1. Chapter 20
Lipids

2. Lipids
Bioorganic compounds that are generally insoluble in water (hydrophobic).
Waxes and Fats
Prostaglandins
Terpenoids
Steroids

3. Waxes Esters of long-chain carboxylic acids with long chain alcohols
Spermaceti
from sperm whale oil
mp 42–47oC

4. Waxes Esters of long-chain carboxylic acids with long chain alcohols
Beeswax
mp 60–82oC
Major components:

5. Fats Esters of long-chain carboxylic acids with glycerol
Fats = glycerides
long-chain carboxylic acids = fatty acids
glycerol
a triglyceride

6. Fats
Trimyristin

7. Common Saturated Fatty Acids
Lauric acid (dodecanoic acid)
Myristic acid (tetradecanoic acid)
Palmitic acid (hexadecanoic acid)
Stearic acid (octadecanoic acid)

8. Common Unsaturated Fatty Acids
Oleic acid (cis-9-octadecenoic acid)
Linoleic acid (cis,cis-9,12-octadecadienoic acid)
Linolenic acid (cis,cis,cis-9,12,15- octadecatrienoic acid)

9. Common Unsaturated Fatty Acids
Note that these unsaturated fatty acids are cis.
This tends to lower the melting points of the corresponding fats.
Tristearin (mp ~55oC)
Triolein (mp ~5oC)

10. Olestra® (Sucrose Polyester)
Non-absorbable lipid.
Substitute for fat in foods to reduce cholesterol.
Mixture of hexa-, hepta-, and octa-fatty acid esters of sucrose.

11. Lipophilic Vitamins Vitamin A (Retinol) Vitamin D3 (Cholecalciferol)
Vitamin E (a-Tocopherol)
Vitamin K (Phylloquinone)

12. Hydrolysis of Fats
This process is called saponification.

13. Hydrolysis of Fats
This process is called saponification.

14. Soap
Sodium stearate:

15. Soap
A soap micelle:
Greasy dirt

16. Sodium dodecyl sulfate
Detergents
hydrophobic
hydrophilic
Sodium dodecyl sulfate

17. Detergents Alkyl benzene sulfonate detergents hydrophilic hydrophobic
Non-biodegradable
hydrophilic
hydrophobic

18. Poly(ethyleneglycol) hydrophilic
Detergents
Non-ionic detergents
less sudsing (suitable for use in dishwashers).
clean synthetic fibers better.
hydrophobic
Poly(ethyleneglycol) hydrophilic

19. Phosphoglycerides
Fats in which glycerol is esterified to two fatty acids and to phosphoric acid:
Phosphoric acid esterified with another alcohol:
phosphatidic acid
(a phosphoglyceride)
choline
ethanolamine

20. Phosphoglycerides a phosphatidyl choline (a lecithin)
a phosphatidyl ethanolamine
(a cephalin)

21. Phosphoglycerides Major components of cell membranes hydrophobic
hydrophilic
A bilayer of phosphoglycerides

22. Prostaglandins Monocyclic hydroxy-fatty acids.
Widespread occurrence in mammalian tissues.
Potent physiological activities.
Derived biosynthetically from arachidonic acid:
prostaglandin E2
arachidonic acid
prostaglandin F2a

23. Terpenoids and Other Isoprenoids
Made up of several “isoprene units”
isoprene

24. Terpenoids and Other Isoprenoids
Monoterpenes
C10 compounds composed of two isoprene units.
geraniol
menthol
b-pinene
camphor

25. Terpenoids and Other Isoprenoids
Sesquiterpenes
C15 (three isoprene units)
bisabolene
farnesol
b-santalol
a-humulene

26. Terpenoids and Other Isoprenoids
Diterpenes
C20 (four isoprene units)
retinal
abietic acid

27. Terpenoids and Other Isoprenoids
Triterpenes
C30 (six isoprene units)
squalene
friedelin
betulin

28. Terpenoids and Other Isoprenoids
Tetraterpenes (Carotenoids)
C40 (eight isoprene units)
lycopene
b-carotene

29. Steroids
Tetracyclic natural products related to terpenes.

30. Steroids
Cholesterol
Precursor to sex hormones, vitamins, etc.

31. Steroids
Stigmasterol
The most abundant plant sterol.

32. Steroids Progesterone
Secreted by corpus luteum during latter half of menstrual cycle.
Antiovulatory activity – if pregnant, secretion continues.

33. Steroids Testosterone Principal hormone of the testes.
Converted to dihydrotestosterone (responsible for male secondary sex characteristics, including male pattern baldness).

34. Steroids
Estradiol
Mammalian estrogenic hormone produced by ovaries by aromatization of testosterone.
Triggers production of gonadotropins leading to ovulation.

35. Steroids Norethindrone (“mini pill”)
Antiovulatory activity.
Compare structure with progesterone:
norethindrone
progesterone

36. Steroids Methandrostenolone (dianabol)
An anabolic (growth promoting) steroid.
Now banned.
acne
liver tumors
 sperm count
testicular atrophy

37. Steroids Androstenedione Compare structure with testosterone.
A testosterone precursor.
Allegedly used by Mark McGwire and Barry Bonds
Compare structure with testosterone.

38. Steroids Androstenedione Compare structure with testosterone.
A testosterone precursor.
Allegedly used by Mark McGwire and Barry Bonds
Compare structure with testosterone.
androstenedione
testosterone

39. Steroids Cortisone A natural glucocorticoid.
Anti-inflammatory activity.
Arthritis
Asthma

40. Steroids Hydrocortisone
Principal glucocorticoid hormone produced by adrenal cortex.

41. Steroids Betamethasone betamethasone hydrocortisone
Synthetic glucocorticoid.
Much stronger than hydrocortisone.
betamethasone
hydrocortisone

42. Steroids Aldosterone A mineralocorticoid steroid.
Regulates absorption of Na+, Cl- by kidneys; water balance in body.

43. Sample Problem
The compound to the right has been isolated from the leaves of Leonotis ocymifolia.
What type of lipid is it?
Locate the isoprene units in the compound.
It has 20 carbon atoms and it follows the isoprene rule – it is a diterpenoid.