_" STEROID "_

       Steroids are organic compounds are not hydrolyzed fatty sterols can dihasil reduction reaction of terpene or skualena. Steroids are an important group of compounds with the basic structure sterana saturated with 17 carbon atoms and 4 rings.

Compounds which include derivatives of steroids, such as cholesterol, ergosterol, progesterone, and estrogen. In general, function as steroid hormones. Steroids have a basic structure consisting of 17 carbon atoms that make up the three cyclohexane rings and one cyclopentane ring. Different types of steroids are steroids that another one is on the functional group is bound by the four-ring oxidation and phase of each ring.  

       Some are anabolic steroids, such as testosterone, metandienon, nandrolone decanoate, 4-androstena-3 17-dione. Anabolic steroids can lead to a number of dangerous side effects, such as lowering the ratio of high density lipoprotein, which is useful for the heart, lowers low-density lipoprotein ratio, stimulation of prostate tumor, coagulation abnormalities and liver disorders, hair loss, thickening hair, acne and the incidence of male breast . In physiology, anabolic steroids can make a person aggressive.

       Steroids are made ​​up of several groups of compounds and grouping based on the physiological effects provided by each groups .

The group are sterols, bile acids, sex hormones, hormone adrenokortikoid, cardiac aglycone, and sapogenin.

In terms of molecular structure, the differences between the various groups steroidini determined by:

• Type substituents R 1, R 2and R 3, which bound to the carbon framework, as noted above
• The difference between the compound one another from certain suatukelompok determined by- carbon chain length of R 1
• functional groups present on the substituents R 1, R 2and R 3
•  The number and position of the oxygen functional groups and double bonds
• And the configuration of the asymmetric centers in the framework dasarkarbon it.

Some examples that represent each of the groups on the list of steroid diatastercntum 4.1.

Listing 4.1. Some natural steroid

Sterol :

ERGOSTREOL

STIGMASTEROL

Sex Hormones :

Sapogenin :

SARSAPOGENIN

               Another example of lipid types of steroids are sex hormones for men and womensuch as testosterone, estradiol and progesterone. The molecular structure and function can be seen in Table 14.8.
Table 14.8. Types of hormones and physiological function

           

          All steroids are made in cells with raw materials such as fatty sterols, either lanosterol in animals or function, or in the form sikloartenol in plants. Both types of fat on top is made of sterol cyclization squalena of triterpena. Cholesterol is a sterol other types of fat are common.

Biosynthesis Of Steroid

         Biogenetics Experiments show that steroids are derived from triterpenes in nature. Steroids found in animal tissue derived from triterpene lanosterol, while present in plant tissues derived from triterpenes sikloartrenol, after experiencing a series of triterpenes certain changes. Early stages of the biosynthesis of steroids are the same for all natural steroids, namely the conversion of acetic acid through mevalonic acid and skualen (a triterpene) to lanosterol or sikloartrenol.

            Biosynthesis of steroid hormones including testosterone begin with the transformation of cholesterol to pregnenolone. Setting steroid hormone biosynthesis mediated by an increase in cAMP-and Ca +2 intaselular melaluijalur inositol triphosphate. Stimulation of cAMP can be acute or chronic. Acute stimulation began delivery of cholesterol to the inner mitochondrial steroidogenic acute mediated regulatory (StAR), whereas chronic stimulation occurs during the conversion of cholesterol to pregnenolone. In this stage, the conversion process takes place in the mitochondria by putting side chain cleavage enzyme (scc). 

NADPH, oxygen and cytochrome P450 on a limited basis as needed. Unlike the protein hormone receptors, steroid receptors located in the cell cytoplasm or nucleus. At first hormone into cells by diffusion and bind to receptor proteins immediately spesifikdi in the cytoplasm. Streroid hormone receptors are inactive are in a heat shock protein 90 (hsp 90). In the event of ties between the hormone and the receptor, the hsp 90 becomes active and self meleaskan. Then the bonding hormone and the receptor will soon be heading to the nucleus. In the nucleus, the bonding hormone receptor complex affects the transcription factor koaktivator and thoroughly to produce an active transcriptional complex that would enhance gene expression and hormone effects sterid.