The chemistry of thujone. VI. Thujone as a chiral synthon for the synthesis of optically active steroid analogues

The thujone derived enone 1 is converted in one step to the pentacyclic compound 4 . The structure of 4 was determined by X-ray diffraction analysis. The acid-catalyzed cyclopropane-ring opening of 4 and of the model compound 9 are described.     

The chemistry of thujone. IX. Thujone as a chiral synthon for the synthesis of optically active steroid analogues. The vinylpicoline route

The thujone-derived enone 1 , upon base-catalyzed reaction with 2-methyl-6-vinylpyridine is converted to the pyridine analogue 5 (Scheme 1). Catalytic reduction of the latter to 6 generates two new centers of chirality which eventually become C(8) and C(14) in the ultimate synthetic steroid analogue 12 . An X-ray analysis of 6 establishes the structure and absolute configuration so as to determine its suitability in subsequent synthetic studies. The acetal derivative 7 , via Birch reduction, hydrolysis, and internal aldol cyclization, is converted into the cyclohexenone analogue 10 (Scheme 2). This ‘one-pot’ process affords an efficient conversion of the pyridine ring into a cyclohexenone system required for A-ring construction of the steroid skeleton. Finally, conversion of 10 , via the unsaturated diketone 11 , provides the chiral steroid analogue 12 .     

The chemistry of thujone. VIII. Thujone as a chiral synthon for the synthesis of optically active steroid analogues. The enol lactone route

The thujone-derived enone 1 is converted via enol lactone intermediates 4 and 5 to the optically active steroidal analogue 13 and the corresponding 19-norsteroid analogue 14 . The structure of 13 was determined by X-ray diffraction analysis. The acid-catalyzed cyclopropane-ring opening of 13 and ozonolysis of the resulting olefin provided the 16-keto-steroid analogue 18 .     

Microgels as drug carriers for sonopharmacology

The ultrasound-induced cleavage of covalent and non-covalent bonds to activate drugs (sonopharmacology) is a promising concept to gain control over the action of active pharmaceutical ingredients by an external trigger. Previously, linear polymer architectures bearing drug payloads were exploited for drug release by using the principles of polymer mechanochemistry. In this work, the carrier design is altered by the polymer topology to improve the ultrasound-triggered release of covalently anchored drugs from polymer scaffolds. We use microgels crosslinked by mechanoresponsive disulfides and copolymerized with Diels-Alder adducts of furylated payload molecules and acetylenedicarboxylate. Force-induced thiol formation induces a Michael-type addition liberating the payload from the microgels. The use of microgels significantly reduces sonication times compared to linear polymer chains and shields the cargo efficiently from non-triggered activation using ultrasound that produces inertial cavitation at a frequency of 20 kHz as model condition.     

Trypanosomal dUTPases as potential targets for drug design

Parasites of the Trypanosomatidae family are responsible for diseases that afflict several million people worldwide. Currently there is an urgent need for new drugs against these diseases and an approach to drug discovery is the study of biochemical and structural properties of a potential target and the subsequent design of specific compounds. Trypanosomatid genes coding for enzymes which distinctively hydrolyze dUTP have been isolated by genetic complementation in Escherichia coli mutants defective in dUTPase activity. An analysis of these sequences from Leishmania major and Trypanosoma cruzi showed that no significant similarity could be established with the family of known dUTPases and that the five consensus motifs were absent. However, limited similarity was identified for three motifs present in an enzyme related in function the dCTPase-dUTPase from T phages and 35 percent identity with a putative dUTPase identified in the eubacteria Campylobacter jejuni. T. cruzi and L. major dUTPases were highly similar and catalyzed in a specific fashion the hydrolysis of dUTP. A detailed kinetic study of both enzymes revealed that dUDP is also an efficient substrate of the enzyme while other nucleotides are poorly hydrolyzed. The enzyme is essential for viability in Leishmania and is up-regulated by inhibitors of dTMP synthesis. Thus, a new family of dUTPases might exist in certain organisms that bear no sequence or structure similarity with eukaryotic enzymes accomplishing the same function and that may constitute potential drug targets for the development of specific inhibitors.     

Anticonvulsant neuropeptides as drug leads for neurological diseases

Anticonvulsant neuropeptides are best known for their ability to suppress seizures and modulate pain pathways. Galanin, neuropeptide Y, somatostatin, neurotensin, dynorphin, among others, have been validated as potential first-in-class anti-epileptic or/and analgesic compounds in animal models of epilepsy and pain, but their therapeutic potential extends to other neurological indications, including neurodegenerative and psychatric disorders. Disease-modifying properties of neuropeptides make them even more attractive templates for developing new-generation neurotherapeutics. Arguably, efforts to transform this class of neuropeptides into drugs have been limited compared to those for other bioactive peptides. Key challenges in developing neuropeptide-based anticonvulsants are: to engineer optimal receptor-subtype selectivity, to improve metabolic stability and to enhance their bioavailability, including penetration across the blood–brain barrier (BBB). Here, we summarize advances toward developing systemically active and CNS-penetrant neuropeptide analogs. Two main objectives of this review are: (1) to provide an overview of structural and pharmacological properties for selected anticonvulsant neuropeptides and their analogs and (2) to encourage broader efforts to convert these endogenous natural products into drug leads for pain, epilepsy and other neurological diseases.     

Artificial neural network‐based drug design for diabetes mellitus using flavonoids

Diabetes mellitus is a chronic metabolic disease involving the failure to regulate glucose blood levels in the body and has been linked with numerous detrimental complications. Studies have shown that these complications can be linked to the activities of aldose reductase (AR), an enzyme of the polyol pathway. Flavonoids have been identified as good AR inhibitors (ARIs) and are also strong antioxidants with radical scavenging (RS) activity. As such, flavonoids show potential to become a better class of ARIs because they are able to concurrently address the oxidative stress issue. In this article, we carried out quantitative structure‐activity relationship analysis of flavones and flavonols (members of flavonoid family) using artificial neural networks. Three computer experiments were conducted to study the influence of hydrogen (H), hydroxyl (? OH), and methoxyl (? CH₃) functional groups on eight substitution sites of the lead flavone molecule and to predict potential ARIs. Of 6561 possible flavones and flavonols, in experiment 1, we predicted 69 potent ARIs, and in experiment 2, we predicted 346 compounds with strong RS activity. In experiment 3, we combined these results to find overlapping compounds with both strong AR inhibition and RS activity and we are able to predict 10 potent compounds with strong AR inhibition (IC₅₀ < 0.3 μM) and RS activity (IC₂₅ < 1.0 μM). These 10 compounds show promise of being good therapeutic agents in the prevention of diabetic complications and is suggested to undergo further wet bench experimentation to prove their potency. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011     

DNA origami as a carrier for circumvention of drug resistance

Although a multitude of promising anti-cancer drugs have been developed over the past 50 years, effective delivery of the drugs to diseased cells remains a challenge. Recently, nanoparticles have been used as drug delivery vehicles due to their high delivery efficiencies and the possibility to circumvent cellular drug resistance. However, the lack of biocompatibility and inability to engineer spatially addressable surfaces for multi-functional activity remains an obstacle to their widespread use. Here we present a novel drug carrier system based on self-assembled, spatially addressable DNA origami nanostructures that confronts these limitations. Doxorubicin, a well-known anti-cancer drug, was non-covalently attached to DNA origami nanostructures through intercalation. A high level of drug loading efficiency was achieved, and the complex exhibited prominent cytotoxicity not only to regular human breast adenocarcinoma cancer cells (MCF?7), but more importantly to doxorubicin-resistant cancer cells, inducing a remarkable reversal of phenotype resistance. With the DNA origami drug delivery vehicles, the cellular internalization of doxorubicin was increased, which contributed to the significant enhancement of cell-killing activity to doxorubicin-resistant MCF?7 cells. Presumably, the activity of doxorubicin-loaded DNA origami inhibits lysosomal acidification, resulting in cellular redistribution of the drug to action sites. Our results suggest that DNA origami has immense potential as an efficient, biocompatible drug carrier and delivery vehicle in the treatment of cancer.     

Regenerated keratin proteins as potential biomaterial for drug delivery

This work aims to preliminarily evaluate the reliability of regenerated keratins (RKs) in the design of microparticulate drug delivery systems by studying their processability and cytotoxicity. RKs were extracted by sulfitolysis from wool waste. A 4.5% w/w RK solution was spray‐dried, and microparticles were sterilized by steam vapor under pressure. Scanning electron microscope, sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, and Fourier transform infrared spectroscopy were used to characterize RKs and microparticles thereof. The in vitro cytotoxicity was determined by assessing the release of lactate dehydrogenase in the human monocytic cell line Tamm–Horsfall glycoprotein‐1. RK‐based microparticles with a narrow and unimodal particle size distribution (~6 µm) were obtained. They had a raisin‐like structure with a smooth surface. Both microparticle morphology and RK molecular weight were well‐preserved after sterilization. The curve fitting of the amide I bands showed that RK in the microparticles was prevalently present in the disordered/α‐helix secondary structures which made the protein soluble in water. To promote crystallization in the β‐sheet secondary structure and, therefore, water insolubility, RK‐based microparticles were immersed in an aqueous solution of acetic acid at pH 3.5 overnight. RK did not induce any appreciable cellular cytotoxicity at any of the concentrations (from 1 up to 1000 µg sterile microparticles in 1 ml cell culture medium) or time‐points (24–72 h) tested. These preliminary data suggest the feasibility of producing RK biocompatible microparticles using waste wool as starting material. Copyright © 2013 John Wiley & Sons, Ltd.     

Natural product hybrids as new leads for drug discovery

Natural products play an important role in the development of drugs, especially for the treatment of infections and cancer, as well as immunosuppressive compounds. However, the number of natural products is limited, whereas millions of hybrids as combinations of parts of different natural products can be prepared. This new approach seems to be very promising in the development of leads for both medicinal and agrochemical applications, as the biological activity of several new hybrids exceeds that of the parent compounds. The advantage of this concept over a combinatorial chemistry approach is the high diversity and the inherent biological activity of the hybrids.     

RNA as a drug target

Historically, the pharmaceutical industry has focused on proteins, rather than nucleic acids, as drug targets. But recent advances in the fields of RNA synthesis, structure determination and therapeutic target identification make the systematic exploitation of RNA as a drug target a realistic goal.     

The promise of electrochemical impedance spectroscopy as novel technology for the management of patients with diabetes mellitus

Self-monitoring of blood glucose is the standard of care in management of hyperglycemia among patients with diabetes mellitus. To increase the sensitivity and specificity of current devices, a novel method of detecting glucose using electrochemical impedance spectroscopy (EIS) technology is explored. The enzyme glucose oxidase (GOx) was fixed to gold electrodes and a sine wave of sweeping frequencies was induced using a wide range of concentrations of glucose. Each frequency in the impedance sweep was analyzed for the highest response and R-squared value. The frequency with both factors optimized is specific for the glucose-GOx binding interaction and was determined to be 1.17 kHz in purified solutions in both higher and lower ranges of glucose. The correlation between the impedance response and concentration at the low range of detection (0-100 mg dL(-1) of glucose) was determined to be 3.53 ohm/ln (mg dL(-1)) with an R-squared value of 0.90 with a 39 mg dL(-1) lower limit of detection. The same frequency of 1.17 kHz was verified in whole blood under the same glucose range. The above data confirm that EIS offers a new method of glucose detection as an alternative to current technology in use by patients. Additionally, the unique frequency response of individual markers allows for modulation of signals so that several other markers important in the management of diabetes could be measured with a single sensor.     

Vanadium-vitamin B12 bioconjugates as potential therapeutics for treating diabetes

The synthesis and blood glucose lowering properties of the first vanadium-vitamin B(12) bioconjugates are reported.     

Fatty Acid synthesis as a target for antimalarial drug discovery

In biological systems, fatty acids can be synthesized by two related, but distinct de novo fatty acid synthase (FAS) pathways. Human cells rely on a type I FAS whereas plants, bacteria and other microorganisms contain type II FAS pathways. This difference exposes the type II FAS enzymes as potential targets for anti-microbial drugs that have little to no side effects in the human host. A number of inhibitors of type II FAS enzymes have been discovered - many of which have anti-bacterial activity. Extensive biochemical and structural studies have shed light on how these compounds inhibit their target enzymes, laying the foundation for the design of inhibitors with increased potency. Recent work has shown that malaria parasites do not contain a type I FAS and rely solely on a type II FAS for the de novo biosynthesis of fatty acids. The malaria FAS enzymes are therefore an exciting source of new drug targets, and are being actively exploited by several drug discovery efforts. Rapid progress has been made, largely due to the vast body of mechanistic and structural information about type II FAS enzymes from bacteria and the availability of inhibitors. Ongoing antimalarial drug discovery projects will be described in this review as well as background information about the well-studied bacterial type II FAS enzymes.     

Synthetic and natural polymers as drug carriers for tuberculosis treatment

Drug forms based polymer carriers of prolong action were created for toxicologic effect of drug to be reduced in spite of long treatment of diseases. In present work a number of synthesis and natural polymers have been studied as carriers of antituberculous drugs for controlled delivery application. Following as drugs as isoniazid and ethionamide were incorporated into polymeric matrix (segmented polyurethanes, polyvinyl alcohol) and chemically bound with the polymer chain by covalent or electrostatic forces (aldehyde- and carboxymethylderivatives of polysaccharides). Biodegradation of polymeric systems and the release of drugs were studied by various physico-chemical methods. It was shown that the drug release depends of method of the immobilization, type of the drug/polymer bonding, drug loading. The bacteriostatic activity of obtained systems was determined. The possibility of tuberculosis treatment was proved in experiments of animals.     

Water-soluble proteins as an excipient for drug administration by inhalation

Microspherical particles of composite drugs based on lysozyme and albumin, which can be used in inhalation administration, were prepared by spray drying. The composition of the complexes was determined using experimental and theoretical methods. The use of the protein matrix makes it possible to increase the dissolution rate of the drug in water. The obtained results can be useful for the development of new drug dosage forms with increased bioavailability.