Covering: January 2013 to September 2018Sulfur-containing natural products are a large class of significant functional molecules. Many of these compounds exhibit potent biological activities and ...pharmacological properties; in fact, some of them have been developed into important drugs. The total synthesis of sulfur-containing natural products is a subject that has long attracted significant attention from synthetic organic chemists; to achieve this goal, various methods have been developed over the past years. This review surveys total syntheses of sulfur-containing natural products that introduce sulfur atoms using different sulfurization agents to construct related sulfur-containing moieties.
Halloysite is an alumosilicate tubular clay with a diameter of 50 nm, an inner lumen of 15 nm and a length of 600–900 nm. It is a natural biocompatible nanomaterial available in thousands of tons at ...low price, which makes it a good candidate for nanoarchitectural composites. The inner lumen of halloysite may be adjusted by etching to 20–30% of the tube volume and loading with functional agents (antioxidants, anticorrosion agents, flame‐retardant agents, drugs, or proteins) allowing for formulations with sustained release tuned by the tube end‐stoppers for hours and days. Clogging the tube ends in polymeric composites allows further extension of the release time. Thus, antioxidant‐loaded halloysite doped into rubber enhances anti‐aging properties for at least 12 months. The addition of 3–5 wt% of halloysite increases the strength of polymeric materials, and the possibility of the tube's orientation promises a gradient of properties. Halloysite nanotubes are a promising mesoporous media for catalytic nanoparticles that may be seeded on the tube surface or synthesized exclusively in the lumens, providing enhanced catalytic properties, especially at high temperatures. In vitro and in vivo studies on biological cells and worms indicate the safety of halloysite, and tests for efficient adsorption of mycotoxins in animals' stomachs are also carried out.
Halloysite, 50 nm diameter tubular clay, is a natural biocompatible material available in thousands of tons. Its inner lumen may be etched, doubling the lumen's volume, and loaded with functional agents, such as antioxidants, anticorrosion materials, flame‐retardants, catalysts, drugs, or proteins, enabling sustained controlled release tuned for hours, days, or months.
This review covers the literature published between January and December in 2018 for marine natural products (MNPs), with 717 citations (706 for the period January to December 2018) referring to ...compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1554 in 469 papers for 2018), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. The proportion of MNPs assigned absolute configuration over the last decade is also surveyed.
In the face of the recent pandemic and emergence of infectious diseases of viral origin, research on parasitic diseases such as malaria continues to remain critical and innovative methods are ...required to target the rising widespread resistance that renders conventional therapies unusable. The prolific use of auxiliary metallo-fragments has augmented the search for novel drug regimens in an attempt to combat rising resistance. The development of organometallic compounds (those containing metal-carbon bonds) as antimalarial drugs has been exemplified by the clinical development of ferroquine in the nascent field of Bioorganometallic Chemistry. With their inherent physicochemical properties, organometallic complexes can modulate the discipline of chemical biology by proffering different modes of action and targeting various enzymes. With the beneficiation of platinum group metals (PGMs) in mind, this review aims to describe recent studies on the antimalarial activity of PGM-based organometallic complexes. This review does not provide an exhaustive coverage of the literature but focusses on recent advances of bioorganometallic antimalarial drug leads, including a brief mention of recent trends comprising interactions with biomolecules such as heme and intracellular catalysis. This resource can be used in parallel with complementary reviews on metal-based complexes tested against malaria.
The chemical composition and antibacterial activity of essential oils from 10 commonly consumed herbs: Citrus aurantium, C. limon, Lavandula angustifolia, Matricaria chamomilla, Mentha piperita, M. ...spicata, Ocimum basilicum, Origanum vulgare, Thymus vulgaris and Salvia officinalis have been determined. The antibacterial activity of these oils and their main components; i.e. camphor, carvacrol, 1,8-cineole, linalool, linalyl acetate, limonene, menthol, a-pinene, b-pinene, and thymol were assayed against the human pathogenic bacteria Bacillus subtilis, Enterobacter cloacae, Escherichia coli O157:H7, Micrococcus flavus, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella enteritidis, S. epidermidis, S. typhimurium, and Staphylococcus aureus. The highest and broadest activity was shown by O. vulgare oil. Carvacrol had the highest antibacterial activity among the tested components.
Bone tissue scaffolds made from either natural or synthetic polymers are employed to promote bone healing. However, lack of sufficient or poor mechanical properties such as low integrity and ...stability reduces their medical applications. Crosslinking, defined as induction of chemical or physical links among polymer chains, is a simple method generally used to modify mechanical, biological and degradation properties of hydrogels. Although crosslinking through chemical reactions improves the mechanical properties of bone substitutes, most of the reagents used for this aim demonstrate undesirable effects and may exert toxic reactions. Glutaraldehyde is a widely-used chemical crosslinker with unique ability to crosslink a wide variety of biomaterials; however, many contradictory views have been recently raised on its cytotoxic effects. By keeping this limit in mind, green chemicals or natural crosslinking agents have been shown to provide desired improvements in mechanical properties of bone scaffolds. Therefore, developing more efficient crosslinking materials and methods are desirable to obtain crosslinked scaffolds with perfect properties in bone tissue engineering from different biopolymers such as collagen, gelatin, cellulose, chitosan, alginate, etc. In this review, we focused on developed or developing modalities used to improve mechanical properties of various bone scaffolds and matrices based on common crosslinking reagents.
Compound Histories: Materials, Governance and Production, 1760-1840 explores the intertwined realms of production, governance and materials, placing chemists and chemistry at the center of processes ...most closely identified with the construction of the modern world. Readership: All interested in European history since the mid-eighteenth century, and anyone interested in the history of industrialization, science, technology, modernization, political economy, environmental history, materials and governance.
Flavonoids are phytochemical compounds present in many plants, fruits, vegetables, and leaves, with potential applications in medicinal chemistry. Flavonoids possess a number of medicinal benefits, ...including anticancer, antioxidant, anti-inflammatory, and antiviral properties. They also have neuroprotective and cardio-protective effects. These biological activities depend upon the type of flavonoid, its (possible) mode of action, and its bioavailability. These cost-effective medicinal components have significant biological activities, and their effectiveness has been proved for a variety of diseases. The most recent work is focused on their isolation, synthesis of their analogs, and their effects on human health using a variety of techniques and animal models. Thousands of flavonoids have been successfully isolated, and this number increases steadily. We have therefore made an effort to summarize the isolated flavonoids with useful activities in order to gain a better understanding of their effects on human health.
A method to assemble stimuli-responsive nucleic acid-based hydrogel-stabilized microcapsule-in-microcapsule systems is introduced. An inner aqueous compartment stabilized by a stimuli-responsive ...hydrogel-layer (∼150 nm) provides the inner microcapsule (diameter ∼2.5 μm). The inner microcapsule is separated from an outer aqueous compartment stabilized by an outer stimuli-responsive hydrogel layer (thickness of ∼150 nm) that yields the microcapsule-in-microcapsule system. Different loads, e.g., tetramethyl rhodamine-dextran (TMR-D) and CdSe/ZnS quantum dots (QDs), are loaded in the inner and outer aqueous compartments. The hydrogel layers exist in a higher stiffness state that prevents inter-reservoir or leakage of the loads from the respective aqueous compartments. Subjecting the inner hydrogel layer to Zn
-ions and/or the outer hydrogel layer to acidic pH or crown ether leads to the triggered separation of the bridging units associated with the respective hydrogel layers. This results in the hydrogel layers of lower stiffness allowing either the mixing of the loads occupying the two aqueous compartments, the guided release of the load from the outer aqueous compartment, or the release of the loads from the two aqueous compartments. In addition, a pH-responsive microcapsule-in-microcapsule system is loaded with glucose oxidase (GOx) in the inner aqueous compartment and insulin in the outer aqueous compartment. Glucose permeates across the two hydrogel layers resulting in the GOx catalyzed aerobic oxidation of glucose to gluconic acid. The acidification of the microcapsule-in-microcapsule system leads to the triggered unlocking of the outer, pH-responsive hydrogel layer and to the release of insulin. The pH-stimulated release of insulin is controlled by the concentration of glucose. While at normal glucose levels, the release of insulin is practically prohibited, the dose-controlled release of insulin in the entire diabetic range is demonstrated. Also, switchable ON/OFF release of insulin is achieved highlighting an autonomous glucose-responsive microdevice operating as an "artificial pancreas" for the release of insulin.