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Hypericin
Hypericin is a carbopolycyclic compound derived from bisanthene with antidepressant properties, found in various ''Hypericum'' species, and is being studied for treating cutaneous T-cell lymphoma. Opinions differ on the extent to which hypericin exhibits antidepressant effects. According to some scholars, hypericin, along with other active compounds in ''Hypericum perforatum'' (St. John’s wort), contributes to the antidepressant effects of the total plant extract. According to others, hypericin does not significantly inhibit monoamine oxidase and thus is unlikely to account for the antidepressant effects of ''Hypericum'' extract. While another hypericin shows affinity mainly for NMDA receptors, suggesting that other plant constituents likely play a more significant role in its antidepressant effects. Hypericin is a structurally complex phenanthroperylene quinone with potential Evidence-based medicine, medical and photoreceptive applications. It is red-colored, photosensiti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypericum
''Hypericum'' is a genus of flowering plants in the family (biology), family Hypericaceae (formerly considered a subfamily of Clusiaceae). The genus has a nearly worldwide distribution, missing only from tropical lowlands, deserts and polar regions. Many ''Hypericum'' species are regarded as invasive species and noxious weeds. All members of the genus may be referred to as St. John's wort, and some are known as goatweed. The white or pink flowered marsh St. John's worts of North America and eastern Asia are generally accepted as belonging to the separate genus ''Triadenum'' Raf. ''Hypericum'' is unusual for a genus of its size because a worldwide taxonomic monograph was produced for it by Norman Robson (botanist), Norman Robson (working at the Natural History Museum, London). Robson recognizes 36 sections within ''Hypericum''. Description ''Hypericum'' species are quite variable in habit, occurring as trees, shrubs, annuals, and perennials. Trees in the sense of single stem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Merck Index
''The Merck Index'' is an encyclopedia of chemical substance, chemicals, pharmaceutical drug, drugs and biomolecule, biologicals with over 10,000 monographs on single substances or groups of related chemical compound, compounds published online by the Royal Society of Chemistry. History The first edition of the Merck's Index was published in 1889 by the German chemical company Merck Group, Emanuel Merck and was primarily used as a sales catalog for Merck's growing list of chemicals it sold. The American subsidiary was established two years later and continued to publish it. During World War I the US government seized Merck's US operations and made it a separate American "Merck" company that continued to publish the Merck Index. In 2012 the Merck Index was licensed to the Royal Society of Chemistry. An online version of The Merck Index, including historic records and new updates not in the print edition, is commonly available through research libraries. It also includes an append ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emodin
Emodin (6-methyl-1,3,8-trihydroxyanthraquinone) is an organic compound. Classified as an anthraquinone, it can be isolated from rhubarb, buckthorn, and Japanese knotweed ('' Reynoutria japonica'' syn. ''Polygonum cuspidatum''). Emodin is particularly abundant in the roots of the Chinese rhubarb (''Rheum palmatum''), knotweed and knotgrass ('' Polygonum cuspidatum'' and '' Polygonum multiflorum'') as well as Hawaii ‘au‘auko‘i cassia seeds or coffee weed (''Semen cassia''). It is specifically isolated from ''Rheum palmatum'' L. It is also produced by many species of fungi, including members of the genera ''Aspergillus'', '' Pyrenochaeta'', and ''Pestalotiopsis'', inter alia. The common name is derived from ''Rheum emodi'', a taxonomic synonym of '' Rheum australe'' (Himalayan rhubarb), and synonyms include emodol, frangula emodin, rheum emodin, 3-methyl-1,6,8-trihydroxyanthraquinone, Schüttgelb (Schuttgelb), and Persian Berry Lake. Pharmacology Emodin is an active compon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemicals In Hypericum
A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combined without reacting, they may form a chemical mixture. If a mixture is separated to isolate one chemical substance to a desired degree, the resulting substance is said to be chemically pure. Chemical substances can exist in several different physical states or phases (e.g. solids, liquids, gases, or plasma) without changing their chemical composition. Substances transition between these phases of matter in response to changes in temperature or pressure. Some chemical substances can be combined or converted into new substances by means of chemical reactions. Chemicals that do not possess this ability are said to be inert. Pure water is an example of a chemical substance, with a constant composition of two hydrogen atoms bonded to a sin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyols
In organic chemistry, a polyol is an organic compound containing multiple hydroxyl groups (). The term "polyol" can have slightly different meanings depending on whether it is used in food science or polymer chemistry. Polyols containing two, three and four hydroxyl groups are diols, triols, and tetrols, respectively. Classification Polyols may be classified according to their chemistry. Some of these chemistries are polyether, polyester, polycarbonate and also acrylic polyols. Polyether polyols may be further subdivided and classified as polyethylene oxide or polyethylene glycol (PEG), polypropylene glycol (PPG) and Polytetrahydrofuran or PTMEG. These have 2, 3 and 4 carbons respectively per oxygen atom in the repeat unit. Polycaprolactone polyols are also commercially available. There is also an increasing trend to use biobased (and hence renewable) polyols. Uses Polyether polyols have numerous uses. As an example, polyurethane foam is a big user of polyether polyols. Polyest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyketides
In organic chemistry, polyketides are a class of natural products derived from a precursor molecule consisting of a chain of alternating ketone (, or its reduced forms) and methylene () groups: . First studied in the early 20th century, discovery, biosynthesis, and application of polyketides has evolved. It is a large and diverse group of secondary metabolites caused by its complex biosynthesis which resembles that of fatty acid synthesis. Because of this diversity, polyketides can have various medicinal, agricultural, and industrial applications. Many polyketides are medicinal or exhibit acute toxicity. Biotechnology has enabled discovery of more naturally-occurring polyketides and evolution of new polyketides with novel or improved bioactivity. History Naturally produced polyketides by various plants and organisms have been used by humans since before studies on them began in the 19th and 20th century. In 1893, J. Norman Collie synthesized detectable amounts of orcinol by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virucides
A virucide (alternatively spelled viricide) is any physical or chemical agent that deactivates or destroys viruses. The substances are not only virucidal but can be also bactericidal, fungicidal, sporicidal or tuberculocidal. Virucides are to be used outside the human body, and as such fall into the category of disinfectants (applied not to the human body) and antiseptics (applied to the surface of skin) for those safe enough. Overall, the notion of virucide differs from an antiviral drug such as Aciclovir, which inhibits the proliferation of the virus inside the body. CDC's Disinfection and Sterilization list of ''Chemical Disinfectants'' mentions and discusses substances such as: alcohol, chlorine and chlorine compounds, formaldehyde, glutaraldehyde, hydrogen peroxide, iodophors, ortho-phthalaldehyde (OPA), peracetic acid, peracetic acid and hydrogen peroxide, phenolics, quaternary ammonium compounds, with different, but usually potent ''microbicidal activity''. Other inacti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
In Vitro
''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology and its subdisciplines are traditionally done in labware such as test tubes, flasks, Petri dishes, and microtiter plates. Studies conducted using components of an organism that have been isolated from their usual biological surroundings permit a more detailed or more convenient analysis than can be done with whole organisms; however, results obtained from ''in vitro'' experiments may not fully or accurately predict the effects on a whole organism. In contrast to ''in vitro'' experiments, ''in vivo'' studies are those conducted in living organisms, including humans, known as clinical trials, and whole plants. Definition ''In vitro'' (Latin language, Latin for "in glass"; often not italicized in English usage) studies are conducted ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalysis
Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst. The rate increase occurs because the catalyst allows the reaction to occur by an alternative mechanism which may be much faster than the noncatalyzed mechanism. However the noncatalyzed mechanism does remain possible, so that the total rate (catalyzed plus noncatalyzed) can only increase in the presence of the catalyst and never decrease. Catalysis may be classified as either homogeneous, whose components are dispersed in the same phase (usual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimerization
In chemistry, dimerization is the process of joining two identical or similar molecular entities by bonds. The resulting bonds can be either strong or weak. Many symmetrical chemical species are described as dimers, even when the monomer is unknown or highly unstable. The term ''homodimer'' is used when the two subunits are identical (e.g. A–A) and ''heterodimer'' when they are not (e.g. A–B). The reverse of dimerization is often called dissociation. When two oppositely-charged ions associate into dimers, they are referred to as ''Bjerrum pairs'', after Danish chemist Niels Bjerrum. Noncovalent dimers Anhydrous carboxylic acids form dimers by hydrogen bonding of the acidic hydrogen and the carbonyl oxygen. For example, acetic acid forms a dimer in the gas phase, where the monomer units are held together by hydrogen bonds. Many OH-containing molecules form dimers, e.g. the water dimer. Dimers that form based on weak electrostatic interaction and/or van der Waals in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biosynthesis
Biosynthesis, i.e., chemical synthesis occurring in biological contexts, is a term most often referring to multi-step, enzyme-Catalysis, catalyzed processes where chemical substances absorbed as nutrients (or previously converted through biosynthesis) serve as enzyme substrate (chemistry), substrates, with conversion by the living organism either into simpler or more complex Product (chemistry), products. Examples of biosynthetic pathways include those for the production of amino acids, lipid membrane components, and nucleotides, but also for the production of all classes of biological macromolecules, and of acetyl-coenzyme A, adenosine triphosphate, nicotinamide adenine dinucleotide and other key intermediate and transactional molecules needed for metabolism. Thus, in biosynthesis, any of an array of Chemical compound, compounds, from simple to complex, are converted into other compounds, and so it includes both the catabolism and anabolism (building up and breaking down) of comple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allergen
An allergen is an otherwise harmless substance that triggers an allergic reaction in sensitive individuals by stimulating an immune response. In technical terms, an allergen is an antigen that is capable of stimulating a type-I hypersensitivity reaction in atopic individuals through immunoglobulin E (IgE) responses. Most humans mount significant immunoglobulin E responses only as a defense against parasitic infections. However, some individuals may respond to many common environmental antigens. This hereditary predisposition is called atopy. In atopic individuals, non-parasitic antigens stimulate inappropriate IgE production, leading to type I hypersensitivity. Sensitivities vary widely from one person (or from one animal) to another. A very broad range of substances can be allergens to sensitive individuals. Examples Allergens can be found in a variety of sources, such as dust mite excretion, pollen, pet dander, or even royal jelly. Food allergies are not as co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
