Phytotherapy

September 17, 2019, 10:44 385

Phytotherapy, the use of plant-derived medications in the treatment and prevention of disease. Phytotherapy is a science-based medical practice and thus is distinguished from other, more traditional approaches, such as medical herbalism, which relies on an empirical appreciation of medicinal herbs and which is often linked to traditional knowledge.There are a number of phytotherapeutic preparations in use. Examples include preparations derived from the leaves of ginkgo (Ginkgo biloba), which are used to treat a range of minor cognitive disorders and certain other disorders of the central nervous system; the aerial parts of St. John’s wort (St. Johnswort; Hypericum perforatum), which typically are used in the treatment of mild to moderate forms of depression; the aerial parts and roots of Echinacea angustifolia (and other species of Echinacea), which are used in the treatment and prevention of the common cold and other respiratory conditions; and parts of African devil’s claw (Harpagophytum procumbens), the root of which is used to treat chronic lower back pain.

Archaeological evidence indicates that the use of medicinal plants dates back to the Paleolithic age, approximately 60,000 years ago. Written evidence of herbal remedies dates back over 5,000 years to the Sumerians, who compiled lists of plants. Some ancient cultures wrote about plants and their medical uses in books called herbals. In ancient Egypt, herbs are mentioned in Egyptian medical papyri, depicted in tomb illustrations, or on rare occasions found in medical jars containing trace amounts of herbs. The earliest known Greek herbals came from Theophrastus of Eresos who, in the 4th century BC, wrote in Greek Historia Plantarum, from Diocles of Carystus who wrote during the 3rd century BC, and from Krateuas who wrote in the 1st century BC. Seeds likely used for herbalism were found in archaeological sites of Bronze Age China dating from the Shang Dynasty (c. 1600–1046 BC). Over a hundred of the 224 compounds mentioned in the Huangdi Neijing, an early Chinese medical text, are herbs. Herbs also commonly featured in the traditional medicine of ancient India, where the principal treatment for diseases was diet.

Herbal teas, or tisanes, are the resultant liquid of extracting herbs into water, though they are made in a few different ways. Infusions are hot water extracts of herbs, such as chamomile or mint, through steeping. Decoctions are the long-term boiled extracts, usually of harder substances like roots or bark. Maceration is the cold infusion of plants with high mucilage-content, such as sage or thyme. To make macerates, plants are chopped and added to cold water. They are then left to stand for 7 to 12 hours (depending on herb used). For most macerates, 10 hours is used.Tinctures are alcoholic extracts of herbs, which are generally stronger than herbal teas.Tinctures are usually obtained by combining 100% pure ethanol (or a mixture of 100% ethanol with water) with the herb. A completed tincture has an ethanol percentage of at least 25% (sometimes up to 90%). Herbal wine and elixirs are alcoholic extract of herbs, usually with an ethanol percentage of 12–38%. Extracts include liquid extracts, dry extracts, and nebulisates. Liquid extracts are liquids with a lower ethanol percentage than tinctures. They are usually made by vacuum distilling tinctures. Dry extracts are extracts of plant material that are evaporated into a dry mass. They can then be further refined to a capsule or tablet.

Many herbs are applied topically to the skin in a variety of forms. Essential oil extracts can be applied to the skin, usually diluted in a carrier oil. Many essential oils can burn the skin or are simply too high dose used straight; diluting them in olive oil or another food grade oil such as almond oil can allow these to be used safely as a topical. Salves, oils, balms, creams and lotions are other forms of topical delivery mechanisms. Most topical applications are oil extractions of herbs. Taking a food grade oil and soaking herbs in it for anywhere from weeks to months allows certain phytochemicals to be extracted into the oil. This oil can then be made into salves, creams, lotions, or simply used as an oil for topical application. Many massage oils, antibacterial salves, and wound healing compounds are made this way. Inhalation, as in aromatherapy, can be used as a treatment

Standardization

A commonly used but often poorly defined concept in phytotherapy is standardization, which is the requirement of having a minimum amount of one or several active compounds or groups of compounds in the plant extract. Often a range from a minimum to a maximum amount is given. In the field of phytotherapy, standardization applies only to extracts and by definition only to those where the active constituents are fully characterized. For example, an extract containing a certain percentage of compound class X (e.g., flavonoids) must contain one specific compound of the group (e.g., the flavonoid rutin). The quantification often is carried out by using chromatography-based techniques (e.g., gas chromatography or high-performance liquid chromatography), capillary electrophoresis, atomic absorption spectroscopy, or mass spectrometry.

Standardization is intended to ensure a reproducible composition of known active constituents. For example, St. John’s wort (H. perforatum) is used in both phytotherapy and herbalism. In the former, the preparations often are industrially produced extracts from the leaves and plant tops that have been standardized according to hypericin and hyperforin content (or sometimes one or the other). These two substances are known to be relevant for their pharmacological effects. The extract is generally formulated as tablets or capsules. By contrast, herbalists are likely to use a tincture of H. perforatum herb that is not standardized on its content of any particular constituent.

References:

  1. https://en.wikipedia.org/wiki/Herbal_medicine
  2. https://www.britannica.com/science/phytotherapy
  3. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/complementary-and-alternative-medicine-products-and-their-regulation-food-and-drug-administration

By Babayeva N.