Biol 1300 Unit 14 Medicinal Plants PDF

**Biol 1300 Unit 14** **MEDICINAL PLANTS** **HISTORY OF PLANTS IN MEDICINE** Plants have been used for medical purposes for at least 5,000 years, providing important pharmaceutical agents like hormones, antibiotics, narcotics, and antihistamines. They also produce hallucinogenic, poisonous, and p...

**Biol 1300 Unit 14** **MEDICINAL PLANTS** **HISTORY OF PLANTS IN MEDICINE** Plants have been used for medical purposes for at least 5,000 years, providing important pharmaceutical agents like hormones, antibiotics, narcotics, and antihistamines. They also produce hallucinogenic, poisonous, and pesticidal substances. They were used to treat a variety of common ailments, e.g. to relieve pain, treat fevers, and heal wounds. For example, ephedra, a source of amphetamine-like stimulants, has been used in Chinese medicine for over 5,000 years to treat asthma and other ailments, while the opium poppy has been a source of pain relievers like morphine and codeine for centuries. In early societies, those knowledgeable about plants and their curative properties were highly esteemed. The earliest pharmacopoeias, or herbal books for medicinal plants, were compiled in Egypt and Arabia, and later in China and Europe. Many early societies believed in the doctrine of signatures, which suggested that a plant\'s appearance indicated its healing properties. For example, heart-shaped leaves were thought to cure heart ailments, and plants with yellow juice were believed to treat jaundice (a blood disorder, a symptom of which is yellowing of the skin). This doctrine was followed by Ancient China, Medieval Europe, and some indigenous groups in western North America. Many medicinal drugs today are still derived directly from plants, as they are not easily or cheaply synthesized in labs. Around 80-100 plant genera are used in modern Western medicine, with even more in other cultures. Approximately 25-30% of Western medicines (about 400-500 drugs) are based on plant chemicals, rising to 50% if microbial and fungal products (e.g. penicillin) are included. The global trade in medicinal plants, estimated at \$30 billion USD in 2002, is split equally between prescription drugs and over-the-counter preparations. Up until the 1950s, over 80% of Western medicines were plant-based. Today, many of these drugs are chemically synthesized. For example, salicylic acid, the main ingredient in aspirin, was originally derived from willow bark (Salix alba). However, more complex chemicals like plant cardiac glycosides (used for heart disease) and morphine derivatives (used for chronic pain relief) are still obtained from plants because they are difficult and expensive to produce synthetically. **PLANT BIOCHEMISTRY** Medically active chemicals are mainly secondary products produced by both plant and fungal species. Secondary products, while not essential to plant survival, are thought to serve as defenses against herbivores by being bitter-tasting, or they attract pollinators and fruit dispersers with bright colors and appealing tastes and smells. Additionally, secondary products help neutralize waste products and toxins, as plants lack an excretory system to dispose of waste. Three major groups of secondary products are of medical significance: **Alkaloids**: These are nitrogenous ring compounds that generally affect the central nervous system (often they are toxic at higher concentrations); examples include caffeine, morphine, quinine, strychnine and nicotine. **Terpenoids**: These consist of two or more five-carbon isoprene units; examples include various essential (or aromatic) oils, as well as the cardiac and steroidal terpenoid glycosides (terpenes with an attached sugar molecule). **Phenolics**: These compounds consist of aromatic rings with one or more hydroxyl (OH) groups; examples include numerous plant pigments, poisons, and various medicinal drugs. Plant medicines have gained attention from Western medical researchers through various means. Some were introduced via traditional folk medicine, like the calabar bean, used as a ritualistic tribal medicine and poison in Africa. An alkaloid derived from this plant is now used for treating glaucoma. Other important secondary products to treat eye conditions include atropine (belladonna plant), cocaine (coca plant), pilocarpine (jaborandi plant), and berberine (golden seal and barberry). Others, initially seen as dangerous poisons, proved beneficial in moderate doses. For example, curare (Strychnos toxifera), a toxic arrow poison used by South American tribes, became a revolutionary muscle relaxant in modern surgery in the 1940s. **SOME IMPORTANT MEDICINAL PLANTS** **QUININE** (Cinchona calisaya): Quinine, an important anti-malarial agent derived from the bark of a South American tree, cinchona, was discovered by 17th-century Europeans and aided their colonization of malaria-infested tropical regions. Quinine\'s related chemical, quinidine, is used to treat heart disease. While most quinine and antimalarial drugs are now chemically synthesized, there\'s renewed interest in natural agents. Quinine was first added to tonic water in British colonial India as an antimalarial drug and is now used for the water′s bitter flavor. **EPHEDRINE** (Ephedra major, E. sinica): an amphetamine alkaloid derived from small Ephedra shrubs native to China, has been used in Chinese medicine for 5,000 years. It helps asthmatics clear nasal and bronchial passages, raises blood pressure in those with low pressure, and treats coma patients. It\'s also a main ingredient in many over-the-counter cough, cold, and flu remedies. **INDIAN SNAKEROOT** (Rauwolfia serpentina): Reserpine, an alkaloid from the root of Indian snakeroot, has been used in India for at least 2,000 years to treat mental illness and snakebites. Western medicine \"discovered\" it in the 1940s. Reserpine effectively lowers blood pressure, acts as a calming agent, and has been used to treat schizophrenia, other mental disorders, and hypertension (high blood pressure). **FOXGLOVE** (Digitalis purpurea): The cardiac glycosides digoxin and digitoxin, obtained from the foxglove, are widely used to strengthen and steady the heartbeat. These compounds are still obtained from the foxglove plants, since they are difficult to synthesize. **MADAGASCAR PERIWINKLE** (Catharanthus roseus): The Madagascar periwinkle, historically used as folk medicine to treat diabetes, now provides alkaloids for treating cancers like leukemia (cancer of the blood) and Hodgkin\'s disease. Other plant-derived anti-cancer drugs include mayapple for leukemia and Pacific yew for ovarian cancer. Many tropical plants still need investigation for potential anti-cancer properties. **YAMS** (Dioscorea species): In 1942, diosgenin, a saponin drug, was isolated from yams. Simple chemical steps converted it into hormones used in contraceptives, fertility drugs, and hydrocortisones (for treating arthritis, allergies, and skin disorders). Yams were a key source of diosgenin for many years and are still cultivated in India and China for hormonal drug production. **GINSENG** (Panax ginseng): Ginseng root has been used medicinally in China for at least 5,000 years, believed to grant wisdom and long life. Recent studies suggest it may have medicinal properties, though results are not definitive. Other studies suggest that ginseng is an \"adaptogen,\" improving fitness, physical performance, and mental alertness under stress. It was used by Russian cosmonauts and Olympic athletes. The benefits come from a complex mix of chemicals, making it hard to replicate synthetically. Wild American ginseng was a key trade commodity in eastern North America in the 1700s and early 1800s but is now rare in the wild. **COCA** (Erythroxylum coca): The coca plant, native to the Andes mountains of northwest South America, was chewed by the Inca peoples as a mild stimulant and to alleviate hunger. Cocaine, its principal active ingredient, is a powerful and addictive central nervous system stimulant. Historically used as a local anaesthetic, cocaine has been replaced by lignococaine or synthetically derived procaine (Novacaine). Cocaine was once an ingredient in Coca-Cola but was banned in 1904 due to its addictive properties. **SENNA** (Senna angustifolia): The natural product senna is the principal ingredient in virtually all commercial laxative products sold today. Several other plant species produce natural laxatives, e.g. the bark of cascara (Rhamnus purshiana), a tree native to coastal British Columbia, was widely harvested for its laxative properties up to the 1950s. **OPIUM POPPY** (Papaver somniferum): Several crucial medicinal drugs come from latex extracts of the opium poppy fruit. Raw opium was a key pain reliever before modern anaesthetics. Heroin, a highly addictive drug, can be produced with a few chemical steps. Important drugs derived from the opium poppy include morphine and oxycodone, both highly addictive but effective painkillers. Codeine, a common household headache pain reliever, is also obtained from opium poppy latex. Due to their addictive potential, opioids are highly regulated and not available over the counter. **TROPANE ALKALOIDS (SOLANACEAE FAMILY)**: Several species in the Tomato (Solanaceae) Family, such as henbane (Hyoscyamus niger) and belladonna (Atropa belladonna), produce tropane alkaloids. In moderate doses, these alkaloids treat asthma, Parkinson\'s disease, central nervous system ailments, ulcers, travel sickness, and cramps. Tropane alkaloids act on smooth muscle tissue and dilate the pupil. Today, most medicinal tropane alkaloids come from commercial corkwood (Duboisia myoporoides) plantations in Australia. **Some extra info** **Plants according to doctrine of signatures**: Liverwort = relieve liver trouble. Snakeroot = antidote for snake venom. Adder's tongue = cure for snakebite wounds, inflammation. Lungwort = cure pulmonary diseases. Bloodroot = cure blood disorders; induce vomiting; laxative. Wormwood = expel intestinal parasites  **Henbane and Belladona** Pain reliever and soporific (sleep-inducing): Hallucinogenic and induces state of complete oblivion. Intoxication: Pressure to head, eyelids being forced closed, blurred vision, visual and other hallucinations; sleep accompanied by disturbing dreams. Henbane and belladonna were the main ingredients of witch's brews and ointments. These ointments were rubbed into skin for absorption and were given to persuade inductees to engage in sabbat rituals.