'Cynanchum' is a genus of plants in the family Apocynaceae, also known as Milkweed or Dogbane family. These plants are primarily found in tropical and subtropical regions around the world. Some species of Cynanchum have medicinal uses, including treatments for skin conditions, inflammation, and pain relief. However, it's important to note that some species may contain toxic compounds and should only be used under the guidance of a medical professional.

Asclepiadaceae is a former family of flowering plants that is now considered to be part of the larger family Apocynaceae. It was named after Asclepius, the Greek god of medicine and healing, due to the medicinal properties of some of its members. The plants in this family are primarily tropical or subtropical vines, shrubs, and trees that have milky sap and opposite leaves. They are known for their unique flower structure, which includes a corona of fleshy, modified stamens surrounding the central reproductive structures. Some examples of plants that were once classified in Asclepiadaceae include milkweeds (Asclepias spp.), periwinkles (Catharanthus roseus), and mandevillas (Mandevilla spp.).

Pregnanes are a class of steroid hormones and steroids that contain a pregnane nucleus, which is a steroid core with a carbon skeleton consisting of 21 carbons. This structure includes four fused rings, labeled A through D, and is derived from cholesterol.

Pregnanes are important precursors for the synthesis of various steroid hormones in the body, including progesterone, which plays a crucial role in maintaining pregnancy and regulating the menstrual cycle. Other examples of pregnanes include cortisol, a stress hormone produced by the adrenal gland, and aldosterone, a hormone that helps regulate electrolyte balance and blood pressure.

It's worth noting that pregnanes can also refer to synthetic compounds that contain this steroid nucleus and are used in various medical and research contexts.

Pregnenes is not a term that is commonly used in medical terminology. However, in biochemistry, pregnenes are steroid compounds containing a carbon skeleton with nine or more rings. They are precursors to various steroid hormones such as progesterone and cortisol.

Pregnenes are derived from cholesterol through a series of enzymatic reactions that involve the removal of several carbons from the cholesterol molecule. The resulting pregnenolone is then further metabolized to produce other steroid hormones, including progesterone, cortisol, androgens, and estrogens.

Therefore, while not a medical term per se, pregnenes are an essential class of compounds in the endocrine system that play a crucial role in various physiological processes, such as sexual development, stress response, and immune function.

Glycosides are organic compounds that consist of a glycone (a sugar component) linked to a non-sugar component, known as an aglycone, via a glycosidic bond. They can be found in various plants, microorganisms, and some animals. Depending on the nature of the aglycone, glycosides can be classified into different types, such as anthraquinone glycosides, cardiac glycosides, and saponin glycosides.

These compounds have diverse biological activities and pharmacological effects. For instance:

* Cardiac glycosides, like digoxin and digitoxin, are used in the treatment of heart failure and certain cardiac arrhythmias due to their positive inotropic (contractility-enhancing) and negative chronotropic (heart rate-slowing) effects on the heart.
* Saponin glycosides have potent detergent properties and can cause hemolysis (rupture of red blood cells). They are used in various industries, including cosmetics and food processing, and have potential applications in drug delivery systems.
* Some glycosides, like amygdalin found in apricot kernels and bitter almonds, can release cyanide upon hydrolysis, making them potentially toxic.

It is important to note that while some glycosides have therapeutic uses, others can be harmful or even lethal if ingested or otherwise introduced into the body in large quantities.