Phytotherapy- a bit of Science.
The chemistry of herbs is subtle and complex, all herbs being very powerful chemical factories. The main active constituents fall into eight main groups: Acids; carbohydrates; phenols; volatile (essential) oils; saponins; glycosides; bitters and alkaloids.
ACIDS: Present in all plants e.g. cichroic acid in Echinacea; citric and ascorbic acid in oranges.
CARBOHYDRATES: Constructed from sugars (saccharides). Recent studies investigating polysaccharides have shown that some compounds have significant immune system stimulating effects, most notably Echinacea augustiflora, Calendula officinalis and Matricaria recutita. Aloe vera is also very high in useful polysaccharides.
PHENOLS: These provide a base for several important active constituents. They are anti-bacterial and antiseptic, e.g., Oil of Thyme contains phenols and can be used as an antiseptic. Another example is Salicin, the precursor of Salicylic acid, from white willow bark, the basis for the aspirin group. Two of the useful phenol subgroups are flavonoids and tannins Flavonoids have several significant properties including antispasmodic, anti-inflammatory, antiseptic and diuretic actions. They are the most widely found phenols in the plant kingdom. Commonly known plants such as ginkgo, crataegus and milk thistle, all contain flavonoids. Tannins are also widely distributed. Their astringent properties are particularly useful for treating wounds and burns. Another group known as anthraquinones possess valuable laxative actions, and are present in plants such as rhubarb, buckthorn and cascara.
VOLATILE OILS: Often referred to as ‘essential oils’, volatile refers to their evaporative properties. They often have a pleasing fragrance, and many have antiseptic and warming properties e.g., menthol, camphor, lavender oils.
BITTERS: Stimulate the autonomic nervous system. An example of their use is with Centaury, in improving digestive function. They activate the bitter sensory area of the tongue, causing a reflex secretion of hormones into the blood, increasing the production of gastric and pancreatic juices and bile.
ALKALOIDS: Commonly found in many plant tissues, they are colourless and odourless. They behave in an alkaline fashion, and can combine with acids to form salts. They all have a bitter taste, and most are soluble in alcohol, but not water. Caffeine is an alkaloid. They are the most potent of all plant constituents and many, though by no means all can be toxic, and require careful use. A plant generally contains a number of related alkaloids, for example the opium poppy contains morphine, codeine and papaverine.
VITAMINS AND MINERALS: Fruit and vegetable, indeed, plants in general, are a rich source of these. Trace elements and minerals are present in most plants.
MUCILAGES: Extremely common in plants, they are facilitatory to the effective action of many herbal prescriptions. They are composed of polysaccharides, partly soluble in water, and swell up to form a mucilaginous gel. All mucilages soothe internal mucosa, especially upper respiratory tract and digestive mucosa. They can help to promote regular, rhythmic bowel activity, aiding against constipation and problems arising from sluggish bowel.