Discovery of Michael reaction acceptors from the leaves of Ailanthus altissima by a modified tactic

Structural characteristics-guided investigation of Ailanthus altissima (Mill.) Swingle resulted in the isolation and identification of seven undescribed potential Michael reaction acceptors (1-7). Ailanlactone A (1) possesses an unusual 1,7-epoxy-11,12-seco quassinoid core. Ailanterpene B (6) was a rare guaianolide-type sesquiterpene with a 5/6/6/6-fused skeleton. Their structures were determined through extensive analysis of physiochemical and spectroscopic data, quantum chemical calculations, and single crystal X-ray crystallographic technology using Cu Kα radiation. The cytotoxic activities of isolates on HepG2 and Hep3B cells were evaluated in vitro. Encouragingly, ailanaltiolide K (4) showed significant cytotoxicity against Hep3B cells with IC50 values of 1.41 ± 0.21 μM, whose covalent binding mode was uncovered in silico.

Chemical constituents from the twigs and leaves of Picrasma quassioides

Two new compounds, including a norsesquiterpenoid, annuionone H (1), and a quassinoid, picraqualide G (2), along with eleven known compounds (3-13), were isolated from the twigs and leaves of Picrasma quassioides. Comprehensive spectroscopic analyses and NMR calculation with DP4+ analysis were used to identify their structures. Moreover, of all these compounds, compound 4 showed a week inhibition rate in the anti-inflammatory screening results against mouse macrophage J774A.1 cell.

Enhanced ROS-Boosted Phototherapy against Pancreatic Cancer via Nrf2-Mediated Stress-Defense Pathway Suppression and Ferroptosis Induction

In situ oxygen generation is the most common strategy to boost reactive oxygen species (ROS) for enhancing the efficacy of phototherapy in cancer, including photodynamic therapy (PDT) and photothermal therapy (PTT). However, hyperoxidation or hyperthermia often triggers stress-defense pathways and promotes tumor cell survival, thus severely limiting the therapeutic efficacy. To overcome the tumor hypoxia and thermal resistance existing in phototherapy, we constructed a self-synergistic nanoplatform for tumors by incorporating brusatol, a nuclear factor erythroid 2-related factor (Nrf2) inhibitor, into the silica nanonetwork. It was then sequentially decorated with MnO₂ and the photosensitizer chlorin e6 (Ce6) and then coated with poly(ethylene glycol)-folate (PEG-FA)-functionalized polydopamine (PDA) (designated as brusatol/silica@MnO₂/Ce6@PDA-PEG-FA). As an oxygen generator, MnO₂ can promote ROS production, which not only directly enhances Ce6-mediated PDT but also strengthens PDA-mediated PTT by attacking heat shock proteins (HSPs). Particularly, brusatol could efficiently inhibit the activation of Nrf2 defense pathway under hyperoxidation and hyperthermia and cause glutathione peroxidase 4 (GPX4) and ferritin heavy chain (FTH) inactivation, thereby inducing ferroptosis and ultimately enhancing the phototherapeutic effects. By exploiting these features, brusatol/silica@MnO₂/Ce6@PDA-PEG-FA exhibited excellent antitumor efficacy with enhanced PDT and PTT both in in vitro and in vivo studies. Overall, our work highlights a promising strategy against hypoxia- and hyperthermia-associated resistance in phototherapy via suppressing stress-defense system and inducing ferroptosis.

Brusatol inhibits laryngeal cancer cell proliferation and metastasis via abrogating JAK2/STAT3 signaling mediated epithelial-mesenchymal transition

AIMS

This study aimed at investigating the role of Brusatol (BR) on human laryngeal squamous carcinoma cell (Hep-2) to study its underlying mechanism through in vitro and in vivo approaches.

MATERIALS AND METHOD

In the present research, we employed various cell-based assays, such as cell proliferation, apoptosis, cell cycle assessment, migration and invasion assays were used to examine the anti-tumor effect of BR on Hep-2 cells. Immunohistochemistry (IHC), qRT-PCR and Western blotting were performed to study the underlying molecular mechanisms. To validate our in vitro findings we used a subcutaneous tumor-bearing model of Balb/c mice with Hep-2 cells of laryngeal carcinoma (LC) to study the inhibitory effect of BR on Hep-2 cells in vivo.

KEY FINDINGS

The results indicated that BR markedly inhibited the viability, migration and invasion capacity of Hep-2 cells, with no significant toxic effect on normal Human bronchial epithelial cell line (BEAS-2B). Also, BR induced cellular apoptosis by blocking the cells in S phase to suppress cell proliferation. Immunohistochemistry results revealed that BR inhibited the protein expression levels of epithelial-mesenchymal transition (EMT)-related markers. Mechanistically, western blotting results exhibited that BR could suppress the protein expression of both JAK2/STAT3 and their phosphorylation levels. Our in vivo experiments further validated the anti-tumor effect of BR on Hep-2 cells in vitro, where BR suppressed the growth of xenograft laryngeal tumor without apparent toxicity.

SIGNIFICANCE

The present study highlights the anti-LC effect of BR by possibly abrogating JAK2/STAT3 signaling mediated EMT process. BR may be a promising therapeutic candidate for the treatment of LC.

Quassinoids with Inhibitory Activities against Plant Fungal Pathogens from Picrasma javanica

A bioactivity-guided study on the leaves of Picrasma javanica led to the isolation of 19 quassinoids, including 13 new compounds. The structures of the new compounds were elucidated by a combination of spectroscopic data analysis, X-ray crystallography studies, and electronic circular dichroism (ECD) data interpretation. Compounds 1-7 are rare examples of quassinoids with a keto carbonyl group at C-12. The biological activities of 11 of the more abundant isolates were evaluated against five phytopathogenic fungi in vitro, and several of them including 6 and 15 showed moderate inhibitory effects that were comparative to those of the positive control, carbendazim. In addition, the preliminary structure-activity relationships (SARs) of these quassinoids were also investigated.

Two Novel Quassinoid Glycosides with Antiviral Activity from the Samara of Ailanthus altissima

Phytochemistry investigations on Ailanthus altissima (Mill.) Swingle, a Simaroubaceae plant that is recognized as a traditional herbal medicine, have afforded various natural products, among which C20 quassinoid is the most attractive for their significant and diverse pharmacological and biological activities. Our continuous study has led to the isolation of two novel quassinoid glycosides, named chuglycosides J and K, together with fourteen known lignans from the samara of A. altissima. The new structures were elucidated based on comprehensive spectra data analysis. All of the compounds were evaluated for their anti-tobacco mosaic virus activity, among which chuglycosides J and K exhibited inhibitory effects against the virus multiplication with half maximal inhibitory concentration (IC50) values of 56.21 ± 1.86 and 137.74 ± 3.57 μM, respectively.

Unprecedented Quassinoids from Eurycoma longifolia: Biogenetic Evidence and Antifeedant Effects

Six new quassinoids (1-6) were isolated from the roots of Eurycoma longifolia, and their structures with absolute configurations were determined unambiguously by spectroscopic analyses and single-crystal X-ray crystallographic experiments. Compounds 1 and 2 are the first members of a new class of quassinoids with an unusual C₂₆ carbon skeleton. Compound 6 features a C₂₀ cage-like scaffold with an unprecedented densely functionalized 2,5-dioxatricyclo[5.2.2.0^4,8]undecane core. The discovery of the two C₂₆ quassinoids 1 and 2 has provided firm evidence for the better understanding the biogenetic process from C₃₀ triterpenoid precursors to quassinoids. Compound 5 exhibited significant antifeedant activity on the diamondback moth (DBM) larvae and excellent systemic absorption and accumulated properties in Brassica chinensis.

Quassinoids with Insecticidal Activity against Diaphorina citri Kuwayama and Neuroprotective Activities from Picrasma quassioides

Six new quassinoids, named kumulactone F (1), kumulactone G (2), kumulactone H (4), kumulactone I (5), kumulactone J (6), and kumulactone K (7), a pair of undescribed epimers α- and β-nigakihemiacetal G (3), 15 known quassinoids (8-22), and a mixture of the known compounds α- and β-neoquassin (23) were separated from the dried stems of the medical plants Picrasma quassioides. The chemical structures of all of the new compounds were established by spectroscopic data analyses (HR-ESI-MS, 1D and 2D NMR spectroscopy, and electronic circular dichroism (ECD)). Biologically, compounds 9 and 21 showed toxicity toward the Asian citrus psyllid Diaphorina citri Kuwayama with potent activity even equal to that of the positive control (Abamectin), compound 11 exhibited an excellent neuroprotective effect against SH-SY5Y cells which were pretreated by H₂O₂ with potent activity equal to that of the positive control (Trolox), and none of them showed cytotoxic activity toward the HeLa or A549 cell lines (IC₅₀ > 100 μM).

A novel recombinant javanicin with dual antifungal and anti-proliferative activities

Resistance to common drugs by microorganisms and cancers has become a major issue in modern healthcare, increasing the number of deaths worldwide. Novel therapeutic agents with a higher efficiency and less side effects for the treatment of certain diseases are urgently needed. Plant defensins have an integral role in a hosts' immune system and are attractive candidates for combatting drug-resistant microorganisms. Interestingly, some of these defensins also showed great potential due to their cytotoxic activity toward cancer cells. In this study, a defensin encoding gene was isolated from five legume seeds using 3' rapid amplification of cDNA ends (3' RACE) with degenerate primers and cDNA cloning strategies. Bioinformatic tools were used for in silico identification and the characterization of new sequences. To study the functional characteristics of these unique defensins, the gene encoded for Sesbania javanica defensin, designated as javanicin, was cloned into pTXB-1 plasmid and expressed in the Escherichia coli Origami 2 (DE3) strain. Under optimized conditions, a 34-kDa javanicin-intein fusion protein was expressed and approximately 2.5-3.5 mg/L of soluble recombinant javanicin was successfully extracted with over 90% purity. Recombinant javanicin displayed antifungal properties against human pathogenic fungi, including resistant strains, as well as cytotoxic activities toward the human breast cancer cell lines, MCF-7 & MDA-MB-231. Recombinant javanicin holds great promise as a novel therapeutic agent for further medical applications.

Quassinoids from Picrasma quassioides and Their Neuroprotective Effects

Quassinoids are a class of highly oxygenated degraded triterpenoids exclusively discovered from plants of the Simaroubaceae family. In this study, eight new (1-8) and 15 known quassinoids (9-23) were isolated from an extract of the stems of Picrasma quassioides. The structures were elucidated by spectroscopic analysis and electronic circular dichroism spectra combined with quantum chemical calculations. Compounds 4 and 5 represent the first examples of 18-nor-quassinoids from P. quassioides. All isolates were screened for their neuroprotective activities toward H₂O₂-induced cell damage in SH-SY5Y cells. Further study revealed that the potential protective activities of these compounds appeared to occur via the suppression of cell apoptosis and downregulation of caspase-3 activation.

Ailanthone reverses multidrug resistance by inhibiting the P-glycoprotein-mediated efflux in resistant K562/A02 cells

Multidrug resistance (MDR) poses a great impediment to cancer treatment. Excessive expression of ATP-binding cassette transport protein AC-1 (P-glycoprotein, P-GLP) is usually involved in MDR. In this study, ailanthone (AIL), a natural compound extracted from the whole seedlings of Ailanthus altissima (Simaroubaceae) was shown to mediate the reversal of P-GLP-induced MDR and restore the susceptibility of K562/A02 cells to doxorubicin (DOX). Further mechanistic studies revealed that AIL increased intracellular DOX accumulation and interrupted Rh123 efflux through suppression of P-GLP, and also suppressed P-GLP ATPase activity. At the same time, it markedly inhibited MDR1 gene expression and P-GLP protein to sensitize the cytotoxic effect of DOX. Furthermore, AIL down-regulated P-GLP expression by inhibiting the PI3K/Akt pathway. Thus, AIL could be a potential therapeutic compound for reversing P-GLP-mediated drug resistant cancer.

Anti-Tobacco Mosaic Virus Quassinoids from Ailanthus altissima (Mill.) Swingle

Quassinoids are bitter constituents characteristic of the family Simaroubaceae. A total of 18 C20 quassinoids, including nine new quassinoid glycosides, named chuglycosides A-I (1-6 and 8-10), were identified from the samara of Ailanthus altissima (Mill.) Swingle. All of the quassinoids showed potent anti-tobacco mosaic virus (TMV) activity. A preliminary structure-anti-TMV activity relationship of quassinoids was discussed. The effects of three quassinoids, including chaparrinone (12), glaucarubinone (15), and ailanthone (16), on the accumulation of TMV coat protein (CP) were studied by western blot analysis. Ailanthone (16) was further investigated for its influence on TMV spread in the Nicotiana benthamiana plant.

Fabrication and characterization of chitosan conjugated eurycomanone nanoparticles: In vivo evaluation of the biodistribution and toxicity in fish

Chitosan nanoparticles (CNPs) have been proven considerable delivery agents due to their remarkable physicochemical properties. Present study reports the fabrication of CNPs by ionic gelation process and their characterization by different approaches. The constructed nanoparticles were successfully conjugated with eurycomanone with significant entrapment efficiency. Particle size of chitosan and chitosan conjugated eurycomanone nanoparticles were 126.2nm and 130nm respectively. Scanning electron microscopy showed that the particles were spherical in shape and well dispersed. Cross-linking between CNPs and eurycomanone (CENPs) were confirmed by Fourier-transform infrared (FTIR) spectroscopy. Fluorescent nanoparticles were prepared by using Rhodamine-6G dye, characterised by SEM and confirmed for conjugation by FTIR. Biodistribution of CENPs showed the presence of fluorescent nanoparticles in liver, kidney, testes and brain of C. magur. The toxicity of CENPs was evaluated by comparing the histological sections of catfish testes collected from treated and control group. No signs of toxicity were seen in testes after the delivery of CENPs. Molecular docking study revealed high spontaneous binding ability of chitosan with eurycomanone and aromatase enzyme. The study reports that CNPs can act as a stabilizing agent for eurycomanone formulation and could be a promising approach to increase the reproductive performance of the fishes.

Eurycomalactone Inhibits Expression of Endothelial Adhesion Molecules at a Post-Transcriptional Level

The C-19 quassinoid eurycomalactone (1) has recently been shown to be a potent (IC₅₀ = 0.5 μM) NF-κB inhibitor in a luciferase reporter model. In this study, we show that 1 with similar potency inhibited the expression of the NF-κB-dependent target genes ICAM-1, VCAM-1, and E-selectin in TNFα-activated human endothelial cells (HUVECtert) by flow cytometry experiments. Surprisingly, 1 (2 μM) did not inhibit TNFα-induced IKKα/β or IκBα phosphorylation significantly. Also, the TNFα-induced degradation of IκBα remained unchanged in response to 1 (2 μM). In addition, pretreatment of HUVECtert with 1 (2 μM) had no statistically significant effect on TNFα-mediated nuclear translocation of the NF-κB subunit p65 (RelA). Quantitative RT-PCR revealed that 1 (0.5-5 μM) exhibited diverse effects on the TNFα-induced transcription of ICAM-1, VCAM-1, and SELE genes since the mRNA level either remained unchanged (ICAM-1, E-selectin, and VCAM-1 at 0.5 μM 1), was reduced (VCAM-1 at 5 μM 1), or even increased (E-selectin at 5 μM 1). Finally, the time-dependent depletion of a short-lived protein (cyclin D1) as well as the measurement of de novo protein synthesis in the presence of 1 (2-5 μM) suggested that 1 might act as a protein synthesis inhibitor rather than an inhibitor of early NF-κB signaling.

HPLC-MS/MS method for bioavailability study of bruceines D & E in rat plasma

Bruceines D and E are quassinoids from seeds of Brucea javanica (L.) Merr. exhibiting hypoglycemia effect. The crude drug is used as a traditional medicine by diabetes patients. The aim of this study is to understand the bioavailability and pharmacokinetics of both the bruceines D & E. A rapid and sensitive HPLC-MS/MS method was developed and validated for the quantification of both quassinoids, bruceines D & E in rat plasma. Both the bruceines D & E were separated with the Zorbax SBC-18 column with gradient elution and mobile phase system of acetonitrile and deionized water with 0.1% formic acid at a flow rate of 0.5mL/min. Analytes were detected in multiple reaction monitoring (MRM) mode with electrospray positive ionization. The quassinoids, namely bruceines D & E were detected with transitions of m/z 411.2→393.2 and m/z 395.2→377.2, respectively. Another quassinoid, eurycomanone was used as the internal standard with transition of m/z 409.2→391.2. The method was validated and conformed to the regulatory requirements. The validated method was applied to pharmacokinetic and bioavailability studies in rats. The pharmacokinetic study indicated both bruceine D and E were rapidly absorbed into the circulation system and reached its peak concentration at 0.54±0.34h and 0.66±0.30h, respectively. Bruceine E was eliminated slower than Bruceine D with t_1/2 value almost increased two-fold compared to Bruceine D. In conclusion, a rapid, selective and sensitive HPLC-MS/MS method was developed for the simultaneous determination of both the bruceines D and E in rat plasma. Both bruceines D and E displayed poor oral bioavailability.

Antimalarial and cytotoxic quassinoids from the roots of Brucea javanica

Two new quassinoids, brujavanol A (1) and brujavanol B (2), along with five known quassinoids (3-7), were isolated from the roots of Brucea javanica. Their structures were elucidated by spectroscopic methods. The antimalarial and cytotoxic activities of the isolated compounds were also assessed. Compounds 1 and 2 exhibited significant in vitro cytotoxicity against human oral cavity cancer (KB) cells with IC₅₀ values of 1.30 and 2.36 μg/ml, respectively, whereas compound 3 showed excellent antiplasmodial activity against the Plasmodium falciparum strains, K1 (IC₅₀ = 0.58 μg/ml).

1HNMR-Based Discriminatory Analysis of Eurycoma longifolia from Different Locations and Establishing a Profile for Primary Metabolites Identification and Quassinoids Quantification

Quassinoids, the major secondary metabolites of Eurycoma longifolia roots, improve male fertility. Hence, it is crucial to investigate their quantitative level in E. longifolia extracts. A profile was established to identify the primary metabolites and major quassinoids, and quantify quassinoids using external calibration curves. Furthermore, the metabolic discrimination of E. longifolia roots from different regions was investigated. The ¹H-NMR spectra of the quassinoids, eurycomanone, eurycomanol, 13,21-dihydroeurycomanone, and eurycomanol-2-O-β-D-glycopyranoside were obtained. The ¹H-NMR profiles of E. longifolia root aqueous extracts from Perak (n = 30) were obtained and used to identify primary metabolites and the quassinoids. Selangor, Kedah, Terengganu (n = 5 for each), and Perak samples were checked for metabolic discrimination. Hotelling's T² plot was used to check for outliers. Orthogonal partial least-squares discriminant analysis was run to reveal the discriminatory metabolites. Perak samples contained formic, succinic, methylsuccinic, fumaric, lactic, acetic and syringic acids as well as choline, alanine, phenylalanine, tyrosine, α-glucose, eurycomanone, eurycomanol, 13,21-dihydroeurycomanone, and eurycomanol-2-O-β-D-glycopyranoside. The extracts from other locations contained the same metabolites. The limit of quantification values were 1.96 (eurycomanone), 15.62 (eurycomanol), 3.91 (13,21-dihydroeurycomanone), and 31.25 (eurycomanol-2-O-β-D-glycopyranoside) ppm. The Hotelling's T² plot revealed no outlier. The orthogonal partial least-squares discriminant analysis model showed that choline, eurycomanol, eurycomanol-2-O-β-D-glycopyranoside, and lactic and succinic acid levels were different among regions. Terengganu and Perak samples contained higher amounts of eurycomanol and eurycomanol-2-O-β-D-glycopyranoside, respectively. The current approach efficiently detected E. longifolia root metabolites, quantified the quassinoids, and discriminated E. longifolia roots from different locations. These findings could be applicable to future research on E. longifolia where the higher content of quassinoids is required.

Quassinoids: Viral protein R inhibitors from Picrasma javanica bark collected in Myanmar for HIV infection

Viral protein R (Vpr) is an accessory protein that plays important roles in the viral pathogenesis of Human Immunodeficiency Virus-1 (HIV-1). An assay for anti-Vpr activity, using TREx-HeLa-Vpr cells, is a promising strategy to discover Vpr inhibitors. The anti-Vpr assay revealed that the CHCl3-soluble extract of Picrasma javanica bark possesses potent anti-Vpr activity. Furthermore, studies of quassinoids (1-15) previously isolated from the extract demonstrated that all of the tested quassinoids exhibit anti-Vpr activity. Among the tested compounds, javanicin I (15) exhibited the most potent anti-Vpr activity ((***)p <0.001) in comparing with that of the positive control, damnacanthal. The structure-activity relationships of the active quassinoids suggested that the presence of a methyl group at C-13 in the 2,12,14-triene-1,11,16-trione-2,12-dimethoxy-18-norpicrasane quassinoids is the important factor for the potent inhibitory effect in TREx-HeLa-Vpr cells.

Apoptosis induction of dehydrobruceine B on two kinds of human lung cancer cell lines through mitochondrial-dependent pathway

BACKGROUND

Brucea javanica is an effective traditional medicine listed in Chinese Pharmacopoeia. In China, the seed oil of B. javanica has long been used as commercially available drug for the treatment of tumor in clinic. Dehydrobruceine B (DHB) is a quassinoid isolated from B. javanica.

PURPOSE

The aim of the present study is to investigate the apoptotic effects induced by DHB in human lung cancer A549 and NCI-H292 cells. The involvement of a mitochondria-mediated intrinsic pathway in the pro-apoptotic action of DHB was also investigated.

MATERIAL AND METHODS

Cell viability was determined by MTT assay. Cell cycle and apoptosis were assessed by flow cytometry analysis. Mitochondrial membrane potential (MMP) was examined through JC-1 staining. The protein translocation in cells was examined by immunostaining. The expression levels of proteins which are closely related to mitochondria-mediated apoptosis pathway were measured by immunoblot analysis.

RESULTS

Treatment with DHB decreased cell viability, induced apoptosis and blocked cell cycle at S phase. DHB-induced apoptosis was found to be mediated through mitochondrial intrinsic pathway, evidenced by the loss of MMP, the release of cytochrome c into cytosol, and the cleavage of caspase-9, caspase-3 and poly (ADP-ribose) polymerase (PARP).

CONCLUSION

DHB triggers apoptosis in A549 and NCI-H292 cells via mitochondrial pathway, making it a promising candidate as a therapeutic agent for lung carcinoma.

Picrajavanicins A-G, Quassinoids from Picrasma javanica Collected in Myanmar

Seven new tetracyclic quassinoids, picrajavanicins A-G (1-7), along with three known analogues, were isolated from a CHCl3-soluble extract of the bark of Picrasma javanica collected in Myanmar. The structures of these compounds were elucidated using spectroscopic techniques, including 1D and 2D NMR. The absolute configuration at C-2 of 2 was determined to be S by the modified Mosher method. All the isolates were tested for their antiproliferative activities against a small panel of five human cancer cell lines. However, none of the isolated compounds exhibited inhibitory activity against any of the cancer cells used (IC50 values >10 μM).

Receptor Polymorphism and Genomic Structure Interact to Shape Bitter Taste Perception

The ability to taste bitterness evolved to safeguard most animals, including humans, against potentially toxic substances, thereby leading to food rejection. Nonetheless, bitter perception is subject to individual variations due to the presence of genetic functional polymorphisms in bitter taste receptor (TAS2R) genes, such as the long-known association between genetic polymorphisms in TAS2R38 and bitter taste perception of phenylthiocarbamide. Yet, due to overlaps in specificities across receptors, such associations with a single TAS2R locus are uncommon. Therefore, to investigate more complex associations, we examined taste responses to six structurally diverse compounds (absinthin, amarogentin, cascarillin, grosheimin, quassin, and quinine) in a sample of the Caucasian population. By sequencing all bitter receptor loci, inferring long-range haplotypes, mapping their effects on phenotype variation, and characterizing functionally causal allelic variants, we deciphered at the molecular level how a subjects’ genotype for the whole-family of TAS2R genes shapes variation in bitter taste perception. Within each haplotype block implicated in phenotypic variation, we provided evidence for at least one locus harboring functional polymorphic alleles, e.g. one locus for sensitivity to amarogentin, one of the most bitter natural compounds known, and two loci for sensitivity to grosheimin, one of the bitter compounds of artichoke. Our analyses revealed also, besides simple associations, complex associations of bitterness sensitivity across TAS2R loci. Indeed, even if several putative loci harbored both high- and low-sensitivity alleles, phenotypic variation depended on linkage between these alleles. When sensitive alleles for bitter compounds were maintained in the same linkage phase, genetically driven perceptual differences were obvious, e.g. for grosheimin. On the contrary, when sensitive alleles were in opposite phase, only weak genotype-phenotype associations were seen, e.g. for absinthin, the bitter principle of the beverage absinth. These findings illustrate the extent to which genetic influences on taste are complex, yet arise from both receptor activation patterns and linkage structure among receptor genes.

Human bitter taste is believed to protect us from the ingestion of poisonous substances, thereby shaping food rejections. Bitter perception differs, however, across individuals, due to genetic variations in the ~25 bitter taste receptor (TAS2R) genes. A famous example known since the 1930s is the inherited bitter taste sensitivity to phenylthiocarbamide, which is associated with genetic polymorphisms in a single TAS2R gene. Yet, such simple receptor-substance associations do not reflect the full complexity of bitter perception, since individual bitter substances frequently activate several TAS2Rs. Here, we provide an in-depth analysis of the genetic variability influencing human bitter taste. While each study subject carried a different set of genetic polymorphisms, we found that most variations reside in just six blocks, each harboring only one to five haplotypes. Thus, besides simple associations between taste and TAS2R gene polymorphisms, we revealed complex associations dependent on linkage between several high- and low-sensitivity alleles. Indeed, subjects carried either sensitive or insensitive alleles for receptors sensitive to grosheimin, a bitter compound in artichoke, or at least one sensitive allele for receptors specific for absinthin, the bitter principle of absinth. In short, simple associations and complex genomic linkage determine sensitivity to selected dietary bitter compounds.

Development and validation of liquid chromatography combined with tandem mass spectrometry methods for the quantitation of simalikalactone E in extracts of Quassia amara L. and in mouse blood

INTRODUCTION

Simalikalactone E (SkE) from Quassia amara, has been proved to be a valuable anti-malarial and anti-cancer compound. As SkE is very scarce, methods of quantitation are needed in order to optimise its isolation process and to determine pharmacokinetic data.

OBJECTIVE

To validate methods using liquid chromatography coupled to mass spectrometry for the quantitation of SkE in plant extracts and in biological fluids.

METHODS

High- and ultrahigh-performance liquid chromatography (UHPLC) coupled to ion trap mass spectrometry (MS) with single ion monitoring detection and to triple quadrupole-linear ion trap tandem mass spectrometry with multiple reaction monitoring detection methods were developed. Validation procedure was realised according to the International Conference on Harmonisation guideline. Methanol extracts of dried Quassia amara leaves, and mouse-blood samples obtained after various routes of administration, were analysed for SkE.

RESULTS

Methods were validated and gave similar results regarding the content of SkE expressed per kilogram of dry leaves in the traditional decoction (160 ± 12 mg/kg) and in the methanol extract (93 ± 2 mg/kg). The recovery of the analyte from mouse blood ranged from 80.7 to 119.8%. Simalikalactone E was only detected using UHPLC-MS/MS (0.2 ± 0.03 mg/L) in mouse blood after intravenous injection: none was detected following intraperitoneal or oral gavage administration of SkE.

CONCLUSION

The LC-MS methods were used for the quantitation of SkE in plant extracts and in mouse blood. These methods open the way for further protocol optimisation of SkE extraction and the determination of its pharmacokinetic data.

The quassinoid isobrucein B reduces inflammatory hyperalgesia and cytokine production by post-transcriptional modulation

Isobrucein B (1) is a quassinoid isolated from the Amazonian medicinal plant Picrolemma sprucei. Herein we investigate the anti-inflammatory and antihyperalgesic effects of this quassinoid. Isobrucein B (1) (0.5-5 mg/kg) inhibited carrageenan-induced inflammatory hyperalgesia in mice in a dose-dependent manner. Reduced hyperalgesia was associated with reduction in both neutrophil migration and pronociceptive cytokine production. Pretreatment with 1 inhibited in vitro production/release of cytokines TNF, IL-1β, and KC/CXCL1 by lipopolysaccharide-stimulated macrophages. To investigate its molecular mechanism, RAW 264.7 macrophages with a luciferase reporter gene controlled by the NF-κB promoter were used (RAW 264.7-Luc). Quassinoid 1 reduced the luminescence emission by RAW 264.7-Luc stimulated by different compounds. Unexpectedly, NF-κB translocation to macrophage nuclei was not inhibited by 1 when evaluated by Western blotting and immunofluorescence. Furthermore, quassinoid 1 did not change the levels of TNF mRNA transcription in stimulated macrophages, suggesting post-transcriptional modulation. In addition, constitutive expression of luciferase in RAW 264.7 cells transiently transfected with a plasmid containing a universal promoter was inhibited by 1. Thus, isobrucein B (1) displays anti-inflammatory and antihyperalgesic activities by nonselective post-transcriptional modulation, resulting in decreased production/release of pro-inflammatory cytokines and neutrophil migration.

Four new quassinoids from the roots of Eurycoma longifolia Jack

Seven compounds were isolated from the roots of Eurycoma longifolia, and characterized by comprehensive analysis of 1D and 2D NMR experiments along with single crystal X-ray diffraction. Among them, four new quassinoids were identified and three of them were diastereomers for each other. Compounds 1-7 were evaluated for cytotoxicities against HT-29, MCF-7, LOVO, BGC-823, MGC-803, HepG2, HeLa, and A549 cancer cell lines. Compounds 2 and 5 exhibited the lowest IC50 values of 24.9 μM, 11.8 μM, and 44.1 μM, 14.1 μM towards MCF-7, MGC-803 cancer cell lines, respectively, while compound 6 exhibited moderate cytotoxicity towards all the selected cancer cell lines.

NF-κB inhibitors from Eurycoma longifolia

The roots of Eurycoma longifolia have been used in many countries of Southeast Asia to alleviate various diseases including malaria, dysentery, sexual insufficiency, and rheumatism. Although numerous studies have reported the pharmacological properties of E. longifolia, the mode of action of the anti-inflammatory activity has not been elucidated. Bioguided isolation of NF-κB inhibitors using an NF-κB-driven luciferase reporter gene assay led to the identification of a new quassinoid, eurycomalide C (1), together with 27 known compounds including 11 quassinoids (2-12), six alkaloids (13-18), two coumarins (19, 20), a squalene derivative (21), a triterpenoid (22), and six phenolic compounds (23-28) from the extract of E. longifolia. Evaluation of the biological activity revealed that C19-type and C20-type quassinoids, β-carboline, and canthin-6-one alkaloids are potent NF-κB inhibitors, with IC50 values in the low micromolar range, while C18-type quassinoids, phenolic compounds, coumarins, the squalene derivative, and the triterpenoid turned out to be inactive when tested at a concentration of 30 μM. Eurycomalactone (2), 14,15β-dihydroklaieanone (7), and 13,21-dehydroeurycomanone (10) were identified as potent NF-κB inhibitors with IC50 values of less than 1 μM.

Brusatol isolated from Brucea javanica (L.) Merr. induces apoptotic death of insect cell lines

Brucea javanica (L.) Merr. is a medicine plant distributed widely throughout Asia where its bitter fruits have been used traditionally in medicine for treating various ailments and controlling some pests. In recent years, concerns over the potential impact of synthetic pesticides on human health and environment have now become more pressing to develop environmentally friendly pesticides. In this paper, brusatol, a quassinoid, was isolated from the fruit of B. javanica, and identified using X-ray crystallographic analysis. Results showed that brusatol has potent contact toxicity (LD50, 2.91 μg/larva, 72 h) and anfieedant activity (AFC50, 17.4 mg/L, 48 h) against the third-instar larvae of Spodoptera exigua. Brusatol demonstrated cytotoxic effects to the tested insect cell lines, IOZCAS-Spex-II and Sf21, in a time- and dose-dependent manner. After brusatol treatment, apoptotic cell death with the DNA fragmentation, activation of caspase-3 and release of cytochrome c was preliminarily observed in both IOZCAS-Spex-II and Sf21. These results indicated the existence of apoptotic death with the mitochondrial-dependent pathway induced by brusatol in Sf21 and IOZCAS-Spex-II cell lines. Our studies will provide important knowledge to understand mechanisms of action of brusatol and to develop brusatol and its derivatives as insecticides.

Bioactive quassinoids from the seeds of Brucea javanica

Six new quassinoids (1-6) and eight known compounds of this type (7-14) were isolated from the seeds of Brucea javanica. Their structures were elucidated by analysis of their spectroscopic data and from chemical evidence. Compounds 1-5 were found to be unusual quassinoids with a 2,3-seco A ring. The configurations at C-4 in 4 and 5 were determined by a difference circular dichroism method. In in vitro bioassays, 8 and 10 showed inhibitory activities for nitric oxide production in LPS-activated macrophages, with IC(50) values of 1.9 and 5.0 μM, respectively, while compounds 6, 8-11, 13, and 14 exhibited cytotoxicity against five human tumor cell lines (HCT-8, HepG2, BGC-823, A549, and SKVO3), having IC(50) values in the range 0.12-9.3 μM.

Eurycomanone suppresses expression of lung cancer cell tumor markers, prohibitin, annexin 1 and endoplasmic reticulum protein 28

Bioactive compounds from the medicinal plant, Eurycoma longifolia Jack have been shown to promote anti-proliferative effects on various cancer cell lines. Here we examined the effects of purified eurycomanone, a quassinoid found in Eurycoma longifolia Jack extract, on the expression of selected genes of the A549 lung cancer cells. Eurycomanone inhibited A549 lung cancer cell proliferation in a dose-dependent manner at concentrations ranging from 5 to 20 μg/ml. The concentration that inhibited 50% of cell growth (GI(50)) was 5.1 μg/ml. The anti-proliferative effects were not fully reversible following the removal of eurycomanone, in which 30% of cell inhibition still remained (p<0.0001, T-test). At 8 μg/ml (GI(70)), eurycomanone suppressed anchorage-independent growth of A549 cells by >25% (p<0.05, T-test, n=8) as determined using soft agar colony formation assay. Cisplatin, a chemotherapy drug used for the treatment of non small cell lung cancer on the other hand, inhibited A549 cells proliferation at concentrations ranging from 0.2 μg/ml to 15 μg/ml with a GI(50) of 0.58 μg/ml. The treatment with eurycomanone reduced the abundance expression of the lung cancer markers, heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1, p53 tumor suppressor protein and other cancer-associated genes including prohibitin (PHB), annexin 1 (ANX1) and endoplasmic reticulum protein 28 (ERp28) but not the house keeping genes. The mRNA expressions of all genes with the exception of PHB were significantly downregulated, 72 h after treatment (p<0.05, T-test, n=9). These findings suggest that eurycomanone at viable therapeutic concentrations of 5-20 μg/ml exhibited significant anti-proliferative and anti-clonogenic cell growth effects on A549 lung cancer cells. The treatment also resulted in suppression of the lung cancer cell tumor markers and several known cancer cell growth-associated genes.

Indole alkaloids and quassinoids from the stems of Brucea mollis

Seven new indole alkaloids, bruceollines H-N (1-7), three new quassinoids, yadanziolides T-V (10-12), and four known analogues, bruceolline E (8), bruceolline F (9), bruceine D (13), and yadanziolide B (14), were isolated from an ethanol extract of the stems of Brucea mollis. The absolute configurations of compounds 2 and 5 were determined by comparison of their experimental and calculated ECD spectra. The absolute configuration of the known compound 9 was determined by using Mo2(OAc)4-induced CD analysis for the first time. Compounds 10, 13, and 14 exhibited cytotoxic activities with IC50 values of 3.00-5.81 μM.

Physico-chemical effects of the major quassinoids in a standardized Eurycoma longifolia extract (Fr 2) on the bioavailability and pharmacokinetic properties, and their implications for oral antimalarial activity

A simple validated LC-UV method for the phytochemical analysis of four bioactive quassinoids, 13alpha(21)-epoxyeurycomanone (EP), eurycomanone (EN), 13alpha,21-dihydroeurycomanone (ED) and eurycomanol (EL) in rat plasma following oral (200 mg/kg) and intravenous administration (10 mg/kg) of a standardized extract Fr 2 of Eurycoma longifolia Jack was developed for pharmacokinetic and bioavailability studies. The extract Fr 2 contained 4.0%, 18.5%, 0.7% and 9.5% of EP, EN, ED and EL, respectively. Following intravenous administration, EP displayed a relatively longer biological half-life (t1/2 = 0.75 +/- 0.25 h) due primarily to its lower elimination rate constant (k(e)) of 0.84 +/- 0.26 h(-1)) when compared with the t1/2 of 0.35 +/- 0.04 h and k(e) of 2.14 +/- 0.27 h(-1), respectively of EN. Following oral administration, EP showed a higher C(max) of 1.61 +/- 0.41 microg/mL over that of EN (C(max) = 0.53 +/- 0.10 microg/mL). The absolute bioavailability of EP was 9.5-fold higher than that of EN, not because of chemical degradation since both quassinoids were stable at the simulated gastric pH of 1. Instead, the higher log K(ow) value of EP (-0.43) contributed to greater membrane permeability over that of EN (log K(ow) = -1.46) at pH 1. In contrast, EL, being in higher concentration in the extract than EP, was not detected in the plasma after oral administration because of substantial degradation by the gastric juices after 2 h. Similarly, ED, being unstable at the acidic pH and together with its low concentration in Fr 2, was not detectable in the rat plasma. In conclusion, upon oral administration of the bioactive standardized extract Fr 2, EP and EN may be the only quassinoids contributing to the overall antimalarial activity; this is worthy of further investigation.

Comparative X-ray and conformational analysis of a new crystal of 13α,21-dihydroeurycomanone with eurycomanone from Eurycoma longifolia and their anti-estrogenic activity using the uterotrophic assay

13 α,21-Dihydroeurycomanone (1), a known quassinoid of Eurycoma longifolia Jack was recrystallized from chloroform into a novel crystal structure in space group P2 (1). Its X-ray data were compared with those of eurycomanone ( 2). Following intraperioneal injections at similar doses of 2.44 µmol/kg/day for 3 consecutive days, 2 displayed comparable potency with tamoxifen but was more potent than 1 in the anti-estrogenic effect against 17 α-ethynylestradiol (EE)-induced uterotrophy of immature rats.

Antitumor Agents. 282. 2'-(R)-O-acetylglaucarubinone, a quassinoid from Odyendyea gabonensis as a potential anti-breast and anti-ovarian cancer agent

A new quassinoid, designated 2'-(R)-O-acetylglaucarubinone (1), and seven known quassinoids (2-8) were isolated, using bioactivity-guided separation, from the bark of Odyendyea gabonensis (Pierre) Engler [syn. Quassia gabonensis Pierre]. The structure of 1 was determined by spectroscopic analysis and by semisynthesis from glaucarubolone. Complete (1)H and (13)C NMR assignments of compounds 1-8 were also established from detailed analysis of two-dimensional NMR spectra, and the reported configurations in odyendene (7) and odyendane (8) were corrected. Compound 1 showed potent cytotoxicity against multiple cancer cell lines. Further investigation using various types of breast and ovarian cancer cell lines suggested that 1 does not target the estrogen receptor or progesterone receptor. When tested against mammary epithelial proliferation in vivo using a Brca1/p53-deficient mice model, 1 also caused significant reduction in mammary duct branching.

Cytotoxic activity of quassinoids from Eurycoma longifolia

Twenty-four quassinoids isolated from Eurycoma longifolia Jack were investigated for their cytotoxicity against a panel of four different cancer cell lines, which includes three murine cell lines [colon 26-L5 carcinoma (colon 26-L5), B16-BL6 melanoma (B16-BL6), Lewis lung carcinoma (LLC)] and a human lung A549 adenocarcinoma (A549) cell line. Among the tested compounds, eurycomalactone (9) displayed the most potent activity against all the tested cell lines; colon 26-L5 (IC50 = 0.70 microM), B16-BL6 (IC50 = 0.59 microM), LLC (IC50 = 0.78 microM), and A549 (IC50 = 0.73 microM). These activities were comparable to clinically used anticancer agent doxorubicin (colon 26-L5, IC50 = 0.76 microM; B16-BL6, IC50 = 0.86 microM; LLC, IC50 = 0.80 microM; A549, IC50 = 0.66 microM).

Anti-tobacco mosaic virus (TMV) Quassinoids from Brucea javanica (L.) Merr

Two new quassinoids, javanicolide E (1) and javanicolide F (2), along with fifteen known C-20 quassinoids were isolated from the seeds of Brucea javanica (L.) Merr. The antitobacco mosaic virus (TMV) activity of these quassinoids was screened by the conventional half-leaf and leaf-disk method along with Western blot analysis. All of the seventeen quassinoids showed potent anti-TMV activity. Among them, eight compounds, brusatol (3), bruceine B (4), bruceoside B (5), yadanzioside I (6), yadanzioside L (7), bruceine D (8), yadanziolide A (9), and aglycone of yadanziolide D (17), showed strong antiviral activities, with IC(50) values in the range of 3.42-5.66 microM, and were much more effective than the positive control, ningnanmycin (IC(50) = 117.3 microM). The antiviral structure-activity relationships of quassinoids against TMV were also discussed.

Quassinoids from Eurycoma longifolia

Ten new structurally diverse quassinoids (1-10) and 14 known compounds were isolated from the stems of Eurycoma longifolia. The new compounds were two eurycomanone-type C(20) quassinoids (1, 2), one klaineanone-type C(20) quassinoid (3), one C(19) quassinoid (4) with a 1,2-seco-1-nor-6(5-->10)-abeo-picrasan-2,5-olide skeleton, and six eurycomalactone-type C(19) quassinoids (5-10). Compounds 5 and 6 both possessed a 3,4-epoxy group observed for the first time in eurycomalactones. Compound 1 had an alpha-oriented OH group at C-14 that had not been reported previously in eurycomanone-type quassinoids. All of the isolates were evaluated for cytotoxicity toward the highly metastatic HT-1080 human fibrosarcoma cell line, and compounds 11, 23, and 24 showed potent cytotoxicity (IC(50) values 0.93-1.1 microM).

Quassinoid constituents of Quassia amara L. leaf herbal tea. Impact on its antimalarial activity and cytotoxicity

AIM OF THE STUDY

Our objective was to assess whether it could be contemplated to recommend Quassia amara young leaf tea for treatment against malaria, and if yes, set up a standard protocol for preparing the herbal tea.

MATERIALS AND METHODS

The leaf tea was extracted with methylene chloride and the organic extract was fractionated with HPLC. Pure compounds were characterized and their in vitro cytotoxicity and antiplasmodial activity was determined.

RESULTS AND DISCUSSION

We discovered that antimalarial Quassia amara young leaf tea contains several quassinoids: simalikalactone D (SkD, 1), picrasin B (2), picrasin H (3), neoquassin (4), quassin (5), picrasin I (6) and picrasin J (7). These last two compounds are new. In addition, our experiments demonstrate that both biological activity and cytotoxicity of the remedy may be attributed solely to the presence of SkD.

CONCLUSION

In conclusion, this preparation should not be recommended for treatment of malaria until a clinical study in humans is performed with SkD.

The effect of Eurycoma longifolia on sperm quality of male rats

The present study investigated the effects of a standardized methanol extract of E. longifolia Jack containing the major quassinoid constituents of 13alpha(21)-epoxyeurycomanone (1), eurycomanone (2), 13alpha,21-dihydroeurycomanone (3) and eurycomanol (4) on the epididymal spermatozoa profile of normal and Andrographis paniculata induced infertile rats. The standardized MeOH extract at doses of 50, 100 and 200 mg/kg, the EtOAc fraction (70 mg/kg), and standardized MeOH extract at 200 mg/kg co-administered with the EtOAc fraction of A. paniculata at 70 mg/kg were each given orally to male Sprague-Dawley albino rats for 48 consecutive days. The spermatozoa count, morphology, motility, plasma testosterone level and Leydig cell count of the animals were statistically analyzed by ANOVA with a post-hoc Tukey HSD test. The results showed that the sperm count of rats given the standardized MeOH extract alone at doses of 50, 100 and 200 mg/kg were increased by 78.9, 94.3 and 99.2%, respectively when compared with that of control (p < 0.01). The low count, poor motility and abnormal morphology of the spermatozoa induced by the A. paniculata fraction were significantly reversed by the standardized MeOH extract of E. longifolia (p < 0.001). The plasma testosterone level of the rats treated with the standardized MeOH extract at 200 mg/kg was significantly increased (p < 0.01) when compared with that of the control and infertile animals. The spermatocytes in the seminiferous tubules and the Leydig cells appeared normal. Testosterone level was significantly higher in the testes (p < 0.01) than in the plasma after 30 days of oral treatment with the standardized MeOH extract. Interestingly, eurycomanone (2) alone was detected in the rat testis homogenates by HPLC-UV and confirmed by LC/MS, and may have contributed towards the improvement of sperm quality. Thus, the plant may potentially be suitable for the management of male infertility.

U2504 determines the species specificity of the A-site cleft antibiotics: the structures of tiamulin, homoharringtonine, and bruceantin bound to the ribosome

Structures have been obtained for the complexes that tiamulin, homoharringtonine, and bruceantin form with the large ribosomal subunit of Haloarcula marismortui at resolutions ranging from 2.65 to 3.2 A. They show that all these inhibitors block protein synthesis by competing with the amino acid side chains of incoming aminoacyl-tRNAs for binding in the A-site cleft in the peptidyl-transferase center, which is universally conserved. In addition, these structures support the hypothesis that the species specificity exhibited by the A-site cleft inhibitors is determined by the interactions they make, or fail to make, with a single nucleotide, U2504 (Escherichia coli). In the ribosome, the position of U2504 is controlled by its interactions with neighboring nucleotides, whose identities vary among kingdoms.

Quassinoid inhibition of AP-1 function does not correlate with cytotoxicity or protein synthesis inhibition

Several quassinoids were identified in a high-throughput screening assay as inhibitors of the transcription factor AP-1. Further biological characterization revealed that while their effect was not specific to AP-1, protein synthesis inhibition and cell growth assays were inconsistent with a mechanism of simple protein synthesis inhibition. Numerous plant extracts from the plant family Simaroubaceae were also identified in the same screen; bioassay-guided fractionation of one extract (Ailanthus triphylla) yielded two known quassinoids, ailanthinone (3) and glaucarubinone (4), which were also identified in the pure compound screening procedure.

Inhibition of CYP1A1 by Quassinoids found in Picrasma excelsa

Infusions of the plant Picrasma excelsa, known as Jamaican bitterwood tea, are commonly consumed to lower blood sugar levels in diabetics who are already on prescription medicines. We therefore investigated the inhibition properties of this tea against a panel of cytochrome P450 (CYP) enzymes, which are primarily responsible for the metabolism of a majority of drugs on the market. The two major ingredients, quassin and neoquassin, were then isolated and used for further characterization. Inhibition of the activities of heterologously expressed CYP microsomes (CYPs 2D6, 3A4, 1A1, 1A2, 2C9, and 2C19) was monitored, and the most potent inhibition was found to be against CYP1A1, with IC (50) values of 9.2 microM and 11.9 microM for quassin and neoquassin, respectively. The moderate inhibition against the CYP1A1 isoform by quassin and neoquassin displayed partial competitive inhibition kinetics, with inhibition constants ( K(i)) of 10.8 +/- 1.6 microM, for quassin and competitive inhibition kinetics, with a K(i) of 11.3 +/- 0.9 microM, for neoquassin. We then docked these two inhibitors into the active site of a model of CYP1A1, which provided insight at the atomic level into the structure-activity relationship of quassinoids with respect to this important CYP isoform known to be an activator of carcinogens, thus providing a useful basis for the search for more potent inhibitors of CYP1A1 that may have implications in chemoprotection.

Antiphytoviral activity of bruceine-D from Brucea javanica seeds

BACKGROUND

Brucea javanica (L.) Merr. is widely distributed throughout the southern parts of China and has been used in traditional medicine to treat a variety of diseases. The objective of the present study was to identify the active antiphytoviral compound in the seeds of B. javanica and evaluate the inhibitory activity of the compound against plant virus.

RESULTS

Bioassay-guided fractionation of the most active extract from the seeds led to the isolation of an antiphytoviral compound which was identified as bruceine-D by conventional spectroscopy methods. The compound exhibited significant inhibitory activity against the infection and replication of tobacco mosaic virus (TMV), with IC(50) values of 13.98 and 7.13 mg L(-1) respectively. The compound also showed a strong inhibitory effect on the infectivity of potato virus Y (PVY) and cucumber mosaic virus (CMV). Furthermore, the compound could effectively inhibit systemic TMV infection in the host tobacco plant under glasshouse conditions.

CONCLUSION

The results suggested that bruceine-D from Brucea javanica may have the potential to be used as a natural viricide, or a lead compound for new viricides.

Screening of Indonesian medicinal plant extracts for antibabesial activity and isolation of new quassinoids from Brucea javanica

Boiled extracts derived from 28 Indonesian medicinal plants were screened for their antibabesial activity against Babesia gibsoni in vitro. Of these extracts, the fruit of Brucea javanica was the most active in inhibiting parasite growth at a concentration of 10 microg/mL. Bioassay-guided fractionation of the fruit extract of Br. javanica led to the isolation of two new quassinoids, bruceantinol B and bruceine J, and the structures of these compounds were elucidated on the basis of their spectroscopic data and by chemical transformation to known compounds. In addition, the known quassinoids bruceines A-D, bruceantinol, and yadanziolide A were isolated. Antibabesial activities were also examined in vitro, and bruceine A and bruceantinol were shown to be more potent than diminazene aceturate, a drug (IC50 = 103 ng/mL) used clinically against B. gibsoni, with IC50 values of 4 and 12 ng/mL, respectively.

A new quassinoid, ailantinol H from Ailanthus altissima

A new quassinoid, ailantinol H, was isolated from a methanol extract of the aerial parts of Ailanthus altissima collected in Taiwan. Its structure was established on the basis of 1D and 2D NMR and HREIMS spectroscopic methods.

A new quassinoid, ailantinol H, fromAilanthus altissima

A new quassinoid, ailantinol H, was isolated from the aerial parts of Ailanthus altissima. The structure was elucidated based on spectral evidence.

Simalikalactone D is responsible for the antimalarial properties of an Amazonian traditional remedy made with Quassia amara L. (Simaroubaceae)

French Guiana (North-East Amazonia) records high malaria incidence rates. The traditional antimalarial remedy most widespread there is a simple tea made out from Quassia amara L. leaves (Simaroubaceae). This herbal tea displays an excellent antimalarial activity both in vitro and in vivo. A known quassinoid, simalikalactone D (SkD), was identified as the active compound, with an IC(50) value of 10nM against FcB1 Plasmodium falciparum chloroquine resistant strain in vitro. Lastly, it inhibits 50% of Plasmodium yoelii yoelii rodent malaria parasite at 3.7 mg/kg/day in vivo by oral route. These findings confirm the traditional use of this herbal tea.

Cymosanine, a novel C19-Quassinoid from Simaba subcymosa

Cymosanine (1) and three further known quassinoids, cedronin (2), chaparrinone (3), and simarolide (4), were isolated from the root bark of Simaba subcymosa. The structures were established by spectroscopic data, mainly 1D, 2D NMR and mass spectra.

Quassinoids from the leaves of the Madagascan Simaroubaceae Samadera madagascariensis

An investigation of the leaves of the Madagascan Simaroubaceae Samadera madagascariensis has yielded three C18 quassinoids, 5beta,6-dihydrosamaderine A, 2-chlorosamaderine A, and samaderolactone A, and a C19 quassinoid, 3,4beta-dihydrosamaderine C, together with the known quassinoids samaderine A, samaderine B, and cedronin. The compounds isolated displayed little or no anti-tumour activity.

A Triple Diene-Transmissive Diels−Alder Strategy To Build the Quassinoid Framework

[chemical reaction: see text]. An advanced intermediate to the highly oxygenated triterpene quassinoids was prepared in 14 steps from tetrahydrofuran. The key steps are three diene-transmissive Diels-Alder cycloadditions. Several features of this synthesis are noteworthy, including a successful Mitsunobu reaction on an allenylic alcohol, a rare [4 + 2] cycloaddition involving an enethiol ether dienophile, and complete control over all 10 chiral centers created.