Notes from Aug. 31
Notes from Aug. 31 HORT 3440
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This 4 page Class Notes was uploaded by Meghan Shah on Monday September 12, 2016. The Class Notes belongs to HORT 3440 at University of Georgia taught by James Affecter in Fall 2016. Since its upload, it has received 2 views. For similar materials see Herbs, Spices, and Medicinal Plants in Biology/Anthropology at University of Georgia.
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Date Created: 09/12/16
Notes from Aug. 31 st Key: Vocab Word Family/Genus/Species Name Compound/Component Part(s) Used Video: How pain relievers work ○ Pain is sensations of extreme discomfort ▪ It causes you to react somehow ○ Pain is the body’s early warning system to protect itself from you and the world around you ○ Nociceptors are the specialized nerve cells that only fire if something happens that could causeor is causing—damage ▪ They make you feel pain ○ Damaged cells send out “tuning signals” (arachidonic acid) to lower the pain threshold, making them more susceptible to pain. ○ Aspirin and Ibuprofen work by blocking the production of prostaglandins ▪ Aspirin blocks and enzyme that is involved in the production of prostaglandins Prostaglandins – hormones that act as chemical mediators that bring about the inflammatory response by vasodilation, making capillaries permeable, and sensitizing nerve cells to pain ▪ Aspirin make it impossible for the arachidonic acid to fit into the active site of the enzymes that are trigger those nerve cells ▪ Ibuprofen sticks in the active sites so the acid molecules can’t get in. Indian Snakeroot – Rauwolfia serpentine ○ Tropic shrub that was native to India ○ It was used as a tranquilizer, to treat epilepsy, hypertension, dysentery, mental disorders and an antidote for bug and snake bites ○ Used in traditional Indian Aruyvedic medicine ○ Reserpine is the active compound ▪ It reduces blood pressure by blocking the neurotransmitter that transmits nerve signals between the sympathetic nervous system and the heart & blood vessels, causing the blood vessels to relax and reduce the heart’s output. ▪ It was used as a psychiatric medicine as an alternative to shock treatments and drastic surgeries (like lobotomies). ▪ People aren’t supposed to harvest Indian snakeroot in the wild, but they do anyway ○ Reserpine is used pharmaceutically as a drug to lower blood and as a treatment for schizophrenia ○ Indian snakeroot has a long history of use. ○ The species is endangered ▪ Indian snakeroot is difficult to propagate They’re propagated by root stock cuttings Seed germination is only 10% Foxglove – Digitalis purpurea ○ Snapdragon family ○ Native to Europe; it’s a popular ornamental plant in people’s gardens ○ Biannual – the first year, the plant doesn’t make flowers; the next year, it produces flowers and then dies ○ Leaves and flowers are very poisonous—like fatally toxic ○ The leaves are the source of the cardiac glycosides digoxin and digitoxin ▪ They slow down and strengthen the heartbeat. ▪ Treats congenitive heart failure ▪ The therapeutic dose is very close to the toxic dose – don’t selfmedicate ○ Digitalis is the active ingredient ○ Dr. William Withering, Account of the Foxglove, 1785 ○ He was an English doctor that figured out that foxglove was good at treating “dropsy” (edema) ○ Digitoxin increase cardiac output and fluid excretion; it decreases edema and fluid in the lungs ○ Vincent van Gogh took it as treatment for his mania and epilepsy ▪ The drug has an occasional side effect called xanthopsia, which causes a person to perceive a yellow tint in their surroundings ▪ Some credit xanthopsia for van Gogh’s yellowtinted paintings The popularity of plant medicines had died down until the 19 and 20 century, when interest increased ○ Advances in “bench chemistry” during the 1800s led to a shift in interest away from natural products toward “more modern” synthetics and derivatives (like aspirin) ○ Interest in discovering new drugs from plants was reawakened following the discovery of penicillin by Alexander Fleming The Discovery of Penicillin by Dr. Alexander Fleming ○ He was looking for treatments for infectious disease ▪ It was a major cause of death, even in ○ In 1928, he accidentally discovered penicillin while studying a type of bacteria that lived in septic wounds, called staphylococcus. ▪ He was cleaning up his lab when he noticed something unusual. By chance, there was a moldy fungus growing on one of his plates, but more importantly, he noticed that there were no bacteria growing around it. ▪ He concluded that the fungus produced a chemical that must have killed the bacteria – just what he’d been looking for Fungus is Penicillium chrysogenum ○ Penicillin stops bacteria by breaking down their cell walls ▪ The bacteria get bigger, but they can’t divide and produce more ▪ Eventually they pop and die. ○ Antibiotic A substance produced by microbes which kills bacteria; a medicine that destroys or slows the growth of microorganisms, primarily bacteria ○ Infection – invasion and multiplication of microorganisms such as bacteria, parasites, and viruses In the 1950s, there was a renewed interest in using “random screening programs” to search for new pharmaceutical medicines from plants and some other things, like soil samples ○ Plant extracts were tested against various bioassays to look for therapeutic properties ▪ Bioassays – tests for biological activity using living organisms (like mice, tissues, cultures, etc.) Madagascar periwinkle – Catharanthus roseus ○ Dogbane family; creeping myrtle and snakeroot are in the same family ○ It was native to Madagascar, but now it’s spread all over the world. ○ It’s an annual plant in temperate climates and a perennial in tropical ones ○ Pantropical weed; it’s related to the common ground cover Vinca (myrtle) ○ Contains the alkaloids vincristine and vinblastine ○ Used as a chemotherapy agent for treatment of leukemia and Hodgkin’s disease Pacific Yew – Taxus brevifolia ○ Yew family ○ Native to the Pacific NW (Oregon and Washington) ○ Conifer like pine trees and fir trees ○ Grows in old forests; Spotted Owl habitat ○ Bark contains paclitaxel (tradename Taxol), used in cancer treatment, particularly breast, lung, testicular, and ovarian cancers Video: How cells divide and how chemotherapy works ○ Humans have around 100 trillion cells; your body is constantly replacing them with new cells via cell division ▪ When a cell divides, it goes through a series of steps, which include a duplication the cell’s DNA, which contains the genetic instructions use in the development and functioning of living organisms ▪ The end result is two identical “daughter” cells ▪ Their life cycles have several stages, including one “resting” and two growth periods, as well as the time that each cell prepares itself to divide ▪ In normal cells, there are checkpoints at every stage of the process of cell division to ensure that the cells grow and divide in a regulated way In cancer cells, these checkpoints are broken and cancer cells grow out of control Chemotherapy drugs act in several different ways to disrupt cell division Some act on “resting” cells as well as actively dividing cells Other chemotherapy drugs act only at specific stages of cell cycle Some chemo drugs bind to DNA exactly when the cell is making a copy of its DNA, thus stopping the cells from dividing Other chemo drugs prevent cells from splitting into two daughter cells ← They prevent the DNA from being equally divided between the two cells, thereby preventing cell division ○ How chemotherapy affects cancer cells ▪ Cancers form when abnormal cells divide rapidly without any control. ▪ Because chemotherapies drugs target different steps during the process of cell division, they’re good at killing cells that are dividing rapidly, like cancer cells. ▪ Chemo drugs can also damage normal cells that are dividing rapidly and this can cause side effects, like hair loss Vinca alkaloids and taxanes (like paclitaxel) are the two main groups of anti microtubule agents, and although both of these groups of drugs cause microtubule dysfunction, their mechanisms of action are completely opposite. The vinca alkaloids prevent the formation of microtubules, whereas the taxanes prevent microtubule disassembly ○ Both paclitaxel and vincristine/vinblastine slow the growth of cancer cells by disrupting the microtubule structure ▪ Paclitaxel (Taxol) stabilizes the microtubule scaffolding, which arrests the cell in middivision ▪ The vinca alkaloids (vincrtine and vinblastine) prevent the lengthwise growth of the protofilaments, making it impossible for cells to divide. rd A 3 chemotherapy agent that interferes with microtubule division comes from one of our southeastern native plants, Mayapple – Podophyllum peltatum. Like the vinca alkaloids, it interferes with microtubule assembly.
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