Medicinal Plants Analyses Prof. Mohammed Abdulaziz Al-Yahya 434 PHG Recent Approaches in Medicinal Plants Analyses Prof. Mohammed Abdulaziz Al-Yahya

Topics to be covered INTRODUCTION General Concepts Medicinal Plants Information Sources PHYTOCHEMICAL STUDY Selection of plant material for study Preparation of plant materials Effective extraction BIOLOGICAL SCREENING Types of assays Common assays for natural products Problems in screening of plant materials High-Throughput screening assays Biologically directed phytochemical study

ISOLATION AND PURIFICATION OF ACTIVE CONSTITUENTS Physical methods Chemical methods Chromatographic methods METHODS OF IDENTIFICATION AND STRUCTURAL ELUCIDATION Physical methods Chemical methods Spectroscopic methods EVALUATION OF HERBAL PRODUCTS Methods of identifications Detection of foreign matters Assay methods for active constituents Safety measures

References Books P.M. Dey and J. B. Harborne, Methods in plant Biochemistry b. Richard J.P. Cannell, Natural Product Isolation, Humana Press, 1998. c. Robert M. Silverstein and Francis X. Webster, Spectrometric Identification of Organic Compounds. 2. Journals Phytochemical Analysis Journal of Chromatography Analytical Biochemistry Journal of Chromatographic Science

Sample questions for midterm and final examinations Q. I Fill the given blank spaces with proper answers ………………..………………………. (0.5x10)    1. High ash value of a herb indicates the ……….…higher amount of inorganic impurities ……….…..in the plant material. 2. Chemoprofiling is one of the methods used for….……………………….…standardization of ……….…….. … herbal products 3. The European Pharmacopeia does not allow ……………..E. coli/Salmonella spp …….as microbial contaminates in herbal preparations. Q. II Indicate, by encircling either T for true or F for false for the following statements.(0.5x10) 1.Alkaloids in free form are usually soluble in organic solvents. T/F 2.Maceration method of extraction is more effective than Soxhletation. T/F 3.Freeze drying is a process mainly used for drying of heat sensitive drugs. T/F Q. III Multiple choice questions, tick the most appropriate option. (0.5x10) 1. Roots and rhizomes are usually collected in — A. Autumn B. Spring C. Flowering stage D. Ripening stage 2. Authentication of plant material can be done by---- A. Taxonomist B. Field Botanist C. Herbarium D. All of above 3. The most common method to avoid enzyme action being brief exposure of the plant material to ethanol vapor under pressure (0.5 atm) is called— A. Oxidation B. Stablization C. Fermentation D. Lyophillization Q. IV Match the following : ………………………………………………(0.5x10) Q. V Rearrange the following steps to accomplish a systematic phytochemical analysis using numbers……………………(0.5x10)

    Selection of promising plant materials. Grinding of the dried plant materials. Authentication of plant materials. Proper collection of selected plant materials. Extraction of plant material.   Preservation of plant materials. Chemical tests for identification of phytoconstituents. Concentration and Solvent Recovery. Methods of identification / characterization of isolated compounds. Methods of separation and purification of Active Constituents.

Introduction

General Concepts The plant may be considered as biosynthetic laboratory, not only for the chemical compounds such as carbohydrates, proteins, and lipids that are utilized as food by man, but also for a multitude of compounds like glycosides, alkaloids, volatile oils, tannins etc., that exert a physiologic or therapeutic effect.

The compounds that are responsible for therapeutic effect are usually the secondary metabolites. A systematic study of a crude drug includes thorough consideration of both primary and secondary metabolites derived as a result of plant metabolism.

The use of plant-derived medicinal dates back many centuries although it is still underestimation in modern medicine.

Plants remain the most important source of natural drugs. - More than 30% of prescription drugs are natural products. - More than 60% of anticancer and anti-infective drugs are natural products.

The main sources of drugs are as follows: 1- Natural substances: From plants, microorganisms, marine, animals,- etc. (totally obtained from nature). * e.g. of plant origin: Alkaloid and glycoside, volatile or fixed oil 2- Semisynthetic substances: These are drugs that are manufactured by partial synthesis/ Semisynthetic analogues. A natural starting material can be modified by chemical or biochemical means to produce a substance having specific pharmacological activities. e.g. steroidal hormones corticosteroids and Etoposides etc.

3- Synthetic substances: These are drugs which are manufactured by total synthesis (i.e. complete synthetic process or processes).

Medicinal plants information sources

1- Medical botany These are published books and periodicals ascribing the native flora of various regions of the world and the medicinal uses for each plant. - It also may include the synonyms of plants and the constituents. Many countries, nowadays are represented by books or review publications on their flora. e.g. Flora of Saudi Arabia (Dr. Mijahid) 2. Official Books : Almost all the countries have their own official books for the medicinals used in health care system. e.g. All the Pharmacopoeias like IP, BP, USP, BPC, Biological Abstracts, Chemical Abstracts, Merck Index etc. 3. Reputed Books on Medicinal Plants: e.g. Materia Medica, Ibn Sina (Avicina), Al-Antaki, ESCOP (European Scientific cooperative for phytotherapy) Monographs etc.

This means the study of the plants in their relationship to human. 4- Ethnobotany This means the study of the plants in their relationship to human. Many report describing the habitual use and relationship of man and the surrounding flora are available.

5- Herbaria (herbarium) Herbarium is a representative whole plant or organ of plant which is preserved to provide a reference specimen when required. Information about: 1-The name (including synonymous names). 2-Date and place of collection. 3-Any field notes that the collector could gather the information including their: use and toxicity (if any) should be recorded on the so called “Herbarium sheet”.

6- Phytopharmacological surveys: These are surveys which are concerned with the biological activities of plant extracts or constituents and they are available in specialized periodicals or books. 7. Information from Personnell: The source may be– A. Trustful patient. B. Data from hospital C. Gardener D. Agriculture department. E. Microbiology Department. 5- Field exploration: Example: Parke Daves and co sponsored expeditions into South America in 1885 which lead to the discovery of (Cascara bark) which contains the medicinally valuable anthraquinones.

8. Journals: Journals on medicinal plant research may be monthly, quarterly or annually. Few examples of reputed journals for medicinal plant research are Planta Medica, Phytochemistry, Ethnopharmacology, Natural Products, Pharmaceutical Biology etc. 9. Important Monographs A. German Commission E monographs B. ESCOP: European Scientific cooperative for phytotherapy. C. AHP: American Herbal Pharmacopoeia. D. WHO: World health organization. E. Royal Botanical Garden , Kew, England : Monographs F. BHP: British Herbal Pharmacopoea

10. Online Medicinal Plant Databases Prelude Medicinal Plants Database (Africa) http://www.metafro.be/prelude Rain Tree (Amazon) http://www.rain-tree.com/plants.htm 3. Brazilian medicinal plants database (Brazil) http://www.brazilian-plants.com/en/ Chinese medicinal plants database (China) http://www.chinese.botanicals.at/?lang=_en Plants for a future (England) http://www.pfaf.org/database/index.php Encyclopedia of Indian Medicinal plants (India) http://www.frlht.org.in/meta/ Foundation for Revitalisation of Local Health Traditions (India) http://www.frlht.org.in/informatics.htm Native American Ethnobotany database, University of Michigan (US) http://herb.umd.umich.edu/ Dr Duke’s Phytochemical and Ethnobotanical databases (US) http://www.ars-grin.gov/duke/ 9. Science finder http://www.scifinder.com

or chemical constituents of plants? When we need to know the biological activities and or chemical constituents of plants? To achieve one or more of the following goals: 1- The discovery of new therapeutic agents. 2- The disclosing of new sources of economic materials for the synthesis of complex chemical substances. 3- Isolation of a novel chemical structure often prompts the chemist to a successful synthesis of a series of synthetic compounds which may have some medicinal value.

4-The knowledge of the chemical constituents of toxic plants will certainly help treating their poisonous effect to humans and animals. 5- The knowledge of the chemical constituents of plants and their chemical structure will help studying their biosynthetic mechanisms and hence may facilitate their synthesis in laboratories. 6- Knowing the chemical constitutes of plants would help expanding the area of chemotaxonomy. (e.g. biotransformation employing tissue culture techniques) Digitoxigenin D. lanata tissues or cells → Digoxigenin.