The medicinal effects of certain plants are well known. German chamomile, for instance, has been taken to alleviate stomach related issues for a great many years, and aloe Vera was referred to Cleopatra as a healing skin remedy.
It is only relatively recently, however, that active constituents responsible for the medicinal actions of plants have been isolated and observed. Knowing a little about the chemicals contained in plants helps you to understand how they work within the body.
Do Plants Make You Feel Better
The Phenols are a very varied group of plant constituents ranging from salicylic acid, a molecule similar to aspirin (acetylsalicylic acid), to complex sugar containing phenolic glycosides. Phenols are often anti inflammatory and antiseptic, and are thought to be produced by plants to protect against infection and feeding by insects.
Phenolic acids, such as rosmarinic acid, are strongly antioxidant and antiinflammatory, and can also have antiviral properties. Wintergreen and white willow both contain salicylates. Many mint family members contain phenols—for example, the strongly antiseptic thymol, found in thyme (Thymus vulgaris).
Like vegetable foods, many medicinal plants provide high levels of minerals. Plants, especially organically grown ones, draw minerals from the soil and convert them into a form that is more easily absorbed and used by the body.
Whether plants are eaten as a vegetable, like cabbage, or taken as a medicine, like bladderwrack, in many cases the mineral content is a key factor in the plant’s therapeutic activity within the body. Dandelion leaf is a potent diuretic, balanced by its high potassium content, while the high silica content of horsetail supports the repair of connective tissue, making it useful in arthritis.
Bitters are a varied group of constituents linked only by their pronounced bitter taste. The bitterness itself stimulates secretions by the salivary glands and digestive organs. Such secretions can dramatically improve the appetite and strengthen the overall function of the digestive system.
With the improved digestion and absorption of nutrients that follow, the body is nourished and strengthened. Many herbs have bitter constituents, notably wormwood, chiretta and hops
Volatile oils which are extracted from plants to produce essential oils are some of the most important medicinally active plant constituents, and are also used widely in perfumery. They are complex mixtures often of 100 or more compounds, mostly made up of monoterpenes molecules containing 10 carbon atoms. Essential oils have many uses.
Tea tree oil is strongly antiseptic, while sweet gale oil is an effective insect repellent. On distillation, some essential oils contain compounds not found in the volatile oil chamazulene, found in German chamomile essential oil, is anti-inflammatory and antiallergenic. Resins—sticky oily substances that seep from plants, for example from the bark of Scots pines are often linked with essential oils (oleoresins) and gums (see Polysaccharides), though they are nonvolatile.
Found only in types of the mustard and cabbage family, glucosilinates have an aggravation impact on the skin, causing irritation and rankling. Applied as poultices to painful or aching joints, they increase blood flow to the affected area, helping to remove the buildup of waste products (a contributory factor in many joint problems).
On eating, glucosilinates are separated and produce a solid, impactful taste. Radish and watercress are typical glucosilinate containing plants.
Tannins are delivered to a more prominent or lesser degree by all plants. The harsh, astringent taste of tannin-laden bark and leaves makes them unpalatable to insects and grazing animals. Tannins are polyphenolic intensifies that agreement and astringe tissues of the body by official with and encouraging proteins henceforth their utilization to “tan” calfskin.
They also help to stop bleeding and to check infection. Tannin-containing herbs are used to tighten up over-relaxed tissues as in varicose veins to dry up excessive watery secretions as in diarrhea and to protect damaged tissue such as skin problems resulting from eczema or a burn. Oak bark and black catechu are both high in tannins.
In spite of the fact that regularly disregarded, numerous restorative plants contain helpful degrees of vitamins. Some are well known for their vitamin content, for example dog rose has high levels of vitamin C, and carrot is rich in betacarotene (pro-vitamin A), but many are less well recognized.
Watercress, for example, contains appreciable levels of vitamins B 1, B2, C, and E as well as beta-carotene, while sea buckthorn can be regarded as a vitamin and mineral supplement in its own right.
Closely related to tannins and flavonoids, these polyphenolic compounds are pigments that give flowers and fruits a blue, purple, or red hue. They are powerfully antioxidant and free-radical scavengers. They protect the circulation from damage, particularly the circulation in the heart, hands, feet, and eyes. Blackberry, red grapes, and hawthorn all contain appreciable quantities of these proanthocyanidins.
Alkaloids – A very mixed group, alkaloids mostly contain a nitrogen-bearing molecule (-NH2) that makes them particularly pharmacologically active. Some are notable medications and have a perceived therapeutic use.
Vincristine, for example, derived from Madagascar periwinkle, is used to treat some types of cancer. Other alkaloids, such as atropine, found in deadly nightshade have a direct effect on the body, reducing spasms, relieving pain, and drying up bodily secretions.
Coumarins of various types are found in many plant species and have broadly different activities.
The coumarins in melilot and horse chestnut help to keep the blood thin, while furanocoumarins such as bergapten, found in celery, stimulate skin tanning, and khellin, found in visnaga, is a powerful smooth-muscle relaxant.
Found in all plants, polysaccharides are multiple units of sugar molecules linked together. From an herbal point of view, the most important polysaccharides are the “sticky” mucilages and gums, which are commonly found in roots, bark, leaves, and seeds. Both mucilage and gum soak up large quantities of water, producing a sticky, jelly-like mass that can be used to soothe and protect irritated tissue, for example, dry irritated skin and sore or inflamed mucous membranes in the gut.
Mucilaginous herbs, such as slippery elm and linseed or flaxseed, are best prepared by soaking in plenty of cold water. Some polysaccharides stimulate the immune system, for example acemannan, which is found in the leaves of aloe vera.
The main active constituents in many key medicinal plants, saponins gained their name because, like soap, they make a lather when placed in water. Saponins occur in two different forms steroidal and triterpenoid. The chemical structure of steroidal saponins is similar to that of many of the body’s hormones, for example estrogen and cortisol, and many plants containing them have a marked hormonal activity.
Wild yam from which the contraceptive pill was first developed, contains steroidal saponins. Triterpenoid saponins occur more commonly for example in licorice and cowslip root but have less hormonal activity. They are often expectorant and aid absorption of nutrients
Anthraquinones are the main active constituents in herbs such as senna and Chinese rhubarb, both of which are taken to relieve constipation.
Anthraquinones have an aggravation laxative impact on the digestive organ, causing withdrawals of the intestinal dividers and invigorating defecation roughly 10 hours subsequent to being taken. They also make the stool more liquid, easing bowel movements.
Found in various medicinal plants, notably in foxgloves and in lily of the valley (Convallaria majalis, p. 194), cardiac glycosides such as digitoxin, digoxin, and convallotoxin have a strong, direct action on the heart, supporting its strength and rate of contraction when it is failing.
Cardiac glycosides are also significantly diuretic. They help to stimulate urine production, thus increasing the removal of fluid from the tissues and circulatory system.
Though these glycosides are based on cyanide, a very potent poison, in small doses they have a helpful sedative and relaxant effect on the heart and muscles.
The bark of wild cherry and the leaves of elder both contain cyanogenic glycosides, which contribute to the plant’s ability to suppress and soothe irritant dry coughs. Many fruit kernels contain significant levels of cyanogenic glycosides, for instance those of apricot.
Found widely throughout the plant world, flavonoids are polyphenolic compounds that act as pigments, imparting color, often yellow or white, to flowers and fruits. They have a wide range of actions and many medicinal uses.
They are antioxidant and especially useful in maintaining healthy circulation. Some flavonoids also have anti-inflammatory, antiviral, and liver-protective activity. Flavonoids such as hesperidin and rutin, found in many plants, notably buckwheat and lemon, strengthen capillaries and prevent leakage into surrounding tissues. Isoflavones, found for example in red clover are estrogenic and valuable in treating menopausal symptoms
Source – Andrew Chevallier (Encyclopedia of Herbal Medicine)