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Active Constituents of Herbs


Alkaloids vary widely from one plant to another in their components and their actions, but are all compounds that contain nitrogen. They tend to have potent effects and in some cases are toxic in large amounts - they are frequently found in herbs whose use is restricted to qualified medical herbalists and doctors in specified doses, and are often unsuitable for home use.

They include morphine from the opium poppy, nicotine in tobacco, atrophine in deadly nightshade, caffeine and thobromide in coffee, black tea and cocoa.

Alkaloids also occur in small non-toxic amounts in some medicinal herbs where they act as catalysts to other healing agents without being involved themselves - pyrrolizidine alkaloids in comfrey and coltsfoot are good examples.


These are glycosides which are yellow, and were often used in the past to produce dyes. They act to stimulate muscular contractions of the large intestine and so have a laxative effect.

Herbs such as dock, cascara, senna and aloes contain anthraquinones, which taken alone can cause griping in the bowel. For this reason they are best combined with carminative (flatulence-treating) herbs such as ginger or fennel which prevent this from happening.

Such laxative herbs are best used for short term treatment of constipation while the underlying causes are dealt with, for longer use can reduce normal bowel reflexes and cause habituation.


There are many herbal remedies containing bitter ingredients.

These mainly exert their beneficial effect in the digestive tract, stimulating the secretion of digestive juices and enzymes in the stomach and intestines, and the flow of bile from the liver.

They enhance the appetite, improve digestion and absorption. They are prescribed for poor appetite, sluggish bowels, indigestion, gal bladder, liver problems, gastritis, nervous exhaustion, and to aid convalescence after flu or other debilitating illness.

Many bitters have other therapeutic actions; some benefit the immune system, acting as natural antimicrobials and antineoplastic (anti-tumour) rememdies, some have a relaxing effect on the nervous system, some have anti inflammatory action.

Well known bitter tonics include: Dandelion, Dock Root, Rosemary, Burdock and Wood Betony. Their beneficial action on the digestive system begins with their effect on the bitter receptors in the mouth, so for good effect they are best tasted, despite our squeamish palates!


This is a sweet, gel like substance which has hydroscopic properties, that is, it draws water to it, so that on the addition of water it swells up to form a viscous fluid.

Mucilage has wonderful demulcent and emollient properties, forming a protective layer over the mucous membranes, and skin, effectively soothing irritation and relieving inflammation.

Plants with a high mucilage content such as flax or psyllium seeds draw water into the bowel and thereby bulk out the stool and make effective laxative remedies which soothe the gut.


Saponins are glycosides found widely among medicinal plants which, like soap, form a leather when mixed with water.

Soapwort has a high saponin content and can be used to make a natural soap. Saponins have a wide variety of different therapeutic actions in the body. Some, such as in cowslips and mullein, have an expectorant effect; others, such as in horestail and asparagus, act as diuretics. Some, as in horse chesnut, benefit the circulatory system, reducing fragility of the blood vessel walls.

The most interesting and most appropriate for treating a wide variety of women's problems are the steroidal saponins. There are similar in structure and function to human sex hormones, produced by the ovaries, adrenal glands, and in men by the testes. There are steroidal saponins which resemble estrogen, cortisone, cholesterol, and progesterone and there are some known as tri-terpenoid saponins which act to regulate the steroidal hormone activity in the body to counter stress.

Remedies which contain hormone regulating properties are known as "adaptogens", the most famous of which is ginseng. Other adaptogen herbs include: false unicorn root, partridge, berry, blue and bloack cohosh, wild yarn and licorice.


The main therapeutic action of tannins is astringent, as a result, of their ability to bind albumen, a protein present in the skin and mucous membranes of the body, to form an insoluble, protective layer that is resistant to disease.

This protective layer can separate micro-organisms, such as bacteria which threaten to invade the body, from the source of their nutrition, either on the skin, or in the linings of the mouth, digestive, respiratory, urinary and reproductive systems.

Tannins also have healing action, protecting areas treated from irritation, while at the same time reducing inflammation. They are the main therapeutic ingredients in astringents such as: oak, bark, witch hazel and beth root.

Such herbs can be used in compress for cuts and wounds, hemmorrhoids, varicose veins, and in medicine for diarrhea, catarrh, heavy periods, and inflammatory conditions of the digestive tract.