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AKALOIDS AlKALOIDS INTRODUCTION 2 NAMING OF ALKALOIDS 3 PROPERTIES OF ALKALOIDS 4 CLASSIFICATION OF ALKALOIDS 5 QUALITATIVE TEST FOR ALKALOIDS 6 QUANTITATIVE DETERMINATION OF ALKALOID 7 EXTRACTION METHOD OF ALKALOIDS 8 CONCLUSION INTRODUCE 3 Properties of alkaloids 1 INTRODUCTION >25000 compounds The term Alkaloid, W Messner in 1819 for basic nitrogen containing compounds of plant origin New definition, Max Pololopxki Alkaloid is an organic compound of natural origin contains a nitrogen atom, is.
AlKALOIDS INTRODUCTION NAMING OF ALKALOIDS PROPERTIES OF ALKALOIDS CLASSIFICATION OF ALKALOIDS QUALITATIVE TEST FOR ALKALOIDS QUANTITATIVE DETERMINATION OF ALKALOID EXTRACTION METHOD OF ALKALOIDS CONCLUSION INTRODUCE INTRODUCTION - >25000 compounds - The term Alkaloid, W Messner in 1819: for basic nitrogen containing compounds of plant origin Properties of alkaloids - New definition, Max Pololopxki: Alkaloid is an organic compound of natural origin: • contains a nitrogen atom, is more or less basic • is of limited distribution • at low doses, marked pharmacological properties • Precipitation reaction with common reagents for alkaloids INTRODUCTION Forms of Alkaloids: • Free bases • Salts with organic acids: Oxalic, acetic acids • Salts with inorganic acids: HCl, H2SO4 • Salts with special acids: Meconic acid in Opium, Quinic acid in Cinchona • Glycosidal form: Solanine in Solanum NAMING OF ALKALOIDS • Numerous methods can be used to name alkaloids: ⁺ Generic plant name –atropine from Atropa belladonna ⁺ Specific name of the plant –cocaine from Erythroxylum coca ⁺ Common name of the herb –ergotamine from ergot (rye) ⁺ Physiological action of the plant –emetine producingemesis ⁺ Other: morphine derived from ancient Greek ⁺ mythology–Morpheus –god of dreams PROPERTIES OF ALKALOIDS • Most alkaloids contain oxygen in their molecular structure • Some alkaloids are colored yellow, orange, or colorless • Most alkaloids are weak bases • Many alkaloids dissolve poorly in water but readily dissolve in organic solvents • Most alkaloids have a bitter taste or are poisonous when ingested CLASSIFICATION OF ALKALOIDS Biological origin There are main groups: Sedatives, Vasodilatation, Local anesthetic, Hallucinating For example: Morphine, cocaine… Properties of alkaloids Chemical classification • • • • True (Typical) alkaloids Proto alkaloids Pseudo alkaloids False alkaloids Biosynthetic pathway • • • • • Ornithine- Tropane, Pyrrolidine, Pyrrolizidine Tyrosine-Benzyl isoquinoline Tryptophane- Indole alkaloids, Quinoline Pyridine, Nicoticnic acid- Pyridine Lysine- Quinolizidine, Piperidine Cocaine Caffeine Ephedrine BELLADONA Atropa belladonna, Solanaceae Use part: folium Chemical composition: • Alkaloid content 0.3-0.6% • Hyoscyamine as chief constituent (90%), occures alongside scopolamine (2%) and their dehydration products (7%) • Small quantity of scopoletol (a coumarine) COCA Erythroxylum coca, Erythroxylaceae Constituents • Variable quantitesof an essential oil including methylsalicilate, flavonoids, tannins • Alkaloids (0.5-1.5 %): Cocaine (=methylbenzoylecgonine, 30-50%), cinnamylcocaine (=methylcinnamylecgonine), truxillines (esters of a dicinnamicacid), several pyrrolidines (hygrine, cuscohygrine) cinnamylcocaine hygrine Datura metel, Solanaceae Chemical composition • Minerals (18-20 %) • Total alkaloid content: 0.04-0.15% • Hyoscyamine is the chief constituent and the percentage of scopolamine can be high (25 % and more) Uses • Hebane is not used much more than stramonium • It is an ingredient of combinations, for example with buckthorn, aloe (stimulant laxative), belladonna (gastrointestinal pain), or ephedrine (asthma) 5 QUALITATIVE TEST FOR ALKALOIDS Mayer’s reagents • Mayer’s reagent is an alkaloid precipitating reagent used for the detection of alkaloids in natural products Most alkaloids are precipitated from neutral or slightly acidic solution by Mayer’s reagent (potassium mercuric iodide solution) to give a white or yellow color precipitate Figure Proposed reaction of Mayer test HgCl2 + 2KI HgI2 + KCl HgI2 + 2KI K2[HgI4] Potassium-Alkaloid precipitate (yellow) QUALITATIVE TEST FOR ALKALOIDS Wagner’ s reagent • The positive results of alkaloid test in Wagner test was confirmed by the presence of brownish to reddish-brown precipitate The precipitate was predicted as the presence of potassium-alkaloid • In Wagner reagent preparation, iodine reacts with I- ion from potassium iodide producing I3- ion (brownish solution) potassium-alkaloid QUALITATIVE TEST FOR ALKALOIDS Dragendorff’s reagent • Dragendorff’s test reagent is a colour reagent that can be used to identify alkaloids in test samples or as a chromatography plate stain Alkaloids will react with Dragendorff’s test reagent and form an orange or orange-red precipitate if they are present in the sample solution BiI3 + 3KNO3 Bi(NO3)3 + 3KI 3+ Bi + H2O BiI3 + KI Brown + + BiO + 2H K[BiI4] + + K[BiI4] Potassium-Alkaloid precipitate [BiI4] Orange QUALITATIVE TEST FOR ALKALOIDS Hager’s reagent • Hager's test was done by adding a few drops of the reagent to plant extracts and appeared a yellow-colored precipitate that indicates the presence of alkaloids Hager's reagent is saturated solution of picric acid Tannic acid solution ( 5% w/v): Gives buff colored ppt which is soluble in dil.acid or ammonia Ammonium reineckate solution: 2% solution, produces precipitates with heterocyclic nitrogen alkaloids, with quaternary some tertiary amine QUANTITATIVE DETERMINATION OF ALKALOID Volumetric methods: These are base on reaction of alkaloidal bases the with acids ( acid – base titration) They include: Aqueous titration: this is carried by either: Direct titration of the alcoholic solution of the alkaloidal residue with standard acid, or Back titration by dissolving the resdue in a know amount of standard acid and back titration of residual acid against standard alkali Non- aqueous titration: this method is suitable for determination of weak bases e.g Caffeine QUANTITATIVE DETERMINATION OF ALKALOID Gravimetric methods: They can be performed by either: Direct weighing of the alkaloidal mixtures Precipitation of the total alkaloids and determination of the weight of the precipitate obtain Spectrophotometric method (Spectrophotometric method foe estimation of alkaloids perceptible with Dragendorff’s reagent in plant materials) Fluorimetric method ( Simplified fluorimetric determination of digitalis alkaloids Datt V Naik) Polarimetric method ( the colorimetric determination of various alkaloid Authors F J Bandelin) EXTRACTION METHOD OF ALKALOIDS The extraction of alkaloids is based on their basic character and solubility pattern: • The fact that alkaloids normally occur in the plant as salts • Solubility of various salts and bases in water and organic solvents • Plant materials often contain significant amounts of fats that, in addition to extraction, by forming emulsions So the fat is reduced by petroleum ether tannins, proteins, resins and colorants, can interfere with STASS-OTTO METHOD Properties of alkaloids MANSKE’S METHOD Properties of alkaloids CONCLUSION Alkaloids are very important compounds for human beings For ages their extracts were used as a cure to rescue people from pain like morphine and some illnesses like quinine in malaria and colchicine in gout Thanks to alkaloids during ages, people can cure the diseases and improve their life Thank you for listening!