10 medical plants

10 medical plants

they might not be able to pull you out ofa freezing lake, or carry you from a burning building, but plants have probably saved yourlife, or at least made you feel a whole lot better. that’s because, at least in the u.s., aquarter of all prescription drugs come from substances that are found only in plants. we humans have a long history of using plantsto treat diseases. most of those treatments were probably discoveredusing blind luck -- like, by people munching on random leaves and seeing how they felt. if they found one that seemed to work, theknowledge would usually get passed around

by word of mouth, but sometimes it would alsobe written down. that’s how we ended up with recipes thatare about as old as writing itself -- like the 5000 year old sumerian clay slab thatlists 250 plants for preparing medicines. of course, the recipes don’t always work,and there are plenty of old herbal remedies that do absolutely nothing. but a few didwork -- and we still use some of them in medicines today. many of the plant-based substances peopleuse belong to a broad group of bitter-tasting, nitrogen-containing compounds called alkaloids. these compounds don’t seem to be strictlynecessary for plants to survive, so they probably

offer evolutionary bonuses – like a defenseagainst anything that tries taking a bite out of it. their names mostly end in i-n-e, and you’veprobably already heard of some of them, like caffeine, nicotine, morphine… and a lot of them have effects on our bodiesthat are pretty strong ... for better or worse. take the deadly nightshade, for example. in 2009, a woman was hospitalized from eatingjust six nightshade berries, which she thought were blueberries. ten berries could have beenfatal. one of the killer compounds in nightshadeis atropine, an alkaloid found all over the

plant. but atropine also has a good side -- it’sactually on the world health organization’s “model list of essential medicines” inthree separate places! surgeons can use it as a sedative for shortoperations, or to dilate the pupils to gain easy access to the back of the eye. and, despite being extracted from a plantso toxic, atropine works an antidote against certain types of poisoning! some pesticides and nerve gases overwork theparasympathetic nervous system, and atropine can counter that deadly effect by blockingthe receptors these toxins over-activate.

other useful plant-based drugs took a lotof hard science to make work -- as in the case of an anti-malarial drug called artemisinin. the compound comes from the sweet wormwoodplant, and youyou tu, the chemical engineer who developed it, was awarded half of thenobel prize for medicine in 2015. using plants to treat malaria is not a newthing. the disease has probably killed half of all humans from the stone age to today,and we haven’t beaten it yet. with so many people suffering, especiallyin developing countries, it’s not surprising people turned to plants for a cure. around the world, more than 1200 plant speciesare used to treat malaria and the fever that

comes with it. but only a fraction of thesehave been properly tested for their effectiveness. one of the first remedies known to be genuinelyeffective was quinine, an alkaloid that comes from the bark of peruvian cinchona trees. a compound known as chloroquine, which wasbased on quinine, was later developed synthetically as a safer and more potent version of thedrug. but it wasn’t long before the plasmodiumparasite that causes malaria started showing resistance to chloroquine. so people startedlooking for an alternative. tu and her team turned to traditional remediesfrom china. they scoured thousands of traditional recipes for potions and medicines that weresaid to reduce fever, looking for the most

promising plants. they found a clear winner. one plant -- thesweet wormwood -- showed up in not just one or two, but hundreds of different recipes. initial tests of sweet wormwood extracts onthe malaria parasite were promising, but inconsistent. some experiments showed sweet wormwood tobe highly effective, but others only slightly. tu thought that the variations might be causedby differences in the way the wormwood extract was prepared, so she went back to the oldtexts to find more clues. most of the remedies suggested processingdried leaves with boiling water, but chinese philosopher ge hong, writing in the year 340ce, had a different suggestion.

he described a preparation process that usedfresh, not dried leaves, and involved extracting the juice by soaking those fresh leaves incold water, wringing them out, then drinking the juice straight down. based on this account, the team developedtheir own extraction method using ether, then tested it out on mice, monkeys, and finallypeople. and it worked! the new-and-improved extract killed off malariaparasites soon after they entered their host’s red blood cells, and with relatively mildside effects. the active compound was called artemisinin after the plant it was found in.

the discovery of artemisinin created a wholenew family of antimalarial drugs that are still used to treat malaria today. then there’s diabetes, another disease thatpeople have been trying to treat for a long time. uncontrolled blood sugar levels in peoplewith diabetes can lead to complications like nerve damage, sight problems and kidney failure. but plants have our backs on this one, too. for the estimated 400 million people who havetype ii diabetes, one of the most widely prescribed treatments is metformin, a relatively simplemolecule that’s made up of just a few nitrogen,

carbon, and hydrogen atoms. the story of metformin starts with an herbknown as goat’s rue, or professor weed. it stands over a meter high, with white, blue,or purple flowers. professor weed has been used to manage diabetesaround the middle east and europe since the middle ages. in the late 1800s, studies found that theplant contained high levels of an alkaloid called guanidine. when isolated, guanidineworked great at reducing blood sugar levels in animals, but it was too toxic to use inpeople. so chemists got to work, trying differentadaptations of guanidine that kept the blood

sugar down, but without the whole poisoningproblem. the result was metformin. safe, effectiveand cheap to make, metformin is helping millions of people manage their diabetes. despite its simple chemical structure andplenty of research, we still don’t really know how metformin lowers blood sugar, orwhy it’s so effective with so few side-effects. so, what thanks do the american people givethis life-saving plant? we slap it on the noxious federal weed list! but, to be fair, that’s because it’s aninvasive species in the us. it’s a lot less destructive when it grows in the middle east,europe and asia.

not all plants are so common, though -- infact, plants containing the secrets to much-needed cures may have gone extinct before we hadthe chance to even name them, let alone study them. and we’ve come close to losing life-savingplants before. in 1987, for example, a botanist named johnburley trekked through a swamp forest in malaysia, collecting plant samples to study back inthe lab. his travels were part of a larger mission to find new treatments for variouscancers, as well as hiv. one of these samples, tagged “burley-and-lee351” didn’t kill cancer cells, but it did do an amazing job of preventing hiv fromreplicating.

so the collectors high-tailed it back to theforest… only to find it gone, cut down for firewood or building. extracts from similartrees didn’t have the same effect, because they were slightly different species. it was only salvaged when a few trees of theright species were found at the singapore botanical gardens. the drug is called calanolidea, and it’s currently in phase ii clinical trials and owned by the local malaysian government. then there’s this pretty little thing -- therosy periwinkle. it might look like something that would beright at home in my backyard, but it’s actually native only to madagascar – though it willhappily grow anywhere warm. the native people

of madagascar used these periwinkle plantsfor all kinds of ailments. in the 1950s, researchers from western pharmaceuticalcompanies studied the periwinkle and discovered that it contained some rather remarkable alkaloids. two of these, called vincristine and vinblastine,are used to treat certain types of cancer by stopping the cells from dividing. vincristine has helped increase success ratesin treating kids with leukemia from just 10% in the 1960s, to well over 80% today. and vinblastine is often a core chemotherapycomponent for lymphoma -- a cancer of the lymphatic system -- as well as testicularcancer.

all kinds of plants have amazing substanceslocked away inside them. so the next time you walk past a tree or flower, give it apat on the leaf -- assuming it’s not, like, thorny, or poisonous to the touch- anythinglike that. you might look a little strange, and the plantwon’t understand, but it probably deserves it anyway. thanks for watching this episode of scishow,which was brought to you by our patrons on patreon. if you want to help support thisshow, just go to patreon.com/scishow. and don’t forget to go to youtube.com/scishowand subscribe!