Chemistry of Natural Products (2) (PHG322/PG 314) October University Fall 2024 PDF

Faculty of Pharmacy The Faculty of Pharmacy of October University for Modern Sciences and Arts is a pioneer in tutelage, scientific research, and community service at the local and regional levels, and holds an advanced position among its counterparts in international Pharmacy subject ranking ‫)...

Faculty of Pharmacy The Faculty of Pharmacy of October University for Modern Sciences and Arts is a pioneer in tutelage, scientific research, and community service at the local and regional levels, and holds an advanced position among its counterparts in international Pharmacy subject ranking ‫) كلية رائدة فى مجال التعليم‬MSA( ‫كلية الصيدلة جامعة اكتوبر للعلوم الحديثة و اآلداب‬ ‫و البحث العلمىى و الماىاركة المجتمعيىة لىى الم ىتوو الوىومى و ا وليمىى و ل ىا ر يى‬.‫متودم فى التصنيف العالمى لكليات الصيدلة‬  The Faculty of Pharmacy of October University for Modern Sciences and Arts is nationally accredited, has British partnership, and is committed to producing graduates who are able to compete in national and international job markets and entrepreneurship, and to be an effective member of the medical team providing best medical care, while heeding professional ethics, through an outstanding academic programme and proficient academic staff. The faculty is devoted also to provide effective community services, and exceptional applied scientific research. :‫رسالة الكلية‬ ‫ لتزم بتخريج صيدلى وادر لى‬،‫ باراكة بريطانية‬،‫كلية الصيدلة جامعة أكتوبر للعلوم الحديثة واآلداب معتمدة محليا‬ ‫ و أن يكون ضو فعال فى الفريق الطبى بتوديم أفضل‬،‫المناف ة فى أسواق العمل المحلية و الدولية و ريادة األ مال‬ ‫ وكذلك لتزم‬،‫ من خالل برنامج عليمى متميز و أ ضاء هيئة دريس أكفاء‬،‫ مرا يا ً أخالويات الم نة‬،‫ر اية صحية‬.‫الكليه بتوديم خدمات مجتمعية فعالة و أبحاث لمية طبيوية متميزة‬  ‫األهداف اإلستراتيجية للكلية‬ Support the competitiveness of the college ‫ دعم تنافسية الكلية‬ Academic excellence ‫ التميز األكاديمى‬ Distinguished applied academic research ‫ بحوث أكاديمية تطبيقية متميزة‬ Distinguished community service ‫ خدمة مجتمعية متميزة‬ Sustainable Development ‫ التنمية المستدامة‬ Ensure Institutional Effectiveness An impressive university life ‫ ضمان الفاعلية المؤسسية‬ ‫ حياة جامعية مؤثرة‬  NARS: National Academic Reference Standards ‫المعايير الوومية المرجعية االكاديمية‬ It is the minimum level of knowledge and skills that a graduate must possess to ensure good practice of his profession. These standards have been set by the National Authority for Quality Assurance of Education and Accreditation agency (NAQAAE) NARS Programme Course LOs LOs Learning outcomes (Knowledge and skills ): measurable achievements that the learner will be able to understand after learning processes is completed NAQAAE issued two versions of these standards in 2009 (outcome based) and 2017 (competency based) consecutively, as a result of upgrading and updating the attributes of pharmacy graduates globally. Competency: the capability of applying the acquired skills and knowledge that enable the student to successfully perform in professional and educational contexts. NARS 2009 (Outcome based) NARS 2017 (Competency based) It depends on make use of all the information the Depends on gaining a huge amount of information student acquired during the study period to solve with minor applications professional problems that he encounters through his/her work, whether in private pharmacies, hospitals or research centers through integrating the knowledge and skills the student gain to solve such problems The aims of the course are to: In continuation with chemistry of natural products (1), this module aims to enable students to demonstrate the knowledge and experience that enables her/ him to understand, describe and deal with the chemistry of alkaloids and volatile oils from plant, and animal origin as well as techniques for their isolation, identification and determination in their respective sources. With the target of understanding the structure activity relationships (SAR) of these natural products derived compounds and their pharmacophoric features.  3. Mapping MLO to programme and NARS key elements NARS Key element Programme Key element Module learning outcome (MLO) 1-1-1- Demonstrate 1-1-1-1 Utilize comprehended 1-1-1-1-1 Comprehend the understanding of knowledge of knowledge of principles of basic different methods used for pharmaceutical, biomedical, and pharmaceutical sciences. isolation and screening of active social, behavioural, constituents. administrative, and clinical sciences. 1-1-3- Integrate knowledge from 1-1-3-1 Integrate knowledge 1-1-3-1-1 Correlate between the fundamental sciences to handle, from fundamental sciences to chemical structure of different identify, extract, design, prepare, design, analyze, and assure classes of alkaloids and volatile analyze, and assure quality of quality of synthetic/natural oils and the optimum method for synthetic/natural pharmaceutical pharmaceutical their isolation, extraction and materials/products. materials/products. identification 1-1-4- Articulate knowledge from 1-1-4-1 Apply knowledge of 1-1-4-1-1- Correlate between the fundamental sciences to explain information from fundamental chemical structure of different drugs’ actions and evaluate their sciences to explain classes of alkaloids and volatile appropriateness, effectiveness, and pharmacological and oils and their biological activities. safety in individuals and populations. toxicological effects of drugs. 2-2-1 Isolate, design, identify, 2-2-1-3 Employ the proper method 2-2-1-3-1- Select a protocol for isolation synthesize, purify, analyze, and for the isolation, identification and and separation of alkaloids and volatile standardize synthetic/natural oils from their natural origins. analysis of the main pharmaceutical materials. phytoconstituents and standardization of plant extracts. 2-3-1 Handle, identify, and dispose 2-3-1-1 Handle, identify, and 2-3-1-1-1- Handle and dispose biologicals, synthetic/natural dispose synthetic/natural materials chemicals safely. materials, biotechnology-based and used in pharmaceutical field. radio-labeled products, and other materials/products used in pharmaceutical field. 2-4-1 Ensure safe handling/use of poisons to 2-4-1-1 Ascertain safe handling/use of 2-4-1-1-1- Apply laboratory skills for avoid their harm to individuals and poisons (illicit drugs, toxic natural isolation, identification, differentiation communities. products and mycotoxins) during the and safe handling of different classes of collection and preservation of any alkaloids. forensic evidence. 2-4-4 Assess toxicity profiles of different 2-4-4-1 Detect and assess different poisons 2-4-4-1-1- Scheme methods for detection and xenobiotics and detect poisons in biological (illicit drugs, toxic natural products and testing of alkaloids specimens. mycotoxins) via laboratory examinations and professionally contribute in forensic teams. 3-2-3 Provide evidence-based information 3-2-3-2 Provide evidence based 3-2-3-2-1- Select the appropriate method for about safe use of complementary medicine information about the pharmacological isolation of volatile oil constituents, their including phytotherapy, aromatherapy, and action and toxicity of natural products used separation from mixtures as well as nutraceuticals. in phytotherapy and aromatherapy. identification of the different classes of volatile oils and their individual components. 3-2-4 Provide information about toxic profiles 3-2-4-1 Asses the toxicity profile of drugs 3-2-4-1-1- Select the suitable drug for treatment of drugs and other xenobiotics including and other xenobiotics including sources, and antidote in case of toxicity according to the sources, identification, symptoms, and nature of active constituents. identification, symptoms, and management management control. control. 3-2-6 Maintain public awareness on 3-2-6-1 Develop and promote 3-2-6-1-1- Promote public social health hazards of drug public awareness on the health awareness on the health misuse and abuse. hazards and social implications hazards and social implications of synthetic/natural drug of natural drug addiction. abuse. 4-1-1 Demonstrate responsibility for 4-1-1-1 Demonstrate effective 4-1-1-1-1- Develop time-management team performance and peer communication and team work skills through working in a team to a evaluation of other team members, skills and enhance time definite deadline. and express time management management abilities. skills. 4-3-2 Practice independent learning 4-3-2-1 Practice independent 4-3-2-1-1- Evaluate information from needed for continuous professional learning through a variety of different sources and make full use of development. the library and internet resources to sources, including libraries, solve problems and maintain databases and internet. independent learning Assessment Details Assignments 15 Mid‐Term 30 Lab Work 40 Quizzes 5 Final Exam 60 150 Assessment Details Assignments 15 Mid‐Term 15 Lab Work 20 Oral Examination 15 Final Exam 35 100 1- Alkaloids, (2015) 2nd Edition, Chemistry, Biology, Ecology, and Applications by Tadeusz Aniszewski, Elsevier Science, ISBN: 9780444594334 2- The Complete Book of Essential Oils and Aromatherapy,(2016), by Valerie Ann Worwood, New World Library, ISBN: 978-1577311393 Learning outcomes of this lecture Define and classify alkaloids Recognize the different methods of the nomenclature of alkaloids Understand the physical and chemical characters of alkaloids Scheme a method for the extraction and isolation of alkaloids Recognize the qualitative and quantitative methods of determination of alkaloids Interactive teaching methods Quizizz Socrative  Ephedra Lobelia Colchicum  Alkaloids alkali like The term alkaloids (or alkali-like) was first and foremost proposed by the pharmacist, W. Meissner, in 1819, Group of natural products that have great influence on the economic, medical, political and social affairs of humans. Many have potent physiological effects (important therapeutic agents) e.g. atropine , quinine etc... Some alkaloids are used for their psychotropic effects e.g. psilocin and psilocybin.  High biological activity Produce varying degrees of physiological and psychological responses - largely by interfering with neurotransmitters In high concentrations In low concentrations highly toxic - fatal have therapeutic value  Ergot alkaloids D-tubocurarine Epidemic poisoning An arrow poison Hyoscyamine Coniine Suicidal purpose Socrate’s excution The Opium Wars (Anglo-Chinese wars) between China and Britain (1839-1859) Are basic, organic, nitrogenous compounds from plants They are physiologically active They have complex structures 1-All alkaloids are nitrogenous, but not all the nitrogenous compounds are alkaloids. 2-Alkaloids have a restricted distribution to certain plant families (c.f. nucleic acid that occur in all plants). They also present in animals, fungi and bacteria. 3-Most but not all possess basic properties due to the presence of an amino nitrogen, certain are amphoteric or even acidic e.g. colchicine. BIOSYNTHETIC PATHWAY CHEMICAL STRUCTURE (the way they are produced in (nucleus containing the plant) nitrogen) BIOLOGICAL ACTIVTY (antispasmodics, anticancer, antihypertensive, psychoactive…....etc)  BIOSYNTHETIC PATHWAY (the way they are produced in the plant) AMINO ACIDS are the basic units in the biosynthesis of the true alkaloids  CHEMICAL STRUCTURE (nucleus containing nitrogen) 1-Heterocyclic or typical alkaloids (sub-classified into different groups according to their ring structure). N H CH 3 N Nicotine 2-Non-heterocyclic ( atypical alkaloids = biological amines= proto alkaloids). OH   NHMe (-)-Ephedrine Analgesics and narcotics e.g morphine and codeine Central stimulants e.g. caffeine Mydriatics e.g. atropine Miotics e.g. physostigmine and pilocarpine Antiasthmatics e.g. ephedrine Antihypertensives e.g. reserpine Smooth muscle relaxants e.g. atropine and papaverine Skeletal muscle relaxants e.g. d-tubucurarine True alkaloids Proto alkaloids Pseudo alkaloids Nitrogen in a Don't have nitrogen in a Nitrogen in a heterocyclic ring heterocyclic ring heterocyclic ring Not derived from Derived from amino acids amino acids BUT derived from: Terpenoids or Purines Ephedrine is regarded as an alkaloid although it OH does not contain nitrogen as a part of  heterocyclic ring.  NHMe (-)-Ephedrine Caffeine is regarded as an alkaloid although it is O CH3 not derived from amino acid. H C 3 N N 7 1 3 O N N CH3 Caffeine  The major source of alkaloids was the flowering plants (90% of known alkaloids) but, recently they have been discovered in animals, bacteria (Pseudomonas aeruginosa) and rarely in fungi (pscilocin from hallucinogenic mushrooms) & marine plants. Among the families rich in alkaloids are Solanaceae, Papaveraceae, Loganiaceae , etc ….. The same alkaloid may occur in different genera of the same family, e.g. hyoscyamine that is present in the genera Atropa, Hyoscyamus & Datura. Large number of alkaloids were isolated from skin of amphibians. Alkaloids isolated from mammals include indole & isoquinoline derivatives.  The pharmacological properties of many of the alkaloids keep asking about their purpose in plants. 1- Protective 2- Source of nitrogen 3-Source of energy 4- End products of detoxification 5- Growth regulators N.B What seems most likely is that there are many reasons why plants elaborate alkaloids, and in many cases the purpose may be unique to a given plant.  Common alkaloid names end with the suffix: ine. Morph ine suffix Generic name of the plant e.g. atropine from Atropa belladonna Species name e.g. cocaine from Erythroxylon coca Common name e.g. ergometrine from Ergot Physiological activity e.g. emetine as emetic Physical character e.g. hygrine which is hygroscopic e.g. pelletierine discovered by Name of the discoverer Pelletier  nor= N-demethylation or N-demethoxylation nicotine nor nicotine pseudo ephedrine nor pseudo ephedrine OH OH N N H CH H H 3 NHMe N N NH2 Nicotine Nornicotine Pseudoephedrine Nor-pseudoephedrine apo = dehydration morphine apo morphine atropine apo atropine Iso , pseudo , neo and epi = different isomers d-ine = Optical isomer quinine quinidine in- = lower pharmacological activity ergometrine ergometrinine 1-Number of nitrogen atoms: -Alkaloids usually contain one nitrogen atom. -Certain alkaloids may contain more than one up to 5 nitrogen atoms Nicotine (2 N atoms ) Ergotamine (5 N atoms ) Primary amine Secondary amine ( basic ) ( basic ) Tertiary amine Quaternary amine ( basic ) ( neutral ) Amide alkaloid Phenolic alkaloid (neutral) (acidic and basic)  2-Type of amino group: Nitrogen in alkaloids exists in the form of amine A primary A tertiary A quaternary amino group amino group ammonium ion A secondary amino group dl-nor-ephedrine Nicotine d-Tubocurarine Ephedrine  Basicity of alkaloids is due to the presence of a lone pair of electrons on the amino nitrogen atom.  Alkaloids resemble ammonia [NH3] in chemical characters. They form salts with acids without liberation of water.  They occur as free bases, salts or N-oxides (NO). + N + H+Cl- N H Cl- or N HCl Amine Hydrochloric Amine hydrochloride acid Factors that may influence the degree of basicity of alkaloids 1. Structure of the molecule e.g. degree of unsaturation of the heterocyclic ring. Unsaturation decreases the basicity  e.g. piperidine alkaloids are more basic than pyridine alkaloids. N N Piperidine Pyridine 2. Presence & position of other substituents & functional groups:  Electron releasing groups, e.g. alkyl groups increase the basicity.  Electron withdrawal groups, e.g. carbonyl groups decrease the basicity.   OCH3  Alkaloids are neutral or slightly acidic when the electron availability on the amino CN nitrogen atom decreases e.g. Ricinine is acidic. N O CH3  Some are amphoteric due to the presence Ricinine of acidic groups in their molecule. e.g.  Phenolic alkaloids: morphine, psychotrine & cephaline.  Alkaloids containing a carboxylic group: narceine.  Amphoteric alkaloids O HO NMe2 O OMe O O MeO COOH N CH3 H H OMe HO Narceine Morphine  Many alkaloids contain one or more asymmetric carbon atoms in the molecule and therefore show optical activity.  In the majority of cases the (-)-isomer (levorotatory) has considerable greater pharmacological activity than the (+)-isomer (dextrorotatory) of the same alkaloid.[ l-ephedrine and l- ergotamine are more active than the corresponding d-isomers ]. Some exceptions:  (+) d-tubocurarine is the medicinally used isomer  (-) quinine and (+) quinidine are medicinally active  Atropine which is (-)(+) –hyoscyamine racemic mixture is pharmacologically active Atropine =dl–hyoscyamine  Optical activity Condition Optically active Colour isomers (levo) are usually Solubility more active Solids Liquids Colourless Volatile Non-volatile Nicotine Coloured Pilocarpine and coniine and hyoscine Colchicine and Alkaloids that lack oxygen in their berberine structure usually occur as volatile liquid (yellow)  Solubility Importance of Solubility 1- Alkaloids are often administered in solution 2- The differences in solubility between alkaloids and their salts are used for their isolation and purification Alkaloid Alkaloid SALT FREE BASES Insoluble in Organic Soluble in Organic solvents, viz. chloroform, solvents, viz. chloroform, ether, ethyl acetate, …etc ether, ethyl acetate, …etc Soluble in water Insoluble in water  Alkaloid FREE BASES Soluble in Organic solvents, viz. chloroform, ether, ethyl acetate, …etc Insoluble in water Ephedrine Caffeine Codeine Pilocarpine Soluble in water 4ry bases, as d-tubocurarine (Bases) Morphine Insoluble in ether Theobromine Insoluble in benzene Theophylline  Alkaloid SALT Insoluble in Organic solvents, viz. chloroform, ether, ethyl acetate, …etc Soluble in water Quinine monosulfate Insoluble in water (Salts) Apotropine HCl Soluble in Lobeline HCl chlororoform Some alkaloidal bases e.g. Colchicine are Soluble in water and organic solvents First activity Quizizz 1-Salt formation 2-Stability A- Effect of acids B- Effect of alkalis C- Effect of heat D- Effect of heat and light in presence of oxygen  According to the nature of alkaloids Basic alkaloids Amphoteric alkaloids Acidic alkaloids Containing Do not form phenolic or carboxylic salts with Weak bases require stronger groups can form acids e.g. acids salts with both colchicine acids and alkalis Strong bases form salts Very weak with bases form unstable salts very weak acids e.g.caffeine A- Effect of acids: hot dil. or conc. acids cause remarkable changes Morphine  apomorphine Dehydration Atropine  apoatropine Demethylation Codeine  morphine Ester linkages e.g. atropine Hydrolysis Glucoalkaloids e.g. solanine Solanine  solanidine + rhamnose + glucose + galactose (gluco-alkaloid) (aglycone) (trisaccharide sugar”solanose”)  B- Effect of alkalis: Strong alkalis Weak alkalis Na or K hydroxides NH4OH and NaHCO3 liberates alkaloid bases from their salts form salts with alkaloids which contain phenolic groups, e.g. form salts with alkaloids which contain morphine. And those which carboxylic groups contain carboxylic groups Hot alkalis Ester alkaloids Alkaloids which contain lactone ring e.g. atropine and cocaine. e.g. pilocarpine hydrolyze on heating with alkalis opening of lactone ring  pilocarpic acid (biologically inactive)  O HO NMe2 O OMe O O MeO COOH N CH3 H H OMe HO Narceine Morphine  N Me 1 N Me 7 2 CH2 OH O 6 5 4 3 O HO  Tropine Atropine  H CH2 OH C HOOC  (dl)-tropic acid C 2 H5 H H H2 CH3 C 2 H5 H H H2 CH3 C N C N KOH O or NaOH O CH2OH O N OH N Pilocarpine Pilocarpic acid C- Effect of heat: Alkaloids are decomposed by heat , except caffeine that sublimes without decomposition D- Effect of heat and light in presence of oxygen: Alkaloids will form N-oxides (3ry amines) which have the following advantages: - water-soluble - delayed release properties - low toxicity - low addictive properties  STAS-OTTO METHOD The technique involve the distribution of alkaloidal bases between acid or aqueous solution and immiscible organic solvent. Extraction, Purification & Separation- Acid base purification Powdered plant material Petroleum ether Pet. ether extract Defatted powder Total alkaloids Fats + Non-alkaloidal impurities 1- Alcohol 2- Concentration 3- + CHCl3 or CH3COOC2H5 4- + Dilute acid Organic layer Acidic aqueous layer Salts of strongly basic alkaloids Non-alkaloidal impurities 1- NH4OH or Na2CO3 2-CHCl3 or CH3COOC2H5 Organic layer aqueous layer Strongly basic alkaloids Ammonia is the alkali of choice as it is : - Sufficiently basic to liberate most alkaloids - Volatile and completely removed after extraction.  Isolation of volatile & sublimable alkaloids Isolation of volatile alkaloids e.g. nicotine & coniine By steam distillation 1. Immerse plant material in water. 2. Add caustic soda (NaOH) or Na2CO3 to liberate free bases (NH3 not used due to its volatility). 3. Steam distill the liberated alkaloid. Isolation of sublimable alkaloids e.g. caffeine By direct sublimation from the dried powdered plant  Powdered plant material (Volatile & non-volatile alkaloids & their salts) 1- + Fixed alkali [NaOH, KOH, Na2CO3 or K2CO3] 2- Steam distillation Non-distillable fraction Distillate Non-volatile alkaloids Volatile alkaloids Organic solvent Organic layer Volatile alkaloids Isolation of volatile alkaloids by steam distillation  Tests for detection & identification - Precipitation reactions  Precipitating reagent + neutral or slightly acidic aqueous solution of alkaloidal salts  crystalline precipitates of different colors.  Reagents that contain heavy metals (Hg, Pt, Bi, Cd)  double salts with most alkaloids.  Reactions are used for extraction & purification.  Precautions: Certain alkaloids do not react e.g. caffeine + Mayer’s reagent no ppt. False positive response may be obtained [most reagents also precipitate proteins, tannins, coumarins & certain flavonoids].  Tests for detection & identification- Color reactions  Color reagents + solid free bases [not the salts]  characteristic colored solutions.  Reagents generally contain conc. H2SO4 + oxidizing agent.  Reagents  colors with most alkaloids, or may be specific for one alkaloid or a group of related alkaloids. Examples : Van-Urk's test: ergot alkaloids + para-dimethyl amino-benzaldehyde (PDAB) in conc. H2SO4  blue color. Vitalis' test: solanaceous alkaloids + conc. HNO3 + alcoholic KOH  violet color.  Colour Test Crystal Test Colour Reagents: Precipitation Reactions Froed’s (ammonium molybdate/conc. Reagents: H2SO4) Mayer’s (potassium mercuric Marqui’s (formaldehyde/ conc. H2SO4) iodide) Wagner’s ( iodine/KI) Dragendorff’s (potassium/bismuth Marme’s (potassium cadmium iodide) iodide) Dragendorff’s (potassium/bismuth iodide) 1-Volumetric methods 2- Colorimetric methods 3-Gravimetric methods 4-Chromatographic methods  Acid /base titration This is carried by either: Direct titration of the alcoholic solution of the alkaloidal residue with standard acid Back titration by dissolving the residue in a known amount of standard acid and back titration of residual acid against standard alkali. Non-aqueous titration: For determination of weak bases, the purified residue is dissolved in glacial acetic acid or chloroform & titrated with standard perchloric acid. Very weak bases can not be determined by volumetric methods  Precipitation of the total alkaloids and determination of the weight of the precipitate obtained This method is recommended for determination of 1- Drugs with high yield of alkaloid. 2- Very weak bases which can not be determined by volumetric methods e.g. caffeine and Colchicine. 3- Mixtures of alkaloids that are obtained from the same plant but differ greatly in their molecular weight e.g. Cinchona and Rauwolfia alkaloids. Drawbacks 1- They are insensitive to micro-amounts of alkaloids. 2- They could not be applied in case of thermolabile and volatile alkaloids. 3- Lipophilic impurities in the residue are calculated as alkaloids. Colorimetric analysis is a method of determining the concentration of a chemical element or chemical compound in a solution with the aid of a color reagent. e.g. Van Urk for ergot alkaloids , vitali`s morin test for tropane alkaloid and nitrous acid test for morphine  Second activity Socrative Room: SHAHIRAEZZAT PHG322-Quiz 1-Lecture 2