Active Constituents of Medicinal Herbs

Medical herbs contain active constituents (principles) or parts which have a direct effect on the human body. These constituents have physiological effects on the body which gives them their medicinal effect. There are two kinds of active constituents:

1.Products of primary metabolism, chiefly carbohydrates (such as sugars and starches) amino acids and fatty oils. These substances are produced in the plants through photosynthesis.

2.Products of secondary metabolism (processes resulting in the production of chemicals from the primary metabolites). Though these products often seem to be relatively useless to the plant, they often are very effective medicines in the human body. These constituents include essential (volatile) oils, glycosides, terpenoids, and alkaline substances called alkaloids. A few of these alkaloids include morphine from the Opium Poppy, and ergotamine from the Ergot fungus.

In this section, we will break down each plant into its constituents, but in doing so, it must be remembered that medicinally active constituents usually occur in groups of closely related compounds, together with other substances which (in all probability) potentiate each other’s effect on the healing process. This synergistic effect is one of the herbalist’s greatest advantages over several conventional medicines. Though various synthetic drugs may be more potent and concentrated, they often have severe side effects.

Herbalists have learned that by using the synergy inherent in plant medicines, they are able to effect substantial medicinal effects without the detrimental side effects of many synthetic or prescription medications. Another advantage that herbalists enjoy is in herbs such as Ginger, which reduces inflammation from flu like symptoms at the same time providing anti viral compounds and compounds to reduce nausea... all of this from just one herb, with no harmful side effects.

The active constituents of plant drugs belong to several different chemical groups, among them are: alkaloids, glycosides, saponins, bitter compounds, tannins, essential oils, volatile oils, terpenes, resins, fatty oils, mucilage, pectines, mineral compounds, organic acids, vitamins and carotenoids.

Active Constituents of Medicinal Herbs

 

Alkaloids

Alkaloids are a diverse group of compounds with alkaline properties. The physiological effects of alkaloids center on the circulatory system and the nervous system. Most herbs in this group have a bitter flavor and are poisonous to varying degrees. There are thousands of alkaloids known and many are used medically. Atropine, codeine, morphine and caffeine are all alkaloids. Plant families rich in alkaloids include the Amaryllidaceae (daffodils), Apocynaceae (Periwinkles), Leguminosae (peas), Liliaceae (lilies), Papaveraceae (poppies), Rubiaceae (bedstraws), & Solanaceae (nightshade).

Glycosides

Glycosides are products of secondary metabolism in plants. When they are hydrolyzed glycosides split into two parts, one of several sugars (glucose, fructose, etc.) which are the glycone component, and the non sugar (aglycone) component. Each glycoside is associated with a specific enzyme in the plant. These enzymes are stored in cells at different locations of the plant. When the plant part is chewed or crushed, the cell walls are broken and the enzymes come in contact with the glycoside, hydrolysis occurs and the aglycone is activated. The sugars act synergistically by increasing the solubility of the glycoside and its absorption into the body, as well as facilitating its transportation to specific organs.

Glycosides include some of the most effective plant drugs available, and some of the plants in this group are the most toxic known. Glycosides are classified by the chemical composition of their aglycone part:

1.Cardiac glycosides: they affect the contraction of the heart muscle and are used to correct arrhythmias in the heartbeat. They’re divided into two groups -- bufadienolides (found in Christmas rose) and cardenolides (found in foxglove, lily of the valley, and oleander). 

2.Cyanogenic glycosides: in these the glycosides, the aglycone, is a cyanohydrin compound bonded to a sugar. Upon hydrolysis in the presence of an enzyme (such as saliva n the mouth) prussic acid (hydrogen cyanide) is liberated in minute or larger amounts. Cyanogenic glycosides have antispasmodic, purgative and sedative actions to varying degrees. They are characteristic of the families Caprifoliaceae (Honeysuckles) Linacaeae (Flaxes). 

3.Mustard glycosides (glucosinolates): these glycosides contain bonded sulfur and are characteristic of the Cruciferae (cabbage) family. In plants, they occur in conjunction with the enzyme myrosinase. When broken down, mustard oils are liberated. These are excellent antiseptics due to the sulfur compounds. Mustard glycosides are found in White mustard and Horseradish root to name a few. 

4.Phenolic glycosides: Phenolic glycosides are divided into four main groups; 

a.Simple phenolic glycosides. These compounds contain a simple phenol. They share a characteristic effect and are aromatic. Medicinally they include salicylic derivatives as are found in Willow Bark and Meadowsweet as well as methyl arbutin and arbutin found in the leaves of Bilberry and Barberry. 

b.Coumarin glycosides. These compounds are phenyl propane derivatives. These herbs and plants have a sweet smell like new mown hay. There are several coumarin glycosides. Hydroxycoumarins are found in Horse Chestnut and Ash. Aesculin is the hydroxycoumarin found in Horse Chestnut bark. It has been found to strengthen the capillary walls. Aesculoside is another coumarin found in Horse Chestnut. It absorbs ultraviolet light and is used in sunscreen applications. 

c.Anthraquinone glycoside. All of these are aromatic. These glycosides are pigmented phenolic compounds which readily break down to lose their sugar molecules. Taken internally, many of these phenolic compounds exert a laxative effect, varying from mild to severe. 

d.Flavonoid glycosides. These are aromatic phenolic compounds which include anthocyanins, largely responsible for the yellow blue and red color of flowers, and bioflavonoids. Bioflavonoids are usually yellow in color as is the dried root of licorice. Rutin from Buckwheat and Rue is exceptionally important medically because, like coumarin aesculin, it affects the permeability and strength of the capillary walls. They are used to treat hypertension and other various heart disorders. The flavonoids of Hawthorns are also hypotensives and cardiotonics. 

5.Saponins: consist of a triterpene aglycone (sapogenin) and a sugar group (glucose or galactose). These glycosides are often associated with cardiac glycosides. The chemical composition of saponins is very similar to that of sex hormones and some saponin containing herbs are used in the manufacture of birth control pills. 

Bitter compounds

These herbs have in common a strong bitter taste that irritate taste buds and stimulate the flow of digestive juices and appetite. Some of these herbs activate the secretion of bile and others increase urine production. They are found in members of the Compositae (daisy) and the Gentianaceae (gentian) families.

Tannins

Tannins are complex polyphenolic compounds that all have the ability to coagulate proteins, alkaloids and heavy metals. This is true, however, only as long as they are fresh enough to dissolve in water. The two types of tannins are condensed tannins (polymers derived from flavonoids) and hydrolysable tannins (esters of gallic acid and glycosides of these esters). Tannins have astringent and antiseptic properties but their chief value in medicine lies in their ability to precipitate proteins in mucous membranes and other tissues, causing a thin layer of coagulation to form. This precipitated matter destroys bacteria by depriving them of nutrition, aiding in the healing of wounds and inflamed mucosa. Tannins also decrease pain by decreasing sensitivity to the inflamed area. Tannins are used in medicines for diarrhea, bronchitis, wounds, hemorrhoids, and mouth and gum infections. Tannins are plentiful in Betulaceae (birch), Ericaceae (willow), and Rosaceae (rose).

Essential oils

Essential oils (volatile oils) are liquid components of plant cells. Unlike fatty or fixed oils, they do not leave a permanent mark on paper. Essential oils primary constituents are complex mixtures of terpenoid substances. Exposed to air or light essential oils oxidize and become less effective.

Medicinally essential oils act as digestive tonics, antiseptics, carminatives, anthelmics, antirheumatics, rubefacients and anti-inflammatories. Many of the essential oils are used for flavoring and are also included in proprietary medicines. These include menthol, thymol and others.

Fatty (fixed) oils

Fatty oils from plants are mixtures of triglycerides, which are water insoluble, but dissolve in organic solvents. Many plant and vegetable oils contain substantial amounts of unsaturated fatty acids and are liquid at room temperature but congeal and become opaque at cooler temperatures. A few of these fatty oils used in medicine include almond oil, corn oil, flax oil, and castor oil.

Mucilages and pectins

Plant mucilages are amorphous mixtures of polysaccharides that dissolve in water to form extremely viscous colloid systems. In cold water they swell and form a slimy gel. In hot water they dissolve, then gel when the water cools. Most are formed by the cell walls of plants. When mucilages pass through the digestive or respiratory tract they leave a thin protective coating over mucous membranes that protect the membranes from irritation. For this reason they are used to treat infections of the chest, intestine and throat. In small doses they slow the peristalsis thereby having an antidiarrheal effect. In large doses they have just the opposite effect and are used to treat constipation. In large doses they are an extremely effective laxative. Pectins (found in quinces, for example) are classified as plant mucilages because both are polysaccharides and form gels in the same way. They are also used in the treatment of diarrhea.

Terpenes

A hydrocarbon derived from essential oils, resins and other vegetable aromatic products.

Vitamins

Herbs consistently have many minerals and trace elements that the body requires. It will be noted when you are looking at the herb constituents that they contain all of the phytochemicals (plant chemicals) and trace elements necessary to form a complete supplementary system to assist their actions. They contain very small amounts of vitamins for the most part. For vitamin supplementation it is much easier to get high vitamin dosages from multiple vitamins than from herbs.