Class 9 Phytochemistry PDF

Class 9 • Nitrogen • What is nitrogen? • This is a chemical element and is found to be the seventh most common in the Milky Way and our Solar System • It is considered to be essential to life developing on earth • This can be found in a gaseous state above -210 degrees Celsius • Where can it be f...

Class 9 • Nitrogen • What is nitrogen? • This is a chemical element and is found to be the seventh most common in the Milky Way and our Solar System • It is considered to be essential to life developing on earth • This can be found in a gaseous state above -210 degrees Celsius • Where can it be found on planet earth? • Within the atmosphere we breath, soil beneath our feet, in the water we drink, foods we consume, within the very structures of our bodies, and the matter we excrete • The atmosphere of earth consists of about 78% N • Why do biological creatures require it? • All life forms on earth require N to build amino acids, RNA, and DNA • Without this critical element we would not have a genetic code or proteins to create from that vital information • Significance • Limiting factors • Generally, most people would considerwater to be the limiting factor in any given ecosystem, because if we do not have any water plants cannot grow and animals cannot survive • While this is true in extreme environments i.e., deserts of extreme heat or cold, it is not true for all other biomes across the earth • Instead, N limits the number of organisms that can grow in any given area at a certain time • Certain organisms, plants/algae/microorganisms,compete quite strongly for this limited resource • The rate at which they grow reflects how ferociously they use N i.e., those who obtain it quickly tend to perish shortly thereafter and those who slowly accumulate it usually experience much longer lives • Availability • N will most commonly be found in 3 different forms that are bioavailable • Amino acids • Ammonia (NH4) • Nitrate (NO3) • Out of the 3 mentioned above ammonia and nitrate are the most common forms • Amino acids will usually be present for a brief moment, during the decay of another lifeform • Only for a moment as microorganisms then quickly consume all that is available • The abundance of N dissolved within an ecosystem greatly depends upon the type of soil, pH, temperature, amount of O2 and water, and time of year Class 9 • N Fixation • This process is defined as the biological process in which N gas is converted into a usable form for plants and other microbes • While N is a key limiting factor when it comes to the ability of organisms such as plants to establish and succeed certain species have an upper hand over others • Plants that can not only survive but thrive in N deficient areas can be referred to as N fixing plants • N fixing plants do not have to worry about competing for this resource within their environment • Relationship • Symbiotic relationships are the close association formed between pairs of a species and can come in a variety of forms • Mutualistic – both species benefit by working together, toward a common goal • Commensal – one species benefits and the other is neither helped or harmed • Parasitic – one species benefits and the other is harmed • So, how does this relate to N? • Well…. In order to fix this costly element bacteria are required and they tend to perform their best when properly supported • This support can come in the form of a stable environment to live and access to glucose (as fixation is so dang expensive, 16 ATP are required per reaction ) • The spaces these bacteria can call home are called nodules and if you recall, plants communicate with these bacteria via phenols • If a non-N fixing bacteria were to live inside of a plant nodule both species would likely perish shortly thereafter , therefore experiencing a brief but turbulent romance. Class 9 • Systemin • What is this? • This is a plant peptide hormone first isolated in 1991 from tomato leaves and studied further in the early 2000s where it was extracted from tobacco leaves • How is it made? • Made up of amino acids • This is involved in wound response • Where can it be found? • This can be found within the cytoplasm and cell walls of plants cells • If it is a plant hormone does it operate through the same pathways as abscisic acid or brassinosteroids? • At this time researchers are unsure as it appears to operate via a different pathway • What purpose does it serve? • To enable growth following an attack from a herbivorous insect • Affects plant development by modifying root growth along with responses to salt stress and UV radiation • In some unique cases this peptide hormone is responsible in affecting flower morphology • Peptides • What is a peptide and how are they made? • This is a short string of 2-50 amino acids (peptide chain) • They are formed by a special type of covalent bond called a peptide bond • What function do they serve? • They regulate specific functions of cells and help to facilitate a variety of biochemical process throughout the body • What can they give rise to? • Most commonly they are referred to as a building block of protein, once multiple peptide chains join together they form proteins • In the case of the lecture today and moving forward we will look at peptides as secondary metabolites • If it is not produced for survival it is used thrive Class 9 • Chitinases • • First off… what is chitin? • This is an aminopolysaccharide polymer , incredibly tough • Where can it be found? • Throughout nature as the cell walls of fungi and in the exoskeletons of crustaceans and insects • What purpose does chitin have? • To support the structure of any organism it is part of Now that we have established that… • • What are chitinases ? • These are enzymes (which are usually made of what macromolecule?) • Plants have to produce rather strong chitinases must then be made What purpose do they serve? • • How are they activated? • • They are used to breakdown chitin which actually contributes to the release of C and N back into the ecosystem Typically caused by an injury from a herbivorous insect or pathogen (fungi) What species of plants contain these enzymes? • Avocados, bananas, chestnuts, kiwifruit, papaya, and tomatoes • Vicilin • What is this and where can it be found? • This is a protein found within pulses such as lentils or peas • What purpose does it serve? • This is used to assist with the storage of proteins (for primary and secondary metabolism) • Assists with the binding of sucrose, possess antifungal action, and modulates oxidative stress • A bit of an odd one • Appears to inhibit amylase (enzyme used to digest carbohydrates) • Once upon a time it appeared to interfere with chitin, possibly weakening it, but never progressed down that path Class 9 • Lectins • Phytohaemaglutinin • What are lectins? • These are proteins that bind quite strongly to carbohydrates • What is this? • A lectin • But wait…. Have we not discussed another compound that binds to macromolecules? • Yes, those are the phenols referred to as tannins and they bind to proteins • When exposed to one another tannins will bind to lectins preventing them from attaching to any carbohydrates • What purpose do they serve? • For plants – their main function is to prevent microorganisms from entering into the cytoplasm along with playing a key role in their defense mechanisms • For humans – They are important in cell-cell interactions, signaling pathways, and several innate immune response against pathogens • Where can they be found? • In most pulses, but in higher concentrations of kidney beans • Why is it called this? • It clots blood when coming in direct contact i.e., in a blood smear on a microscope slide and not within the human body • What type of effect does this have? • As with other lectins it binds to carbohydrates , selectively • If kidney beans are consumed raw they can induce vomiting and diarrhea in some people • How can we get around this? • Denature them by exposing to heat or pressure i.e., slow cooking, stove top boiling, or pressure cooking Class 9 • Ricin • Castor Oil • What is ricin and where can it be found? • Ricin is a protein that can be found within castor beans • It is worth noting that ricin is not present within castor oil • Ricin is found within skin coats of the beans • Ricin is a protein and not a lipid • Processing • Castor bean skins are removed • The beans are then boiled at least 3 times, for around 7-8 hours at a time, to denature proteins • The seeds are then cold pressed to remove the remaining oil • Castor oil (lipid) • Rich in ricinoleic acid (strong laxative) • This is a storage form of energy in a sprout • What type of metabolite is this? • Where does it bind? • To prostanoid receptors found within smooth muscle • Excessive stimulation of the receptors sites induces a laxative effect, nausea, severe cramping, vomiting, and so on • Why is it of concern? • Its incredibly toxic nature • If you were to collect enough ricin that would fill a grain of salt it would have the capacity to wipe out of 250 people • How can ricin interact with humans? • First off, this compound is pH stable within the stomach and once there it catches an easy ride into someone's system via a carbohydrate • Secondly, it is misidentified as a misfolded protein causing chaperone proteins to attempt to unfold it • Thirdly, the chaperone protein activates a portion of the ricin which induces its lethal activity . This prevents cells from making proteins required to maintain function . • Typically, 48-72 hours after injection or inhalation of this substance an individual can experience cardiac arrest Class 9 • Peanut Agglutinin • Nonprotein Amino Acids • What is this? • A lectin • How shall we define these? • They are amino acids that are not used to build a protein • Where can it be found? • Within a peanut • This protein is isolated and extracted when studied • How are they similar to amino acids used to build proteins? • They must both have an amine group, acid group, and something filling up the R group • What type of effectivity would this have on individuals? • Within the GIT of humans it rapidly breaks down once exposed to stomach acid • Within insects it acts profoundly • Other human uses • Within lab tests i.e., fertility testing of sperm or identifying cell types • Fluorescent molecule can be added to improve tracking and labeling molecules • What purpose do they end up serving? • Plants tend to produce countless nonprotein amino acids to act as intermediates or directly as defensive compounds • Defensively they can store N in a form inaccessible to herbivores, act as signalling molecules to produce or release secondary metabolites , obstruct metabolism of herbivores, etc. Class 9 • Quisqualic Acid • What is this? • A non-protein amino acid • Where can it be found? • Typically found within tropical species of trees i.e., pelargoniums • What type of action does this exert? • They mimic glutamine within the CNS, typically this is either turned into the neurotransmitters glutamate (excitatory) or GABA (depressing) • Quisqualic acid tends to overexcite nerve cells which leads to their death and destruction of the nervous system • Mimosine • What is this? • A non-protein amino acid • Where can it be found in nature? • This was first isolated within Mimosa pudica • It can also be found in other leguminous trees • What kind of action does it perform within an organism? • Mimosine acts as a mimic of the amino acid tyrosine • Once this compound enters a cell it heads straight for the nucleus • DNA replication is then inhibited • What types of organisms does this typically affect? • Livestock within the tropics tend to consume these plants, fall ill, and then slowly die as they cannot produce new cells • Canavanine • What is this? • A mimic of the amino acid arginine • Where can it be found? • This can be commonly found in Canavali spp., soybeans, and alfalfa • How does this affect protein synthesis? • As this mimics the amino acid arginine once ingested the body tags it as that to use later for building proteins • Then when tRNA are handing off amino acids to the ribosome to construct proteins they will end up using canavanine • The newly constructed protein now has an altered structure and therefore function • N.B. plants that produce this compound contain enzymes so they can tell a difference between it and arginine • What happens to organisms consuming this non-protein amino acid? • In herbivorous insects, this causes dramatic and often fatal defects in development • The consumption of this compound has been associated with the onset of lupus-like diseases in humans and other animals Class 9 • Cyanogenic Glycosides • What are they? • They are a tiny group of secondary metabolites • Are they harmful? • These plant toxins can be harmful when consumed in high amounts over a short period of time • Recall that cyanide is an inhibitor of the ETC in plants, animals, fungi, and bacteria • How are they metabolised? • The plant which created this compound is usually safe from its affect as the cyanide is bound to a carbohydrate • They are activated after being crushed , or exposed to the stomach or small intestine • Can they be used therapeutically? • Conventionally, these compounds have been found to display anti-cancerous activity • Hawthorn berries contain cyanogenic glycosides ? • Technically it is the seed that does and not the fruit pulp • What type of cyanogenic glycoside is present? • Amygdalin • How is amygdalin created? • Believe it or not but from phenylalanine , shikimic acid pathway • Is the public aware of this anti-cancerous activity? • Most individuals have heard of this compound as laetrile or vitamin B17 • Typically sourced from stone fruit pits and seeds • Currently, most researchers within the scientific community • Do not view this compound as a viable treatment for cancer • N.B. a body of evidence is beginning to grow in favour of its use adjunctively to other forms of therapy • Glucosinolates • What are these? • They are compounds that contain N and a lot of S attached to a carbohydrate • Glucosinolates originate from amino acids • What is unique about them? • If you slice a vegetable then experience watery eyes, it means that they usually contain these compounds • Where can they be found? • Most commonly found within cruciferous vegetables (horseradish, garlic, onion, etc.) • What type of effects do they exert on the body? • These compounds are associated with inhibiting the uptake of iodine, which is not a problem when consuming occasionally, however, long-term consumption is different • Beneficially they are known to cause a reduction in inflammation, modulated stress response, antioxidant activity, and antimicrobial actions following consumption