Carotenoids are yellow or red pigments found in all photosynthesizing plants. With anthocyanins they contribute to autumn foliage shades when chlorophyll is lost. There are two types of carotenoids: the carotenes and xanthophylls. Carotenes are hydrocarbons (tetraterpenes), which are converted to vitamin A in the body. Xanthophylls are oxygenated derivatives of carotenes; they have no provitamin A activity.
Medicinal plants contain varying amounts of mineral substances, but they are rarely prescribed to replace minerals that have been lost from the body. Silicic acid is especially characteristic of horsetails and grasses, and some members of the Labiatae (mint) and Boraginaceae (borage) families (for example, Hemp nettles and Common Gromwell). Common Gromwell also contains abundant calcium salts, and nettles and Watercress iron. Potassium salts are found in Dandelion, Kidney Bean and Nettles, and in some fruits. Plants rich in potassium may be useful in low-sodium diets.
Few plants contain sufficient amounts of any vitamin for them to be medically prescribed when there is a deficiency, but any vitamin-rich herb is an excellent addition to the diet, especially during the winter months. As examples; Carrot, Dandelion and Watercress are sources of carotenes, which are precursors of vitamin A; many cereals, including Common Oat, are good sources of vitamin B complex; vitamin C is abundant in fruits such as Black Currant, Green Pepper and Sea Buckthorn, and in the leaves of Dandelion, Nettles, Parsley and Watercress; vitamins D and E are found in Watercress; and nettles are a source of vitamin K. The vitamin content is always greatest in fresh, uncooked plant parts.
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 warm water they dissolve into colloid systems that gel when cooled. Most are formed by the plant cell walls.[ Members Only Content - please sign up to view it... ]
Most of the volatile oils are based on simple molecules like isoprene or isopentane, which can combine in many different ways to form terpenes, containing multiples of the basic 5-carbon molecules, sometimes with slight variation, making up the volatile oils. We can find the volatile oils in the aromatic plants such as Peppermint or Thyme,[ Members Only Content - please sign up to view it... ]
Here we show you how things work.
The Chemistry of Herbs
Plants contain a vast range of chemicals, ranging from water and inorganic salts, sugars and carbohydrates to highly complex proteins and alkaloids. We will focus here on the role these substances have to play, not in the plant itself, but in the body. We will mainly concentrate on the groups that act medicinally, though we shall look at some which are important nutrients and thus influence the body.
We will look at plant pharmacology, briefly examining the various groupings that the numerous constituents have been divided into, looking at their function, and giving some examples of where they occur. These groupings are referred to throughout the newsletters, website and the encyclopaedia and, as far as they are known, the relevant constituents are given in the Medicinal herbs explained. The groupings followed here are based on the structure of the constituents rather than on their function, which is dealt with in the section on The Actions of Herbs.
Knowledge of plant pharmacology is not essential to a herbalist, but is a great help in understanding the plant.