University of California
Type of paper: Thesis/Dissertation Chapter
Thin-Layer Chromatography of Steroid Hormones
The purpose of this experiment was to test the solubility of various steroids in order to obtain more information about their structure. An unknown was also given to be included in the experiment. The test that was performed was thin-layer chromatography which required a glass plate. The known steroids used in this experiment were estradiol, hydrocortisone, cortisone, corticosterone and deoxycorticosterone. Introduction Steroid hormones are a subgroup of lipids. They are found in one of the primary endocrine glands in the body, the adrenal glands, which are located directly superior to the kidneys.
The structures of the adrenal glands begin with the outer layer known as the cortex. This region is most commonly referred to as the adrenal cortex and provides the gland with approximately 80% of its total mass. Within the adrenal cortex there are three layers: the outermost layer is known as the zona glomerulosa, the middle layer is known as the zona fasciculata, and the innermost layer is known as the zona reticularis. Each of these layers is comprised of many cells that synthesize and secrete hormones appropriately named the adrenocorticoids. The second portion of the adrenal gland is known as the adrenal medulla.
It is the inner region and account for the remaining 20% in each of the adrenal glands. The adrenal medulla is responsible for the release of epinephrine and norepinephrine into the bloodstream. Adrenocorticoids include three types of steroid hormones. Each class belongs to a specific layer in the adrenal cortex and each class secretes specific hormones. The first group of adrenocorticoids is referred to as mineralcorticoids. These hormones are secreted by the zona glomerulosa and are responsible for the regulation of both the reuptake of sodium and the secretion of potassium.
The mineralcorticoid used in this experiment was the more potent, deoxycorticosterone. Abnormal levels of minercorticoids can be associated with hypertension and can be induced by various problems, such as, low blood sodium, high blood potassium, cardiac failure, kidney failure, or even cirrhosis of the liver. The second group of adrenocorticoids is referred to as the glucocorticoids. These are produced by the second layer in the adrenal cortex, the zona fasciculata. The functions of glucocorticoids include stimulating gluconeogenesis through the use of amino acids and breaking down of muscle proteins.
In this experiment the glucocorticoids used were hydrocortisone and corticosterone. These hormones are used medically to suppress the immune system by inhibiting the inflammation process. However, too much secretion of these hormones can be indicative of Cushing’s syndrome, pregnancy, and stress that comes from disease or other sorts of bodily trauma. The third group of adrenocorticoids that will be discussed are sex hormones. Sex hormones are not only secreted by the adrenal cortex. They are largely secreted in the reproductive system of each respective gender.
Sex hormones can be further categorized into androgenic hormones, estrogenic hormones, and progestational hormones. Androgenic hormones are found predominately in the testes of the male, and there is it secreted by the interstitial Leydig cells. The most common and most powerful androgenic hormone is testosterone. Estrogenic hormones are only slightly different from their counterparts. Estrogenic hormones are identified by their 18 carbon ring structure whereas androgens are identified by their 19 carbon ring structure. Estrogenic hormones are secreted by the female reproductive organs known as the ovaries.
The most potent estrogenic hormone is called estradiol and its release fluctuates throughout a woman’s menstrual cycle, with its peak volumes being around the time of ovulation. The last subgroup of sex hormones is called progestational hormones, or progesterone. Progesterone is responsible for the final maturation of the endometrium. Located in the ovaries, it is released from the corpus luteum during the luteal phase of the menstrual cycle and also increases in volume during pregnancy as the fetus progresses. Progesterone is different from the other two classes of sex hormones in that it is a 21 carbon ring structure.
The modality used in this experiment was a chromatogram. Thin-layer chromatography is the type of chromatography that uses a small glass sheet covered in a thin layer of an adsorbent material. Once solutes are obtained, they are carefully placed on the glass sheet on the origin line. Then the glass sheet is soaked in a solvent for a certain period of time that varies with each chromatography technique. After it is through soaking, the solutes can be observed and the distance that each solute has moved can be measured.
This value is obtained by using the R? ormula which takes the distance a solute travels from the origin line divided by the distance that the solvent traveled (this measure is known as the solvent front). This R? value can help determine unknowns as well. The final result of this experiment is known as a chromatogram, and depending on which technique is used, the steroids can be seen through regular light, or via a UV lamp. A UV light lamp was required for this experiment. Chromatography is a very useful tool in identifying the solubility properties of steroid hormones and revealing variants in hormone structure.