Chemical constituents

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  • From the root of Calotropis gigantea, six compounds were isolated: 12-O-benzoyllineolon (1), 12-O-benzoyldeacetylmetaplexigenin (2), calotropone (3), 2,3-dimethoxyphenol (4), 2,5- dimethoxyphenol (5), 2-formyl-5-hydroxymethylfuran (6). The chemical structure of these compounds were elucidated by their NMR spectra and comparison with references.

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  • From the roots of Codonopsis sp. (Campanulaceae), diacetylenic polyolefinic alcohol lobetyol together with 5-hydroxymethyl-2-furaldehyde and bis-(2-ethylhexyl)- phthalate were isolated. Their structures have been identified by MS, 1 H- and 13C-NMR spectroscopy.

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  • A new 8,1-neolignan, tatarinone, 4-[2-(1,2,3-trimethoxybenz-5-yl)-1-methylethyl]-2,5- dimethoxy-4-(2-propenyl)-2,5-cyclohexadien-1-one, has been isolated from Acorus tatarinowii rhizome and its structure determined by spectroscopic methods, including 2D-NMR spectra. Asarylaldehyde and a mixture of -asarone and -asarone were also isolated and indentified.

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  • -Sitosterol, stigmasterol, cardamomin (1), chalconaringenin 2-O-methyl ether (2), alpinetin (3), and naringenin 5-O-methyl ether (4) were isolated from the MeOH extract of Alpinia conchigera Griff. (Zingiberaceae). Their structures were determined on the basis of spectroscopic analyses. The antimicrobial and free radical scavenging activities of the isolates 1-4 were evaluated in correlation with those of the soluble fractions.

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  • Two alkaloids have been isolated from Z. sativa fruits besides butane-2,3-diol and glycerol. The structures of alkaloids were established as stepharine and 1,2-dimethoxy,5,6,6a,7-tetrahydro- 4H-dibenzo-quinoline by using MS, NMR spectroscopic data and by comparison with reported data.

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  • Croton tonkinensis Gagnep., commonly named in Vietnamese as "Kho sam Bac Bo", is a tropical shrub native to the Northern Vietnam. Its dried leaves (Folium Tonkinensis) have been used in Vietnamese traditional medicine to treat boils, abscesses, impetigo, abdominal pain, dyspepsia, dysentery, gastric and duodenal ulcers [1, 2]. The plant is of our interest since its varied biological activities demonstrated in our various in vitro bioassays including anti-inflammatory, anticancer, antiplasmodial, antibacterial and antifungal.

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  • From the whole plant of Hedyotis auricularia L., a new glycoside, 1’-deoxy-6’-O-(1- hydroxymethyl-2-hydroxy-1-methoxy)ethylglucopyranoside (1) was isolated along with 1’-O- ethyl- -D-galactopyranoside (2), 2-formyl-5-hydroxymethylfuran (3), stigmasta-5,22-diene-3-O- -D-glucopyranoside (4), ursolic acid (5) and oleanolic acid (6). Among them (1), (2), (3), (4) were the first time known to be present in this plant.

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  • Friedelan-3 -ol (1); -amyrine acetate (2) and 3 -tigloyloxykaur-16-en-19-oic acid (3) were isolated from leaves of Wedelia trilobata (L.) Hitch. Compounds (1) and (2) even though had presented in other plants but this is the first time they were known to be in this plant.

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  • Before any water or wastewater can be treated, it must first be characterized. Thus, characterization needs to be addressed. Waters and wastewaters may be characterized according to their quantities and according to their constituent physical, chemical, and microbiological characteristics. Therefore, Part I is composed of two chapters: “Quantity of Water and Wastewater,” and “Constituents of Water and Wastewater.”

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  • In our studies on the phytochemistry and biological activities of Croton tonkinensis Gagnep. (Euphorbiaceae) oriented by traditional medicine interesting biological activities of the plant were demonstrated in correlation with the ent-kaurane-type diterpenoid constituents. The high accumulation of the active principle ent-18-acetoxy-7-hydroxykaur-16-en-15-one (1) led to our recent study on the chemical modification of this lead compound. In this paper the transformations of 1 into several derivatives by hydrolysis, acetylation, and oxydation were reported.

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  • Agriculture and forestry are poised on the brink of a quantum leap forward through the further application of exciting new tools such as genomics and transgenic plants. In the near future, it will be possible to produce a higher quantity of improved quality crops than even imagined just a few years ago.  In addition to feed and food, it will be possible to provide raw materials for industrial uses. For example, cotton fibers, wood ligno-celluloses, corn  carbohydrates, soybean oils, and other plant constituents will be altered via designed changes in metabolic pathways.

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  • Caffeic acid, chlorogenic acid, methyl ester of chlorogenic acid, tricin, apigenin, 4’-O- methyl ether of apigenin (acacetin), quercetin and 3’-O-methyl ether of quercetin were isolated from the flowers of Lonicera japonica Thunb., Caprifoliaceae, grown as a medicinal plant for commercial purposes in Vietnam. Their chemical structures were determined by EIMS, 1 H NMR, 13 C NMR, DEPT, COSY, HMQC and HMBC.

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  • Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of carbon-based compounds, hydrocarbons, and their derivatives. Organic compounds are structurally diverse. The range of application of organic compounds is enormous. They either form the basis of, or are important constituents of, many products including plastics, drugs, petrochemicals, food, explosives, and paints....

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  • Herbs and traditional medicines are being extensively used for healthcare in almost all the countries since times immemorial. Ancient religious texts are replete with references on the use of natural products with medicinal properties. Because of local beliefs and practices and also from cost considerations herbal medicines remain a popular mode of treatment in the developing countries. Even in the industrialised society the rising cost of prescription drugs and ensuing side effects of the treatment make it highly attractive to use the traditional medicine particularly for minor ailments....

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  • Bacteria are non-chlorophyllated unicellular organisms that reproduce by fission and do not present nuclear envelope. Gram´s stain is a staining technique used to classify bacteria based on the different characteristic of their cell walls. Gram-positive or Gram-negative bacteria are determined by the amount and location of peptidoglycan in the cell wall, exhibiting different chemical compositions and structures, cell-wall permeabilities, physiologies, metabolisms, and pathogenicities.

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  • Fiber composite technology is based on taking advantage of the high strength and high stiffness of fibers, which are combined with matrix materials of similar/ dissimilar natures in various ways, creating inevitable interfaces. In fiber composites, both the fiber and the matrix retain their original physical and chemical identities, yet together they produce a combination of mechanical properties that cannot be achieved with either of the constituents acting alone, due to the presence of an interface between these two constituents.

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  • Hydrogen peroxide is particularly effective when it reacts with ferrous iron (Fe2+ ) to produce Fenton's Reagent. Ferrous iron may be naturally present in the subsurface soils and/or groundwater, or it can be added as a catalyst solution together with the hydrogen peroxide to produce this aggressive chemical reaction. Hydrogen peroxide in the presence of ferrous iron (Fe2+ ) reacts to form hydroxyl radicals (OH•), ferric iron (Fe3+ ), and hydroxyl ions (OH- ). The hydroxyl ions are very powerful oxidizers, and react particularly with organic compounds.

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  • Edible oils are mainly vegetable oils which have been subjected to several processes to removed undesirable constituents. In order to make them suitable for human consumption, most edible oils are subjected to refining processes, such as neutralization, bleaching and deodorization. Among edible oils, only virgin olive oil (a natural juice obtained by olive pressing), can be consumed without refining. Edible oils are characterized by a wide range of physical and chemical prop-erties, since their composition depend on the type of oil (Rossell1991).

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  • Agriculture and forestry are poised on the brink of a quantum leap forward through the further application of exciting new tools such as genomics and transgenic plants. In the near future, it will be possible to produce a higher quantity of improved quality crops than even imagined just a few years ago. In addition to feed and food, it will be possible to provide raw materials for industrial uses. For example, cotton fibers, wood ligno-celluloses, corn carbohydrates, soybean oils, and other plant constituents will be altered via designed changes in metabolic pathways.

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  • The sense of taste is very similar to the sense of smell. Taste is the sense through which the chemical constituents of a solid are detected and information about them is transmitted to the brain. The molecules are detected by five types of taste buds that are on the tongue and throat; some areas of the tongue are more sensitive to certain basic flavors than others, but the commonly-referenced Tongue Taste Map has been debunked. For example, you can taste bitterness more towards the back of your tongue, but the entire tongue can taste it. The five basic tastes detected...

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