Medicinal Plants Lecture 4 PDF

10/24/2022 Medicinal Plants Lecture 4 Dr. Samar Bassam Ergastic cell contents  Non–living substances present in the cell.  Can be identified in plants by microscopical examinat...

10/24/2022 Medicinal Plants Lecture 4 Dr. Samar Bassam Ergastic cell contents  Non–living substances present in the cell.  Can be identified in plants by microscopical examination or by chemical and physical tests.  Found in cytoplasm and vacuole. 1  10/24/2022 Ergastic cell contents Primary metabolites Secondary metabolites Essential for plant survival Not Essential for plant survival Organic compounds involved in They are organic compounds that are not directly growth, development, and involved in the normal growth, development or reproduction of the organism, thus, reproduction of an organism. often referred to as a central Have other functions, e.g defense, by products of metabolite metabolism Carbohydrates, proteins, lipids Alkaloids, volatile oils, tannins, flavonoids, … Unlike primary metabolites, absence of secondary metabolites does not result in immediate death Primary metabolites Carbohydrates Proteins Lipids 2  10/24/2022 Secondary metabolites Tannins Alkaloids Volatile oils Glycosides Alkaloids - Compounds of biological origin and having a Nitrogen atom. - Known for their pharmacological activities as they are N derived from amino acids. - Their names end with the suffix –ine e.g. caffeine All alkaloids contain Morphine Popular alkaloids Vincamine nitrogen, but not all Quinine compounds containing Ephedrine nitrogen are classified Increase Analgesic peripheral blood as alkaloids From Papaver Antimalarial supply decongestant From Ephedra From Cinchona From Vinca 3  10/24/2022 Chemical Identification of alkaloids 1- Alkaloids+ Mayer’s reagent….. creamy white precipitate. N.B. it is +ve test with most alkaloids except caffeine. 2- Alkaloids+ Dragendorff’s reagent …..orange colour Tannins Phenolic compounds Astringent Tannins are polyphenols which have the ability to precipitate protein. Historically, These compounds have been used for decades to convert raw animal hides into leather. In this process, tannin molecules crosslink the protein and make it more resistant to bacterial and fungal attack. There are two major types of tannins: Hydrolyzable tannins and Condensed tannins 4  10/24/2022 Test for hydrolysable and condensed tannins Plant water extract Ferric chloride Dark greenish black color Dark bluish black color Condensed Tannins Hydrolysable Tannins Pharmacological actions of Tannins Due to their astringent action anti-diarrheals and haemostatics Due to their chelating action antidote in poisoning by heavy metals & alkaloids Due to their polyphenolic nature antioxidant and anticancer 5  10/24/2022 Volatile oils Also known as essential oils Essential oils are volatile aromatic complex mixtures of relatively low molecular weight compounds (terpenes). Although they may contain up to 60 components, yet they are characterized by the presence of two or three major components at fairly high concentrations (20–70%) compared to other components present in trace amounts They give red color with Sudan III Mentha piperita essential oil with menthol (59%) and menthone (19%) being the major constituents. Generally, these major components determine the biological properties of the essential oils. Some pharmacological actions of volatile oils - Antiseptic and antimicrobial, e.g Thyme oil - Analgesic, e.g Mentha oil, clove oil - Sedative, e.g Lavander oil - Spasmolytic, e.g anise oil - As fragrance, e.g lemon peel oil 6  10/24/2022 Secretory structures Volatile oils are secreted from - Glandular hairs - Secretory cavities (oil glands) - Secretory ducts (vitta) - Secretory cells Glandular hairs Oil glands Oil ducts Fixed oils Volatile oils Volatility Non-volatile volatile Metabolite Primary metabolite Secondary metabolite type Effect of O2 Rancid on oxidation Resinify on oxidation Composition Formed of triglycerides Formed of volatile compounds (terpenoids) Test Red color with sudan III Red color with sudan III Test Leave a permanent spot on paper Leave no permanent spot on paper 7  10/24/2022 Glycosides Biomolecules composed of 2 parts: sugar part + non- sugar part N.B Non-sugar Hydrolysis with Sugar structure structure (s) acids, alkalis or = Aglycone = Genin = Glycone enzymes, yields genin and sugar Glycosidic bond The aglycone part is responsible for the pharmacological activity Based on the type of aglycone, there are several types of glycosides Steroidal glycosides Glycosides (cardiac glycosides) Phenolic glycosides Cyanogenic glycosides Thio-glycosides Saponin glycosides Aglycone has Aglycone contain Aglycone contain Form persistent phenolic structure cyanogenic group sulfur atom froth on shaking - CN -S e.g liquorice Most important subclasses: - Flavonoid glycosides Release HCN gas on (antioxidants) hydrolysis…toxic - Anthraquinone glycosides (laxatives) 8 10/24/2022 9