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72-419: Cisplatin is a chemical compound with formula cis - [Pt(NH 3 ) 2 Cl 2 ] . It is a coordination complex of platinum that is used as a chemotherapy medication used to treat a number of cancers . These include testicular cancer , ovarian cancer , cervical cancer , bladder cancer , head and neck cancer , esophageal cancer , lung cancer , mesothelioma , brain tumors and neuroblastoma . It

144-498: A double bond connects the atoms on either side of them. A triple bond may be expressed with three lines ( HC≡CH ) or three pairs of dots ( HC:::CH ), and if there may be ambiguity, a single line or pair of dots may be used to indicate a single bond. Molecules with multiple functional groups that are the same may be expressed by enclosing the repeated group in round brackets . For example, isobutane may be written (CH 3 ) 3 CH . This condensed structural formula implies

216-620: A structural formula is useful, as it illustrates which atoms are bonded to which other ones. From the connectivity, it is often possible to deduce the approximate shape of the molecule . A condensed (or semi-structural) formula may represent the types and spatial arrangement of bonds in a simple chemical substance, though it does not necessarily specify isomers or complex structures. For example, ethane consists of two carbon atoms single-bonded to each other, with each carbon atom having three hydrogen atoms bonded to it. Its chemical formula can be rendered as CH 3 CH 3 . In ethylene there

288-444: A Mr. Jaquin extracted from the scales of the fish Alburnus alburnus so-called "pearl essence", which is crystalline guanine. In the cosmetics industry, crystalline guanine is used as an additive to various products (e.g., shampoos), where it provides a pearly iridescent effect. It is also used in metallic paints and simulated pearls and plastics. It provides shimmering luster to eye shadow and nail polish . Facial treatments using

360-443: A chemical formula is complicated by being written as a condensed formula (or condensed molecular formula, occasionally called a "semi-structural formula"), which conveys additional information about the particular ways in which the atoms are chemically bonded together, either in covalent bonds , ionic bonds , or various combinations of these types. This is possible if the relevant bonding is easy to show in one dimension. An example

432-735: A correct structural formula. For example, ethanol may be represented by the condensed chemical formula CH 3 CH 2 OH , and dimethyl ether by the condensed formula CH 3 OCH 3 . These two molecules have the same empirical and molecular formulae ( C 2 H 6 O ), but may be differentiated by the condensed formulae shown, which are sufficient to represent the full structure of these simple organic compounds . Condensed chemical formulae may also be used to represent ionic compounds that do not exist as discrete molecules, but nonetheless do contain covalently bound clusters within them. These polyatomic ions are groups of atoms that are covalently bound together and have an overall ionic charge, such as

504-499: A different connectivity from other molecules that can be formed using the same atoms in the same proportions ( isomers ). The formula (CH 3 ) 3 CH implies a central carbon atom connected to one hydrogen atom and three methyl groups ( CH 3 ). The same number of atoms of each element (10 hydrogens and 4 carbons, or C 4 H 10 ) may be used to make a straight chain molecule, n - butane : CH 3 CH 2 CH 2 CH 3 . The alkene called but-2-ene has two isomers, which

576-479: A formula might be written using decimal fractions , as in Fe 0.95 O , or it might include a variable part represented by a letter, as in Fe 1− x O , where x is normally much less than 1. A chemical formula used for a series of compounds that differ from each other by a constant unit is called a general formula . It generates a homologous series of chemical formulae. For example, alcohols may be represented by

648-432: A mechanism of interfering with mitosis, although this is probably not its primary method of action. Cisplatin combination chemotherapy is the cornerstone of treatment of many cancers. Initial platinum responsiveness is high, but the majority of cancer patients will eventually relapse with cisplatin-resistant disease. Many mechanisms of cisplatin resistance have been proposed, including changes in cellular uptake and efflux of

720-494: A mineral formed from the excreta of sea birds, which is known as guano and which was used as a source of fertilizer; guanine was named in 1846. Between 1882 and 1906, Emil Fischer determined the structure and also showed that uric acid can be converted to guanine. Trace amounts of guanine form by the polymerization of ammonium cyanide ( NH 4 CN ). Two experiments conducted by Levy et al. showed that heating 10 mol·L NH 4 CN at 80 °C for 24 hours gave

792-400: A molecular formula of C 6 H 14 , and (for one of its isomers, n-hexane) a structural formula CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 , implying that it has a chain structure of 6 carbon atoms, and 14 hydrogen atoms. However, the empirical formula for hexane is C 3 H 7 . Likewise the empirical formula for hydrogen peroxide , H 2 O 2 , is simply HO , expressing

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864-482: A molecule than its empirical formula, but is more difficult to establish. In addition to indicating the number of atoms of each elementa molecule, a structural formula indicates how the atoms are organized, and shows (or implies) the chemical bonds between the atoms. There are multiple types of structural formulas focused on different aspects of the molecular structure. The two diagrams show two molecules which are structural isomers of each other, since they both have

936-503: A number of other sugars , including fructose , galactose and mannose . Linear equivalent chemical names exist that can and do specify uniquely any complex structural formula (see chemical nomenclature ), but such names must use many terms (words), rather than the simple element symbols, numbers, and simple typographical symbols that define a chemical formula. Chemical formulae may be used in chemical equations to describe chemical reactions and other chemical transformations, such as

1008-432: A prefixed superscript in a chemical formula. For example, the phosphate ion containing radioactive phosphorus-32 is [ PO 4 ] . Also a study involving stable isotope ratios might include the molecule O O . A left-hand subscript is sometimes used redundantly to indicate the atomic number . For example, 8 O 2 for dioxygen, and 8 O 2 for the most abundant isotopic species of dioxygen. This

1080-623: A soluble platinum complex which inhibited binary fission in Escherichia coli ( E. coli ) bacteria. Although bacterial cell growth continued, cell division was arrested, the bacteria growing as filaments up to 300 times their normal length. The octahedral Pt(IV) complex cis -[PtCl 4 (NH 3 ) 2 ], but not the trans isomer, was found to be effective at forcing filamentous growth of E. coli cells. The square planar Pt(II) complex, cis -[PtCl 2 (NH 3 ) 2 ] turned out to be even more effective at forcing filamentous growth. This finding led to

1152-453: A true structural formula, which is a graphical representation of the spatial relationship between atoms in chemical compounds (see for example the figure for butane structural and chemical formulae, at right). For reasons of structural complexity, a single condensed chemical formula (or semi-structural formula) may correspond to different molecules, known as isomers . For example, glucose shares its molecular formula C 6 H 12 O 6 with

1224-424: A yield of 0.0007%, while using 0.1 mol·L NH 4 CN frozen at −20 °C for 25 years gave a 0.0035% yield. These results indicate guanine could arise in frozen regions of the primitive earth. In 1984, Yuasa reported a 0.00017% yield of guanine after the electrical discharge of NH 3 , CH 4 , C 2 H 6 , and 50 mL of water, followed by a subsequent acid hydrolysis. However, it

1296-413: Is boron carbide , whose formula of CB n is a variable non-whole number ratio with n ranging from over 4 to more than 6.5. When the chemical compound of the formula consists of simple molecules , chemical formulae often employ ways to suggest the structure of the molecule. These types of formulae are variously known as molecular formulae and condensed formulae . A molecular formula enumerates

1368-503: Is cis –diamminedichloroplatinum, where ammine with two m's indicates an ammonia (NH 3 ) ligand , as opposed to an organic amine with one m. The compound cis -[Pt(NH 3 ) 2 Cl 2 ] was first described by Italian chemist Michele Peyrone in 1845, and known for a long time as Peyrone's salt. The structure was deduced by Alfred Werner in 1893. In 1965, Barnett Rosenberg , Van Camp et al. of Michigan State University discovered that electrolysis of platinum electrodes generated

1440-420: Is a double bond between the carbon atoms (and thus each carbon only has two hydrogens), therefore the chemical formula may be written: CH 2 CH 2 , and the fact that there is a double bond between the carbons is implicit because carbon has a valence of four. However, a more explicit method is to write H 2 C=CH 2 or less commonly H 2 C::CH 2 . The two lines (or two pairs of dots) indicate that

1512-429: Is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule , using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus (+) and minus (−) signs. These are limited to a single typographic line of symbols, which may include subscripts and superscripts . A chemical formula

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1584-440: Is convenient when writing equations for nuclear reactions , in order to show the balance of charge more clearly. The @ symbol ( at sign ) indicates an atom or molecule trapped inside a cage but not chemically bound to it. For example, a buckminsterfullerene ( C 60 ) with an atom (M) would simply be represented as MC 60 regardless of whether M was inside the fullerene without chemical bonding or outside, bound to one of

1656-522: Is given by injection into a vein . Common side effects include bone marrow suppression , hearing problems including severe hearing loss, kidney damage , and vomiting . Other serious side effects include numbness, trouble walking, allergic reactions , electrolyte problems , and heart disease . Use during pregnancy can cause harm to the developing fetus. Cisplatin is in the platinum-based antineoplastic family of medications. It works in part by binding to DNA and inhibiting its replication . Cisplatin

1728-461: Is isolated as a yellow compound. When silver nitrate in water is added insoluble silver iodide precipitates and [Pt(OH 2 ) 2 (NH 3 ) 2 ](NO 3 ) 2 remains in solution. Addition of potassium chloride will form the final product which precipitates In the triiodo intermediate the addition of the second ammonia ligand is governed by the trans effect . A one-pot synthesis of cisplatin from K 2 PtCl 4 has been developed. It relies on

1800-511: Is not a chemical name since it does not contain any words. Although a chemical formula may imply certain simple chemical structures , it is not the same as a full chemical structural formula . Chemical formulae can fully specify the structure of only the simplest of molecules and chemical substances , and are generally more limited in power than chemical names and structural formulae. The simplest types of chemical formulae are called empirical formulae , which use letters and numbers indicating

1872-576: Is possible to collate chemical formulae into what is known as Hill system order. The Hill system was first published by Edwin A. Hill of the United States Patent and Trademark Office in 1900. It is the most commonly used system in chemical databases and printed indexes to sort lists of compounds. A list of formulae in Hill system order is arranged alphabetically, as above, with single-letter elements coming before two-letter symbols when

1944-418: Is slowly displaced by water to give the aquo complex cis -[PtCl(NH 3 ) 2 (H 2 O)], in a process termed aquation . Dissociation of the chloride is favored inside the cell because the intracellular chloride concentration is only 3–20% of the approximately 100 mM chloride concentration in the extracellular fluid. The water molecule in cis -[PtCl(NH 3 ) 2 (H 2 O)] is itself easily displaced by

2016-454: Is the condensed molecular/chemical formula for ethanol , which is CH 3 −CH 2 −OH or CH 3 CH 2 OH . However, even a condensed chemical formula is necessarily limited in its ability to show complex bonding relationships between atoms, especially atoms that have bonds to four or more different substituents . Since a chemical formula must be expressed as a single line of chemical element symbols , it often cannot be as informative as

2088-492: Is unknown whether the presence of guanine was not simply a resultant contaminant of the reaction. A Fischer–Tropsch synthesis can also be used to form guanine, along with adenine , uracil , and thymine . Heating an equimolar gas mixture of CO, H 2 , and NH 3 to 700 °C for 15 to 24 minutes, followed by quick cooling and then sustained reheating to 100 to 200 °C for 16 to 44 hours with an alumina catalyst, yielded guanine and uracil: Another possible abiotic route

2160-586: The N - heterocyclic bases on DNA . Guanine preferentially binds. A model compound has been prepared and crystals were examined by X-ray crystallography Subsequent to formation of [PtCl(guanine-DNA)(NH 3 ) 2 ], crosslinking can occur via displacement of the other chloride, typically by another guanine. Cisplatin crosslinks DNA in several ways, interfering with cell division by mitosis . The damaged DNA elicits DNA repair mechanisms, which in turn activate apoptosis when repair proves impossible. In 2008, apoptosis induced by cisplatin on human colon cancer cells

2232-560: The bicyclic molecule is planar. Guanine, along with adenine and cytosine, is present in both DNA and RNA, whereas thymine is usually seen only in DNA, and uracil only in RNA. Guanine has two tautomeric forms, the major keto form (see figures) and rare enol form . It binds to cytosine through three hydrogen bonds . In cytosine, the amino group acts as the hydrogen bond donor and the C-2 carbonyl and

Cisplatin - Misplaced Pages Continue

2304-523: The sulfate [SO 4 ] ion. Each polyatomic ion in a compound is written individually in order to illustrate the separate groupings. For example, the compound dichlorine hexoxide has an empirical formula ClO 3 , and molecular formula Cl 2 O 6 , but in liquid or solid forms, this compound is more correctly shown by an ionic condensed formula [ClO 2 ] [ClO 4 ] , which illustrates that this compound consists of [ClO 2 ] ions and [ClO 4 ] ions. In such cases,

2376-486: The 1:1 ratio of component elements. Formaldehyde and acetic acid have the same empirical formula, CH 2 O . This is also the molecular formula for formaldehyde, but acetic acid has double the number of atoms. Like the other formula types detailed below, an empirical formula shows the number of elements in a molecule, and determines whether it is a binary compound , ternary compound , quaternary compound , or has even more elements. Molecular formulae simply indicate

2448-463: The DNA, where cisplatin exerts its pharmacological action. Secondly, the stereo-conformation of transplatin is such that it is unable to form the characteristic 1,2-intrastrand d(GpG) adducts formed by cisplatin in abundance. Cisplatin is the square planar coordination complex cis-[Pt(NH 3 ) 2 Cl 2 ]. The prefix cis indicates the cis isomer in which two similar ligands are in adjacent positions. The systematic chemical name of this molecule

2520-514: The N-3 amine as the hydrogen-bond acceptors. Guanine has the C-6 carbonyl group that acts as the hydrogen bond acceptor, while a group at N-1 and the amino group at C-2 act as the hydrogen bond donors. Guanine can be hydrolyzed with strong acid to glycine , ammonia , carbon dioxide , and carbon monoxide . First, guanine gets deaminated to become xanthine . Guanine oxidizes more readily than adenine,

2592-592: The adducts, and the less common 1,2-intrastrand d( Ap G) adducts. Coordination chemists have obtained crystals of the products of reacting cisplain with small models of DNA. Here is a POVray plot of the platinum binding to a small model of DNA. 1,3-intrastrand d(GpXpG) adducts occur but are readily excised by the nucleotide excision repair ( NER ). Other adducts include inter-strand crosslinks and nonfunctional adducts that have been postulated to contribute to cisplatin's activity. Interaction with cellular proteins, particularly HMG domain proteins, has also been advanced as

2664-468: The available resources used above in simple condensed formulae. See IUPAC nomenclature of organic chemistry and IUPAC nomenclature of inorganic chemistry 2005 for examples. In addition, linear naming systems such as International Chemical Identifier (InChI) allow a computer to construct a structural formula, and simplified molecular-input line-entry system (SMILES) allows a more human-readable ASCII input. However, all these nomenclature systems go beyond

2736-468: The carbon atoms. Using the @ symbol, this would be denoted M@C 60 if M was inside the carbon network. A non-fullerene example is [As@Ni 12 As 20 ] , an ion in which one arsenic (As) atom is trapped in a cage formed by the other 32 atoms. This notation was proposed in 1991 with the discovery of fullerene cages ( endohedral fullerenes ), which can trap atoms such as La to form, for example, La@C 60 or La@C 82 . The choice of

2808-406: The cells, to guanine, as it can be excreted with minimal water loss. Guanine is also found in specialized skin cells of fish called iridocytes (e.g., the sturgeon ), as well as being present in the reflective deposits of the eyes of deep-sea fish and some reptiles , such as crocodiles and chameleons . On 8 August 2011, a report, based on NASA studies with meteorites found on Earth,

2880-399: The charge on a particular atom may be denoted with a right-hand superscript. For example, Na , or Cu . The total charge on a charged molecule or a polyatomic ion may also be shown in this way, such as for hydronium , H 3 O , or sulfate , SO 2− 4 . Here + and − are used in place of +1 and −1, respectively. For more complex ions, brackets [ ] are often used to enclose

2952-480: The chemical formula CH 3 CH=CHCH 3 does not identify. The relative position of the two methyl groups must be indicated by additional notation denoting whether the methyl groups are on the same side of the double bond ( cis or Z ) or on the opposite sides from each other ( trans or E ). As noted above, in order to represent the full structural formulae of many complex organic and inorganic compounds, chemical nomenclature may be needed which goes well beyond

Cisplatin - Misplaced Pages Continue

3024-455: The condensed formula only need be complex enough to show at least one of each ionic species. Chemical formulae as described here are distinct from the far more complex chemical systematic names that are used in various systems of chemical nomenclature . For example, one systematic name for glucose is (2 R ,3 S ,4 R ,5 R )-2,3,4,5,6-pentahydroxyhexanal. This name, interpreted by the rules behind it, fully specifies glucose's structural formula, but

3096-444: The cure rate from 10% to 85%. Syntheses of cisplatin start from potassium tetrachloroplatinate . Several procedures are available. One obstacle is the facile formation of Magnus's green salt (MGS), which has the same empirical formula as cisplatin. The traditional way to avoid MGS involves the conversion of K 2 PtCl 4 to K 2 PtI 4 , as originally described by Dhara. Reaction with ammonia forms PtI 2 (NH 3 ) 2 which

3168-551: The dissolving of ionic compounds into solution. While, as noted, chemical formulae do not have the full power of structural formulae to show chemical relationships between atoms, they are sufficient to keep track of numbers of atoms and numbers of electrical charges in chemical reactions, thus balancing chemical equations so that these equations can be used in chemical problems involving conservation of atoms, and conservation of electric charge. A chemical formula identifies each constituent element by its chemical symbol and indicates

3240-493: The droppings, or guano, from Japanese nightingales have been used in Japan and elsewhere, because the guanine in the droppings makes the skin look paler. Guanine crystals are rhombic platelets composed of multiple transparent layers, but they have a high index of refraction that partially reflects and transmits light from layer to layer, thus producing a pearly luster. It can be applied by spray, painting, or dipping. It may irritate

3312-415: The drug, increased detoxification of the drug, inhibition of apoptosis , increased DNA repair or changes in metabolism. Oxaliplatin is active in highly cisplatin-resistant cancer cells in the laboratory; however, there is little evidence for its activity in the clinical treatment of patients with cisplatin-resistant cancer. The drug paclitaxel may be useful in the treatment of cisplatin-resistant cancer;

3384-457: The entire formula of the ion with charge +3. This is strictly optional; a chemical formula is valid with or without ionization information, and Hexamminecobalt(III) chloride may be written as [Co(NH 3 ) 6 ] Cl − 3 or [Co(NH 3 ) 6 ]Cl 3 . Brackets, like parentheses, behave in chemistry as they do in mathematics, grouping terms together – they are not specifically employed only for ionization states. In

3456-409: The eyes. Its alternatives are mica , faux pearl (from ground shells), and aluminium and bronze particles. Guanine has a very wide variety of biological uses that include a range of functions ranging in both complexity and versatility. These include camouflage, display, and vision among other purposes. Spiders, scorpions, and some amphibians convert ammonia, as a product of protein metabolism in

3528-402: The formula C n H 2 n + 1 OH ( n ≥ 1), giving the homologs methanol , ethanol , propanol for 1 ≤ n ≤ 3. The Hill system (or Hill notation) is a system of writing empirical chemical formulae, molecular chemical formulae and components of a condensed formula such that the number of carbon atoms in a molecule is indicated first, the number of hydrogen atoms next, and then

3600-491: The head and neck and ovarian cancer ), lymphomas , bladder cancer , cervical cancer , and germ cell tumors . The introduction of cisplatin as a standard treatment for testicular cancer improved remission rates from 5-10% before 1974 to 75-85% by 1984. Cisplatin has a number of side effects that can limit its use: Cisplatin interferes with DNA replication, which kills the fastest proliferating cells, which in theory are cancerous. Following administration, one chloride ion

3672-499: The ionic formula, as in [B 12 H 12 ] , which is found in compounds such as caesium dodecaborate , Cs 2 [B 12 H 12 ] . Parentheses ( ) can be nested inside brackets to indicate a repeating unit, as in Hexamminecobalt(III) chloride , [Co(NH 3 ) 6 ] Cl − 3 . Here, (NH 3 ) 6 indicates that the ion contains six ammine groups ( NH 3 ) bonded to cobalt , and [ ] encloses

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3744-477: The latter case here, the parentheses indicate 6 groups all of the same shape, bonded to another group of size 1 (the cobalt atom), and then the entire bundle, as a group, is bonded to 3 chlorine atoms. In the former case, it is clearer that the bond connecting the chlorines is ionic , rather than covalent . Although isotopes are more relevant to nuclear chemistry or stable isotope chemistry than to conventional chemistry, different isotopes may be indicated with

3816-495: The mechanism for this activity is as yet unknown. Transplatin , the trans -stereoisomer of cisplatin, has formula trans -[PtCl 2 (NH 3 ) 2 ] and does not exhibit a comparably useful pharmacological effect. Two mechanisms have been suggested to explain the reduced anticancer effect of transplatin. Firstly, the trans arrangement of the chloro ligands is thought to confer transplatin with greater chemical reactivity, causing transplatin to become deactivated before it reaches

3888-405: The name is not a chemical formula as usually understood, and uses terms and words not used in chemical formulae. Such names, unlike basic formulae, may be able to represent full structural formulae without graphs. In chemistry , the empirical formula of a chemical is a simple expression of the relative number of each type of atom or ratio of the elements in the compound. Empirical formulae are

3960-531: The number of all other chemical elements subsequently, in alphabetical order of the chemical symbols . When the formula contains no carbon, all the elements, including hydrogen, are listed alphabetically. By sorting formulae according to the number of atoms of each element present in the formula according to these rules, with differences in earlier elements or numbers being treated as more significant than differences in any later element or number—like sorting text strings into lexicographical order —it

4032-433: The number of atoms to reflect those in the molecule, so that the molecular formula for glucose is C 6 H 12 O 6 rather than the glucose empirical formula, which is CH 2 O . However, except for very simple substances, molecular chemical formulae lack needed structural information, and are ambiguous. For simple molecules, a condensed (or semi-structural) formula is a type of chemical formula that may fully imply

4104-494: The numbers of each type of atom in a molecule of a molecular substance. They are the same as empirical formulae for molecules that only have one atom of a particular type, but otherwise may have larger numbers. An example of the difference is the empirical formula for glucose, which is CH 2 O ( ratio 1:2:1), while its molecular formula is C 6 H 12 O 6 ( number of atoms 6:12:6). For water, both formulae are H 2 O . A molecular formula provides more information about

4176-409: The numerical proportions of atoms of each type. Molecular formulae indicate the simple numbers of each type of atom in a molecule, with no information on structure. For example, the empirical formula for glucose is CH 2 O (twice as many hydrogen atoms as carbon and oxygen ), while its molecular formula is C 6 H 12 O 6 (12 hydrogen atoms, six carbon and oxygen atoms). Sometimes

4248-514: The observation that cis -[PtCl 2 (NH 3 ) 2 ] was indeed highly effective at regressing the mass of sarcomas in rats . Confirmation of this discovery, and extension of testing to other tumour cell lines launched the medicinal applications of cisplatin. Cisplatin was approved for use in testicular and ovarian cancers by the U.S. Food and Drug Administration on 19 December 1978. and in the UK (and in several other European countries) in 1979. Cisplatin

4320-519: The other purine-derivative base in DNA. Its high melting point of 350 °C reflects the intermolecular hydrogen bonding between the oxo and amino groups in the molecules in the crystal. Because of this intermolecular bonding, guanine is relatively insoluble in water, but it is soluble in dilute acids and bases. The first isolation of guanine was reported in 1844 by the German chemist Julius Bodo Unger  [ de ] (1819–1885), who obtained it as

4392-603: The proportionate number of atoms of each element. In empirical formulae, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, by ratios to the key element. For molecular compounds, these ratio numbers can all be expressed as whole numbers. For example, the empirical formula of ethanol may be written C 2 H 6 O because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom. Some types of ionic compounds, however, cannot be written with entirely whole-number empirical formulae. An example

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4464-645: The rate-limiting enzyme of inosine monophosphate dehydrogenase . The word guanine derives from the Spanish loanword guano ('bird/bat droppings'), which itself is from the Quechua word wanu , meaning 'dung'. As the Oxford English Dictionary notes, guanine is "A white amorphous substance obtained abundantly from guano, forming a constituent of the excrement of birds". In 1656 in Paris,

4536-463: The same molecular formula C 4 H 10 , but they have different structural formulas as shown. The connectivity of a molecule often has a strong influence on its physical and chemical properties and behavior. Two molecules composed of the same numbers of the same types of atoms (i.e. a pair of isomers ) might have completely different chemical and/or physical properties if the atoms are connected differently or in different positions. In such cases,

4608-635: The slow release of ammonia from ammonium acetate. Cisplatin has been studied with Auger therapy to increase the therapeutic effects of cisplatin, without increasing normal tissue toxicities. However, due to significant side effects, the search for structurally novel Pt(II) and Pd(II) compounds exhibiting antineoplastic activity is extremely important and aims to develop more effective and less toxic drugs. Cisplatin-like molecules ([PtCl(NH 3 ) 2 ] and [Pt(NH 3 )Cl 2 ]) linked by variable length alkandiamine chains have attracted some interest in cancer chemotherapy. Chemical formula A chemical formula

4680-426: The standard for ionic compounds , such as CaCl 2 , and for macromolecules, such as SiO 2 . An empirical formula makes no reference to isomerism , structure, or absolute number of atoms. The term empirical refers to the process of elemental analysis , a technique of analytical chemistry used to determine the relative percent composition of a pure chemical substance by element. For example, hexane has

4752-498: The standards of chemical formulae, and technically are chemical naming systems, not formula systems. For polymers in condensed chemical formulae, parentheses are placed around the repeating unit. For example, a hydrocarbon molecule that is described as CH 3 (CH 2 ) 50 CH 3 , is a molecule with fifty repeating units. If the number of repeating units is unknown or variable, the letter n may be used to indicate this formula: CH 3 (CH 2 ) n CH 3 . For ions ,

4824-527: The symbol has been explained by the authors as being concise, readily printed and transmitted electronically (the at sign is included in ASCII , which most modern character encoding schemes are based on), and the visual aspects suggesting the structure of an endohedral fullerene. Chemical formulae most often use integers for each element. However, there is a class of compounds, called non-stoichiometric compounds , that cannot be represented by small integers. Such

4896-404: The symbols begin with the same letter (so "B" comes before "Be", which comes before "Br"). The following example formulae are written using the Hill system, and listed in Hill order: Guanine With the formula C 5 H 5 N 5 O, guanine is a derivative of purine , consisting of a fused pyrimidine - imidazole ring system with conjugated double bonds. This unsaturated arrangement means

4968-433: Was explored by quenching a 90% N 2 –10%CO–H 2 O gas mixture high-temperature plasma. Traube's synthesis involves heating 2,4,5-triamino-1,6-dihydro-6-oxypyrimidine (as the sulfate) with formic acid for several hours. [REDACTED] Guanine is not synthesized de novo , instead it's split from the more complex molecule, guanosine , by the enzyme guanosine phosphorylase : Guanine can be synthesized de novo, with

5040-510: Was first reported in 1845 and licensed for medical use in 1978 and 1979. It is on the World Health Organization's List of Essential Medicines . Cisplatin is administered intravenously as short-term infusion in normal saline for treatment of solid and haematological malignancies. It is used to treat various types of cancers, including sarcomas , some carcinomas (e.g., small cell lung cancer , squamous cell carcinoma of

5112-496: Was shown to depend on the mitochondrial serine-protease Omi/Htra2 . Since this was only demonstrated for colon carcinoma cells, it remains an open question whether the Omi/Htra2 protein participates in the cisplatin-induced apoptosis in carcinomas from other tissues. Most notable among the changes in DNA are the 1,2-intrastrand cross-links with purine bases. These include 1,2-intrastrand d( Gp G) adducts, which form nearly 90% of

5184-519: Was the first to be developed. In 1983 pediatric oncologist Roger Packer began incorporating cisplatin into adjuvant chemotherapy for the treatment of childhood medulloblastoma . The new protocol that he developed led to a marked increase in disease-free survival rates for patients with medulloblastoma, up to around 85%. The Packer Protocol has since become a standard treatment for medulloblastoma. Likewise, cisplatin has been found to be particularly effective against testicular cancer , where its use improved

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