Introduction of Secondary Metabolite - Alkaloids.

Brief Outline of Occurrence, Distribution, Isolation, Identification, Therapeutic Activity and Pharmaceutical Applications of Alkaloids

1. Brief outline of Occurrence , Distribution , Isolation , Identification tests, Therapeutic activity and Pharmaceutical applications- -Alkaloids- By Prof. Dattaprasad N. Vikhe HOD Diploma in Pharmacy / Asst. Professor Department of Pharmacognosy Pravara Rural College of Pharmacy, Pravaranagar CHAPTER :- 4 First Year D. Pharmacy As per ER 2020 By Dattaprasad N. Vikhe

2. Contents General considerations (Introduction) Defination Properties Occurance Classification Nomenclature & Chemistry (Including Qualitative & Quantitative analysis) By Dattaprasad N. Vikhe

3. Introduction The term alkaloid was coined by German pharmacist Meissner in 1819 The mankind using alkaloids for purposes like Poison Medicines Teas Poultices Alkaloids are secondary metabolites Alkaloids are obtained from both animal and plant sources By Dattaprasad N. Vikhe

4. Introduction Alkaloids, derived from the term "Alkali-like," refer to basic nitrogenous compounds commonly found in plants. These compounds, which can be primary, secondary, or tertiary amines, are physiologically active. Approximately 21,000 alkaloids have been identified to date. Alkaloids are typically not found in isolation but exist as mixtures of major and minor compounds within a biosynthetic unit, exhibiting variations in functional groups By Dattaprasad N. Vikhe

5. Defination Alkaloids are organic compounds containing one or more nitrogen atoms in heterocyclic ring. Alkaloids are organic products of natural or synthetic origin. They are primary, secondary, tertiary amines or as quaternary salts. The alkaloids are basic in nature (because of nitrogen presence). Alkaloids are defined from the chemically, Biochemically, Physiologically. Alkaloids possess specific physiological action on humans & animals when used in small quantities. By Dattaprasad N. Vikhe

6. Basic Classes of alkaloids Alkaloids are distinguish between three classes True Alkaloids Proto Alkaloids Pseudo Alkaloids By Dattaprasad N. Vikhe

7. True Alkaloids Proto or Amino alkaloids Pseudo Alkaloids The true alkaloids are toxic in nature The proto alkaloids or amino alkaloids are simple amines The pseudo-alkaloids are not derived from amino acids They contain heterocyclic nitrogen which derived from amino acids. They do not contain nitrogen in heterocyclic ring It includes mainly Steroidal, terpenoids , purines They are normally present in plants as a salt of organic acids They are occurs in plants They give standard qualitative test for alkaloids They are basic in nature The proto alkaloids are basic in nature E.g. Morphine, Cocaine, Quinine, Dopamine E.g. Ephedrine, Colchicine . E.g. Caffeine They are considered as biological amines By Dattaprasad N. Vikhe

8. Properties of Alkaloids 1. Physical Properties Alkaloids are colourless or some are coloured ( eg . Betanidin is red, berberine is yellow ) They are crystalline solids Some are amorphous gum They are having high melting points or decomposition range Some liquid alkaloids like Nicotine are volatile in nature Alkaloids are generally bitter in taste They are optically active By Dattaprasad N. Vikhe

9. Free bases of alkaloids are soluble in non-polar, organic solvants Insoluble in water Salts of alkaloids are soluble in water Sparingly soluble in organic solvents Pseudo and proto alkaloids are highly soluble in water (Caffeine, Colchicine ) The solubility of alkaloids and their salts is useful in pharmaceutical industry For the a) Extraction Purpose b) To make a formulation c) For final pharmaceutical preparations. By Dattaprasad N. Vikhe

10. 2. Chemical Properties Most of alkaloids are basic in reaction, due to availability of lone pair of electrons or nitrogen. The alkaloids may contain one or more number of nitrogen It may exist in the form of Primary amines (R-NH2) eg . Mescaline. Secondary amines (R2-NH) eg . Ephedrine Tertiary amines (R3N) eg . Atropine Quaternary Ammonium salts (R4N+X) eg tubocurarine chloride By Dattaprasad N. Vikhe

11. Occurrence and distribution The alkaloids are found mostly in Plants Also occurs in Animals, Fungi, Bacteria. They may also synthesized in laboratories. They are occur in all parts of plants They are usually localized in one organ ( eg . Barks or Seeds). By Dattaprasad N. Vikhe

12. In the plant kingdom alkaloids are distributed in certain families like : Leguminosae Solanaceae Rubiaceae Piperaceae Berberidaceae Taxaceae Liliaceae By Dattaprasad N. Vikhe

13. Chemical Tests for Alkaloids The C.T. is used for the identification or detection of alkaloids 1) Mayer’s Reagent (Test) : Potassium mercuric iodide solution - Cream coloured Precipitate 2) Dragendroff’s Reagent (Test): Potassium Bismuth iodide solution – Reddish brown precipitate 3) Wagner’s Reagent (Test) :- Iodine- Potassium iodide solution – Reddish Brown Precipitate 4) Hagers Reagent (Test):- Picric acid – Yellow precipitate 5) For purine alkaloid- caffeine or any purine alkaloid in petridish + Hydrochloric acid+ potassium chlorate and heat to dryness – Purple colour + addition of alkali will reduce the colour 6) For opium alkaloid – opium dissolved in water + ferric chloride – Reddish purple colour which fade the colour after addition of hydrochloric acid. By Dattaprasad N. Vikhe

14. Isolation & Extraction of Alkaloids General methods of extraction Stass otto Method Soxhelt extraction method Kippenberger process By Dattaprasad N. Vikhe

15. I solation/ Extraction Alkaloids are isolated using various methods, including: Stass -Otto Process : ● De-fatting of powdered materials with non-polar solvents and treatment with NH3 . ● Extraction with organic solvents (e.g., chloroform, ether) followed by concentration. ● Dissolution of alkaloid salt and basification with ammonia or sodium bicarbonate. ● Obtaining free alkaloids in the organic phase and drying them By Dattaprasad N. Vikhe

16. I solation/ Extraction The alkaloid present as a complex mixture Plant also contain different organic acids, fats, waxes, pigments, alkaloids etc Steps involved in isolation of alkaloids as Separation of crude alkaloid from plant extract Isolation and purification of individual alkaloids from crude alkaloids Purification done by following ways which may vary for individual alkaloid . Qualitative analysis of plant extract By Dattaprasad N. Vikhe

17. 1) Direct Crystallisation from solvent T his is simple method of isolation M ay not be used in case of complex mixtures 2) Steam distillation T his method is specially employed for the volatile liquid alkaloid E g. C oniine, sparteine , N icotine T his method is not suitable for the high molecular weight alkaloids By Dattaprasad N. Vikhe

18. 3) Chromatographic Techniques T his method is ideal method for the separation of alkaloid D ifferent type of chromatographic techniques is used for the separation of individual alkaloid from complex mixture Thin layer chromatography Column chromatography gas chromatography L iqui d ion exchange chromatography HPTLC etc. Paper chromatography By Dattaprasad N. Vikhe

19. Powdered Drug Containing alkaloid salts Defat if necessary with alkaline solution of sodium carbonate/Ammonia/Calcium hydroxide Alkaloids are freed as a bases Extracted with organic solvents e.g. Chloroform, Ether etc. Extract Concentrate and shake with Successive quantities of inorganic acids Filter Residual organic fraction Aqueous acid solution (Like pigments, Fats, sulphates,impurities ) (Alkaloidal Salts) (Extracted with miscible solvent like chloroform) Filter Residual fraction Organic solution of alkaloid Distill off with solvent Crude alkaloid mixture is obtained Purification by the fractional crystallization, chromatographic separation etc Structural identification by modern analytical techniques such as UV, IR, NMR, GC, Mass spectrometry.

20. Function of Alkaloids in Plants They may act as protective against insects. They may act as protective herbivores due to their bitterness and toxicity. They are, in certain cases, the final products of detoxification ( waste products) . Source of nitrogen in case of nitrogen deficiency. They , sometimes, act as growth regulators in certain metabolic systems. They may be utilized as a source of energy in case of deficiency in carbon dioxide assimilation. By Dattaprasad N. Vikhe

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23. Classification of Alkaloids Various method of classification of alkaloids are as follows 1) Pharmacological Classification – Depending upon the physiological response alkaloids are classified under various p’cological categories CNS Stimulant CNS depressant Sympathomimetic Analgesic Purgative Cardiac Depressant Antimalarial Antitussive By Dattaprasad N. Vikhe

24. 2) Taxonomic Classification – This method classifies the vast no. of alkaloids Based on the distribution in various plant families From this type of classification the chemotaxonomic classification has been derived 3 ) Biosynthetic Classification – This method gives significance to the precursor from which alkaloid are biosynthesized in the plant If they are derived from same precursor then they are grouped together For example- alkaloids are derived from amino acid precursor as ornithine, lysine, tyrosine, trypotophan etc. 4) Chemical Classification – T his is most accepted way of classification of alkaloids This type is the criteria for chemical class as the type of fundamental ring structure present in alkaloid The alkaloidal drugs are divided into two divisions A) Heterocyclic alkaloid : they are divided into 12 groups according to nature of their heterocyclic ring(True alkaloids) B) Non-Heterocyclic alkaloids : they are Pseudo or Proto alkaloids The following table indicates type,occurance in various plants with the basic ring. By Dattaprasad N. Vikhe

25. Therapeutic and Pharmaceutical Applications of Alkaloids : - ● Central Nervous System (CNS) Effects: Depressants (e.g., Morphine) Stimulants (e.g., Caffeine) ● Autonomic Nervous System (ANS) Effects: Sympathomimetic (e.g., Ephedrine) Parasympathomimetic (e.g., Pilocarpine ) Anticholinergic (e.g., Atropine, Hyoscyamine ) ● Local Anesthetic or Analgesic Properties: Cocaine and Morphine ● Therapeutic Uses: Antitumor (e.g., Vinblastine) Antimalarial (e.g., Quinine) Antibacterial (e.g., Berberine ) By Dattaprasad N. Vikhe