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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.

  23. Synthetic Steroids

  24. Recognizing Lipids: Structural Differences

  25. 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

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

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

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

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