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Steroids

Steroids. Steroids. Steroid A/B and B/C Rings Resemble Decalin. Steroid B/ C, and C/D rings are trans fused. Methyl groups at C-10 and C-13 are “angular” methyl groups. Cholesterol. CH 3. CH 3. CH 3. CH 3. CH 3. H. H. H. HO. Structure of Cholesterol.

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Steroids

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  1. Steroids

  2. Steroids

  3. Steroid A/B and B/C Rings Resemble Decalin

  4. Steroid B/ C, and C/D rings are trans fused Methyl groups at C-10 and C-13 are “angular” methyl groups

  5. Cholesterol

  6. CH3 CH3 CH3 CH3 CH3 H H H HO Structure of Cholesterol • Cholesterol has the fundamental steroid skeleton modified as shown.

  7. Biosynthesis of Cholesterol

  8. CH3 CH3 CH3 CH3 CH3 H H H HO Cholesterol

  9. Vitamin D

  10. CH3 CH3 CH3 CH3 CH3 H H H HO Cholesterol • Cholesterol is the precursor to vitamin D. • Enzymes dehydrogenate cholesterol to introduce a second double bond in conjugation with the existing one. The product of this reaction is called 7-dehydrocholesterol.

  11. 7-Dehydrocholesterol CH3 CH3 • Sunlight converts 7-dehydrocholesterol on the skin's surface to vitamin D3. CH3 CH3 CH3 H H HO

  12. Vitamin D3 CH3 CH3 • Insufficient sunlight can lead to a deficiency of vitamin D3, interfering with Ca2+ transport and bone development. Rickets can result. CH3 CH3 H HO

  13. Bile Acids

  14. CH3 CH3 CH3 CH3 CH3 H H H HO Cholesterol • Oxidation in the liver degrades the cholesterol side chain. Cholic acid is the most abundant of the bile acids.

  15. O CH3 HO OH CH3 CH3 H H H HO OH H Cholic Acid • Salts of cholic acid amides (bile salts) act as emulsifying agents to aid digestion.

  16. Corticosteroids

  17. CH3 CH3 CH3 CH3 CH3 H H H HO Cholesterol • Enzymatic degradation of the side chain and oxidation of various positions on the steroid skeleton convert cholesterol to corticosteroids.

  18. Cortisone O OH CH3 • Corticosteroids are involved in maintaining electrolyte levels, in the metabolism of carbohydrates, and in mediating the allergic response. O OH CH3 H H H O

  19. Sex Hormones

  20. OH H3C H3C H H H O Testosterone • Testosterone is the main male sex hormone.

  21. Estradiol OH H3C • Estradiol is a female sex hormone involved in regulating the menstrual cycle and in reproduction. H H H HO

  22. O H3C H3C H H H O Progesterone • Supresses ovulation during pregnancy. FDA registers Enovid May 11, 1960 an estrogen and a progestin

  23. Elwood V. Jensen (1920-2012) Estrogen & Breast Cancer Enzyme: ER-α Using radiolabeled markers, Dr. Jensen discovered that estrogen (steroid based hormones) bind to a specific receptor protein, ER, in about 30% of breast cancer cells. In those cancers that are ER positive, inhibition of estrogen stops cell growth. What type of enzyme inhibition could best stop the multiplication of breast cancer cells?

  24. Enzyme Inhibition: Estrogen & Breast Cancer Inhibiting a cancer cell’s division Enzyme: ER-α

  25. Estrogen Biosynthesis

  26. Testosterone Biosynthesis “Andro”, Androstenedione*

  27. Enzyme Inhibition: Estrogen & Breast Cancer Inhibiting a cancer cell’s division Cytochrome p450

  28. Enzyme Inhibition Exemestane Androstenedione Letrozole Anastrozole Aromatase: Cytochrome p450

  29. Synthetic Steroids

  30. Recognizing Lipids: Structural Differences

  31. Question • Which of the triglycerides below is optically active? • A) 1 and 3 B) 2 and 3 E) none • C) 3 only D) 1, 2, and 3

  32. Question • Misoprostol is classified as a • A) terpene. B) wax. • C) steroid. D) prostaglandin.

  33. Question • The backbone of cephalosporin P is classified as a • A) prostaglandin. B) steroid. • C) cholesterol. D) sesterpene.

  34. Question • Farnesol is classified as a • A) monoterpene. • B) sesquiterpene. • C) diterpene. • D) triterpene.

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