Complex Inhibitory Mechanism of Glycomimetics with Heparanase.

Heparanase (HPSE) is the only mammalian endo-ß-glucuronidase known to catalyze the degradation of heparan sulfate. Dysfunction of HPSE activity has been linked to several disease states, resulting in HPSE becoming the target of numerous therapeutic programs, yet no drug has passed clinical trials to date. Pentosan polysulfate sodium (PPS) is a heterogeneous, FDA-approved drug for the treatment of interstitial cystitis and a known HPSE inhibitor. However, due to its heterogeneity, characterization of its mechanism of HPSE inhibition is challenging. Here, we show that inhibition of HPSE by PPS is complex, involving multiple overlapping binding events, each influenced by factors such as oligosaccharide length and inhibitor-induced changes in the protein secondary structure. The present work advances our molecular understanding of the inhibition of HPSE and will aid in the development of therapeutics for the treatment of a broad range of pathologies associated with enzyme dysfunction, including cancer, inflammatory disease, and viral infections.

The useful biological properties of sucrose esters: Opportunities for the development of new functional foods.

Sucrose esters have been deployed as surfactants in many food products since the 1950s. In addition to their useful physical characteristics, sucrose esters also have interesting biological properties that enhance their utility. This review critically examines the broad suite of biological activities that has been attributed to both synthetically-derived and naturally-occurring sucrose esters. These include insecticidal, molluscicidal, plant growth-regulating, anti-microbial, anti-tumor, anti-oxidant, anti-depressive, neuro-protective, anti-inflammatory and anti-plasmodial effects. In addition to providing a summary of the structure-activity profiles of sucrose esters, the various known mechanisms-of action of these compounds are also discussed. Furthermore, since sucrose esters are well-known surfactants, the potential to advantageously apply their industrially desirable physical characteristics in combination with their biological properties is considered. Recent advances in synthetic chemistry that have facilitated the deployment of biologically active sucrose esters as food additives are also described.

Ribisins and Certain Analogues Exert Neuroprotective Effects through Activation of the Keap1-Nrf2-ARE Pathway.

Oxidative stress contributes to the pathogenesis of various neurodegenerative diseases and induction of the Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) pathway is a validated neuroprotective strategy. Synthetically-derived samples of members of the ribisin class of natural product together with a range of analogues were evaluated for their neuroprotective capacities. Four of the twenty-four compounds tested were found to strongly stimulate antioxidant response element-dependent transcriptional activity in human-derived SH-SY5Y cells. Further, in rat pheochromocytoma PC12 cells and mouse brain cortical cultures these compounds upregulated levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream target gene products, namely heme oxygenase (HO-1) and NAD(P)H quinone reductase 1 (NQO1). Functionally speaking, the compounds conferred protection in these cell models challenged with H2 O2 . In silico molecular modeling suggests that certain of the ribisins can dock in the Nrf2-binding Kelch domain in Keap1, while cysteine labeling by biotinylated iodoacetamide suggest that cysteine residues within Keap1 react with the ribisins. It is thus proposed that the most active compounds exert their neuroprotective activities by targeting Keap1, thereby activating Nrf2 and so increasing transactivation of Nrf2-responsive genes that encode for detoxifying and antioxidant enzymes.

α-Iodo-α,ß-Unsaturated Ketones as Vicinal Dielectrophiles: Their Reactions with Dinucleophiles Provide New Annulation Protocols for the Formation of Carbo- and Heterocyclic Ring Systems.

α-Iodo-α,ß-unsaturated ketones such as compound 1 serve as vicinal dielectrophiles and react with a range of dinucleophiles including pentane-2,4-dione and 1,3-indandione to produce [3 + 2]- and [2 + 1]-adducts such as 5 and 38, respectively. [4 + 2]- and [5 + 2]-cycloadducts have been obtained from compound 1 by related means. Preliminary studies reveal that α-iodinated α,ß-unsaturated esters can also participate in at least some of these same processes.

The Isoflavanoid (+)-PTC Regulates Cell-Cycle Progression and Mitotic Spindle Assembly in a Prostate Cancer Cell Line.

Prostate cancer is the second most common malignancy in men and the development of effective therapeutic strategies remains challenging when more advanced, androgen-independent or insensitive forms are involved. Accordingly, we have evaluated, using flow cytometry, confocal microscopy and image analysis, the anti-proliferative effects of (+)-2,3,9-trimethoxypterocarpan [(+)-PTC, 1] on relevant human prostate cancer cells as well as its capacity to control mitosis within them. In particular, the studies reported herein reveal that (+)-PTC exerts anti-proliferative activity against the PC-3 cell lines by regulating cell-cycle progression with mitosis being arrested in the prophase or prometaphase. Furthermore, it emerges that treatment of the target cells with this compound results in the formation of monopolar spindles, disorganized centrosomes and extensively disrupted γ-tubulin distributions while centriole replication remains unaffected. Such effects suggest (+)-PTC should be considered as a possible therapy for androgen-insensitive/independent prostate cancer.

A Rapid and Mild Sulfation Strategy Reveals Conformational Preferences in Therapeutically Relevant Sulfated Xylooligosaccharides.

Although sulfated xylooligosaccharides are promising therapeutic leads for a multitude of afflictions, the structural complexity and heterogeneity of commercially deployed forms (e. g. Pentosan polysulfate 1) complicates their path to further clinical development. We describe herein the synthesis of the largest homogeneous persulfated xylooligomers prepared to date, comprising up to eight xylose residues, as standards for biological studies. Near quantitative sulfation was accomplished using a remarkably mild and operationally simple protocol which avoids the need for high temperatures and a large excess of the sulfating reagent. Moreover, the sulfated xylooligomer standards so obtained enabled definitive identification of a pyridinium contaminant in a sample of a commercially prepared Pentosan drug and provided significant insights into the conformational preferences of the constituent persulfated monosaccharide residues. As the spatial distribution of sulfates is a key determinant of the binding of sulfated oligosaccharides to endogenous targets, these findings have broad implications for the advancement of Pentosan-based treatments.

The Effects of the Alkaloid Tambjamine J on Mice Implanted with Sarcoma 180 Tumor Cells.

The tambjamines are a small group of bipyrrolic alkaloids that, collectively, display a significant range of biological activities including antitumor, antimicrobial and immunosuppressive properties. The key objective of the present study was to undertake preclinical assessments of tambjamine J (T-J) so as to determine its in vivo antitumor effects. To that end, sarcoma 180 cells were transplanted in mice and the impacts of the title compound then evaluated using a range of protocols including hematological, biochemical, histopathological, genotoxic and clastogenic assays. As a result it was established that this alkaloid has a significant therapeutic window and effectively reduces tumor growth (by 40 % and 79 % at doses of 10 and 20 mg/kg/day, respectively). In this regard it displays similar antitumor activity to the anticancer agent cyclophosphamide and alters animal weight in an analogous manner.

Sucrose fatty acid esters: synthesis, emulsifying capacities, biological activities and structure-property profiles.

The notable physical and chemical properties of sucrose fatty acid esters have prompted their use in the chemical industry, especially as surfactants, since 1939. Recently, their now well-recognized value as nutraceuticals and as additives in cosmetics has significantly increased demand for ready access to them. As such a review of current methods for the preparation of sucrose fatty acid esters by both chemical and enzymatic means is warranted and is presented here together with an account of the historical development of these compounds as surfactants (emulsifiers). The somewhat belated recognition of the antimicrobial, anticancer and insecticidal activities of sucrose esters is also discussed along with a commentary on their structure-property profiles.

Emulsifying Properties of an Homologous Series of Medium- and Long-Chain d-Maltotriose Esters and their Impacts on the Viabilities of Selected Cell Lines.

The development of functional as well as nutritional surfactants for the food industry remains a matter of great interest. In the present study, a series of 6″-O-acylmaltotriose monoesters bearing alkyl side chains of 10-18 carbons was prepared by enzymatic means. The emulsions derived from those monoesters incorporating palmitoyl, stearoyl, and oleoyl side chains generally displayed advantageous shelf-lives, superior resistance to environmental variations, and more favorable droplet size distributions as well as stronger cytotoxic effects against various cancer cell lines. Ester 6 was shown to significantly inhibit the proliferation of MCF-7 breast cancer cells by inducing G1 phase arrest. Specifically, the levels of the G1 phase-related markers cyclin D1 and cyclin E as well as the cycle-dependent kinase 4 were suppressed by this particular ester. This study thus reveals that maltotriose esters can not only serve as novel functional food emulsifiers but also act, in vitro, as notable cytotoxic agents through a well-defined mechanism-of-action.

Antitumor Potential of the Isoflavonoids (+)- and (-)-2,3,9-Trimethoxypterocarpan: Mechanism-of-Action Studies.

Synthetically derived samples of (+)-(6aS,11aS)-2,3,9-trimethoxypterocarpan [(+)-1] and its enantiomer [(-)-1], both of which are examples of naturally occurring isoflavonoids, were evaluated, together with the corresponding racemate, as cytotoxic agents against the HL-60, HCT-116, OVCAR-8, and SF-295 tumor cell lines. As a result it was established that compound (+)-1 was particularly active with OVCAR-8 cells being the most sensitive and responding in a dose-dependent manner. A study of cell viability and drug-induced morphological changes revealed the compound causes cell death through a mechanism characteristic of apoptosis. Finally, a computational study of the interactions of compound (+)-1 and (S)-monastrol, an established, synthetically derived, potent, and cell-permeant inhibitor of mitosis, with the kinesin-type protein Eg5 revealed that both bind to this receptor in a similar manner. Significantly, compound (+)-1 binds with greater affinity, an effect attributed to the presence of the associated methoxy groups.

Structural Modifications of a Flaxseed Lignan in Pursuit of Higher Liposolubility: Evaluation of the Antioxidant and Permeability Properties of the Resulting Derivatives.

While lignans and their biogenetic precursors can have various health benefits, the poor liposolubilities of such phenolic systems have restricted their application as antioxidants in the food industry. The research reported here was aimed at addressing these matters through derivatizing certain forms of such compounds and then assessing their properties as potential nutraceuticals. In particular, crude flaxseed lignan was purified to afford secoisolariciresinol diglucoside (SDG, 1) that was then subjected to structural modification. By such means, the SDG long-chain fatty acid esters 4-9 and 11-13, the fully acetylated SDG 10, secoisolariciresinol (SECO, 2), and anhydrosecoisolariciresinol (ASECO, 14) were obtained. The antioxidant activities of these derivatives were determined while their permeability properties were evaluated. Such studies revealed that certain SDG derivatives possessing useful liposolubilities also retained their antioxidative properties, as well as being capable of permeating Caco-2 cell monolayers while being nontoxic to them. SDG fatty acid esters 4-9 and 11-13 could be developed into emulsifiers with enhanced health benefits, especially considering their improved antioxidative (ca. <11 000 µmol Trolox/g) and permeability properties. This study thus highlights strategies for the structural modification of SDG so as to generate derivatives with superior properties in terms of their utility in the food and pharmaceutical industries.

Cytotoxicity and Anti-inflammatory Properties of Apigenin-Derived Isolaxifolin.

The rare flavonoid isolaxifolin, a potent insecticide, has been touted as a potential grain-protecting agent. In order to assess any impact of this natural product on human health and to explore its various other biological properties, we have established a semisynthesis from the simpler but structurally related and more abundant natural product apigenin. The five-step reaction sequence has provided, for the first time, sufficient material for an in-depth evaluation of the cytotoxic properties of the title natural product. The impact of isolaxifolin on certain pro-inflammatory cytokines in murine macrophage RAW 264.7 cells has also been examined. Such studies have revealed that isolaxifolin displays no toxic effects toward normal cells while displaying greater cytotoxicities against certain cancer cell lines than its synthetic precursor apigenin. Furthermore, unlike apigenin, isolaxifolin only reduced NO, TNF-α, and IL-6 secretions in LPS-induced RAW 264.7 cells in a rather modest and dose-independent manner.

Enzymatic Preparation of a Homologous Series of Long-Chain 6- O-Acylglucose Esters and Their Evaluation as Emulsifiers.

Sugar fatty acid esters are nonionic surfactants that are widely exploited in the food and cosmetics industries, as well as in the oral care and medical supply fields. Accordingly, new methods for their selective synthesis and the "tuning" of their emulsifying properties are of considerable interest. Herein we report simple and irreversible enzymatic esterifications of d-glucose with seven fatty acid vinyl esters. The foaming and emulsifying effects of the resulting 6- O-acylglucose esters were then evaluated. In accord with expectations, when the length of the alkyl side chain associated with the 6- O-acylglucose esters increases, then their hydrophilic-lipophilic balance (HLB) values decrease, while the stabilities of the derived emulsions improve. In order to maintain good foaming properties, alkyl side chains of at least 9 to 11 carbons in length are required. In the first such assays on 6- O-acylglucose esters, most of those described herein are shown to be nontoxic to the HepG2, MCF-7, LNacp, SW549, and LO-2 cell lines.

Conversion of the Enzymatically Derived (1S,2S)-3-Bromocyclohexa-3,5-diene-1,2-diol into Enantiomerically Pure Compounds Embodying the Pentacyclic Framework of Vindoline.

The enzymatically derived and enantiomerically pure (1S,2S)-3-bromocyclohexa-3,5-diene-1,2-diol (7) has been elaborated over 17 steps into compounds 8 and 32, each of which embodies the pentacyclic framework and much of the functionality associated with the alkaloid vindoline (3). This work sets the stage for effecting the conversion of the related metabolite (1S,6R)-5-ethyl-1,6-dihydroxycyclohexa-2,4-diene-1-carboxylic acid (4) into compound 3, the latter being a biogenetic precursor to the clinically significant anticancer agents vinblastine and vincristine.

Consecutive gold(I)-catalyzed cyclization reactions of o-(buta-1,3-diyn-1-yl-)-substituted N-aryl ureas: a one-pot synthesis of pyrimido[1,6-a]indol-1(2H)-ones and related systems.

Treatment of readily available o-(buta-1,3-diyn-1-yl-)-substituted N-aryl ureas such as 1 with the Au(I)-catalyst 11 affords, via a twofold cyclization process, the isomeric pyrimido[1,6-a]indol-1(2H)-one 3 in good yield.

3,4'-Linked bis(piperidines) related to the haliclonacyclamine class of marine alkaloids: synthesis using crossed-aldol chemistry and preliminary biological evaluations.

Compounds 2-5, incorporating various elements of the 3,4'-bis(piperidine) core associated with the sponge-derived alkaloid haliclonacyclamine A (HA, 1), have been prepared through, inter alia, aldol-type reactions of N-substituted piperidin-4-ones and certain derivatives. Screening of these compounds in various assays, including an ecological one, reveals that compound 5 exhibits allelochemical properties similar to those associated with HA itself.

Structure of the lycorinine alkaloid nobilisitine A.

The structure 3 recently proposed, on the basis of computed NMR chemical shifts, for the natural product nobilisitine A has been synthesized from its C5-epimer (+)-clividine (4). The spectral data derived from compound 3 match those reported for the natural product.

Antimicrobial and cytotoxic activities of synthetically derived tambjamines C and E - J, BE-18591, and a related alkaloid from the marine bacterium Pseudoalteromonas tunicata.

In the first comprehensive biological assessment of the tambjamine class of marine alkaloids, synthetically derived samples of compounds 1-9 have been subjected to evaluation as antimicrobial agents and screened for their cytotoxic effects on various human cancer cell lines. Most were strongly active against the fungus Malassezia furfur (>amphotericin B) and showed considerable, but non-selective, antiproliferative activity against both human cancer and normal cell lines. Tambjamines I and J (6 and 7, resp.) displayed significant apoptosis-inducing effects.

Biological evaluation of ent-narciclasine, ent-lycoricidine, and certain enantiomerically-related congeners.

The non-natural enantiomeric forms of narciclasine and lycoricidine ((-)-1 and (-)-2, respectively), as well as congeners 3-6 are available through chemoenzymatic synthesis. Accordingly, they have now been tested for their cytotoxic effects in a 13-member human cancer cell-line panel and found to be only weakly active. In contrast, an authentic sample of the natural enantiomeric form of narciclasine ((+)-1) was found to be highly active in the same screens.

4,5-Diaryl-1H-pyrrole-2-carboxylates as combretastatin A-4/lamellarin T hybrids: synthesis and evaluation as anti-mitotic and cytotoxic agents.

The 4,5-diarylated-1H-pyrrole-2-carboxylates 3-8 have each been prepared as hybrids of the potent anti-mitotic agent combretastatin A-4 (1) and the similarly active marine alkaloid lamellarin T (2). The key steps involved selective lithium-for-halogen exchange at C5 within the N-PMB protected 4,5-dibromopyrrole 22 and Negishi cross-coupling of the derived zincated species with the relevant aryl iodide. The ensuing 5-aryl-4-bromopyrrole then engaged in Suzuki-Miyaura cross-coupling with the appropriate arylboronic acid to give the 4,5-diarylated pyrroles 4, 6 and 8. TFA-promoted removal of the N-PMB group within these last compounds then gave the N-unsubstituted congeners 3, 5 and 7. Compounds 3-8 have all been evaluated for their anti-mitotic and cytotoxic properties and two of them, 3 and 5, display useful activities although they are less potent than combretastatin A-4.