Phytochem class 5.pdf

Class 5 • Secondary Metabolism • Plant Ecology • Define • Here the substances produced are used to allow for plants to engage competitively in their own environment • Primary metabolism • Allows for plants to survive • This is necessary • Define • This is the study of the relationship of plant...

Class 5 • Secondary Metabolism • Plant Ecology • Define • Here the substances produced are used to allow for plants to engage competitively in their own environment • Primary metabolism • Allows for plants to survive • This is necessary • Define • This is the study of the relationship of plants with biotic and abiotic factors surrounding them • Bacteria, fungi, and other plants • Moisture, temperature, soil, sunlight, and water • Secondary metabolism • Allows for plants to thrive i.e., defense against predators and pathogens, and allows for communication amongst individuals to occur • This is not necessary • Primary metabolism must happen BEFORE these metabolites are manufactured • As plants are unable to move away from harsh environments they must acclimate, adapting to their surroundings • A trick they have up their sleeve though is to help regulate the environment they live in i.e., shading the ground beneath them to minimize water loss, add more soil to a slopped area, offer structure and stability to the ground in which they grow • These adaptations are necessary for their ability to survive and eventually to produce offspring Class 5 • Plant Predators • Defenses • Human-centric perspective • For many people when we imagine predators, we first think of carnivores i.e., big cats, wolves, orcas, sharks, etc. • When it comes to plants, they do not have to directly worry about them as they are not made of meat, so instead they will be focussed on herbivores • Types of defenses that plants have • Physical includes touch bark, hairs/trichomes, spikes, thorns, etc. • Chemical includes various secondary metabolites i.e., alkaloids • We can add more layers to this • Induced requires a plant to sense the nature of an injury such as a wound from a herbivore attack • Constitutive includes many preformed barriers such as cell walls, cuticles, and bark • Plant-centric perspective • The herbivores that come to your mind i.e., gazelles, cows, pigs, zebras, etc. affect plants in a minor way in comparison to insects • Insects can shape their environment based upon how much they consume, rather quickly • Pathogens such as fungi can also be a big problem for plants, as they become sick • Bacteria and viruses also play a role here • • Direct defenses immediately exert a negative impact on herbivores i.e., spikes on a hawthorn tree Indirect defenses include traits that do not have a direct impact on attacking herbivores, but can attract their natural enemies and thus reducing plant loss • I.e., volatile organic chemicals (terpenes, alcohols, ketones, aldehydes, ethers, etc.) Class 5 • Plant Mutualists • Terpenes • Mutualism • Is a type of symbiotic relationship where all species involved benefits from their interactions • Defined • A large group of volatile unsaturated hydrocarbons found in the essential oils of plants • They used to be referred to as isoprenoids • This is a diverse group of molecules that share similar building blocks • Plant forms these types of relationships with • Animals i.e., ants living within hollowed sections of acacia trees • Bacteria i.e., plant growth promoting rhizobacteria • Fungi i.e., mycorrhizal mycelium networks exchanging water and nutrients • How is this signalling performed to distinguish between friend or foe? • Chemically; this occurs because of secondary metabolism • Where can this group of compounds be found in nature? • In most plants, especially pine and citrus, fungi, and animals • In humans – the terpene squalene eventually becomes cholesterol which is then converted into a steroid hormone • Typically, we view this group of compounds containing little to no value but occasionally we see them as therapeutic and deadly Class 5 • Pathways to produce terpenoids • To produce terpenes • Plants have two pathways • The Mevalonic acid pathway • The non-Mevalonic acid pathway/MEP/DOXP • What do these pathways produce? • They create isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) • Both pathways produce these products • These building blocks are required to produce all terpenes • Mevalonic Acid Pathway • In what organisms does this pathway occur? • Animals, plants, and many bacteria • Where does it take place? • Within the cytoplasm of a cell • What substrate is involved? • Acetyl-CoA • What end products are created from this? • Animals – cholesterol • Plants – sesqui- and triterpenes • MEP/DOXP Pathway • In what organisms does this pathway occur? • Plants, and some bacteria and protists i.e., malaria • Why can this pathway not occur in animals? • Chloroplasts are required • What substrates are used? • Pyruvate and G3P (through an enzymatic process this is turned into pyruvate) • What kinds of terpenes does this pathway produce? • Every other kind of terpene except for sesqui- and triterpenes Class 5 • Statins • Isoprene • What are statins? • These are pharmaceuticals that can lower cholesterol • What is this? • Referred to as the littlest terpene • What do they have to do with the mevalonic acid pathway? • They are inhibitors of this pathway – Mevalonic Acid Pathway • In turn this lowers the production of cholesterol and other risk to the CVS • Why have people focused on studying it? • Researchers have focussed on isoprene due to its size • What is this medication derived from? • Lovastatin was initially identified in fungi • We have come to understand that fungi use this to prevent plants from producing terpenes, to defend themselves • What elements are used to build isoprene? • C and H, why it is referred to as a hydrocarbon • Where are they produced? • Only within plants, as they conduct DMAPP • This compound is not actually used as a building block for larger and more complex terpenes • Contains 5 C that can be organized in a variety of ways Class 5 • Terpene Naming • Isoprene Emissions • What is the purpose of counting terpenes? • To understand the volatility of the compound i.e., the fewer the units the more volatile they are • By counting the number of isoprene units present in a terpene we can end up knowing its size and can then name it accordingly • N.B. Isoprene is not a monomer for terpenes (polymer) • What are they called? • Hemi- (5 C), mono- (10 C), sesqui- (15 C), di(20 C), sester- (25 C), tri- (30 C), Sesquar(35 C), tetra- (40 C), and poly- (>40) • What is this made from? • Consists of isoprene • What species engage in this activity? • The plant species including Eucalyptus globulus, Pueraria spp. (kudzu), Quercus spp. (oak), Populus spp. (polar), and Salix spp. (willow) • What is the purpose? • On hot days, 30-40 degrees and higher, up to 20% of the total carbon that has been fixed leaves the plant as isoprene • This action is an attempt to help stabilize membranes in extreme temperatures • Around ¾ of Australian forests are dominated by Eucalyptus Class 5 • Essential Oils • Monoterpenes • What exactly are essential oils? • Also referred to as volatile oils and ethereal oils • This is a secondary metabolite produced by plants • Essential simply refers to the scent that they leave • 10 C • Is this terpene volatile? • Usually yes, as it is a smaller molecule with no hydrogen bonds forming • To float away they must bump off one another first, causing agitation • How are they organized? • Structurally they can usually be found in a linear or cyclic shape • What pathway produces this compound? • MEP/DOXP pathway (non-Mevalonic acid pathway) • What are they composed of? • They are made of a mixture of various hydrocarbons • Typically, smaller terpenes (fewer Cs) Class 5 • Pinene • Mountain Pine Beetle • What is this? • A monoterpene • That is commonly found in coniferous trees, rosemary, and sage • This is a beetle native to the forests of western North America • With a range from Mexico to central British Columbia • What is their preferred food? • Lodgepole pine • What forms does it have? • Alpha- and beta-isomers • When and how did they begin to create a problem in BC? • In the ‘90s • Warming climate combined with forestry practices have allowed for an explosion in its population • Lodgepole pine • Will use alpha-pinene as an insect repellant • Unfortunately, when the beetles detect its presence, it causes them to enter a frenzy • Beetles • They coalesce into swarms, generated via chemical signalling from about 1km away, and attack the tree • This overwhelms the trees' ability to defend itself • Healthier beetles are more resilient to effects of alpha-pinene • What are isomers? • These are molecules with the same molecular formulas, but with a different arrangement of atoms • Alpha-pinene • Strong insect repellant • Has displayed antioxidant, bronchodilating, anxiolytic, anti-inflammatory, and enhancement of short-term memory impairment actions Class 5 • Caryophyllene • Limonene • • • • • What is this? • A monoterpene • That is commonly found rosemary, cloves, black pepper, hops, oregano, cinnamon, basil, lavender, cannabis, etc. What forms does it have? • Alpha- and beta-isomers Funny thing to know • Alpha-caryophyllene is also referred to as alpha-humulene; which is commonly found in hops and cannabis where it exerts antiinflammatory, anti-allergic, and anti-tumor actions • Structurally this a ring opened-isomer Beta-caryophyllene • Beta-caryophyllene is found to exert potent anti-inflammatory, antimicrobial, anti-nociceptive, and anti-oxidant actions • This is found to act as an attractant for two insects (nematodes • What is this? • A monoterpene • That is commonly found in the rind of citrus fruits, thus its name, and cannabis What forms does it have? • • • R and S optical-isomers What does that mean? • This is a case of chirality; they are mirror-image’s of one another • Each version is responsible for a very distinct scent i.e., R-limonene is found in citrus and S-limonene has a piney odor and will be found in caraway/dill/bergamot Limonene • Has displayed antioxidant, anxiolytic, thymoleptic, anti-inflammatory, and anti-nociceptive actions to name a just a handful • When dealing with predators this oil destroys the wax layer of their respiratory system so that once it is applied directly, the insect will suffocate Class 5 • Menthol • Thujone • What is this? • A monoterpene • That is commonly found in mint family plants but is most heavily associated with peppermint • What is this? • A monoterpene • That is commonly found in western red cedar, juniper, wormwood, etc. • What forms does it have? • Alpha- and beta-thujone • Alpha- is 2-3x stronger than beta-thujone • Alpha-thujone • In excess it is toxic/potent repellant/antifeedant/insecticide to insects and is a convulsant in mammals, excitatory • This acts as a GABA antagonist • GABA deals with dopamine signalling and pain relief • Induces hypersensitivity by increasing the rate of nerve firing (excitatory) • Neurotoxic, convulsant, hallucinogenic • It also has therapeutic anti-inflammatory and anti-fungal actions • What forms does it come in? • 8 different stereoisomers/optical-isomer • These isomers have the same atoms (building blocks) but are arranged in vastly different ways • Menthol • Has displayed a variety of actions including but not limited to analgesia, bronchodilator, antinociceptive, antimicrobial, anti-ulcerogenic, etc. • It exerts biocidal properties and is effective at controlling mites, mosquito larvae, and seems to posses repellent properties to dogs, cats, and insects