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Glycosides

Glycosides are organic plant principles which play an important role in the plant’s protective, regulatory, and sanitary functions. They are a compound that contains a sugar part attached to a non-sugar part called the aglycone [sugar + aglycone = glycoside]. When the sugar part is glucose, the substance may be called a glucoside. Glycosides vary greatly in solubility, but nearly all are soluble in alcohol. Optimal amounts of glycosides are derived with menstrua having 30 percent to 60 percent alcohol. Glycosides are usually of a neutral character until hydrolyzed (reacting with water) in metabolism, at which point they become active. In plants, glycosides are frequently associated with alkaloids, and in many instances they are said to constitute the “active ingredient” of a plant medicine. Glycoside compounds can be broken apart by enzymatic action which can continue after a plant is harvested unless the plant is dehydrated or preserved in alcohol while fresh. Glycosides are distinguished from alkaloids by the ending in. Examples: hypericin—which is also soluble in fixed oil (St. John’s Wort), arbutin (Uva Ursi), glycyrrhizin (Licorice root), aloin (Aloes) and salicin (Willow).

Gums (Gummata)

Gums are contained in great abundance in vegetation. They are exudates that are soluble in water, forming a mucilaginous liquid, or softening to form a jelly-like adhesive mass or paste. All softened forms are emollient or demulcent, and have a soothing, lubricating, and often nutritional quality. The dry concrete (unsoftened) state of this substance is more specifically referred to as a gum. Gums are insoluble in alcohol. When gums are undesirable in a preparation, a solvent such as alcohol is selected so it will inhibit solution of the gummy constituents. (This is an example of employing alcohol’s “negative strength.”) Examples: Acacia, Tragacanth.

Gum-resins (Gummi-resinae)

Gum-resins are milky exudates composed of (1) a gum or gums partly or wholly soluble in water and (2) a resin or resins soluble in alcohol. When triturated and admixed with water, gum-resins yield emulsions, the gum constituent more or less dissolving while the resin is mechanically suspended in the solution. Examples: Myrrh, Asafoetida.

Mucilages

Mucilages (like gums) are expressly soluble in water (they are best extracted in cold water) and insoluble in alcohol. Extraction of mucilaginous constituents must be done with as low an alcohol content as possible. Prove this principle to yourself sometime (intentionally rather than accidentally) by attempting to make a fresh plant Comfrey extract using 190-proof ethyl alcohol. Or, even more entertaining, blend a liquid Comfrey extract with a high alcohol content tincture—herbal escargot! You can salvage the results by adding sufficient water.

Oils (Olea) and fats

Oils are fluid substances, and fats are solid or semisolid bodies, both having a greasy or unctuous feel. Oils are of two types: nonvolatile and volatile.

Non-volatile or fixed oils (Olea pinguia) are organic substances of a semisolid or solid consistency, readily soluble in chloroform and ether, in volatile oils, or other fats. Fixed oils are insoluble in water or glycerin. More than a small amount of fixed oil in a plant tissue will greatly reduce the solvent action of an alcohol or water menstruum. Heated in the presence of alkalis, fixed oils form soaps; an important by-product is glycerin, a tri-atomic alcohol. Glycerin is an excellent extractant and preservative component of a fixed oil. Examples of fixed vegetable oils: Peanut oil, Olive oil, and Castor oil.

Volatile or essential oils (Olea volatilia) are aromatic, flammable liquids obtained predominantly by steam distillation and to a lesser extent by expression (pressing). They are soluble in alcohol and in fixed oils; some essential oils are very slightly soluble in water. Essential oils are volatile, oxidizing, and evaporating upon exposure to air. Not all plants produce essential oils.