Recomendados
Más contenido relacionado
La actualidad más candente
La actualidad más candente (20)
Similar a Terpenes
Similar a Terpenes (20)
Más de Junaid Abbas
Más de Junaid Abbas (20)
Último
Último (20)
Terpenes
- 1. TERPENES
- 2. A Natural Mechanism • In natural habitats plants are surrounded by number of enemies such as bacteria, viruses, fungi nematodes, insects and herbivores animals. • Plants can not avoid themselves by moving away from these enemies. • They protect themselves in other ways, e.g. Cuticle(waxy outer layer) • Periderm (secondary protective tissue) • which provide barrier to bacterial and fungal activity .
- 3. A Natural Mechanism • Plants also defend themselves against herbivores and pathogenic microbes by producing some defensive chemical compound called secondary compounds. • These secondary compounds may serve other important functions such as; • Structural support (lignin) • or • Pigments (anthocyanins).
- 4. Metabolites • Primary metabolites • Primary metabolites are produce in all plants and have direct role in growth and development e.g. amino acids, nucleotides and sugars etc. • Secondary metabolites • A diverse array of organic compounds have no direct function in growth and development and have restricted distribution in plant kingdom e.g. limonene, carotinoids and anthocyanins etc.
- 5. Classes of Secondary Metabolites • Three major classes of secondary metabolites – 1- Terpenes – 2- Phenolics – 3- Nitrogen containing compounds
- 7. Terpenes and Terpenoids • Terpenes • are largest class of secondary metabolite, some are volatile and insoluble in water, biosynthesize from acetyle-Co A or glycolytic intermediate. • Terpenoids – are terpene like substances or derivatives of terpenes or modified terpenes.
- 8. Nomenclature • All terpenes are formed by union of five carbon elements that is iso-pentane • All basic structure of terpenes are called isoprene units, because terpenes can decompose on high temperature to give isoprenes. These five carbon units polymerize to give rise to large number of terpenes.
- 9. Classification of Terpenes TYPE OF NUMBER OF ISOPRENE TERPENE CARBON ATOMS UNITS Hemiterpene Monoterpene Sesquiterpene Diterpene Triterpene Tetraterpene Rubber C5 C10 C15 C20 C30 C40 > 500 one two three four six eight > 100 hemi = half di = two sesqui = one and a half tri = three tetra = four NOTE: Sesterterpene C25 five
- 12. Representative Monoterpenes a-Phellandrene (eucalyptus) Menthol (peppermint) Citral (lemon grass)
- 19. Biosynthesis of Terpenes • Terpenes are biosynthesized from primary metabolites at least in two different ways 1. Mavalonic Acid Pathway • 2. Methylerythritole Phopsphate (MEP) Pathway
- 20. Mevalonic Acid Pathway • Three molecules of acetyle-CoA join together to form a molecule of mevalonic acid. CH3COH O CH3COH O CH3COH O + + HOCCH2CCH2CH2OH CH3 OH O Mevalonic acid
- 21. C CH2 CH2 CH3 OH C CH2 O OH OH mevalonic acid C CH2 CH2 CH3 O C CH2 O O O P H P P :B-Enz 2 ATP ADP AMP CH2 H CH2 CH3 OPP CH3 H CH2 CH3 OPP 3,3-dimethylallyl pyrophosphate isopentenyl pyrophosphate Enz-B: H+ MEVALONIC ACID PATHWAY The isopentenyl and 3,3-dimethylallyl pyrophosphate intermediates These five-carbon intermediates are responsible for the formation of all the terpenes. DMAPP IPP Pyrophosphorylation + Decarboxylation+dehydration
- 22. CH2 H CH2 CH3 OPP CH3 H CH2 CH3 OPP 3,3-dimepyrophosphate thylallyl isopentenyl pyrophosphate Enz-B: H+ Methylerythritole phopsphate(MEP) pathway The isopentenyl and 3,3-dimethylallyl pyrophosphate intermediates DMAPP IPP + These five-carbon intermediates are responsible for the formation of all the terpenes.
- 23. CH2 H CH2 CH3 OPP CH3 H CH2 CH3 OPP 3,3-dimepyrophosphate thylallyl isopentenyl pyrophosphate Enz-B: H+ DMAPP (isoprene C5)IPP (isoprene C5)
- 24. Role in Growth and Development • Certain terpenes have well characterized function in plant growth and development considered as primary rather than secondary metabolites. • e.g. • 1- Gibberellins ( diterpenes) causes tallness. • 2- Sterol (triterpenes) essential component of cell membrane .
- 25. Role in Growth and Development • 3- Red, orange and yellow Caretenoids (tetraterpenes) assessory photosynthetic pigment and prevent photo oxidation (UV). • 4- Abscisic acid (sesquiterpene) aging hormone. • 5- Polyterpene alcohol; carries of sugars in cell wall and glycoprotein synthesis. • 6- Phytol side chain of chlorophyll which help to anchor certain molecules in membranes.
- 27. Terpenes Defend against Herbivores in Many Plants• Terpenes are toxins and feeding deterrents to many plantfeeding insects and mammals. • 1- The monoterpene esters called Pyrethroids that occur in the leaves and flowers of Chrysanthemum species show very striking insecticidal activity. • 2- In conifers (pine and fir), monoterpenes are toxic to numerous insects, including bark beetles
- 28. Volatile Terpenes (Essential Oils) • Many plants contain mixtures of volatile monoterpenes and sesquiterpenes, called • essential oils. • Peppermint, lemon, basil,and sage are examples of plants that contain essential oils. • Peppermint oil is menthol, Lemon oil is limonene. • Essential oils have well-known insect repellent properties.
- 29. Volatile Terpenes (Essential Oils)• Menthol ( Peppermint) • stimulation of the skin‘s cold receptors which produce a cooling effect. • Similar to the capsaicin (hot peppers) which stimulates heat receptors. • They does not change the skin's temperature, but produces the sensation of temperature change.
- 30. Essential Oil as Antiherbivores • They are frequently found in glandular hairs that project outward from the epidermis and serve to “advertise” the toxicity of the plant, repelling potential herbivores even before they take a trial bite.
- 31. Terpene Antiherbivore Compounds • Limonoids • a group of triterpenes (C30). • Limonene • a bitter substance in citrus fruit.
- 32. Terpene Antiherbivore Compounds • Azadirachtin • a complex limonoid from the neem tree (Azadirachta indica) . • It is the most powerful feeding deterrent to some insects at doses as low as 50 PPB. • It is insect control commercial agent because of its low toxicity to • mammals.
- 33. Terpene Antiherbivore Compounds • Phytoecdysones • (isolated from common fern) • a group of plant steroids that have the same basic structure as insect molting hormones. •
- 34. Terpene Antiherbivore Compounds • Triterpenes that are active against vertebrate herbivores include • cardenolides and saponins. • Cardenolides are glycosides that taste bitter and are extremely toxic to higher animals. • In humans, they have dramatic effects on the heart muscle through their influence on Na+/K+-activated ATPases. In carefully regulated doses, they slow and strengthen the heartbeat.
- 35. Terpene Antiherbivore Compounds • Saponins • are steroid and triterpene glycosides having soaplike properties. • The toxicity of saponins is a result of their ability to form complexes with sterols and interfere with sterol uptake from the digestive system or disrupt cell membranes after being absorbed into the bloodstream.
- 38. Scientists discover cloud-thickening chemicals in trees that could offer a new weapon in the fight against global warming
- 39. Secondary Organic Aerosol (SOA) Formation • Terpenes (Pine forests distinctive smell), react in the air to form tiny particles called aerosols. • Natural aerosols has found that they contained two previously unknown compounds, which are photooxidation products of isoprene. • These compounds are hygroscopic and could impact cloud formation, rainfall and climate •
- 40. Global Air Conditioners • These aerosol particles help turn water vapour, in the atmosphere, into clouds. • The aerosol particles double the thickness of clouds some 1,000 m above the forests, and reflect an extra 5% more sunlight back into space. • Terpenes are released even more abundantly in warmer conditions causing trees to act as • “Global Air Conditioners”.