ISOLATION OF NICOTINE

Nicotine is a type of chemical compound belonging to the class of alkaloids because they have properties and characteristics of alkaloids.

Isolation of Alkaloids

Alkaloid extracted from the leaves of plants, flowers, fruit, bark, and roots are dried and then crushed. Extraction of alkaloids in general are as follows:

a.       Alkaloid extracted with solvents, eg ethanol, and then evaporated.

b.      Extracts were obtained inorganic acids to produce a quaternary ammonium salt and then extracted again.

c.       Quaternary ammonium salt obtained was treated with sodium carbonate to produce these alkaloids were then extracted with a solvent-free such as ether and chloroform.

d.      Mixture - a mixture of alkaloids obtained finally separated in various ways, such as chromatographic methods (Tobing, 1989).

There are other ways to get the alkaloids from the acid solution by absorption using Lloyd reagent, and then eluted with dilute alkali alkaloids. Alkaloid that is hydrophobic absorbed by XAD-2 resin and then eluted with an acid or a mixture of ethanol-water. Many alkaloids which can be precipitated by Mayer's reagent (potassium mercury (II) iodide) or salt Reineccke.

This study used a general way that the isolation of alkaloids extracted with an organic solvent, acidification, formation of quaternary ammonium salts with bases, extraction with organic solvents, and purification using column chromatography, thin layer chromatography, or electronic instruments (IR, GC-MS , UV-Vis).

Nicotine
Nicotine is an alkaloid with the chemical name 3 - (1-methyl-2-pirolidil) pyridine. When extracted from the leaves of tobacco, nicotine is colorless, but soon becomes brown when in contact with air. Nicotine can evaporate and be purified by steam distillation from the basified solution.

Nicotine is a substance that is toxic alkaloid tertiary amine compound, is a weak base with a pH of 8.0. At pH, as many as 31% of the nicotine in the form of ions and can not pass through the cell membrane. At this pH the nicotine is in the form of ions and can not pass through the membrane rapidly resulting in only a slight cheek mucosa absorption of nicotine from cigarette smoke.

Nicotine is an alkaloid that is naturally in tobacco plants. Nicotine is also found in other plants of the family Solanaceae biological such as tomatoes, potatoes, eggplant and green pepper at very small compared to tobacco. Alkaloid substances are known to have pharmacological properties, such as the stimulant effects of caffeine increases blood pressure and heart rate.

Alkaloid nicotine undergo metabolic processes, which is a process by which nicotine undergo structural changes due to the chemical compounds in the vicinity. The metabolism of nicotine in tobacco is presented in figure 4.

Most of the in vivo metabolites of nicotine are konitin lactams. The transformation of these metabolites represent all 4-electron oxidation. In vitro studies showed a loss of nicotine from the incubation mixture was not inhibited, although the formation of nicotine completely blocked.

Oxidative metabolism of nicotine by making mirkosomal rabbit liver in the presence of cyanide ion is shown by the second isomer of nicotine cyano compounds. Formation of structures of N-(sianometil) nornikotin obtained from nucleophilic attack by cyanide ion on methyl iminium intermediate types. These compounds are formed by ionization type N hydroxymethyl nornikotin. The same compound karbinolamin seen in N-demetilasi of nicotine into nornikotin (Wolff, 1994).

Nicotine can be synthesized from the amino acid ornithine. Biosynthesis nicotine from ornithine amino acids can be made schemes like Figure 5.

In the biosynthesis of nicotine, pyrrolidine ring comes from the amino acid ornithine and pyridine rings derived from nicotinic acid that is found in tobacco plants. Amino groups attached to the ornithine used to form the pyrrolidine ring of nicotine

MID SEMESTERS EXAM ANSWERS CHEMISTRY OF NATURAL PRODUCTS

Name  : VEBRIA ARDINA

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1.      The way to obtain a preparation containing an active compound from a natural material with an appropriate solvent. Why should it be removed? In order to extract only contains the active compounds contained in the raw ingredients / natural that were penyari the fluid most optimal able to attract the active compound.
Method of extraction. There are several methods of extraction of crude natural materials, such as maceration, infundasi, digestion, percolation and soxletasi.

Active a pure compound can be administered in the form of repetition, more accurate dose given. This, of course, can be achieved when we managed to get a pure compound plays a role in biokativitasnya and share experimental dilakuakn selnajutnya to find the dose, dose prepared in the right way and the right way to give. The term is no longer gambling here. Everything is scientifically proven.
The compound was isolated can be more developed in the process of finding the most effective compounds. By knowing the chemical structure of the compound will be a "lead compound" in formation so that it can be synthetically on a large scale. O modification of the structure of the compound will be able to withstand the compounds that can be more active.

Pure compounds which have been isolated can also be tested against a variety of bioactivity, not only based on the bioactivity associated with traditional uses. The possibility is always there, that the slogan for researchers.

2.      New drugs found from nature usually find obstacles in the industry because their numbers are very limited, especially when the drug is derived from marine invertebrates or microbes. For it is made ​​of natural materials synthesis memperlajari how to produce compounds of natural materials en masse and clearly this is not easy because of the diversity of natural products is very high and complicated (especially marine natural ingredients). Ingredients sourced from wild plants and animals is not only widely used in traditional medicine, but also increasingly valued as raw material in the manufacture of modern medicine and herbal preparations. Greater demand and increasing human population which leads to an increased level and often unsustainable exploitation of wild sourced ingredients.

Plants and animals have been used as a source of medicines from ancient times, and even in modern times, animal and plant-based systems continue to play an essential role in health care .  Additionally, a significant portion of the currently available non-synthetic and/or semi-synthetic pharmaceuticals in clinical use is comprised of drugs derived from higher plants, followed by microbial, animal and mineral products, in that order.

Over 50% of commercially available drugs are based on bioactive compounds extracted (or patterned) from non-human species, including some lifesaving medicines such as cytarabine, derived from a Caribbean sponge, which is reputed as the single most effective agent for inducing remission in acute myelocytic leukemia. Other examples of drugs from biological sources include: quinidine to treat cardiac arrhythmias, D-tubocurarine to help induce deep muscle relaxation without general anesthetics, vinblastine to fight Hodgkin's disease, vincristine for acute childhood leukemias, combadigitalis to treat heart failure, ranitidine to fight ulcers, levothyroxine for thyroid hormone replacement therapy, digoxin to treat heart disease, enalapril maleate to reduce high blood pressure, and even aspirin.

A great number of these natural products have come to us from the scientific study of remedies traditionally employed by various cultures, most of them being plant-derived.

There has been increasing attention paid to animals, both vertebrates and invertebrates, as sources for new medicines. Animals have been methodically tested by pharmaceutical companies as sources of drugs to the modern medical science, and the current percentage of animal sources for producing essential medicines is quite significant. Of the 252 essential chemicals that have been selected by the World Health Organization, 11.1% come from plants, and 8.7% from animals.

One excellent example of successful drug development from a component of snake venom (Bothrops jararaca [Wied 1824]) is that of the inhibitors of angiotensin-converting enzyme (ACE). This enzyme is responsible for converting an inactive precursor into the locally active hormone angiotensin, which causes blood vessels to constrict and hence raises blood pressure [62]. Other excellent example is the work initially conducted by Daly during the 1960s of the skin secretions of dendrobatid frogs from Ecuador, and of other "poison dart" frog species in Central and South America. This work has led to the identification of a number of alkaloid toxins that bind to multiple receptors in the membranes of nerve and muscle cells. One compound derived from these studies, which binds to nicotinic acid receptors associated with pain pathways, the synthetic ABT 594 (Abbott Laboratories), is in Phase II clinical trials, and has generated a great deal of interest, as it has been shown to be 30–100 times more potent as an analgesic than morphine [10]. The marine environment is a rich source of biologically active natural products of diverse structural types, many of which have not been found in terrestrial sources [63]. The sponge Luffariella variabilis (Poléjaeff, 1884) produces relatively large amounts of a chemical with anti-inflammatory activity known as monoalide. It was found that monoalide inhibits the action of an enzyme called phospholipase A2. The powerful immunosuppressive agent discodermolide originates from another sponge, Discoderma sp. [64].

Ingredients sourced from wild plants and animals are not only widely used in traditional medicines, but are also increasingly valued as raw materials in the preparation of modern medicines and herbal preparations. Greater demand and increased human populations are leading to increased and often unsustainable rates of exploitation of wild sourced ingredients.

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3.      Criteria for selection of the solvent:

a.       The solvent dissolves the material easily extract

b.      The solvent does not mix with the juice extracted

c.       Solvent extract impurities that there are little or no

d.      Solute easily separated from the solvent

e.       The solvent does not react with the solute through any means

Type of solvent used

Related to the type of solvent polarity of the solvent. Things to be considered in the extraction process is a compound that has the same polarity will be easier interested / dissolved by the solvent that has the same polarity. Correlated to the polarity of the solvent, there are three classes of solvents, namely:

a.       polar solvents

It has a high level of polarity, suitable for extracting polar compounds from plants. Polar solvents tend to be used universally because normally if polar, can still cite compounds with lower levels of polarity. An example is the polar solvents: water, methanol, ethanol, acetic acid.

b.      semipolar solvent

Semipolar polarity solvent has a lower rate than the polar solvent. It is a good solvent for semipolar compounds from plants. Examples of these solvents are: acetone, ethyl acetate, chloroform

c.       nonpolar solvents

Non-polar solvents, almost completely polar. It is a good solvent to extract the compounds do not dissolve in polar solvents. The compound is better to extract different types of oils. Example: hexane, ether

The flavonoids possess a less polar, if extracted with a non-polar solvent, then it will not be possible to obtain the compound to be our extraction. To extract flavonoids we use polar or semi-polar solvents. As methanol.

Alkaloids, such as coffee powder caffeine dissolved in diethyl ether is because non-polar so as to dissolve the caffeine which is also non-polar, but is also due to the low boiling point of chloroform. Because if the high boiling point solvent means possible to approach the boiling point of caffeine can lead to caffeine obtained crystals evaporate so little. With a low boiling point solvent, allowing it to evaporate only koroformnya.

Terpenoid polar nature so that it can be used semi-polar or polar solvents such as methanol and ethanol.

Steroids have properties that can be used polar solvents polar or semi-polar such as acetone, chloroform.

4.      Covering ultraviolet spectroscopic methods, infrared and nuclear magnetic resonance.
In essence, the explanation structure using spectroscopic methods of UV / Vis, IR, MS and NMR. However, in practice, is in the head NMR, integrated by MS. MS is sometimes become very important in the elucidation especially for long-chain compounds. IR is not so helpful in the elucidation of the structure, while the dereplikasi UV / Vis more useful.

NMR as the primary means of generating NMR spectra for H and C (typical), the data are called 1D NMR. While 2D NMR correlation gives date2 H / C with H / C in the form of HSQC, HMBC, COSY, TOCSY, ADEQUATE, etc.
NMR data obtained through the planar structure of a compound and from here is to determine the stereochemistry (if it contains a chiral atom) whose methods are divided into three: chemical reactions, physical (NMR and circular dichroism), and X-ray chrystallography .

Determination of the stereochemistry of the end of the elucidation of structure-activity.
Throughout the process structure elucidation, there are two important things were done. The first is a test of bioactivity that can be done at the beginning / middle (for screening) or at the end of pure compound (for the determination of the activity) and dereplikasi.

In summary, dereplikasi is a method to quickly identify known compounds. Since the objective laboratory natural materials is usually a new compound, the compound is not new, all the work, must be identified as soon as possible, in order not to lose time (with membuang2 resources of compounds which are no longer new).

Biosynthesis Of Cholestrol

Cholesterol Is Made from Acetyl-CoA in Four Stages

Cholesterol, like long-chain fatty acids, is made from acetyl-CoA, but the assembly plan is quite different in the two cases. In early experiments animals were fed acetate labeled with 14C in either the methyl carbon or the carboxyl carbon. The pattern of labeling in the cholesterol isolated from the two groups of animals (Fig. 20-30) provided the blueprint for working out the enzymatic steps in cholesterol biosynthesis.

Figure 20-30

Figure 20-30 The origin of the carbon atoms of cholesterol, deduced from tracer experiments with acetate labeled in the methyl carbon (black) or the carboxyl carbon (red). The individual rings in the fused-ring system are designated A through D.

The process occurs in four stages (Fig. 20-31). In stage 1 the three acetate units condense to form a six-carbon intermediate, mevalonate. Stage 2 involves the conversion of mevalonate into activated isoprene units, and stage 3 the polymerization of six 5-carbon isoprene units ta form the 30-carbon linear structure of squalene. Finally (stage 4, the cyclization of squalene forms the four rings of the steroid nucleus, and a further series of changes (oxidations, removal or migration of methyl groups) leads to the final product, cholesterol.

Figure 20-31

Figure 20-31 A summary of cholesterol biosynthesis, showing the four stages discussed in the text. The isoprene units in squalene are set off by red dashed lines.

1. Synthesis of Mevalonate from Acetate

The first stage in cholesterol biosynthesis leads to the intermediate mevalonate (Fig. 20-32). Two molecules of acetyl-CoA condense, forming acetoacetyl-CoA, which condenses with a third molecule of acetyl-CoA to yield the six-carbon compound β-hydroxy-β-methylglutaryl-CoA (HMG-CoA). These first two reactions, catalyzed by thiolase and HMG-CoA synthase, respectively, are reversible and do not commit the cell to the synthesis of cholesterol or other isoprenoid compounds.

The third reaction is the committed step: the reduction of HMGCoA to mevalonate, for which two molecules of NADPH each donate two electrons. HMG-CoA reductase, an integral membrane protein of the smooth endoplasmic reticulum, is the major point of regulation on the pathway to cholesterol, as we shall see.

Figure 20-32

Figure 20-32 Formation of mevalonate from acetyl-CoA. The origin of C-1 and C-2 of mevalonate from acetyl-CoA is shown in red.

2. Conversion of Mevalonate to Two Activated Isoprenes In the next stage of cholesterol synthesis, three phosphate groups are transferred from three ATP molecules to mevalonate (Fig. 20-33). The phosphate attached to the C-3 hydroxyl group of mevalonate in the intermediate 3-phospho-5-pyrophosphomevalonate is a good leaving group; in the next step this phosphate and the nearby carboxyl group both leave, producing a double bond in the five-carbon product, Δ³-isopentenyl pyrophosphate. This is the first of the two activated isoprenes central to cholesterol formation. Isomerization of Δ³-isopentenyl pyrophosphate yields the second activated isoprene, dimethylallyl pyrophosphate (Fig. 20-33)

Figure 20-33

Figure 20-33 Conversion of mevalonate into activated isoprene units. Six of these units will combine to form squalene. The leaving groups of 3-phospho-5-pyrophosphomevalonate are shaded in red.

3. Condensation of Six ActiUated Isoprene Units to Form Squalene

Isopentenyl pyrophosphate and dimethylallyl pyrophosphate now undergo a "head-to-tail" condensation in which one pyrophosphate group is displaced and a 10-carbon chain, geranyl pyrophosphate, is formed (Fig. 20-34). (The "head" is the end to which pyrophosphate is joined.) Geranyl pyrophosphate undergoes another head-to-tail condensation with isopentenyl pyrophosphate, yielding the 15-carbon intermediate farnesyl pyrophosphate. Finally, two molecules of farnesyl pyrophosphate join head to head, with the elimination of both pyrophosphate groups, forming squalene (Fig. 20-34). The common names of these compounds derive from the sources from which they were first isolated. Geraniol, a component of rose oil, has the smell of geraniums, and farnesol is a scent found in the flowers of a tree, Farnese acacia. Many natural scents of plant origin are synthesized from isoprene units. Squalene, first isolated from the liver of sharks (genus Squalus), has 30 carbons, 24 in the main chain and 6 in the form of methyl group branches.

Figure 20-34

Figure 20-34 Formation of squalene (30 carbons) by successive condensations of activated isoprene (five-carbon) units.

4.Conversion of Squalene to the Four-Iling Steroid Nucleus

When the squalene molecule is represented as in Figure 20-35, the relationship of its linear structure to the cyclic structure of the sterols is apparent. All of the sterols have four fused rings (the steroid nucleus) and all are alcohols, with a hydroxyl group at C-3; thus the name "sterol." The action of squalene monooxygenase adds one oxygen atom from O₂ to the end of the squalene chain, forming an epoxide. This enzyme is another mixed-function oxidase (Box 20-1); NADPH reduces the other oxygen atom of O₂ to H₂O. The double bonds of the product, squalene2,3-epoxide, are positioned so that a remarkable concerted reaction can convert the linear squalene epoxide into a cyclic structure. In animal cells, this cyclization results in the formation of lanosterol, which contains the four rings characteristic of the steroid nucleus. Lanosterol is finally converted into cholesterol in a series of about 20 reactions, including the migration of some methyl groups and the removal of others. Elucidation of this extraordinary biosynthetic pathway, one of the most complex known, was accomplished by Konrad Bloch, Feodor Lynen, John Cornforth, and George Popjak in the late 1950s.

Cholesterol is the sterol characteristic of animal cells, but plants, fungi, and protists make other, closely related sterols instead of cholesterol, using the same synthetic pathway as far as squalene-2,3-epoxide. At this point the synthetic pathways diverge slightly, yielding other sterols: stigmasterol in many plants and ergosterol in fungi, for example (Fig. 20-35).

Figure 20-35

Figure 20-35 Ring closure converts linear squalene into the condensed steroid nucleus. The first step in this sequence is catalyzed by a mixed-function oxidase (a monooxygenase), for which the cosubstrate is NADPH. The product is an epoxide, which in the next step is cyclized to the steroid nucleus. The final product of these reactions in animal cells is cholesterol, but in other organisms, slightly different sterols are produced

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