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Macrolide Antibiotics
The Macrolides are a class of natural products that consist of a large macrocyclic lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, may be attached. The lactone rings are usually 14-, 15-, or 16-membered. Macrolides belong to the polyketide class of natural products. Some macrolides have antibiotic or antifungal activity and are used as pharmaceutical drugs. Rapamycin is also a macrolide and was originally developed as an antifungal, but is now used as an immunosuppressant drug and is being investigated as a potential longevity therapeutic. Macrolides are bacteriostatic in that they suppress or inhibit bacterial growth rather than killing bacteria completely. Definition In general, any macrocyclic lactone having greater than 8-membered rings are candidates for this class. The macrocycle may contain amino nitrogen, amide nitrogen (but should be differentiated from cyclopeptides), an oxazole ring, or a thiazole ring. Benzene rings are excluded ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erythromycin A
Erythromycin is an antibiotic used for the treatment of a number of bacterial infections. This includes respiratory tract infections, skin infections, chlamydia infections, pelvic inflammatory disease, and syphilis. It may also be used during pregnancy to prevent Group B streptococcal infection in the newborn, as well as to improve delayed stomach emptying. It can be given intravenously and by mouth. An eye ointment is routinely recommended after delivery to prevent eye infections in the newborn. Common side effects include abdominal cramps, vomiting, and diarrhea. More serious side effects may include ''Clostridium difficile'' colitis, liver problems, prolonged QT, and allergic reactions. It is generally safe in those who are allergic to penicillin. Erythromycin also appears to be safe to use during pregnancy. While generally regarded as safe during breastfeeding, its use by the mother during the first two weeks of life may increase the risk of pyloric stenosis in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amide
In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it is part of the main chain of a protein, and an isopeptide bond when it occurs in a side chain, such as in the amino acids asparagine and glutamine. It can be viewed as a derivative of a carboxylic acid () with the hydroxyl group () replaced by an amine group (); or, equivalently, an acyl (alkanoyl) group () joined to an amine group. Common examples of amides are acetamide (), benzamide (), and dimethylformamide (). Amides are qualified as primary, secondary, and tertiary according to whether the amine subgroup has the form , , or , where R and R' are groups other than hydrogen. The core of amides is called the amide group (specifically, carboxamide group). Amides are pervasive in nature and technology. Proteins and important plastics l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gram-positive Bacteria
In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bacteria take up the crystal violet stain used in the test, and then appear to be purple-coloured when seen through an optical microscope. This is because the thick peptidoglycan layer in the bacterial cell wall retains the stain after it is washed away from the rest of the sample, in the decolorization stage of the test. Conversely, gram-negative bacteria cannot retain the violet stain after the decolorization step; alcohol used in this stage degrades the outer membrane of gram-negative cells, making the cell wall more porous and incapable of retaining the crystal violet stain. Their peptidoglycan layer is much thinner and sandwiched between an inner cell membrane and a bacterial outer membrane, causing them to take up the counterstain (sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clarithromycin
Clarithromycin, sold under the brand name Biaxin among others, is an antibiotic used to treat various bacterial infections. This includes strep throat, pneumonia, skin infections, ''H. pylori'' infection, and Lyme disease, among others. Clarithromycin can be taken by mouth as a pill or liquid. Common side effects include nausea, vomiting, headaches, and diarrhea. Severe allergic reactions are rare. Liver problems have been reported. It may cause harm if taken during pregnancy. It is in the macrolide class and works by slowing down bacterial protein synthesis. Clarithromycin was developed in 1980 and approved for medical use in 1990. It is on the World Health Organization's List of Essential Medicines. Clarithromycin is available as a generic medication. It is made from erythromycin and is chemically known as 6-O-methylerythromycin. Medical uses Clarithromycin is primarily used to treat a number of bacterial infections including pneumonia, ''Helicobacter pylori'', and as an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Azithromycin
Azithromycin, sold under the brand names Zithromax (in oral form) and Azasite (as an eye drop), is an antibiotic medication used for the treatment of a number of bacterial infections. This includes middle ear infections, strep throat, pneumonia, traveler's diarrhea, and certain other intestinal infections. Along with other medications, it may also be used for malaria. It can be taken by mouth or intravenously. Common side effects include nausea, vomiting, diarrhea and upset stomach. An allergic reaction, such as anaphylaxis, QT prolongation, or a type of diarrhea caused by ''Clostridium difficile'' is possible. No harm has been found with its use during pregnancy. Its safety during breastfeeding is not confirmed, but it is likely safe. Azithromycin is an azalide, a type of macrolide antibiotic. It works by decreasing the production of protein, thereby stopping bacterial growth. Azithromycin was discovered in 1980 by the Yugoslav pharmaceutical company Pliva and approved f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penicillin
Penicillins (P, PCN or PEN) are a group of β-lactam antibiotics originally obtained from ''Penicillium'' moulds, principally '' P. chrysogenum'' and '' P. rubens''. Most penicillins in clinical use are synthesised by P. chrysogenum using deep tank fermentation and then purified. A number of natural penicillins have been discovered, but only two purified compounds are in clinical use: penicillin G (intramuscular or intravenous use) and penicillin V (given by mouth). Penicillins were among the first medications to be effective against many bacterial infections caused by staphylococci and streptococci. They are still widely used today for different bacterial infections, though many types of bacteria have developed resistance following extensive use. 10% of the population claims penicillin allergies but because the frequency of positive skin test results decreases by 10% with each year of avoidance, 90% of these patients can tolerate penicillin. Additionally, those with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erythromycin
Erythromycin is an antibiotic used for the treatment of a number of bacterial infections. This includes respiratory tract infections, skin infections, chlamydia infections, pelvic inflammatory disease, and syphilis. It may also be used during pregnancy to prevent Group B streptococcal infection in the newborn, as well as to improve delayed stomach emptying. It can be given intravenously and by mouth. An eye ointment is routinely recommended after delivery to prevent eye infections in the newborn. Common side effects include abdominal cramps, vomiting, and diarrhea. More serious side effects may include ''Clostridium difficile'' colitis, liver problems, prolonged QT, and allergic reactions. It is generally safe in those who are allergic to penicillin. Erythromycin also appears to be safe to use during pregnancy. While generally regarded as safe during breastfeeding, its use by the mother during the first two weeks of life may increase the risk of pyloric stenosis in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tacrolimus
Tacrolimus, sold under the brand name Prograf among others, is an immunosuppressive drug. After allogeneic organ transplant, the risk of organ rejection is moderate. To lower the risk of organ rejection, tacrolimus is given. The drug can also be sold as a topical medication in the treatment of T-cell-mediated diseases such as eczema and psoriasis. For example, it is prescribed for severe refractory uveitis after a bone marrow transplant, exacerbations of minimal change disease, Kimura's disease, and vitiligo. It can be used to treat dry eye syndrome in cats and dogs. Tacrolimus inhibits calcineurin, which is involved in the production of interleukin-2, a molecule that promotes the development and proliferation of T cells, as part of the body's learned (or adaptive) immune response. Chemically, it is a macrolide lactone that was first discovered in 1987, from the fermentation broth of a Japanese soil sample that contained the bacterium ''Streptomyces tsukubensis''. It is on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ansamycin
Ansamycins is a family of bacterial secondary metabolites that show antimicrobial activity against many Gram-positive and some Gram-negative bacteria, and includes various compounds, including streptovaricins and rifamycins. In addition, these compounds demonstrate antiviral activity towards bacteriophages and poxviruses. Structure They are named ansamycins (from the Latin ansa, ''handle'') because of their unique structure, which consists of an aromatic moiety bridged by an aliphatic chain. The main difference between various derivatives of ansamycins is the aromatic moiety, which can be a naphthalene ring or a naphthoquinone ring as in rifamycin and the naphthomycins. Another variation consists of benzene or a benzoquinone ring system as in geldanamycin or ansamitocin. Ansamycins were first discovered in 1959 by Sensi et al. from ''Amycolatopsis mediterranei'', an actinomycete bacterium. Examples Rifamycins are a subclass of ansamycins with high potency against mycobact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactam
A lactam is a cyclic amide, formally derived from an amino alkanoic acid. The term is a portmanteau of the words ''lactone'' + ''amide''. Nomenclature Greek prefixes in alphabetical order indicate ring size: * α-Lactam (3-atom rings) * β-Lactam (4-atom rings) * γ-Lactam (5-atom rings) * δ-Lactam (6-atom rings) * ε-Lactam (7-atom rings) This ring-size nomenclature stems from the fact that a hydrolyzed α-Lactam leads to an α-amino acid and a β-Lactam to a β-amino acid, ''etc''. Synthesis General synthetic methods exist for the organic synthesis of lactams. Beckmann rearrangement Lactams form by the acid-catalyzed rearrangement of oximes in the Beckmann rearrangement. Schmidt reaction Lactams form from cyclic ketones and hydrazoic acid in the Schmidt reaction. Cyclization of amino acids Lactams can be formed from cyclisation of amino acids via the coupling between an amine and a carboxylic acid within the same molecule. Lactamization is most efficient in this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tannin
Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner'', from Medieval Latin ''tannāre'', from ''tannum'', oak bark) refers to the use of oak and other bark in tanning animal hides into leather. By extension, the term ''tannin'' is widely applied to any large polyphenolic compound containing sufficient hydroxyls and other suitable groups (such as carboxyls) to form strong complexes with various macromolecules. The tannin compounds are widely distributed in many species of plants, where they play a role in protection from predation (acting as pesticides) and might help in regulating plant growth. The astringency from the tannins is what causes the dry and puckery feeling in the mouth following the consumption of unripened fruit, red wine or tea. Likewise, the destruction or modification of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzene
Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, benzene is classed as a hydrocarbon. Benzene is a natural constituent of petroleum and is one of the elementary petrochemicals. Due to the cyclic continuous pi bonds between the carbon atoms, benzene is classed as an aromatic hydrocarbon. Benzene is a colorless and highly flammable liquid with a sweet smell, and is partially responsible for the aroma of gasoline. It is used primarily as a precursor to the manufacture of chemicals with more complex structure, such as ethylbenzene and cumene, of which billions of kilograms are produced annually. Although benzene is a major industrial chemical, it finds limited use in consumer items because of its toxicity. History Discovery The word "''benzene''" derives from "''gum benzoin''" (benzoin res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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