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Phytoalexin
Phytoalexins are antimicrobial substances, some of which are antioxidative as well. They are defined, not by their having any particular chemical structure or character, but by the fact that they are defensively synthesized ''de novo'' by plants that produce the compounds rapidly at sites of pathogen infection. In general phytoalexins are broad spectrum inhibitors; they are chemically diverse, and different chemical classes of compounds are characteristic of particular plant taxa. Phytoalexins tend to fall into several chemical classes, including terpenoids, glycosteroids and alkaloids, however the term applies to any phytochemicals that are induced by microbial infection. Function Phytoalexins are produced in plants to act as toxins to the attacking organism. They may puncture the cell wall, delay maturation, disrupt metabolism or prevent reproduction of the pathogen in question. Their importance in plant defense is indicated by an increase in susceptibility of plant tissue t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allixin
Allixin is a phytoalexin found in garlic (''Allium sativum'') bulbs. It was first isolated and characterized in 1989. When garlic is stored for long periods of time, it can form visible accumulations of crystalline allixin on its surface, particularly in areas where tissue has become necrotic. After 2 years of storage, the amount of allixin accumulated can approach 1% of the dry weight of the cloves. Since allixin has weak antimicrobial activity, these high concentrations are thought to be produced by the garlic bulb to protect itself from further damage from microorganisms. Since allixin is found in high concentrations in garlic, there has been scientific interest in determining if it is responsible for any of the known health benefits of garlic. As a result of ongoing research, a variety of biological activities have been attributed to allixin. Pharmaceutical drug discovery research based on derivatives of allixin has followed. Laboratory synthesis Two laboratory synthese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capsidiol
Capsidiol is a terpenoid compound that accumulates in tobacco ''Nicotiana tabacum'' and chili pepper ''Capsicum annuum'' in response to fungal infection.Maldonado-Bonilla LD, Betancourt-Jiménez M,Lozoya-Gloria E (2008) "Local and systemic gene expression of sesquiterpene phytoalexin biosynthetic enzymes in plant leaves". ''European J. Plant Path.'' 121(4), 439-449. Capsidiol is categorized under the broad term of phytoalexin, a class of low molecular weight plant secondary metabolites that are produced during infection. Phytoalexins are also characterized as a part of a two pronged response to infection which involves a short term response consisting of production of free radicals near the site of infection and a long term response involving the production of hormones and an increase in enzymes to biosynthesize phyoalexins such as capsidiol. Mechanism of production Capsidiol is produced in the pepper fruit ''Capsicum annuum'' or tobacco ''Nicotiana tabacum'' after infe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypersensitive Response
Hypersensitive response (HR) is a mechanism used by plants to prevent the spread of infection by microbial pathogens. HR is characterized by the rapid death of cells in the local region surrounding an infection and it serves to restrict the growth and spread of pathogens to other parts of the plant. It is analogous to the innate immune system found in animals, and commonly precedes a slower systemic (whole plant) response, which ultimately leads to systemic acquired resistance (SAR). HR can be observed in the vast majority of plant species and is induced by a wide range of plant pathogens such as oomycetes, viruses, fungi and even insects. HR is commonly thought of as an effective defence strategy against biotrophic plant pathogens, which require living tissue to gain nutrients. In the case of necrotrophic pathogens, HR might even be beneficial to the pathogen, as they require dead plant cells to obtain nutrients. The situation becomes complicated when considering pat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyphenol
Polyphenols () are a large family of naturally occurring organic compounds characterized by multiples of phenol units. They are abundant in plants and structurally diverse. Polyphenols include flavonoids, tannic acid, and ellagitannin, some of which have been used historically as dyes and for tanning garments. Etymology The name derives from the Ancient Greek word (''polus'', meaning "many, much") and the word phenol which refers to a chemical structure formed by attaching to an aromatic benzenoid (phenyl) ring to a hydroxyl (-OH) group as is found in alcohols (hence the ''-ol'' suffix). The term polyphenol has been in use at least since 1894. Definition The term polyphenol is not well-defined, but is generally agreed that they are natural products "having a polyphenol structure (i.e., several hydroxyl groups on aromatic rings)" including four principal classes: "phenolic acids, flavonoids, stilbenes, and lignans". *Flavonoids include flavones, flavonols, flavanol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxon
In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and given a particular ranking, especially if and when it is accepted or becomes established. It is very common, however, for taxonomists to remain at odds over what belongs to a taxon and the criteria used for inclusion. If a taxon is given a formal scientific name, its use is then governed by one of the nomenclature codes specifying which scientific name is correct for a particular grouping. Initial attempts at classifying and ordering organisms (plants and animals) were set forth in Carl Linnaeus's system in ''Systema Naturae'', 10th edition (1758), as well as an unpublished work by Bernard and Antoine Laurent de Jussieu. The idea of a unit-based system of biological classification was first made widely available in 1805 in the i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethylene
Ethylene ( IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene is widely used in the chemical industry, and its worldwide production (over 150 million tonnes in 2016) exceeds that of any other organic compound. Much of this production goes toward polyethylene, a widely used plastic containing polymer chains of ethylene units in various chain lengths. Ethylene is also an important natural plant hormone and is used in agriculture to force the ripening of fruits. The hydrate of ethylene is ethanol. Structure and properties This hydrocarbon has four hydrogen atoms bound to a pair of carbon atoms that are connected by a double bond. All six atoms that comprise ethylene are coplanar. The H-C-H angle is 117.4°, close to the 120° for ideal sp² hybridized carbon. The molecule is also relatively weak: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
7,12-Dimethylbenz(a)anthracene
7,12-Dimethylbenz 'a''nthracene (DMBA) is an immunosuppressor and a powerful organ-specific laboratory carcinogen. DMBA is widely used in many research laboratories studying cancer. DMBA serves as a tumor initiator. Tumor promotion Tumor promotion is a process in carcinogenesis by which various factors permit the descendants of a single initiated cell to survive and expand in number, i.e. to resist apoptosis and to undergo clonal growth. This is a step toward tumor progre ... can be induced with treatments of 12-''O''-tetradecanoylphorbol-13-acetate (TPA) in some models of two-stage carcinogenesis. This allows for a greatly accelerated rate of tumor growth, making many cancer studies possible. References {{DEFAULTSORT:Dimethylbenz(a)anthracene, 7,12- Polycyclic aromatic hydrocarbons Carcinogens Anthracenes Immunosuppressants ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
12-O-Tetradecanoylphorbol-13-acetate
12-''O''-Tetradecanoylphorbol-13-acetate (TPA), also commonly known as tetradecanoylphorbol acetate, tetradecanoyl phorbol acetate, and phorbol 12-myristate 13-acetate (PMA) is a diester of phorbol. It is a potent tumor promoter often employed in biomedical research to activate the signal transduction enzyme protein kinase C (PKC). The effects of TPA on PKC result from its similarity to one of the natural activators of classic PKC isoforms, diacylglycerol. TPA is a small molecule drug. In ROS biology, superoxide was identified as the major reactive oxygen species induced by TPA/PMA but not by ionomycin in mouse macrophages. Thus, TPA/PMA has been routinely used as an inducer for endogenous superoxide production. TPA is also being studied as a drug in the treatment of hematologic cancer TPA has a specific use in cancer diagnostics as a B-cell specific mitogen in cytogenetic testing. To view the chromosomes, a cytogenetic test requires dividing cells. TPA is used to stimulate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tumor
A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists in growing abnormally, even if the original trigger is removed. This abnormal growth usually forms a mass, when it may be called a tumor. ICD-10 classifies neoplasms into four main groups: benign neoplasms, in situ neoplasms, malignant neoplasms, and neoplasms of uncertain or unknown behavior. Malignant neoplasms are also simply known as cancers and are the focus of oncology. Prior to the abnormal growth of tissue, as neoplasia, cells often undergo an abnormal pattern of growth, such as metaplasia or dysplasia. However, metaplasia or dysplasia does not always progress to neoplasia and can occur in other conditions as well. The word is from Ancient Greek 'new' and 'formation, creation'. Types A neoplasm can be benign, potenti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aflatoxin
Aflatoxins are various poisonous carcinogens and mutagens that are produced by certain molds, particularly '' Aspergillus'' species. The fungi grow in soil, decaying vegetation and various staple foodstuffs and commodities such as hay, sweetcorn, wheat, millet, sorghum, cassava, rice, chili peppers, cottonseed, peanuts, tree nuts, sesame seeds, sunflower seeds, and various spices. In short, the relevant fungi grow on almost any crop or food. When such contaminated food is processed or consumed, the aflatoxins enter the general food supply. They have been found in both pet and human foods, as well as in feedstocks for agricultural animals. Animals fed contaminated food can pass aflatoxin transformation products into eggs, milk products, and meat. For example, contaminated poultry feed is the suspected source of aflatoxin-contaminated chicken meat and eggs in Pakistan. Children are particularly affected by aflatoxin exposure, which is associated with stunted growth, delaye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stress (mechanics)
In continuum mechanics, stress is a physical quantity. It is a quantity that describes the magnitude of forces that cause deformation. Stress is defined as ''force per unit area''. When an object is pulled apart by a force it will cause elongation which is also known as deformation, like the stretching of an elastic band, it is called tensile stress. But, when the forces result in the compression of an object, it is called compressive stress. It results when forces like tension or compression act on a body. The greater this force and the smaller the cross-sectional area of the body on which it acts, the greater the stress. Therefore, stress is measured in newton per square meter (N/m2) or pascal (Pa). Stress expresses the internal forces that neighbouring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material. For example, when a solid vertical bar is supporting an overhead weight, each particle in the bar pu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Garlic
Garlic (''Allium sativum'') is a species of bulbous flowering plant in the genus ''Allium''. Its close relatives include the onion, shallot, leek, chive, Welsh onion and Chinese onion. It is native to South Asia, Central Asia and northeastern Iran and has long been used as a seasoning worldwide, with a history of several thousand years of human consumption and use. It was known to ancient Egyptians and has been used as both a food flavoring and a traditional medicine. China produces 76% of the world's supply of garlic. Etymology The word ''garlic'' derives from Old English, ''garlēac'', meaning ''gar'' ( spear) and leek, as a 'spear-shaped leek'. Description ''Allium sativum'' is a perennial flowering plant growing from a bulb. It has a tall, erect flowering stem that grows up to . The leaf blade is flat, linear, solid, and approximately wide, with an acute apex. The plant may produce pink to purple flowers from July to September in the Northern Hemisphere. The b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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