Carbohydrate Chemistry

Introduction 

         Carbohydrates have the general molecular formula (CH₂O)n, and thus were once thought to represent "hydrated carbon".

         All sugars are very soluble in water because of their many hydroxyl groups.

         They are called sugars because they are sweet in taste & crystalline in nature.

         Sugars are the most important source of energy for many cells.

Definition:

         Hydrates of carbon C_n(H₂O)_n

o       {exceptions:

         Acetic acid, C₂H₄O₂ & lactic Acid, C₃H₆O₃ Formaldehyde, CH₂Oare not carbohydrates but

         Deoxy Ribose C₆H₁₂O₅ is a carbohydrate

         carbohydrates are polyhydroxy aldehydes or ketones or compounds, which yields these on hydrolysis.

Classification:

• Classified as
  
  • Monosaccharides
    
  • Disaccharides
    
  • Oligosaccharides
    
  • Polysaccharides
    

• Monosaccharides
  

  • Simple sugars that cannot be hydrolyzed to yield another Carbohydrate.
    
  • Classification
    
    • Based on the functional group
      
      • They are classified as ALDOSES (-CHO) and KETOSES (=C=O)
        
    • Based on the number of Carbon atoms as
      
      • Triose (C3)
        
      • Tetrose(C4)
        
      • Pentose(C5)
        
      • Hexose(C6)
        
      • Heptose(C7)
        
      • Nonose (C9)
        
  • Examples
    
  • Trioses - C₃H₆O₃
    
    • Aldotriose
      
      • Glyceraldehyde
        
    • Ketotriose       
      
      • Dihydroxy acetone
        
  • Tetroses - C₄H₈O₄                                 
    

             Aldotetrose
    

            Erythrose
    

             Ketotetrose
    

            Erythrulose
    

  • Pentoses - C₅H₁₀O₅                               
    

             Aldopentose
    

            Ribose                        
    

             Ketopentose
    

            Ribulose
    

  • Hexoses -C₆H₁₂O₆                                 
    

             Aldohexose
    

            Glucose
    

            Mannose
    

            Galactose
    

             Ketohexose
    

            Fructose
    

  • Heptoses - C₇H₁₄O₇
    

             Sedoheptulose
    

  • Nonoses - C₉H₁₈O₉
    

             Sialic acid or Neuramic acid
    

• Disaccharides
  

  • Disaccharides are made up of two monosaccharides joined by Glycosidic bond.
    
  • The disaccharides on hydrolysis gives two monosaccharides
    
  • Examples
    
    • Biologically important Disaccharides are
      
      • Maltose
        
      • Sucrose
        
      • Lactose
        
    • Others include
      
      • Cellobiose
        
      • Trehalose
        
• Maltose C₃H₆O₃
  
  • Reducing in nature
    
  • the major degradation product of starch
    
  • composed of 2 glucose monomers in an alpha-(1,4) glycosidic bond.
    
• Lactose C₃H₆O₃
  
  • Milk Sugar
    
  • Reducing in nature
    
  • consists of galactose and glucose in a beta-(1,4) glycosidic bond.
    
• Sucrose C₃H₆O₃
  
  • Cane sugar and sugar beets
    
  • Non-Reducing in nature
    
  • composed of glucose and fructose through an alpha-(1,2)beta-glycosidic bond.
    

• Oligosaccharides
  

  • They are made up of 3 to 10 Monosaccharides joined by glycosidic bonds.
    
  • They on hydrolysis yields 3-10 monosaccharides
    
  • Examples
    
    • Maltotriose
      

              Glucose + Glucose + Glucose
      

              Degradation product of starch hydrolysis
      

    • Raffinose
      

              A trisaccharide that occurs in sugar beets and cotton seeds and cereals
      

    • Stachyose
      

              A tetrasaccharide found in the tubers of the Chinese artichoke
      

• Polisaccharides
  

  • Are madeup of more than 10 monosaccharides
    
  • They yields more than 10 Monosaccharides on hydrolysis.
    
  • Classified in to TWO types
    
    • Homopolysaccharides
      
    • Heteropolysaccharides
      

• Homopolysaccharides (Homoglycans)
  

  • Homopolysaccharides are polymer of a single type of Monosaccharide.
    
  • Classified in to
    
    • Storage Homopolysaccharides
      
    • Structural Homopolysaccharides
      

• Storage Homopolysaccharides
  

  • Examples
    
    • Starch
      
      • Polymer of Glucose
        
      • Source : Potato,tapioca,rice,wheat,&grains
        
      • Importance :Plant storage form of Energy
        
      • Gives blue colour with iodine
        
    • Amylose
      
      • Unbranched starch
        
      • Contains alpha 1-4 linkages
        
    • Amylopectin
      
      • Branched starch (at every 18-22 Glucose)
        
      • Contains both alpha 1-4 and alpha 1-6 linkages
        
    • Glycogen
      
      • Polymer of Glucose
        
      • Source : Liver (5%) and muscle
        
      • Branched (at every 8-10 Glucose)
        
      • Importance :Animal Storage form of Energy
        

• Structural Homopolysaccharides
  

  • Examples
    
    • Cellulose
      
      • Polymer of glucose
        
      • Contains beta 1-4 linkages
        
      • Considered as dietary fiber undigested by man
        
    • Chitin
      
      • Polymer of  N-Ac-Glucosamine
        
      • Present in the Exoskeleton of Insects
        

• Other homopolysaccharides
  

  • Inulin
    
    • Fructose
      
      • Source : various bulbs&tubers(onion,garlic)
        
      • Used for :Renal clearance studies.
        

• Hetroplysaccharides (Hetroglycans)
  

  • polymer of two or more types of sugar residues
    
  • Examples
    
•          Agar
  
•         Polymer of : Glu +Gal + other
  
•         Obtained from Sea weeds
  
  • A colloidal extract of algae; used especially in culture media and as a gelling agent in foods (undigested by bacteria, dissolves at 100 ^oC and upon cooling sets into a Gel)
    

• MUCOPOLYSACCHARIDES (MPS) or GLYCOSAMINOGLYCANS (GAG)
  

  • Are Carbohydrates containing Uronic Acid & Amino Sugars.
    
  • Examples
    

         Hyaluronic acid

•         A viscous mucopolysaccharide found in the connective tissue space and the synovial fluid of movable joints and the humours of the eye; a cementing and protective substance
  

         Heparin

• A polysaccharide produced in basophils (especially in the lung and liver) and that inhibit the activity of thrombin in coagulation of the blood.
  

         Chondroitin SO₄

•        Inground substance of connective tissues (cartilage, tendon, bone)
  

         Keratan SO₄

•         In cornea & tendons.
  

Carbohydrates

CARBOHYDRATES

Carbohydrates have the general molecular formula (CH₂O)n, and thus were once thought to represent "hydrated carbon". All sugars are very soluble in water because of their many hydroxyl groups. They are called sugars because they are sweet in taste & crystalline in nature. Although not as concentrated a fuel as fats, sugars are the most important source of energy for many cells. Carbohydrates provide the bulk of the calories (4 kcal/gram)

1)Definition:

a)Hydrates of carbon C_n(H₂O)_n{exceptions: Acetic acid, C₂H₄O₂ & lactic Acid, C₃H₆O₃ Formaldehyde, CH₂Oare not carbohydrates but Rahnose,C₆H₁₂O₅ is.}

b)carbohydrates are polyhydroxy aldehydes or ketones or compounds, which yields these on hydrolysis.

2)Classification:

a)Monosaccharides:simple sugars that cannot be hydrolyzed to yield Carbohydrates

Name	Aldose	Ketose	Formula
Trioses	Glyceraldehyde	Dihydroxy acetone	C3H6O3
Tetroses	Erythrose	Erytrulose	C4H8O4
Pentoses	Ribose	Ribulose	C5H10O5
Hexoses	Glucose,Mannose, Galactose	Fructose	C6H12O6
Heptoses	Sedoheptulose		C7H14O7
Nonoses	Sialic acid or Neuramic acid		C9H18O9

b)Disaccharides: yields two molecules of Monosaccharides on hydrolysis

Name	Monosaccharides	Formula	Sources	Properties
Maltose	Glucose + Glucose	C3H6O3	Malt sugar, starch	Reducing
Lactose	Glucose + Galactose	C3H6O3	Milk Sugar	Reducing
Sucrose	Glucose + Fructose	C3H6O3	Cane sugar	Non-Reducing

Sucrose: prevalent in sugar cane and sugar beets, is composed of glucose and fructose through an a-(1,2)b-glycosidic bond.

Lactose: is found exclusively in the milk of mammals and consists of galactose and glucose in a b-(1,4) glycosidic bond.

Maltose: the major degradation product of starch, is composed of 2 glucose monomers in an a-(1,4) glycosidic bond.

c)Oligosaccharides: yields 3 to 10 Monosaccharides on Hydrolysis.

Maltotriose	Glucose + Glucose + Glucose
Raffinose	A trisaccharide that occurs in sugar beets and cotton seeds and cereals
Stachyose	A tetrasaccharide found in the tubers of the Chinese artichoke

d)Polisaccharides: yields more than 10 Monosaccharides on hydrolysis. They are of two types.

i)Homopolysaccharides (Homoglycans) Polymer of a single type of Monosaccharide.

Name	Monosacc.	Sources	Importance
Starch	Glucose	Potato,tapioca,rice,wheat,&grains	Plant source of Energy
Amylose	Glucose	Un branched starch similar to cellulose, containing alpha(1->4) linkages
Amylopectin	Glucose	Branched starch containing both 1,4 and 1,6 linkages.
Glycogen	Glucose	5% of liver mass> branched & compact	Animal storage of Glucose
Inulin	Fructose	various bulbs&tubers(onion,garlic)	Renal clearance studies.
Dextrins	Glucose	Product. ofstarch digestion	White dextrin is used in pharmaceutical preparations
Chitin	N-Ac-Glucosamine	Exoskeleton of Insects

 

ii)Hetroplysaccharides (Hetroglycans): polymer of two or more types of sugar residues

Agar	Glu +Gal + other	Obtained from Sea weeds
A colloidal extract of algae; used especially in culture media and as a gelling agent in foods (undigested by bacteria, dissolves at 100 oC and upon cooling sets into a Gel)

iii)MUCOPOLYSACCHARIDES (MPS) or GLYCOSAMINOGLYCANS (GAG)

Are Carbohydrates containing Uronic Acid & Amino Sugars.

Name	Functions
Hyaluronic acid	A viscous mucopolysaccharide found in the connective tissue space and the synovial fluid of movable joints and the humours of the eye; a cementing and protective substance
Heparin	A polysaccharide produced in basophils (especially in the lung and liver) and that inhibit the activity of thrombin in coagulation of the blood.
Chondroitin SO4	Inground substance of connective tissues (cartilage, tendon, bone)
Keratan SO4	In cornea & tendons.

 

e)Isomerism

i)D & L Isomerism

oThe configuration of the asymmetric carbon atom ( carbon atom whose 4 valencies are filled up by 4 different groups)farthest from the aldehydic or ketonic group

oIf –OH group is attached to the right then 'D' series & left then 'L' series.

ii)Pyranose - Furanose ring Structure

oWhen ring structure were suggested by Haworth (projections)

oFive member ring structure is calledFuranose and Six number as Pyranose

iii)Alpha & Beta Anomerism

oThe anomeric carbon (which originally was a part of the aldo or keto group) forms a hemiacetal or hemiketal in the ring structure generating a new asymmetric centre.

oIf hydroxyl gp (-OH) of the anomeric carbon is to the right then it is -form and if to the left it -form.

iv)Epimerism

oEpimers differ in the position of the Hydroxyl gp at only one of their assymetric C-atom.

oD-Glucose & D-Galactsoe are C-4 Epimers

oD-Glucose & D-Mannose are C-2 epimers

v)Enantiomers

oStereo isomers that are mirror images of each other

oEg: D-Glyceraldehyde & L-Glyceraldehyde.

vi)Mutarotation

oWhen D-Glucose is crystallized at RT and fresh solution is prepared, its specific rotation of polarized light is +112 ^o; but after few hrs it changes to +52.5 ^o. This change in rotation is called Mutarotation. This b'se D-Glucose has two anomers  &  forms. (-D-Glucose has specific rotation of +112 ^o and -D-Glucose has +19 ^o at equilibrium 1/3 is  form and 2/3 is  form to get a specific rotation of +52.5 ^o

3)Other Physiologically important carbohydrates.

Sugar	Present where	Importance&clinical Significance
D-Ribose	Nucleic acids	Nucleic acid co-enzymes.
D-Ribulose	Metabolic Product	Pentose-PO4 pathway intermediate.
D-Arabinose	Gum arabic, Plum & Cherry gum	Constituent of Glycoproteins
D-Xylose	Wood gums, GAG's	Constituent of Glycoproteins
D-Xylulose	Intermediate in Uronic acid pathway	Found in the Urine of patients with Essential pentosuria

4)CHEMISTRY

a)Reactions

i)Benedict's Reaction

Contains Na₂CO₃, Na-Citrte,CuSO₄

In alkaline medium (Na₂CO₃), the copper remains as cupric hydroxide in presence of sodium citrate

5 ml Benedict's reagent+ 0.5 ml Urine boil for 2 minutes. If sugar present copper is reduced to produce green, yellow, orange, red precipitate depending on the concentration of the sugar.

_SugarEnediolCu⁺⁺(cupric)  CuSO ₄(Reagent)

Sugar AcidCu⁺(cuprous) 2Cu(OH)[Yellow]Cu ₂O [Red]

Chemical propertie s
1	Reactions of aldehyde / keto group
		Reactions			Reagents	Result
	a.	Osazone formation			Sugar+Phenyl Hydrazine HCl+ Sodium Acetate (boil+cool)	Glucosazone-needle shapedLactosazone - Powder puff Maltosazone - Sunflower
	b.	Reduction → Alcohol			Sodium amalgum / Hydrogen	Glucose - sorbitolFructose - Manitol
	c.	Oxidation
		I.	Mild (CHO → COOH)		Br2 H2O	Glucose - gluconic acid
		ii.	Srong (CHO & CH2OH to COOH		HNO3	glucose - Glucosaccharic acid
		iii.	Oxdn of CH2OH alone		Enzymatic (living cells only)	Glucose to glucuronic acid
	d.	Tautomerisation( Inter conversions)			Weak alkaliBa (OH)2, Ca(OH)2	Glucose ↔ fructose ↔ Mannose
	e.	Reduction Reactions			CuSO4, alkaline medium( cupric -> cuprous)	Benedicts, Fehlings & Barfoeds Test( Cuprous oxide- Red ppt)
2	Reactions of Alcoholic group
	a.	Glycosides			1→4 &1→6 bond in glycosidic bonds in glycogen
		I.	Cardiac		Derivatives of DIGITALIS,	Drugs in cardiac insufficiency
		ii.	Oubin		strophanthus sp.	Sodium pump inhibitor (cardiac)
		iii.	Phlorbizin		Root/bark of apple tree	block transport of sugar
		iv.	Streptomycine		produced by the actinomycete Streptomyces griseus	Antibioticused to treat tuberculosis
	b.	Acetilation/Ester formation			Alcohol + acids	phosphates ( glucose -1-phosphate)
	c.	Dehydratin( Molisch, Selivanoffs, Bials tests)			Strong acids (Con.H2SO4)	Pentose→ Furfurals,Hexose→ Hydroxy methyl Furfural.
TESTS
	Name of test			Substrate	Reagents	Result
1	Molisch's Test			Sugar	3d Alfa-Naphthol in Methanol +H2SO4 (side)	Violet color in the Junction.
2	Iodine test			Starch	Dil. Iodine	Deep Blue Colour
3	Benedict's			Reducing Sugar(0.5 ml/ 8 dps)	CuSO4+Na2CO3+NaCitrate(5 ml)	Cuprous Oxide (Red Precipitate)
4	Fehling's Test			Reducing Sugar	CuSO4+KOH+NaK Tartrate	Cuprous Oxide (Red Precipitate)
5	Barfoed's test			Monosaccharide.	CuAcetate+Dil.AceticAcid	(Red Precipitate) in < 5'
6	Bial's Test			Pentose	Orcinol Hydrochloride (Boil)	Green
7	SelivanoffsTest			Ketoses	Dil. Resorcinol in Dil.HCl (heat)	Cherry red
8	Tollent's Test			Reducing Sugar	Ammoniacal Silver nitrate	Metalic Siver Mirror

METABOLISM OF BILIRUBIN

METABOLISM OF BILIRUBIN

 
 

After 120 days of lifespan RBC's are broken down to release Hemoglobin

The hemoglobin then broken down to form Haem and Globin

            Globin being a protein is used as such or converted to amino acids and taken to amino acid pool

The Haem is then broken down to release a porphyrin compound and Iron

            The iron is taken to Iron pool and re utilized

The porphyrin ring opens and is converted to Biliveridin a green pigment

The biliveridin is immediately reduced to Bilirubin an yellow pigment

The formation of Bilirubin is taking place in the reticulo endothelial cells of  Spleen, Bone marrow and

 
 

The Bilirubin thus formed being water insoluble is then attached with the transport protein albumin and is then transported to liver through the blood. This albumin Bilirubin complex is known as the Unconjugated Bilirubin or Indirect Bilirubin or Free Bilirubin

 
 

Liver.

In liver there are three processes taking place

1. Uptake of Bilirubin in to liver cells (hepatocytes)
   
2. Conjugation of Bilirubin with Glucuronic acid
   
3. Excretion of Conjugated Bilirubin in to Bile
   

The albumin is removed form the Bilirubin and is taken in to the  hepatocytes where they are conjugated.

            The Bilirubin in the hepatocyte is conjugated with two molecules of the UDP Glucuronic acid to form the Bilirubin Di Glucuronide and is known as the Conjugated Bilirubin or Direct Bilirubin.

            The conjugated Bilirubin being water soluble is excreted in to the bile and it reaches the small intestine

Small Intestine:

In small intestine the glucuronides are removed and the Bilirubin is converted to urobilinogen by the intestinal bacteria.

A part of the urobilinogen is reabsorbed back in to the liver through the portal circulation and reaches the liver and thus in to the general circulation. Then it is excreted in to the urine via kidneys. The urobilinogen in urine is the cause of yellow coloration to urine and when it is exposed to oxygen is converted to dark Urobilin.

The remaining urobilinogen in the small intestine is excreted in to the feces as Stercobilinogen. This Stercobilinogen in the stool is the cause of yellow coloration to the stool and when it is exposed to the oxygen it is converted to dark colored stercobilin.

Adsorption Chromatography

INTRODUCTION

• Adsorption chromatography is probably one of the oldest types of chromatography around.
  
• It utilizes a mobile liquid or gaseous phase that is adsorbed onto the surface of a stationary solid phase.
  
• The equilibriation between the mobile and stationary phase accounts for the separation of different solutes.
  

PRINCIPLE

• Classic form of Chromatography by Tswett  
  

Principle

• Based on the principle that certain solid materials, collectively known as adsorbents have the ability to hold molecules at their surface.
  
• This adsorbing process which involves weak non-ionic attractive forces of van der Waal's and hydrogen bond occurs at specific adsorption site.
  
• These sites have the ability to discriminate between the molecules and the adsorption of the molecule depends on the strength of the interaction.
  
• As elutes continuously pass down the column, difference in their binding eventually lead to the separation for the analytes.
  
• Binding depends on the functional groups present in the molecules
  
  • Hydroxyl, aromatic groups - increase interaction with the binding surface
    
  • Aliphatic groups - decrease interaction with the binding surface
    

STATIONARY PHSAE / ADSORBENT

Silica

• with Silanol groups (Si-OH) groups on its surface
  
• Are slightly acidic in nature
  
• Can interact with polar functional group of the analyte or eluent.
  
• The topology (arrangement of Si-OH explains their differential separation
  
• Silica is acidic - good for the separation of basic substances
  
• Available for both LPLC & HPLC
  

Alumina

• Available for both LPLC & HPLC
  
• Alumina is basic - good for the separation of acidic substances
  

Carbon

• Available for both LPLC & HPLC
  

MOBILE PHASE ELUENT

• Depends on k' (partition ratio / capacity ratio) of analyte. (which is the time spent by analyte in the stationary phase relative to the time spend in the mobile phase)
  
• Eluent with polarity comparable to the most polar compound in the analyte mixture is selected as mobile phase.
  
  • Alcohol is selected for analytes with hydroxyl (-OH) groups
    
  • Acetone/esters is selected for analytes with carbonyl groups (=C=O) groups
    
  • Hexane / heptane /toluene (hydrocarbons) is selected for non polar analytes
    
  • Mixture of solvents also can be used in gradient elution.
    
• Presence of small amounts of water in the MP is beneficial when silica is the stationary phase – which selectively block more active Silanol groups leaving a more selective population of weaker binding sites.
  

MODES/ APPLICATION -USES

Modes

• Column
  
• Thin layer
  

Application/USES

• Most commonly used to separate non ionic water insoluble substances
  
  • Triglycerides
    
  • PTH
    
  • Aminoacids
    
  • Vitamins
    
  • Many drugs
    

TWO MAJOR TYPES

• Hydroxylapatite Chromatography
  
• Hydrophobic interaction  Chromatography
  

HYDROXY(L)APATITE CHROMATOGRAPHY

• Also known as hydroxyapatite chromatography
  
• Adsorbent used
  
  • Crystalline  hydroxyapatite (Ca10(PO4)6(OH)2)
    
• Mechanism
  
  • Involves both Ca & PO4 ions on the surface
    
  • Involve dipole-dipole interaction
    
  • Involve electrostatic interaction
    

APPLICATION/ USES OF HC

• Used to separate single stranded DNA from double stranded DNA
  
• Both single stranded and double stranded binds at low phosphate buffer concentration
  
• At increased buffer concentration single stranded DNA is selectively desorbed
  
• Further increase in buffer concentration desorbs double stranded DNA also
  
• Used of Cot Analysis
  
• So DNA can be separated from mixture of RNA and protein of cell Extracts.
  

COMMERCIAL

• Suitable for both LPLC & HPLC
  
• Crystalline or spheroidal hydroxy apatite is bonded to the agarose matrix
  
• Adsorption capacity is maximum around the neutral pH using 20 mM phosphate buffer
  
• Elution is done at 500 nM
  

HYDROPHOBIC INTERACTION CHROMATOGRAPHY

• Used to purify protein exploiting their surface hydrophobicity (non polar amino acids)
  
• In aqous solution these hydrophobic regions of proteins are covered with an ordered film of water molecules that effectivel mast these hydrophobic groups
  
• Exposed by the addition of salt ions
  
• Then these hydrophobic regions interact together and is the basis of salting out by the addition of ammonium sulphate
  
• If hydrophobic groups are attached to a suitable matrix the hydrophobic groups on the proteins will interact with them on the matrix to facilitate a protein-matrix attraction
  
• Most commonly used stationary phases are
  
  • Alkyl (hexyl , Octyl)
    
  • Phenyl groups
    
  • Attached to Agarose matrix
    

Commercial

LPLC(HIC)

• Phenyl Sepharose , Phenyl SPW
  

HPLC (HIC)

• Biogel TSK phenyl, Spherogel TSK Phenyl
  
• Ammonium sulphate is present in the sample since it fractionated before analysis with it which help to expose the hydrophobic centers.
  

Elution process.

• Gradually decrease the ionic strength
  
• Increase the pH
  
• Selective displacement by displaces that has s stronger affinity for the stationary phase than has the protein
  
  • Non ionic detergents like
    
    • Tween 20
      
    • Trinton –X100
      
  • Aliphatic Alcohols like
    
    • Butanol
      
    • Ethylene Glycol
      
  • Aliphatic Amines
    
    • Butylamine
      
• Some of these elution condition may cause protein denaturation
  
• Protein purified -->Aldolase, Transferrin, Cytochrom c, thyroglobulin etc.
  

ACID BASE Reactions

Syllabus

Acid base reactions
Strength of an acid
Concepts of pH & pOH
Henderson Hasselbalch Equation

Acid

The word "acid" comes from the Latin acidus meaning "sour,"
Chemical compound when combined with water gives a pH less than 7

Different definitions are given by

Lavoisier.
Arrhenius:
Brønsted-Lowry:
Solvent-system definition:
Lewis:
E.g.
Acetic acid
In vinegar
Sulphuric acids
In car batteries

Lavoisier's definition

The first scientific definition was proposed by the French chemist Antoine Lavoisier. Since Lavoisier's knowledge of strong acids was mainly restricted to oxoacids, which tend to contain central atoms in high oxidation states surrounded by oxygen, such as HNO3 and H2SO4, and since he was not aware of the true composition of the hydrohalic acids, HCl, HBr, and HI, He defined acids in terms of their containing oxygen which in fact he named from Greek words meaning "acid-former". When the elements chlorine, bromine, and iodine were identified and the absence of oxygen in the hydrohalic acids was established by Sir Humphry Davy in 1810, this definition had to be rejected.

Acid - Arrhenius:

Swedish chemist Svante Arrhenius
An acid is a substance that increases the concentration of hydronium ion (H3O+) when dissolved in water, while Bases are substances that increase the concentration of hydroxide ions (OH-).
This definition limits acids and bases to substances that can dissolve in water.
Around 1800, many French chemists, including Antoine Lavoisier, incorrectly believed that all acids contained oxygen. English chemists, including Sir Humphry Davy at the same time believed all acids contained hydrogen. Arrhenius used this belief to develop this definition of acid.

Acid - Brønsted-Lowry

An  acid is a proton (hydrogen nucleus) donor and
A  base is a proton acceptor.
The acid is said to be dissociated after the proton is donated.
An acid and the corresponding base are referred to as conjugate acid-base pairs.
Brønsted and Lowry independently formulated this definition, which includes water-insoluble substances not in the Arrhenius definition.
The protonic (Brønsted-Lowry)
The Brønsted-Lowry definition, formulated independently by its two proponents
Johannes Nicolaus Brønsted , Martin Lowry in 1923 revolves around an acid's ability to donate protons (H+) to another compound, called a base, in a chemical reaction.
A base is a proton acceptor.
In Brønsted-Lowry acid-base reactions, there is a "competition" between two bases for a proton, so that if X and Y are two species, the equilibrium
HX + Y- ↔ HY + X- occurs.
Both HX and HY are Brønsted-Lowry acids;
both X- and Y- are Brønsted-Lowry bases.
If the reaction runs mostly to the left, then HY is the stronger acid and X- the stronger base;
if the reaction runs mostly to the right, then HX is the stronger acid and Y- the stronger base.

Acid-solvent-system definition

According to this definition, an acid is a substance that, when dissolved in an autodissociating solvent, increases the concentration of the solvonium cations, such as
H3O+ in water,
NH4+ in liquid ammonia,
NO+ in liquid N2O4,
SbCl2+ in SbCl3, etc.
Base is defined as the substance that increases the concentration of the solvate anions, respectively
OH-, NH2-, NO3-, or SbCl4-.
This definition extends acid-base reactions to nonaqueous systems and even some aprotic systems, where no hydrogen nuclei are involved in the reactions.
This definition is not absolute, a compound acting as acid in one solvent may act as a base in another.

Acid -Lewis

According to this definition developed by Gilbert N. Lewis,
an acid is an electron-pair acceptor and
a base is an electron-pair donor.
(These are frequently referred to as "Lewis acids" and "Lewis bases," and are electrophiles and nucleophiles, respectively, in organic chemistry; Lewis bases are also ligands in coordination chemistry.)
Lewis acids include substances with no transferable protons (ie H+ hydrogen ions), such as iron(III) chloride, and hence the Lewis definition of an acid has wider application than the Brønsted-Lowry definition.
The Lewis definition can also be explained with molecular orbital theory. In general, an acid can receive an electron pair in its lowest unoccupied orbital (LUMO) from the highest occupied orbital (HOMO) of a base.  That is, the HOMO from the base and the LUMO from the acid combine to a bonding molecular orbital. Although not the most general theory, the Brønsted-Lowry definition is the most widely used.

The Usanovich definition

The most general definition is that of the Russian chemist Mikhail Usanovich, and can basically be summarized as defining an acid as anything that accepts negative species or donates positive ones, and
a base as the reverse. This tends to overlap the concept of redox (oxidation-reduction), and so is not highly favored by chemists

The Lux-Flood definition

This definition, proposed by German chemist Hermann in 1939, further improved by Håkon Flood circa 1947 commonly used in modern geochemistry and electrochemistry of molten salts, describes an acid as an oxide ion acceptor and a base as an oxide ion donor. For example:
MgO (base) + CO2 (acid) → MgCO3
CaO (base) + SiO2 (acid) → CaSiO3
NO3- (base) + S2O72- (acid) → NO2+ + 2SO42-[16]

The Pearson definition

In 1963 Ralph Pearson proposed an advanced qualitative concept known as Hard Soft Acid Base principle, later made quantitative with help of Robert Parr in 1984. 'Hard' applies to species which are small, have high charge states, and are weakly polarizable. 'Soft' applies to species which are large, have low charge states and are strongly polarizable. Acids and bases interact and the most stable interactions are hard-hard and soft-soft. This theory has found use in both organic and inogranic chemistry.
Base - Chemical compound that absorbs H3O+ ion in aqueous solution or a proton accepter

Strength of an acid

The strength of an acid is its ability to donate H+ ions
It is best described by acid dissociation constant
Acid dissociation constant, denoted by Ka, is an equilibrium constant for the dissociation of a weak acid.
 According to the Brønsted-Lowry theory of acids and bases an acid is only recognized by its reaction with a base.
In aqueous solution, the base is water itself.
HA +H2O   A- + H3O+
Acid dissociation constants are also known as
the acidity constant or
the acid-ionization constant.
The term is also used for pKa,
which is equal to negative  logarithm of Ka
Acid dissociation constant (Ka)
When an acid, HA, dissolves in water,
some molecules of the acid 'dissociate' to form
hydronium ions (H3O+ as H+) and
the conjugate base, (A-), of the acid.
HA ----> H+ + A-
The dissociation constant Ka can be written as
Ka = [H+][A-] / [HA]
where the square brackets are usually taken to signify concentration.
H2O is omitted from these expressions because in dilute solution the concentration of water may be assumed to be constant.
pKa = -log Ka
Weak and strong acids
A weak acid may be defined as an acid with pKa greater than about -2.
An acid with pKa = -2 would be 99% dissociated at pH 0, that is, in a 1M solution.
Any acid with a pKa less than about -2 is said to be a strong acid.
Strong acids are said to be fully dissociated.
On the pKa scale of acid strength, a large values indicates a very weak acid, and a small value indicates a not so weak one.

Ionization of water

1 L of water at 25 degrees will have 10-7  moles of H+ and 10-7 moles of OH-
H2O ------> H+ + OH-
Equilibrium constant
Keq = [H+] [OH-] / [H2O]
Kw, the ion product of water
 =Kw = 55.5 Keq
= 10-14 = [H+][OH-]