Active Constituents of Plants
The active constituents of plants are the chemical compounds that are responsible for their various medicinal actions, both in the body and on the skin.
Plant-derived active constituents specifically include volatile oils, phenols, tannins, flavonoids, saponins and a variety of other components as outlined below.
By understanding a little about some of the chemical constituents found in plants, we may find it easier to better understand how and why they work on the skin.
These are the aromatic compounds extracted from plants to produce essential oils, which are their most medicinally active components.
Essential oils are usually made up of 100 or more compounds, such as a-pinene, b-pinene, citral, citronellol, eugenol, farnesol, geraniol, limonene, linalool and nerol. Each compound within an essential oil gives the oil its active properties.
For example, chamazulene, which is found in Chamomile (Matricaria recutita), is a strong anti-inflammatory and, as such, is consumed as a soothing tea and included in many skin care products.
Phenols are a varying group of compounds which inlude salicylic acid (Willow) and rosmarinic acid (Rosemary).
Phenols are usually strongly antibacterial, antioxidant, anti-inflammatory, anti-septic and anti-viral, and are found in plants such as basil, cinnamon, thyme, wintergreen, rosemary and the mints.
It is believed phenols are present in plants in order for the plant to ward off infection or attack by insects. In skin care products, phenol-containing herbs are often used as contributors to natural preservative systems.
Tannins are polyphenolic compounds that are astringent, meaning they tend to shrink or constrict body tissues, making them useful for tightening up loose tissue, such as that which is found in varicose veins, and for drying up secretions.
Tannins are styptic (they help stop bleeding) and somewhat disinfectant on the skin. Some of the plants that contain strong tannins include Ladies Mantle (Alchemilla vulgaris), Elder Flowers (Sambucus nigra) and Witch Hazel (Hamamelis virginiana) and, as such, extracts of these herbs are often found in natural facial toners.
Flavonoids are polyphenolic compounds found in a wide variety of plants. They impart a yellow or white pigment to flowers and fruit and have a wide range of activity. Flavonoids are particularly useful for maintaining healthy circulation and some are antioxidant, while others are anti-inflammatory, anti-viral or capillary strengthening (eg. Lemon - Citrus limon).
Many key medicinal plants contain Saponins as their main ingredient. As the name suggests, saponins make a lather, like soap, when mixed with water. One useful type of saponin for skin care is a triterpenoid saponin, which can be found in herbs such as Licorice root (Glycyrrhiza glabra). This particular saponin can aid the absorption of nutrients.
Proanthocyanins are the pigments that give berries and flowers a blue, red or purple color. They are closely related to tannins and flavonoids and are powerful antioxidants, making plants that contain these especially useful in anti-aging skin care products. Proanthocyanins are found in fruits such as grapes (Vitis vinifera) or black currants.
Polysaccharides are found in all plants, however the most important polysaccharides in terms of their medicinal value to the skin, are those that are mucilagenous, or gum-like. Mucilagenous polysaccharides can form a soothing gel that protects and hydrates irritated skin tissue. Mucilagenous polysaccharide is found in Marshmallow (Althea officinalis), a well known and often used skin care herb.
Glucosilinates are irritant and produce inflammation and blistering on the skin. They are found exclusively in the mustard and cabbage family of plants, which includes Nasturtium (N. officinale - Watercress). It is generally best to avoid this chemical in skin care, particularly if the individual has sensitive skin.
Vitamins and Minerals
Surprisingly to many, numerous plants contain a considerable number and quantity of vitamins and minerals, some of which are highly beneficial to the skin. For example, Stinging Nettles (Urtica dioica) contain a substantial amount of Vitamins A and C, as well as iron, and Sea Buckthorn Berry (Hippophae rhamnoides) contains one of the highest natural sources of vitamins A, E and carotenes, and very high amounts of vitamins B, C, K and P, all wonderfully useful for the care of the skin.
There are also some very specific actives that are found in individual plants but not found in others. For example, Oenothein B is a unique compound found in Fireweed (Epilobium angustifolium) and is a potent anti-irritant.
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