Lipid Derivatives

Lipid Derivatives BI 171 [Handout]
Representative Lipid Derivatives of Biological Importance
Derivative Importance
  1. Phospholipids - Glycerol joined to two fatty acid molecules, the third place is occupied by a phosphate group; major lipid constituent of cell membranes; found in human plasma; abundant in seeds and egg yolk; found in high concentrations in brains, nerves, and neural tissues generally.
  2. Waxes - Lipids composed of fatty acids with long chain alcohols, not glycerol.
    1. Suberin - Waterproofing material found in cell walls of cork
    2. Cutin - Waterproofing substance covering the epidermis of leaves, stems, and fruits.
  3. Carotenoids - Plant and animal pigments.
    1. Carotenes - Occur in all leaves; responsible for orange, red, , yellow, and cream-white colors of tomatoes, carrots, egg yolk, milk, and other plant and animal products; Vitamin A is a derivative of carotenes; a further derivative of Vitamin A, retinene, acts as a photoreceptor in the retina of the eye.
    2. Xanthophylls - Examples include lutein, a yellow substance in autumn leaves, and fucoxanthin, a pigment in brown and other algae.
  4. Steroids - All are related in that they possess a structure similar to that of cholesterol; regulate sexual development and influence numerous aspects of metabolism.
    1. Cholesterol - Present in all animal cells, blood, and particularly nervous tissue; found in cell membranes.
    2. Vitamin D - Synthesized in human skin upon exposure to ultraviolet light.
    3. Cortisone - Hormone produced by adrenal glands of vertebrates.
    4. Androgens - Male sex hormones; testosterone most influential.
    5. Estrogens - Female sex hormones; progesterone most powerful.
    6. Bile Salts - Emulsify fats prior to digestion in vertebrates.
  5. Porphyrins - Pigment compounds distantly related to lipids which are combined with proteins.
    1. Chlorophyll - Green pigments of photosynthetic organisms.
    2. Hemoglobin - Oxygen-transporting substance in blood or tissues of many animals.
    3. Cytochromes - Electron-carrying proteins involved in respiration
    4. Bile pigments - Bilirubin (reddish) and biliverdin (green) have their origin in hematin, a derivative of hemoglobin; responsible for brown color of feces.
  6. Other lipoid substances - Among other lipid-like compounds in living matter are xanthocyanins, plant pigments; Vitamin E, the antihemorrhagic vitamin; and Coenzyme Q, a substance that functions in respiration.