anti-tumor effect of triterpene acid compounds

Abstract: Recent studies have found that triterpene acid type compounds has many effects including antiinflammatory, regulating blood sugar level, antiviral and antitumor activity. More importantly, triterpene acid type compounds has become one of the most popular topics recently because its selective toxic effects on cancer cells and harmless to normal cells at the same time. This review summarized the antitumor activity and the mechanism of triterpene acid type compounds, providing guideline for further research and development of new antitumor natural products.

Synthesis and Anti-HCV Entry Activity Studies of β-Cyclodextrin–Pentacyclic Triterpene Conjugates

Abstract: In our previous studies, oleanolic acid (OA) and echinocystic acid (EA), isolated from Dipsacus asperoides, were found to have anti-HCV entry properties. The major issue for members of this type of triterpene is their low water solubility. In this study, a series of new water-soluble triazole-bridged b-cyclodextrin (CD)–pentacyclic triterpene conjugates were synthesized via click chemistry. Thanks to the attached b-CD moiety, all synthesized conjugates showed lower hydrophobicity (Alog P) than their parent compounds. Several conjugates exhibited moderate anti-HCV entry activity. With the exception of per-O-methylated b-CD–pentacyclic triterpene conjugates, all other conjugates showed no cytotoxicity based on an alamarBlue assay carried out with HeLa, HepG2, MDCK, and 293T cells. More interestingly, the hemolytic activity of these conjugates disappeared upon the introduction of b-CDs. Easy access to such conjugates that combine the properties of b-CD and pentacyclic triterpenes may provide a way to obtain a new class of anti-HCV entry inhibitors.

α-Amylase inhibitory triterpene from Abrus precatorius leaves.

Abstract: In the screening experiments for porcine pancreatic α-amylase inhibitors in 18 plants obtained from Indonesia, a potent inhibitory activity was detected in the extract of leaves of Abrus precatorius. The enzyme assay-guided fractionation of the extract led to the isolation of a triterpene ketone, lupenone (1), as a potent α-amylase inhibitor, together with 24-methylenecycloartenone (2) and luteolin (3). The mode of inhibition of compound 1 against porcine pancreatic α-amylase was a mixed inhibition. This is the first report that describes the potent α-amylase inhibitory activity of the low-polar triterpene ketone similar to compound 1. A comparison of the activities of the isolate and related compounds indicated the importance of C-3 ketone and the lupane skeleton in the α-amylase inhibitory activity.

Structure Elucidation of Five Novel Isomeric Saponins from the Viscera of the Sea Cucumber Holothuria lessoni

Abstract: Sea cucumbers are prolific producers of a wide range of bioactive compounds. This study aimed to purify and characterize one class of compound, the saponins, from the viscera of the Australian sea cucumber Holothuria lessoni. The saponins were obtained by ethanolic extraction of the viscera and enriched by a liquid-liquid partition process and adsorption column chromatography. A high performance centrifugal partition chromatography (HPCPC) was applied to the saponin-enriched mixture to obtain saponins with high purity. The resultant purified saponins were profiled using MALDI-MS/MS and ESI-MS/MS which revealed the structure of isomeric saponins to contain multiple aglycones and/or sugar residues. We have elucidated the structure of five novel saponins, Holothurins D/E and Holothurinosides X/Y/Z, along with seven reported triterpene glycosides, including sulfated and non-sulfated saponins containing a range of aglycones and sugar moieties, from the viscera of H. lessoni. The abundance of novel compounds from this species holds promise for biotechnological applications.

Triterpene Lactones from Cultures of Ganoderma sp. KM01

Abstract: A revised structure of colossolactone G (1), seven new triterpene lactones, ganodermalactones A-G (2-8), and five known triterpene lactones, colossolactone I (9), schisanlactone B (10), colossolactone B (11), colossolactone E (12), and colossolactone IV (13), and ergosterol have been isolated from cultured biomass of the macrofungi Ganoderma sp. KM01. Their structures were identified by spectroscopic methods. Structures and relative configurations of 3, 7, and 8 were confirmed by X-ray crystallographic analysis. Compounds 7, 10, and 12 exhibited antimalarial activity against Plasmodium falciparum in the range 6.0-10.0 μM (IC50).

Analysis of saponins as bioactive zoochemicals from the marine functional food sea cucumber Bohadschia cousteaui

Abstract: The edible portion of sea cucumber, body walls, is a source of natural bioactive compounds. Triterpene saponins are the main chemical constituents in sea cucumber that have potential interest for the body health and food industry. Twenty-one lanostane-type non-sulphated triterpene glycosides were isolated from the methanol/methylene chloride extract of the body walls of Bohadschia cousteaui. Ten new saponins called coustesides A (1), B (3), C (9), D (10), E (11), F (12), G (15), H (16), I (17) and J (18), including two pentasaccharide and eight hexasaccharide saponins, together with eleven known triterpene glycosides, were isolated by reversed-phase semi-preparative HPLC. Their structures were mainly determined by 1D- and 2D-NMR (1H, 13C, COSY, TOCSY, HSQC, HMBC and ROESY) as well as MS experiments and acid hydrolysis. Most of the isolated compounds showed good antifungal activity against Candida albicans. Moreover, sea cucumber B. cousteaui is a rich source of biologically active saponins. Therefore, sea cucumbers are eaten for their therapeutic values as a functional food than for their seafood taste.

Triterpenes from Perilla frutescens var. acuta and Their Cytotoxic Activity

Abstract: Nine triterpenes were isolated from the petroleum ether and MeOH extract of Perilla frutescens var. acuta leaves. Their structures were determined to be arjunic acid (1), maslinic acid (2), oleanolic acid (3), euscaphic acid (4), tormentic acid (5), 3-O-trans-p-coumaroyltormentic acid (6), 28-formyloxy-3β-hydroxy-urs- 12-ene (7), ursolic acid (8), and corosolic acid (9) by spectroscopic methods. The compounds 1, 2, 4, 6, and 7 were isolated for the first time from this plant and the Genus Labiatae. The isolated compounds (1-9) were tested for cytotoxicity against four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15) in vitro using a Sulforhodamin B bioassay. Keywords − Perilla frutescens var. acuta, Labiatae, triterpene, cytotoxicity

The apoptotic effect of D Rhamnose β-hederin, a novel oleanane-type triterpenoid saponin on breast cancer cells.

Abstract: There is growing interest in development of natural products as anti-cancer and chemopreventive agents. Many triterpenoids have been proved as potential agents for chemoprevention and therapy of breast cancer. Ginsenosides from ginseng, which mostly belong to dammarane-type triterpenoids, have gained great attention for their anti-breast cancer activity with diverse mechanisms. However, studies of other kinds of triterpenoid saponins on breast cancer are limited. Previously, we purified and identified a novel oleanane-type triterpene saponin named D Rhamnose beta-hederin (DR beta-H) from Clematis ganpiniana, a Chinese traditional anti-tumor herb. In the present study, DR beta-H showed strong inhibitory activity on the growth of various breast cancer cells and induced apoptosis in these cells. DR beta-H inhibited PI3K/AKT and activated ERK signaling pathway. PI3K inhibitor LY294002 synergistically enhanced DR beta-H-induced apoptosis whereas MEK inhibitor U0126 reduced the apoptosis rate. Moreover, DR beta-H regulated the ratio of pro-apoptotic and anti-apoptotic Bcl-2 family proteins. Furthermore, DR beta-H induced depolarization of mitochondrial membrane potential which released Apaf-1 and Cytochrome C from the inter membrane space into the cytosol, where they promoted caspase-9 and caspase-3 activation. This is the first report on the pro-apoptotic effects of DR beta-H, a novel oleanane-type triterpenoid saponin, on breast cancer cells and its comprehensive apoptosis pathways. It implied that oleanane-type triterpenoid saponin DR beta-H could be a promising candidate for chemotherapy of breast cancer.

Solid-phase library synthesis of bi-functional derivatives of oleanolic and maslinic acids and their cytotoxicity on three cancer cell lines.

Abstract: A wide set of 264 compounds has been semisynthesized with high yields and purities. These compounds have been obtained through easy synthetic processes based on a solid-phase combinatorial methodology. All the members of this library have one central core of a natural pentacyclic triterpene (oleanolic or maslinic acid) and differ by 6 amino acids, coupled with the carboxyl group at C-28 of the triterpenoid skeleton, and by 10 different acyl groups attached to the hydroxyl groups of the A-ring of these molecules. According to the literature on the outstanding and promising pharmacological activities of other similar terpene derivatives, some of these compounds have been tested for their cytotoxic effects on the proliferation of three cancer cell lines: B16–F10, HT29, and Hep G2. In general, we have found that around 70% of the compounds tested show cytotoxicity in all three of the cell lines selected; around 60% of the cytotoxic compounds are more effective than their corresponding precursors, that is, ole...

Chemical Constituents of Gold‐red Apple and Their α‐Glucosidase Inhibitory Activities

Abstract: Ten compounds were isolated and purified from the peels of gold-red apple (Malus domestica) for the 1st time. The identified compounds are 3β, 20β-dihydroxyursan-28-oic acid (1), 2α-hydroxyoleanolic acid (2), euscaphic acid (3), 3-O-p-coumaroyl tormentic acid (4), ursolic acid (5), 2α-hydroxyursolic acid (6), oleanolic acid (7), betulinic acid (8), linolic acid (9), and α-linolenic acid (10). Their structures were determined by interpreting their nuclear magnetic resonance and mass spectrometry (MS) spectra, and by comparison with literature data. Compound 1 is new, and compound 2 is herein reported for the 1st time for the genus Malus. α-Glucosidase inhibition assay revealed 6 of the triterpenoid isolates as remarkable α-glucosidase inhibitors, with betulinic acid showing the strongest inhibition (IC50 = 15.19 μM). Ultra-performance liquid chromatography-electrospray ionization MS analysis of the fruit peels, pomace, flesh, and juice revealed that the peels and pomace contained high levels of triterpenes, suggesting that wastes from the fruit juice industry could serve as rich sources of bioactive triterpenes.

Anti-inflammatory diterpenoids from the root bark of Acanthopanax gracilistylus.

Abstract: Five new ent-pimarane (1–3, 7, and 8) and three new ent-kaurane diterpenoids (4–6) and a new oleanane triterpene acid (9), together with 22 known compounds, were isolated from the root bark of the medicinal herb Acanthopanax gracilistylus. The structures of 1–9 were established based on the interpretation of high-resolution MS and 1D- and 2D-NMR data. The absolute configurations of 7 and 11 were determined by single-crystal X-ray diffraction and electronic circular dichroism analysis. Compounds 7 and 8 represent rare naturally occurring structures based on the devinyl ent-pimarane skeleton. Compounds 3, 10, 14, 16, and 17 exhibited potent inhibitory effects on the release of interleukin-1β (IL-1β), interleukin-8 (IL-8), and tumor necrosis factor (TNF-α) in lipopolysaccharide-stimulated peripheral blood mononuclear cells.

Variegatusides: new non-sulphated triterpene glycosides from the sea cucumber Stichopus variegates semper.

Abstract: Four new triterpene glycosides, variegatusides C–F (1–4), together with three structurally known triterpene glycosides, variegatusides A and B (5, 6), and holothurin B (7), were isolated from the sea cucumber Stichopus variegates Semper (Holothuriidae), collected from the South China Sea. Their structures were elucidated on the basis of extensive spectral analysis (nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESIMS)) and chemical evidence. Variegatusides C–F exhibit the same structural feature consisting of the presence of a 23-hydroxyl group at the holostane-type triterpene aglycone side chain. Variegatuside C (1) has a double bond (24, 25) in this same chain, while variegatuside D (2) exhibits a 8(9)-ene bond in the holostane-type triterpene aglycone, which has not been extracted from other sea cucumber species. Compound 4 is a native compound from the sea cucumber S. variegates Semper, which has been reported to be desacetylstichloroside B1. Except for holothurin B, these glycosides have no sulfate group in their sugar chain and show potent antifungal activities in vitro biotests.