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salicylic acid

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  1. 1. University of Salahaddin-Erbil College of Science Environmental science department 1 Halala Rahman Qadir M.Sc. Plant physiology 2015
  2. 2. Outline Definition of Salicylic acid Structure of salicylic acid Properties of Salicylic acid Effects of salicylic acid 2
  3. 3. Definition of Salicylic acid 3 Salicylic acid (SA): is a phenolic derivative, distributed in a wide range of plant species. It is a natural product of phenylpropanoid metabolism. Decarboxylation of transcinnamic acid to benzoic acid and its subsequent 2- hydroxylation results to SA. It undergoes metabolism by conjugating with glucose to SA glucoside and an ester.
  4. 4. Properties of SA • An odorless, crystalline solid substance. • Has a sweetish taste. • Used externally for treatment of skin diseases. • It has a remote action after absorption. • Causes marked irritation of gastric mucous membrane. 4
  5. 5. Medical uses • Salicylic acid is known for its ability to ease aches and pains and reduce fevers. • salicylic acid is a key ingredient in many skin-care products for the treatment of seborrhoeic dermatitis, acne, psoriasis, calluses, corns, keratosis pilaris, acanthosis nigricans, ichthyosis, and warts. • SA is used in the production of other pharmaceuticals including 4-aminosalicylic acid, sulpiride, letimide (via Salethamide). 5
  6. 6. SA as a plant hormone • Salicylic acid (SA) is a phenolic phytohormone • Is found in plants with roles in plant growth and development, photosynthesis, transpiration, ion uptake and transport. • SA also induces specific changes in leaf anatomy and chloroplast structure. • SA is involved in endogenous signaling, mediating in plant defense against pathogens. • It plays a role in the resistance to pathogens by inducing the production of pathogenesis-related proteins. • It is involved in the systemic acquired resistance (SAR) in which a pathogenic attack on one part of the plant induces resistance in other parts. • The signal can also move to nearby plants by salicylic acid being converted to the volatile ester, methyl salicylate 6
  7. 7. Effects of Salicylic acid SA has direct involvement in plant growth, thermogenesis, flower induction and uptake of ions. It affects ethylene biosynthesis, stomatal movement and also reverses the effects of ABA on leaf abscission. Enhancement of the level of chlorophyll and carotenoid pigments photosynthetic rate and modifying the activity of some of the important enzymes are other roles assigned to SA. 7
  8. 8. Production • Salicylic acid is biosynthesized from the amino acid phenylalanine. In Arabidopsis thaliana it can also be synthesized via a phenylalanine- independent pathway. 8