Amino acids and peptides

Amino acids, as the name implies, contain both an amino and a carboxylic acid group, and are the building blocks of proteins. Twenty different amino acids are used to synthesize proteins, and these are alanine (Ala, A), arginine (Arg, R), asparagine (Asn, N), aspartic acid (Asp, D), cysteine (Cys, C), glutamine (Gln, Q), glutamic acid (Glu, E), glycine (Gly, G), histidine (His, H), isoleucine (Ile, I), leucine (Leu, L), lysine (Lys, K), methionine (Met, M), phenylalanine (Phe, F), proline (Pro,...

Maltose and cellobiose

Maltose is a disaccharide, composed of two units of glucose linked (a linkage) between C-1 of one and C-4 of the other via oxygen. Chemically, it can be called 4-O-a-D-glucopyranosyl-D-glucopyranose. Cellobiose is also composed of two units of glucose, but the 1,4'- link is b, instead of a. Thus, it can be called 'Linkage' always refers to 'left-hand' sugar. For example, in maltose, since the 'linkage' is a, and is in between C-1 of one glucose and C-4 of the other, the 'linkage' is called a...

Chemistry of vision role of vitamin A

B-carotene is converted to vitamin A1 (retinol) in our liver. Vitamin A1 is a fat-soluble vitamin found in animal products, e.g. eggs, dairy products, livers and kidneys. It is oxidized to an aldehyde called all-trans-retinal, and then isomerized to produce 11-cis-retinal, which is the light-sensitive pigment present in the visual systems of all living beings. Rod and cone cells are the light sensitive receptor cells in the retina of the human eye. About three million rod cells are responsible...

Oxidation of aldehydes preparation of carboxylic acids

Any aqueous oxidizing reagent, e.g. chromic acid (CrO3 in aqueous acid), Jones' reagent (CrO3 in acetone) and KMnO4 in basic solution, can oxidize aldehydes to carboxylic acids. Aldehydes can also be oxidized selectively in the presence of other functional groups using silver (I) oxide (Ag2O) in aqueous ammonium hydroxide (Tollen's reagent). Since ketones have no H on the carbonyl carbon, they do not undergo this oxidation reaction. 5.7.12 Baeyer-Villiger oxidation of aldehydes and ketones...

Introduction to natural product drug discovery process

Natural products are products from various natural sources, plants, microbes and animals. Natural products can be an entire organism (e.g. a plant, an animal or a micro-organism), a part of an organism (e.g. leaves or flowers of a plant, an isolated animal organ), an extract of an organism or part of an organism and an exudate, or pure compound (e.g. alkaloids, coumarins, flavonoids, lignans, steroids and terpenoids) isolated from plants, animals or micro-organisms. However, in practice, the...

Info

After completing this chapter the student should be able to describe the role of chemistry in modern life define some of the physical properties of drugs, e.g. polarity, solubility, melting point, boiling point and acid-base properties explain the terms pH, pKa, buffer and neutralization. 1.1 Role of chemistry in modern life Chemistry is the science of the composition, structure, properties and reactions of matter, especially of atomic and molecular systems. Life itself is full of chemistry...

Wolff Kishner reduction preparation of alkanes

This method reduces acyl benzenes as well as aldehydes and ketones, but does not reduce alkenes, alkynes or carboxylic acids. Hydrazine reacts with aldehyde or ketone to give hydrazone (see Section 5.3.2). The hydrazone is treated with a strong base (KOH) to generate alkane. Mechanism. The aqueous base deprotonates the hydrazone, and the anion produced is resonance stabilized. The carbanion picks up a proton from water, and another deprotonation by the aqueous base generates an intermediate,...

Pyrrole and pyrrolidine alkaloids

These alkaloids contain pyrrole or modified pyrrole, e.g. pyrrolidine, ring system. The simplest example of this class is nicotine. A pyrrolidine ring is the central structure of the amino acids proline and hydroxyproline. These alkaloids are also found in many drug preparations, e.g. procyclidine hydrochloride, which is an anticholinergic drug mainly used for the treatment of drug-induced Parkinsonism, akathisia and acute dystonia. Hygrine Hygrine, molecular formula C8H15NO, is found mainly in...

Diterpenes

The diterpenoids constitute a large group of 20-carbon-containing compounds derived from 2E,6E,10E-geranylgeranyl pyrophosphate (GGPP) or its allylic geranyl linaloyl isomer through condensation of IPP with 2E,6E-FPP. They are found in higher plants, fungi, insects and marine organisms. One of the simplest and most significant of the diterpenes is phytol, a reduced form of geranylgeraniol, which constitutes the lipophilic side-chain of the chlorophylls. Phytol also forms a part of vitamin E...

Phenylethylamines

Phenylethylamine, a neurotransmitter or neuromodulator, is a monoamine. Although the nitrogen is not a part of the ring, phenylethylamine and its derivatives are classified as alkaloids. Phenylethylamine itself is a colourless liquid, and it is biosynthesized from phenylalanine through enzymatic decarboxylation. The phenylethylamine moiety can be found in various complex ring systems, e.g. the ergoline system in lysergic acid diethylamide (LSD) or the morphinan system in morphine. A number of...

Heterocyclic compounds and their derivatives

Cyclic compounds that have one or more of atoms other than carbon, e.g. N, O or S (hetero-atoms), in their rings are called heterocyclic compounds or heterocycles, e.g. pyridine, tetrahydrofuran, thiophene and so on. N is the hetero-atom O is the hetero-atom S is the hetero-atom Among the heterocyclic compounds, there are aromatic, e.g. pyridine, as well as nonaromatic, e.g. tetrahydrofuran, compounds. Similarly, there are saturated (e.g. tetrahydrofuran) and unsaturated (e.g. pyridine)...

Pyridine and piperidine alkaloids

Alkaloids, e.g. piperine, coniine, trigonelline, pilocarpine, nicotine and sparteine, possess a pyridine or modified pyridine heterocyclic ring system (e.g. piperidine ring). Piperine Piperine, molecular formula Ci7H19NO3, a component of black pepper (Piper nigrum), has been used in various traditional medicine preparations, and also as an insecticide. Piperine has various effects on human drug metabolizing enzymes, and is marketed under the brand name, Bioperine , as an adjunct for increasing...

CH3CH2 Ch Ch Ch2Cl

1-Chloro-3-pentanol (The -OH is at C-3 of pentane) Alcohols with double or triple bonds are named using the -ol suffix on the alkene or alkyne name. Numbering gives the hydroxyl group the lowest possible number. When numbers are also given for the multiple bond position, the position of the hydroxyl can be written immediately before the -ol prefix. If the hydroxyl group is only a minor part of the structure, it may be named as a hydroxy- substituent. Diols are compounds with two hydroxyl...

Y

Sumatriptan A drug for migraine treatment Melatonin A hormone found in all living beings Ergolines Alkaloids that contain an ergoline skeleton are called ergoline alkaloids, and some of them are psychedelic drugs, e.g. LSD. A number of ergoline derivatives are used clinically as vasoconstrictors (e.g. 5-HT 1 agonists, ergotamine), and in the treatment of migraine and Parkinson's disease, and some are implicated in the disease ergotism. Ergine, molecular formula C16H17N3O, is the amide of...

Tropane alkaloids

These are the group of alkaloids that possess a 8-methyl-8-aza-bicyclo 1,2,3 octane or tropane skeleton, e.g. atropine, cocaine and scopolamine. Tropane alkaloids occur mainly in plants from the families Solanaceae and Erythroxylaceae. 8-Aza-bicyclo 1,2,3 octane, i.e. tropane without the 8-methyl group, is known as nortropane. Atropine Atropine, molecular formula C17H23NO3, is a tropane alkaloid, first isolated from the 'deadly nightshade' (Atropa belladonna), and also found in many other...

Aromatic compounds and their derivatives

All drugs are chemicals and many of them are aromatic compounds. Therefore, in order to understand the chemical nature, physical properties, stability, pharmacological actions and toxicities of a majority of drug molecules, the knowledge of aromatic chemistry is extremely important. Before we look into the specific examples of various drugs that belong to this aromatic class, let us try to understand what aromaticity really is. Generally, the term 'aromatic compounds' means fragrant substances....

Conversion of alkyl tosylates

Tosylates are excellent leaving groups, and can undergo a variety of SN2 reactions. The reaction is stereospecific, and it occurs with inversion of configuration. For example, S -2-butanol reacts with TsCl in pyridine to produce S -2-butane tosylate, which reacts readily with NaI to give R -2-iodobutane via SN2 reaction. Similarly, alkyl tosylate reacts with other nucleophiles, e.g. H , X , HO , R'O, R' , NH2 or NH3, CN_, N3 and R'CO2 following the SN2 reaction mechanism, and produces a number...

Significance of stereoisomerism in determining drug action and toxicity

Pharmacy is a discipline of science that deals with various aspects of drugs. All drugs are chemical entities, and a great majority 30-50 per cent of them contain stereocentres, show stereoisomerism and exist as enantiomers. Moreover, the current trend in drug markets is a rapid increase of the sales of chiral drugs at the expense of the achiral ones. In the next few years, chiral drugs, whether enantiomerically pure or sold as a racemic mixture, will dominate drug markets. It is therefore...

Major structural types

While there are a number of acyclic diterpenes such as phytol, cyclization of these acyclic diterpenes, driven by various enzymes, leads to the formation of cyclic diterpenes. A number of other biogenetic reactions, e.g. oxidation, also bring in variation among these cyclic diterpenes. Some of the major structural types encountered in diterpenes are shown below. Caesaljapin Cleistanthane diterpenoids 7 17 , 10 14 -Fusicoccadiene Isocopalane diterpenoids 7 17 , 10 14 -Fusicoccadiene Isocopalane...

Pyrrole furan and thiophene fivemembered unsaturated heterocycles

Pyrrole is a nitrogen-containing unsaturated five-membered heterocyclic aromatic compound. It shows aromaticity by delocalization of a lone pair of electrons from nitrogen. In pyrrole, there are four p electrons, two short of the Huckel criteria for aromaticity. The nitrogen atom is sp2-hybridized, formally containing a lone pair of electrons in the p orbital at right angles to the ring. However, the system delocalizes and pushes the lone pair of electrons into the ring to complete the sextet...