Biochemistry Lecture 6 PDF

Biochemistry Derived lipids LECTURE (6) DR. El-Sawy 0  Biochemistry Derived lipids...

Biochemistry Derived lipids LECTURE (6) DR. El-Sawy 0  Biochemistry Derived lipids These are substances derived from simple lipids and compound Def : lipids by hydrolysis OR related to lipids. Fatty acids Include Alcohol (glycerol) Steroids Definition:  Compounds contain steroid nucleus which consists of 3 cyclohexane rings (A, B and C) and 1 cyclopentane ring (D), fused together. Cardiac glycosides DR. El-Sawy 1  Biochemistry Derived lipids Cholesterol Ergosterol Source Animal Plant No of C 27 C 28 C atoms Absorption Easily absorbed Poorly absorbed Structure of all body cells. Precursor for all steroid Function hormones, bile acids (liver) Pro-vitamin D2. 7-dehyrocholesterol → pro- vitamin D3 (UV Rays) Cholesterol 1. Exogenous (dietary): Diet rich in cholesterol as butter, cream, milk, egg & meat. Sources 2. Endogenous: Synthesized in body.  Normal level  ˂ 200 mg/dl.  Hyper-cholesteremia associated with atherosclerosis, Blood level myocardial infarction & cerebral stroke. 75% of cholesterol  carried in LDL , 25% HDL.  Widely present in body tissues. Occurrence  In largest amounts in brain ,liver, skin , small intestinal & adrenal cortex. 1- Free Cholesterol. Forms 2- Cholesterol ester (70%): linked with F.A at OH group of C3. DR. El-Sawy 2  Biochemistry Derived lipids DR. El-Sawy 3  Biochemistry Derived lipids Male sex hormone : Female sex hormones : Adrenal cortex hormones ( C) : Testosterone Estrogen Progesterone Glucocorticoids Mineralocorticoids carbon No 19 18 21 21 21  11- Deoxy cortico- 1. Estrone,  Corticosterone. sterone (DOC). 2. Estradiol (most  Cortisol (17-OH Forms  11- Deoxy cortisol, active) corticosterone)→  Aldosterone (most 3. Estriol. (most active). active) Adrenal cortex + Site of secretion Leydig cells of testis. Ovary & Placenta.  Development of  Development  Increase blood  Promote Na  Prepare male sex organs of female sex glucose retention & K uterus for & 2ry male sex organs and (hyperglycemic). excretion. implantation characters. 2ry female  Suppress immune,  ↑ Na & Cl of ovum  Spermatogenesis. sex characters. allergic & reabsorption & ↓ K (hormone of  Strong anabolic  Anabolic inflammatory reabsorption by pregnancy). effect. effect. response. kidney. DR. El-Sawy 4  Biochemistry Derived lipids 1- Vitamin D3: from 7-dehydrocholesteorl by U.V rays. Examples 2- Vitamin D2 : from ergosterol by U.V rays Site of  Skin synthesis Site of  Liver & kidney activation  Increase Ca absorption from GIT Functions  Increase bone ossification Primary bile acids Secondary bile acids By action of intestinal Formation From cholesterol in liver. bacteria on 1ry bile acids. Cholic acid (main bile acid). Lithocholic acid. Example Chenodeoxycholic acid. Deoxycholic acid. formation of bile salts : Bile acids unit with glycine  glycocholic acid Bile acids unit with taurine  taurocholic acid Glycocholic acid and taurocholic acid unit with NA or K to form Na or K to form Na or K glycocholate or taurocholate (bile salts). DR. El-Sawy 5  Biochemistry Derived lipids Function of bile salts : 1. Lipid digestion. 2. Lipid absorption. Structure  Steroid + Sugar (Glucose or Galactose)  Cardiac glycosides as digitalis (cardiac stimulant) are used in Clinical significance treatment of arrhythmias & congestive heart failure. DR. El-Sawy 6  Biochemistry Derived lipids  Samira is a 62-year-old woman with a history of hyperlipidemia presented to the hospital with weakness of the right side.  On examination, she had right hemiplegia. CT showed a left middle cerebral artery occlusion. a. What is your possible diagnosis? b. What is biochemical basis of this disease? c. Explain structure of lipid deposit on the wall of artery? DR. El-Sawy 7