LIPIDS Definition its Classification Classification of lipids examples

LIPIDS Definition & its Classification

Classification of lipids (examples) SIMPLE LIPIDS COMPOUND LIPIDS DERIVED LIPIDS TAG PHOSPHOLIPID CHOLESTEROL WAXES SPHINGOLIPIDS STEROID HORMONES Phosphingolipid FATTY ALDEHYDES GLYCOLIPID KETONE BODIES Cerebosides FAT SOLUBLE VITAMINS Gangliosides (ADEK) Sulfatides EICOSANOIDS LIPOPROTEINS Prostaglandin Leukotriene BILE ACIDS/SALTS GLYCEROL

Functions of Lipids • • Energy provision as ATP Building block Thermal Insulator Specialized functions – Messenger/Signaling – Bone strength – Visual pigment – Antioxidant – Electron Transport Chain

Simple fat have simple function • • • They are neutral lipid Storage in adipose tissues Body contouring Insulation Store of energy

Complex/Compound Lipids • Esters of fatty acids with alcohol, containing non-lipid Group (PO 4, Nitrogenous base, or sugar) • Compound Lipids are Further Classified as: 1. PHOSPHO-LIPIDS 2. GLYCO-LIPIDS 3. PROTEO-LIPIDS (LIPO-PROTEINS) 4. SULPHO-LIPIDS

PHOSPHOLIPIDS 1. Glycerophospholipids (Backbone is Glycerol) • Phosphatidic acid is the parent compound for all • PO 4 with additional group form Polar head. • 2 Fatty acids form non polar tail. • Amphipathic molecule

Types of Glycero-phospholipids • depending upon the type of head alcohol Common GPL are 1. Phosphotidyl Choline. (Lecithin) 1. 2. 3. 4. 5. Present in membrane, plasma, & bile Forms component of cell membrane Decrease surface tension of aqueous later of lung Detergent property solubilize cholesterol in bile (Gall stone) LCAT esterify cholesterol in HDL 2. Phosphotidyl Ethanol amine. (Cephalin) 1. Brain lipid

Types of Glycero-phospholipids 3. Phosphotidyl Serine. Apoptosis 4. Phosphotidyl Inositol 1. Precursor of Second Messengers 5. Phosphatidyl Glycerol. 6. Cardiolipin. 3. Mitochondrial Membranes

2. Sphingolipids (backbone is Sphingosine) • Ceramide is the parent compound for spingolipid. • Amino alcohol (sphingosine) • Fatty acid

GLYCOLIPIDS

Ceramides + Sugar residue (β-glycosidic bond) 1. Cerebrosides Glucosylcerebrosides Ceramides + Glucose Non neuronal accumilate in Liver (GAUCHER’S Disease) Galactosylcerebrosides Ceramides + Galactose Neuronal tissues- White matter Sulfatides Ceramides + Galactose + Sulfate

Ceramides + Sugar residue (β-glycosidic bond) 2. Gangliosides • Ceramides + branched oligosaccharides • Have acidic sugar (Sialic Acid/NANA) • Glc-Gal. NA-Gal …………………. GM 1 NANA • Glc-Gal. NA-Gal …………………. GM 2 NANA • Glc-Gal- …………………. GM 3 NANA

• Oligosaccharide present on outer membrane for receptor of GP hormones • Gangliosides present in brain & liver • TAY SACH’s disease occur B/o deposition of gangliosides in brain (hexoseaminidase)

BRAIN LIPIDS • • • Caphalin Sphingomyelin Cerebresides (Galactosyl) Gangliosides Cholesterol • 35% of the dry weight of brain

III-LIPOPROTEINS • Clusters of lipids associated with proteins that serve as transport vehicles for lipids in the lymph and blood

Lipoproteins • Distinguished by size and density • Each contains different kinds and amounts of lipids and proteins – The more lipid, the lower the density – The more protein, the higher the density

Lipoproteins • • • Chylomicrons VLDL – Very low density lipoprotein IDL – Intermediate density lipoprotein LDL – Low density lipoprotein HDL – High density lipoprotein

Properties of Plasma Lipoproteins Property Chylomicron Density (g/m. L) <1. 006 VLDL IDL LDL HDL <1. 006 - 1. 019 - 1. 0631. 019 1. 063 1. 21 Lipids (%) 98 92 85 79 50 Protein (%) 2 8 15 21 50

Lipids (%) in Plasma Lipoproteins Lipid Chylomicron VLDL IDL LDL HDL Cholesterol 9 22 35 47 19 Triglyceride 82 52 20 9 3 Phospholipid 7 18 20 23 28

Lipoproteins and cardiovascular disease (CVD) risk • LDL is positively associated with CVD • HDL is negatively associated with CVD

Cardiovascular disease (CVD) Cardio = heart, & Vascular = blood vessels • General term for all diseases of the heart and blood vessels – Atherosclerosis is the main cause of CVD • Atherosclerosis leads to blockage of blood supply to the heart, damage occurs (coronary heart disease, CHD)

LDL and atherosclerosis

Recommended blood lipids • • Total cholesterol: <200 mg/d. L (WHO-<150) LDL cholesterol: <130 mg/d. L HDL cholesterol: >35 mg/d. L Triglycerides: <200 mg/d. L

Effect of lipids on lipoproteins and CVD risk • Dietary cholesterol – No effect on blood cholesterol • Saturated fats – Raise LDL • Trans fats – Raise LDL and lower HDL • Monounsaturated fats – Lowers LDL • Omega-3 (n-3) polyunsaturated fats – Lowers blood cholesterol

What is Cholesterol? • Steroids are derived lipids in which the basic or principle structure is Cyclopentano Perhydro Phenanthrne Nucleus • (CPPP Nucleus) (Steroid Nucleus) • Examples: – Steroid hormones, Vitamin D etc.

Derived lipid (cholesterol) • 27 -C cyclic isoprene unit, derived from acetyl Co. A • • • Phenenthrene nucleus Cyclopentane ring OH gp at 3 rd C Double bond at 5 th position Aliphatic chain at C-17 Methyl gp at C 18, 19.

Cholesterol is white waxy compound Widely distributed in almost all the tissues of the body especially in brain, other nervous tissues, adrenals and liver.

Desirable Blood Cholesterol Levels • Total cholesterol. Less than 200 mg/d. L • LDL ("bad" cholesterol) Less than 100 mg/d. L • HDL ("good" cholesterol)40 mg/DL or higher • Triglycerides Less than 150 mg/d. L

Important biological functions Of Cholesterol • One of the important members of membrane lipids. • Precursor of Steroids & Vitamin D. • Forms Adrenal hormones • Forms Bile acids and salts • Relation with various diseases like: – Hypertension – Diabetes Mellitus – Thyroid Diseases.

Eicosanoids • Porstanoids – Prostaglandins (PGs) – Prostacyclins (PGIs) – Thromboxanes (TXs) • Leukotrienes (LTs) • Lipoxins (LXs)

Eicosanoids Derivatives of the Arachidonic acid • Physiologically they are considered to act as local hormones. • Many of these compounds have profound effects on smooth muscles, inflammation, blood clotting and many other important biological functions.

Prostaglandins Belong to a group of 20 Carbon fatty acids containing a 5 Carbon ring in their structure • They are of interest because of their extraordinary physiological and biochemical effects on: – Smooth muscles of many organs like blood vessels, uterus, kidney, stomach. – Adipose tissues. • On the basis of difference in the chemical structure various types of prostaglandins are described, such as Pgα, Pgβ, Pg and so

Different types of prostaglandins have variety of effects on different tissues • • • Role on adipose tissues. Stimulation of inflammation. Role on kidney. On cardiovascular system. On respiratory system. Effects on platelet aggregation. On gastrointestinal tract. On female reproductive system. On central nervous system.

Clinical Application of Prostaglandins in Medical Practice • To facilitate the labor or therapeutic abortion. • Contraception. • Asthma. • Management of blood pressure. • Gastric ulcer. • Prostaglandin inhibitors commonly used as Analgesics (Pain killers)