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Copyright © 1997 by Academic Press. All rights of reproduction in any form reserved.

All steroids belong to the chemical class of substances known as terpenoids or terpenes. Other biologically important terpenoid compounds include the plant hormones gibberellic acid and abscisic acid, insect hormone (juvenile hormone), farnesol (a plant oil), and plant-produced isoprenoids, which include carotene (a precursor of vitamin A), ubiquinone (a vitamin K analog), plastoquinones (participants in photosynthesis), and natural rubber. All terpenoids have in common the same two C5H8 isoprene precursors employed for their biosynthesis, namely, isopentenyl pyrophosphate and dimethylallyl pyrophosphate. These structural relationships are summarized in Figure 2-1.

B. Historical Perspective

The development of our modern understanding of hormones and the science of endocrinology has closely paralleled studies on the isolation, chemical character ization, and synthesis of steroids and the subsequent elucidation of their pathways of biosynthesis and ca-tabolism. However, the foundation of many of these developments with steroid hormones is to be found in a lengthy series of papers that appeared in the late 1920s and early 1930s from Professor A. Windaus' laboratory in Gottingen, Germany, and led to the structural determination of cholesterol. This was an extraordinarily challenging problem given the limitation that the techniques of nuclear magnetic resonance spectroscopy (NMR), mass spectrometry, and ultraviolet (UV) and infrared (IR) spectroscopy were not available at that time. Instead, the structure was determined through elaborate classical organic chemistry manipulations, which involved the conversion of the compound under study to known reference compounds. At the present time, application of the powerful separation techniques of high-performance liquid chromatog-

Cardiac glycosides Bile acids

Sapogenins

Cardiac glycosides Bile acids

Sapogenins

Hormones Estrogens Androgens Mineralocorticoids Glucocorticoids Vitamin D + metabolites Ecdysterone

Cholesterol (3)

Cholesterol (3)

Cephalosporin P (an antibiotic) Squalene

Hormones Estrogens Androgens Mineralocorticoids Glucocorticoids Vitamin D + metabolites Ecdysterone

Alkaloids

Rubber

Cure Tennis Elbow Without Surgery

Cure Tennis Elbow Without Surgery

Everything you wanted to know about. How To Cure Tennis Elbow. Are you an athlete who suffers from tennis elbow? Contrary to popular opinion, most people who suffer from tennis elbow do not even play tennis. They get this condition, which is a torn tendon in the elbow, from the strain of using the same motions with the arm, repeatedly. If you have tennis elbow, you understand how the pain can disrupt your day.

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