Phytochemistry I Glycosides Lecture 2 PDF

10/7/2024 Phytochemistry I Glycosides Prof. Dr. Mohamed elgendy Dr. MostafaHassan Phenolic Glycosides 2 Phytochemistry I Code: Pharm 339 - Level 3 1 ...

10/7/2024 Phytochemistry I Glycosides Prof. Dr. Mohamed elgendy Dr. MostafaHassan Phenolic Glycosides 2 Phytochemistry I Code: Pharm 339 - Level 3 1  10/7/2024 Phenolic Glycosides Source: In higher plants, storage tissues (seeds, berries), dead tissues (heartwood) Phenolic glycosides are classified into: A. Simple phenolic glycosides ( Arbutin ) B. Phenolic ester glycosides (Gaultherin ) C. Phenolic alcohol glycosides (Salicin) D. E-Flavonoid glycosides E. Coumarin glycosides A-Simple phenolic glycosides Arbutin Source: the leaves of Uva ursi (Ericaceae) Chemical tests: + FeCl3 blue color + HCl/ heat crystals needles of O-glucose hydroquinone OH Arbutin 4 Phytochemistry I Code: Pharm 339 - Level 3 2  10/7/2024 O-glucose Uses: OH 1. Diuretic and urinary antiseptic Arbutin 2. Both hydroquinone and arbutin have skin bleaching action and antioxidant properties, which help protect the skin from oxidative stress and environmental damage. 5 Phytochemistry I Code: Pharm 339 - Level 3 Hydrolysis: O-glucose OH Acid or + Glucose Emulsin enzyme OH OH Arbutin Hydroquinone 6 Phytochemistry I Code: Pharm 339 - Level 3 3  10/7/2024 Types of Arbutin: 1. Alpha-Arbutin: The synthetic form of arbutin that is more stable and potent than the natural form. It is often used in high- performance skincare products. 2. Beta-Arbutin: The natural form of arbutin, derived from plants. It is effective but less potent compared to alpha-arbutin 7 Phytochemistry I Code: Pharm 339 - Level 3 8 Phytochemistry I Code: Pharm 339 - Level 3 4  10/7/2024 B- Phenolic ester glycosides Gaultherin Source: Gaultheria procumbens (Wintergreen) Uses: Analgesic, Antipyretic, Anti-rheumatic COOCH3 O-xylose-glucose Gaultherin 9 Phytochemistry I Code: Pharm 339 - Level 3 Hydrolysis: Acid or enzyme (gaultherase enzyme) hydrolysis yields methyl salycilate (volatile), xylose and β-D-glucose COOCH3 COOCH3 O-xylose-glucose OH Acid or + Glucose + Xylose Enzyme Gaultherin Methyl salicylate 10 Phytochemistry I Code: Pharm 339 - Level 3 5  10/7/2024 C- Phenolic alcohol glycosides 1. Salicin: O-Hydroxybenzyl glucoside Source: in Willow barks e.g. Salix fragilis. CH2OH O-glucose Salicin 11 Phytochemistry I Code: Pharm 339 - Level 3 Uses: Analgesic, Antipyretic and Anti-rheumatic. When applied topically, salicin can help treat skin conditions such as acne, psoriasis, and eczema. Side Effects: High doses of salicin can cause side effects similar to those of aspirin, such as stomach ulcers, bleeding, and allergic reactions. 12 Phytochemistry I Code: Pharm 339 - Level 3 6  10/7/2024 Extracting salicin from willow bark: 1. Harvesting: The bark is typically harvested from young willow branches, as they contain higher concentrations of salicin. The best time for harvesting is in the spring when the sap is rising. 2. Drying: The bark is dried after deactivation of enzyme to prevent hydrolysis and degradation of the active compounds. The bark are spread in a well-ventilated area away from direct sunlight. once dried, the bark is ground into a fine powder to increase the surface area for extraction. 3. Extraction: The powdered bark is then subjected to a solvent extraction process. Common solvents include water, ethanol, or a mixture of both.Phytochemistry I Code: Pharm 339 - Level 3 13 4. Add lead acetate to remove tannins. 5. Pass H2S gas to remove ecxss of lead acetate. 6. Filtration: The mixture is filtered to remove the solid material, leaving behind a liquid extract rich in salicin. 7. Concentration: The liquid extract is often concentrated by evaporating under reduce pressure. 8. Purification: Purification by chromatographic techniques. 14 Phytochemistry I Code: Pharm 339 - Level 3 7  10/7/2024 15 Phytochemistry I Code: Pharm 339 - Level 3 Hydrolysis: CH2OH CH2OH O-glucose OH Acid Hydrolysis + D-glucose Salicin saligenin CH2OH CH2OH OH O-glucose O H2C HCl / heat Salicin Saliretin 16 Phytochemistry I Code: Pharm 339 - Level 3 8  10/7/2024 Chemical tests: Salicin with concentrated sulphuric acid gave red color, disappear by water. Salicin with Froehd’s reagent gave a violet color. Salicin with Mandalin’s reagent gave a purple color. Salicin with Erdman’s reagent gave a red color. 17 Phytochemistry I Code: Pharm 339 - Level 3 2. Populin Its 6’- benzoyl salicin Source: Populus species 18 Phytochemistry I Code: Pharm 339 - Level 3 9  10/7/2024 Hydrolysis: By Alkali: It gives benzoic acid and slicin. By Acid: It gives benzoic acid, glucose and saligenin 19 Phytochemistry I Code: Pharm 339 - Level 3 3. Coniferin: Its m-methoxy-p-hydroxy cinnamyl alcohol glycosides Source: Coniferous plant Uses: Preparation of Vanillin 20 Phytochemistry I Code: Pharm 339 - Level 3 10  10/7/2024 Coniferin 21 Phytochemistry I Code: Pharm 339 - Level 3 Flavonoid Glycosides 11  10/7/2024 E- Flavonoid Glycosides One of the most diverse and widespread group of natural products Distribution In fruits, vegetables, nuts, seeds, stems, flowers as well as tea, and are one of the most important constituents of the human diet. Free or in glycosidal form, more common in higher plants Skeleton Diphenyl propane derivatives [ C6-C3-C6 ] 15 carbons 12  10/7/2024 Role in plant 1- Role in plant defense mechanism is very limited. phenolics in response to fungal infection or other external stimuli. 2- Pigments in flowers, attract pollinating insects. 3- Plant growth regulators, inhibiting or activating enzymes. Pharmacological activities due to:  Binding to enzymes and cell membranes.  Chelation of heavy metal ions.  Electron transfer in enzyme systems, e.g. oxido-reductases.  Free radical scavenging (antioxidant). 13  10/7/2024 Identification of Flavonoids 1. Reaction with AlCl3 Yellow 2. Shinoda’s test: Alc. soln. + Mg metal/HCl Orange, red or violet 3. FeCl3 test 4. Ammonia test: Flavonoid extract with ammonia give yellow color UV spectral absorption: UV spectra of flavonoids show 2 absorption maxima: Band I (210-290 nm) (hypthochromic shift) (due to cinnamoyl system of ring B + C4=O) Band II (300-400 nm) (Bathochromic shift) (due to benzoyl system of ring A, + C4=O) B A 14  10/7/2024 Flavone glycosides 15 10/7/2024 16  10/7/2024 OH OH Apiose-glucose - O Glucose - O O O Partial Hydrolysis + Apiose OH O OH O Apiin 7- glucoapigenin Total Hydrolysis OH Aglycone part of HO O Apiin is Apigenin + Apiose + Glucose OH O Apigenin Hydrolysis of Apiin OMe OMe Glucose - O O Rhamnose-glucose - O O OH OH Partial Hydrolysis + Rhamnose OH O OH O Diosmin 7- glucodiosmin Total Hydrolysis OMe Aglycone part of HO O Diosmin is Diosmetin OH + Rhamnose + Glucose OH O Diosmetin Hydrolysis of Diosmin 17  10/7/2024 Flavonols Quercetin Flavonol Aglycone Glycosides Rutin Quecetin Qurcetrin Myricetin Myricetrin 18  10/7/2024 Myricetrin (myricetin 3-O-Rhamnoside) Isolated from different species Uses: Antioxident and antiinflammatory Hepatoprotective Antidiabetic 19  10/7/2024 Hydrolysis:** Acid hydrolysis yields hesperitin, rhamnose and glucose. N.B: Rutinose is a sugar moiety formed from rhamnose and glucose.*** 20  10/7/2024 Isoflavonoid Glycosides Diadizin and genistin Diadizin occurs in soya beans (Glycine max) genistin occurs in Genista lupines and Prunus spp. Hydrolysis: diadizin by acid yields diadzein (Aglycone) and glucose genistin yields genistein (Aglycone) and glucose. Uses: Isoflavones are considered as dietary phytoestrogens. They are cancer protective compounds. Diadzin is used as antioxidant. Glucose-O O HO O Hydrolysis R O R O OH OH Diadzin R= H Diadzein R= H Genistin R=OH Genistein R=OH biflavones glycoside. Amentoflavone It occurs in Ginkgo biloba Linkage between two molecules of Apigenin where c-5΄ of one molecule linked with C-8 of the other one Uses: It is used as uterine antispasmodic. Delay diabetic cataract & diabetic neuropathies. Cardiotonic. OH HO O OH HO O OH O Amentoflavone OH O Apigenin 21  10/7/2024 Flavanolignans Silymarin (a mixture of various flavanonol or flavanol derivatives)  The principle components are: 1-Silybin 2-Silychristin 3-Silydianin  in the fruits of Silybum marianum Uses:  Hepatoprotective  Prophylactic from liver damage caused by metabolic toxins.  in liver dysfunction and after hepatitis treatment.  in chronic degenerative liver condition (liver cirrhosis, fatty liver) 22 10/7/2024 23  10/7/2024 Coumarins Coumarins Derivatives of benzo-α-pyrone Free & in glycosidic “classified as phenolic just for convenience” Some are toxic “Aflatoxins”, but other are imp. as anticoagulant & antibiotic Have fragrant odor & bitter aromatic, burning taste, sol. in alc 5 4 6 3 2 OH HO O O O 7 O O 8 1 O-hydroxycinnamic acid Pyrone Coumarin (O-coumaric acid) (Benzo--pyrone) 24  10/7/2024 R1 5 4 3 Coumarin, R1 = H, R2 = H, R3 = H R2 O O Umbelliferone, R1 = H, R2 = OH, R3 = H 1 Aesculetin, R1 = OH, R2 = OH, R3 = H R3 Scopoletin, R1 = OCH3, R2 = OH, R3 = H 25  10/7/2024 Khellin It occurs in fruits of Ammi visnaga; Familly, Umbelliferae one of the active principles of the Egyptian OCH O 3 traditional medicine known as "khella". Uses: O It is used as coronary vasodilator. O CH3 OCH3 Vitiligo (leukoderma) Khellin Kidney Stones Mostafa Hassan Detection of coumarins: reflux with 50ml 70% ethanol and filter Powdered drug Addition of Ammi visnaga (5g) ammonia exposed to UV-365 blue fluorescence color 26  10/7/2024 Coumarin derivatives of pharmaceutical importance Anticoagulants 4-Hydroxycoumarins Bishydroxycoumarin (Dicoumarol) from Melilotus officinalis (infected leaves) Coumarin antibiotics Novobiocin & coumermycin A OH from Streptomyces sp. CH3 MeO O CH3 O O CH3 OH Novobiocin OOCNH2 Poisonous coumarins (Aflatoxins) Toxins produced by fungi & are Hepatotoxic or carcinogenic 27  10/7/2024 Cyanogenic glycosides 55 Phytochemistry I Code: Pharm 339 - Level 3 56 Phytochemistry I Code: Pharm 339 - Level 3 28  10/7/2024 Cyanogenic Glycosides  Cyanogenetic or Cyanophore glycosides  plants containing these compounds are used as flavoring agents  On hydrolysis release HCN gas  Role in plants, “chemical defense” against organisms damaging or feeding on plant tissues and lead to release of HCN gas, which is toxic R1 CN R2 OSugar 57 Phytochemistry I Code: Pharm 339 - Level 3 Cyanogenic Glycosides Detection of cyanophore glycosides in vegetable drugs  Guignard's Reaction: Sodium picrate paper + HCN sodium isopurpurate (Yellow) (brick red color) R1 CN R2 OSugar 58 Phytochemistry I Code: Pharm 339 - Level 3 29  10/7/2024 Linamarin: Source: Linamarin is a cyanophore glucoside which occurs in linseed (Linum usitatissimum, F. Linaceae). Hydrolysis: Linamarin gives glucose and acetone cyanohydrin. Further hydrolysis gives glucose, acetone and hydrocyanic acid. CN HO CH3 O O CH3 OH HO OH 59 Phytochemistry I Code: Pharm 339 - Level 3 60 Phytochemistry I Code: Pharm 339 - Level 3 30  10/7/2024 Amygdalin: Source: bitter almond seeds (Prunus amygdalus), kernels of apricots (Prunus armeniaca), peaches, plumes. Uses: Preparation of benzaldehyde (volatile oil of bitter almond): bactericidal, antispasmodic, sedative. 61 Phytochemistry I Code: Pharm 339 - Level 3 Hydrolysis Amygdalin + (mixture of 3 enzymes: Amygdalin hydrolase + prunasin hydrolase + mandelonitrile lyase) give benzaldehyde + HCN + 2 glucose. 62 Phytochemistry I Code: Pharm 339 - Level 3 31  10/7/2024 63 Phytochemistry I Code: Pharm 339 - Level 3 Method of isolating amygdalin: 1. The fruits are cracked to obtain the kernels, which are dried in the sun or in ovens. 2. The kernels are boiled in ethanol; on evaporation of the solution and the addition of diethyl ether, amygdalin is precipitated as white crystals. 64 Phytochemistry I Code: Pharm 339 - Level 3 32  10/7/2024 Thioglycosides (Glucosinolates) S-glycosides  anions having Glc. & sulfate (S atom conjugated to Glc, & S in sulfoxime gp)  Rich sources: oil seeds (rapeseed), condiments (mustard) & vegetables (broccoli, cabbage, and turnips)  **Black mustard is a local irritant & emetic. Pharmacological action & Uses:  Externally: rubefacient  Commercially: condiment  Anticarcinogenic. 65 Phytochemistry I Code: Pharm 339 - Level 3 66 Phytochemistry I Code: Pharm 339 - Level 3 33  10/7/2024 Sinigrin Source: in seeds Brassica nigra (black mustard) Hydrolysis + Glucose + SO4 67 Phytochemistry I Code: Pharm 339 - Level 3 Sinalbin Source: in seeds of Brassica alba (White mustard) Hydrolysis: Myrosinase enzyme p- hydroxybenzyl isothiocyanate + sinapine acid SO4 + Glc 68 Phytochemistry I Code: Pharm 339 - Level 3 34  10/7/2024 69 Phytochemistry I Code: Pharm 339 - Level 3 35