Download Carbohydrates ( CHO )

Pharmacognosy ( II )
Third Class
1st.semister
Lec. ( 2 )
Carbohydrates ( CHO )
1234-
Definition & empirical formula
Chemical grouping of CHO
Role of CHO in Living things
Saccharides and their derivatives include many other important
biomolecules that play key roles in the :
A- Immune system
B- Preventing pathogenesis, Blood clotting, and Development
Structure :
Natural Saccharides are generally built of simple CHO called
Monosaccharides with general formula ( CH2O)n , where n is three or more.
Ex. Of Monosaccharides ( Glucose, Fructose and Glyceraldehyde ).
Monosaccharides can be linked together in to what are called
Polysaccharides ( or Oligosaccharides ) in a large variety of ways.
Use in Living Organisms
Monosacch. are the major source of Fuel for Metabolism, being used both
as Energy source ( Glucose ) and in Biosynthesis.
When Monosacch. are not immediately needed by Cells they are often
converted to Polysaccharides as storage forms, ex: ( Glycogen ) in humans
and Animals, especially in Liver and Muscle cells, and in Plants ( Starch ) is
used for the same purpose.
Disaccharides : ( Sucrose & Lactose )
Sucrose : is a common disacch. ( Simplest Polysaccharide ) Its composed of
two monosacch. units ( D-glucose L. & D-fructose R. ) bound together by a
covalent bond known as a ( glycosidic Linkage ).
Sucrose is the most abundant disacch. and the main form in which CHO are
transported in Plants.
Oligosaccharides and Polysaccharides
Amylose : is a linear polymer of glucose mainly linked with alpha (1-4)
bonds, it can be made of several thousands of glucose units. It is one of the
two components of Starch, the other being amylopectin.
Cellulose and Chitin are examples of polysaccharides. Cellulose is used in
cell walls of plants and other organisms, Cellulose has many uses such as a
significant role in the paper & textile industries, and is used as a feedstock
for the production of Rayon.
Chitin has a similar structure, but has nitrogen –containing side branches,
increasing its strength. It is found in arthropod exoskeletons and in the cell
wall of some Fungi. It also has multiple uses, including surgical threads.
Other polysaccharides include ( callose or laminarin, chrysolaminarin, xylan,
arabinoxylan, mannan, fucoidan and galactomannan.
In Nutrition
Grain products : rich sources of CHO, Foods high in CHO include (
fruits,sweets,soft drinks,breads,pastas, beans,potatoes, bran, rice, and
cereals ).
The brain and neurons generally cannot burn fat for energy , but use glucose
or ketones.
CHO contains 15.8 kilojoules ( 3.75 kilocalories ) per gram.
Organisms typically cannot metabolize all types of CHO to yield energy.
Glucose is a nearly universal and accessible source of calories. Many
organisms have the ability to metabolize other monosaccharides and
disaccharides.
Polysaccharides are also common sources of energy. Many organisms can
easily break down starches into glucose, however, most organisms cannot
metabolize cellulose or other polysaccharides like chitin and arabinoxylans.
These CHO types can be metabolized by some bacteria and protists.
Ruminants and termites, for ex, use microorganisms to process cellulose.
Even though these complex CHO are not very digestible, they may comprise
important dietary elements for humans. Called dietary fiber, these CHO
enhance digestion among other benefits.
Metabolism
Catabolism
Catabolism is the metabolic reaction cells undergo to extract energy. There
are two major metabolic pathways of monosaccharide catabolism:
Glycolysis and the Citric acid cycle.
In glycolysis, oligo / polysaccharides are cleaved first to smaller
monosaccharides by enzymes called glycoside hydrolases. The
monosaccharide units can then enter into monosaccharide catabolism. In
some cases, as with humans, not all CHO types are usable as the digestive
and metabolic enzymes necessary are not present.
Carbohydrates in therapeutics
Carbohydrate based or modified therapeutics are used extensively in
cardiovascular and hematological treatments ranging from inflammatory
diseases and anti-thrombotic treatments to wound healing. Heparin is a
well-known and widely used example of a carbohydrate-based drug but
will not be discussed as it has been extensively reviewed. We will detail
carbohydrate-based and -modified therapeutics, both those that are
currently marketed or in various stages of clinical trials and those that are
potential therapeutics based on promising preclinical investigations.
Carbohydrate-based
therapeutics
include
polysaccharide
and
oligosaccharide anti-inflammatory, anti-coagulant and anti-thrombotic
agents from natural and synthetic sources, some as an alternative to
heparin and others which were designed based on known structurefunctional relationships. Some of these compounds have multiple
biological effects, showing anti-adhesive, anti-HIV and anti-arthrithic
activities. Small molecules, derivatives or mimetics of complement
inhibitors, are detailed for use in limiting ischemia/ reperfusion injuries.
Monosaccharides, both natural and synthetic, have been investigated for
their in vivo anti-inflammatory and cardio protective properties.
Modification by glycosylation of natural products, or glycosylationmimicking modification, has a significant effect on the parent molecule
including increased plasma half-life and refining or increasing desired
functions. It is hoped that this review will highlight the vast therapeutic
potential of these natural bioactive molecules.
What Are Carbohydrates?
Carbohydrates are one of the main types of nutrients and the one needed
in the largest amounts by the body. Between 45 and 65 percent of
calories should come from carbs, according to the Dietary Reference
Intakes set by the Institute of Medicine. Carbohydrates are often
maligned for contributing to weight gain, but they are needed for your
body to function well and should be part of every person’s diet.
Role of Carbs
The role of carbohydrates is to provide energy, as they are the body’s
main source of fuel, needed for physical activity, brain function and
operation of the organs. All the cells and tissues in your body need carbs,
and they are also important for intestinal health and waste elimination.
Once in the body, carbohydrates are easily converted to fuel.
How the Body Uses Carbs
The digestive system changes carbohydrates into glucose, also known as
blood sugar. Some glucose is used for energy and the rest is stored in the
liver and muscles for later use. As your blood sugar rises, your pancreas
pumps out more and more insulin, a hormone that tells cells to absorb
glucose for energy or storage. As cells absorb the glucose, blood sugar
levels begin to fall, which signals the pancreas to start making glucagon, a
hormone that tells the liver to release stored glucose.
Types of Carbohydrates
The two types of carbohydrates are simple and complex. Simple
carbohydrates, also called simple sugars, include sugars founds in fruits,
vegetables and milk, as well as sugars added during food processing.
Complex carbohydrates, also called starches, include whole-grain breads
and cereals, starchy vegetables and legumes. Most complex carbs contain
fiber, which helps digestive health and increases satiety, reducing
overeating and weight gain. Additionally, high-fiber foods help lower
cholesterol and decrease the risk of heart disease.
Tips
Because some types of carbohydrates are better for your health than
others, choose your carbohydrates wisely. MayoClinic.com recommends
buying fresh, frozen and canned fruits and vegetables without added
sugar instead of fruit juices and dried fruits, which have more calories.
Also, opt for whole grains over refined, which are stripped of the parts of
the grain that contain many nutrients. Stick with low-fat dairy products to
reduce saturated fat and calories. Limit intake of foods with added sugars
– these types of carbohydrates can lead to poor nutrition, tooth decay
and weight gain.
Carbohydrates in therapeutics.
Awareness of the importance of carbohydrates in living systems and
medicine is growing due to the increasing understanding of their
biological and pharmacological relevance. Carbohydrates are ubiquitous
and perform a wide array of biological roles. Carbohydrate-based or modified therapeutics are used extensively in cardiovascular and
hematological treatments ranging from inflammatory diseases and antithrombotic treatments to wound healing. Heparin is a well-known and
widely used example of a carbohydrate-based drug but will not be
discussed as it has been extensively reviewed. We will detail
carbohydrate-based and -modified therapeutics, both those that are
currently marketed or in various stages of clinical trials and those that are
potential therapeutics based on promising preclinical investigations.
Carbohydrate-based
therapeutics
include
polysaccharide
and
oligosaccharide anti-inflammatory, anti-coagulant and anti-thrombotic
agents from natural and synthetic sources, some as an alternative to
heparin and others which were designed based on known structurefunctional relationships. Some of these compounds have multiple
biological effects, showing anti-adhesive, anti-HIV and anti-arthrithic
activities. Small molecules, derivatives or mimetics of complement
inhibitors, are detailed for use in limiting ischemia/ reperfusion injuries.
Monosaccharides, both natural and synthetic, have been investigated for
their in vivo anti-inflammatory and cardioprotective properties.
Modification by glycosylation of natural products, or glycosylationmimicking modification, has a significant effect on the parent molecule
including increased plasma half-life and refining or increasing desired
functions.
Professor Dr. Saad Ali Ihsan
Ph.D. in Pharmacognosy & Medicinal Plants
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