New Natural Products and Plant Drugs with Pharmacological, Biological or Therapeutical Activity

The fact that, of the approximately 600,000 plant species existing on the earth, only some 5 % have been specifically investigated chemically or pharmacologi­ cally, is a challenge to chemists spezializing in na­ tural substances and to pharmacologists. In view of the limited number of research capacities and the ever­ diminishing financial means, this challenge can only be met if, together with an improvement and refinement of methods of analysis, medicinal plant research is carried out on a broader interdisciplinary basis, with comparable, scientifically recognized screening methods, and if it is better coordinated, with greater use of modern documentation means. It is thus necessary in the future to concentrate specifically on projects leading to the development of new medicinal prepara­ tions. The plenary lectures hold in the present symposium of the 1st International Congress for Research on Medi­ cinal Plants reflect these efforts and tendencies. At the same time they provide a survey of some of the fields of medicinal plant research which are at present most actual and most intensively researched. They range from plant screening, isolation and structure eluci­ dation of new principles, to the therapeutical opti­ mization of a natural product. The lectures given at this congress show clearly the necessity, in addition to national phytochemical so­ cieties, for a central international organisation, in which all active medicinal plant researchers in the world are included. Their aim should be to provide the impulse for more optimal, rational research, aimed at the solution of specific projects.

Contenu

Problems and Prospects of Discovering New Drugs from Higher Plants by Pharmacological Screening.- A. Introduction.- B. Value of Drugs Obtained from Higher Plants.- I. Commercial Value of Plant-Derived Drugs.- II. Role of Plant-Derived Drugs as Therapeutic Agents.- III. Uses Other than as Drugs for Plant-Derived Chemicals.- C. Apathy in Plant-Derived Drug Development.- D. Current Level of Worldwide Research on Plant-Derived Drugs.- E. Pharmacological Screening Programs for Plant Extracts.- I. Random Selection Approach.- II. Selection of Plants Containing Specific Types of Chemical Compounds.- III. Selection of Plants Based on a Combination of Criteria.- F. Problems in the Pharmacological Screening of Extracts from Higher Plants.- I. Variation from Sample to Sample.- II. Unexpected Dose-Response Relationships.- III. Variation Within Samples from the Same Lot of Plant Material.- IV. Failure to Obtain Positive Results with an Extract Containing Active Principles.- V. Miscellaneous Considerations in Screening Plant Extracts.- G. Prospects for the Future.- References.- Pharmacological Approaches to Natural Product Screening and Evaluation.- A. Ideal Requirements for a Primary Screen.- B. Past Approaches to Primary Pharmacological Screening.- I. Single Technique-Single Goal Screening.- II. Screening Using a Battery of Specific Procedures.- III. Single Technique-Multiple Goals Screening.- IV. Combinations of Specific and Multipurpose Procedures.- C. Multidimensional Primary Screening.- I. The Rat "Hippocratic" Screen.- 1. Variations of Hippocratic Screening.- 2. Computerized Hippocratic Evaluation.- II. The Mouse Multidimensional Screen.- III. Relative Merits of the Mouse and Rat Primary Screens.- D. Multidimensional Secondary Screening of Extracts and Pure Compounds.- I. The Dog Pharmacodynamic Screen.- II. Other Approaches to Secondary Evaluation.- E. Tertiary Evaluation.- F. Addendum-Sample Print-Out of Computerized Hippocratic Evaluation.- References.- Recent Experimental and Clinical Data Concerning Antitumor and Cytotoxic Agents from Plants.- A. Introduction.- B. Terpenoids.- I. Sesquiterpenes.- II. Diterpenes.- III. Simaroubolides.- C. Miscellaneous Compounds.- D. Alkaloids.- I. Pyrrolizidine Alkaloids.- II. Isoquinoline Alkaloids.- III. Benzophenanthridines.- IV. Miscellaneous Alkaloids.- V. Monomeric Indole Alkaloids.- VI. Camptothecine.- VII. Cephalotaxus Alkaloids.- VIII. Dimeric Indole Alkaloids.- IX. Maytansinoids.- E. Summary.- References.- Recent Advances in the Field of Antibiotics.- A. Introduction.- B. Acetate/Propionate-Derived Metabolites.- I. Tetracyclines.- II. Anthracyclines.- III. Aflatoxins.- IV. Macrolides.- V. Cytochalasans.- VI. Polyethers.- VII. Macrotetrolides.- VIII. Nonadrides.- IX. Ansamycins.- X. Ovalicin and Pseurotins.- C. Isoprenoid Metabolites.- D. Amino Acid-Derived Metabolites.- I. Penicillins and Cephalosporins.- II. Other Natural ß-Lactams.- III. Cyclic Polypeptides.- E. Conclusion.- References.- Progress in the Chemistry of Alkaloids with Pharmacological or Biological Activity.- References.- Plant Mono-, Di- and Sesquiterpenoids with Pharmacological or Therapeutical Activity.- A. Introduction.- B. Classification.- C. General Biological Properties.- D. Monoterpenes.- I. Normal Monoterpenes.- 1. Antiseptic, Disinfectant, Anthelmintic Properties.- 2. Irritant, Skin Stimulant, Expectorant, Diuretic Properties.- 3. Sedative, Carminative, Spasmolytic Properties.- II. Cyclopentanoid Monoterpenes and Derivatives.- 1. Biological Activity of the Methylcyclopentanoid Monoterpenes of the Nepetalactone Type.- 2. Pharmacological Activity of the Iridoids and Secoiridoids.- Antimicrobial Activity.- Hypotensive Effect.- Analgetic and Antiphlogistic Properties.- Bitter Tonic.- Sedative Agents.- Laxative Properties.- Antileukemic Activity.- Various Other Effects.- 3. Cantharidin.- E. Sesquiterpenes and Diterpenes.- I. Antiphlogistic and Spasmolytic Agents.- II. Bitter Substances.- III. Antitumor Activity.- F. Conclusion.- References.- Saponins with Biological and Pharmacological Activity.- A. Introduction.- B. Saponins of Licorice.- I. Corticoidal Activities of Glycyrrhizin.- II. Antiinflammatory Activities of Glycyrrhizin.- III. Antigastric Ulcer Effects of Glycyrrhizin.- IV. Metabolic Effects of Glycyrrhizin.- C. The Saponins of Bupleuri Radix and Platycodi Radix.- D. Saponins of Polygalae Radix and Senegae Radix.- E. Saponins of Akebiae Vitis.- F. Aescin, the Saponins of the Seeds of Aesculus hippocastanum.- G. Saponins of Ginseng.- I. Chemical Studies on the Saponins and Sapogenins of Ginseng and its Congeners.- II. Pharmacological and Biochemical Studies on Ginseng Saponins.- III. Pharmacological Studies on Japanese Chikusetsu-Ginseng1.- H. Saponins of Zizyphus Spinosi Semen.- I. Concluding Remarks.- References.- Dimeric Natural Compounds with Pharmacological Activity.- A. Definitions and Classification.- B. The Formation of Dimeric Compounds.- C. Pharmacological and Physiological Activity.- I. Lignahs.- II. Dimeric Photosensitizers.- III. Coumarins.- References.- Chemical and Biological Investigations on Indian Medicinal Plants.- A. Introduction.- B. Alkaloids.- I. Tylophora Alkaloids.- II. Ancistrocladus Alkaloids.- III. Alkaloids of Croton sparsiflorus Morong.- IV. Alkaloids of Mappia foetida Miers.- V. Alkaloids of Piper trichostaehyon C.Dc.- VI. Alkaloids from some Menispermaceae Plants.- 1. Alkaloids from Tiliacora racemosa Colebr.- 2. Alkaloids of Cocculus pendulus (Forsk) Diels and Cocculus laurifolius Dc.- 3. Alkaloids of Cissampelos pareira Linn.- C. Oxygen Heterocycles.- I. Cryptocaryalactone and Cryptocaryone.- II. Surangin A and B.- III. Tuberosin.- D. Terpenoids.- I. Sesquiterpenes of Cedrus deodara Loudon.- II. Enhydrin.- III. Tagitinins A and F.- IV. Coleonol.- V. Diosbulbine.- VI. Dysobinin.- VII. Triterpenes of Salacia prinoides DC.- E. Glycosides.- I. Cleistanthin.- II. Ipolearoside.- III. Stigmasta-7, 22-diene-3 ?-O-glucoside.- IV. Scuttelarein-5-glucuronide.- V. Glycosides of Picrorhiza kurrooa Benth.- VI. Asclepin.- VII. Shatavarins I-IV.- VIII. Glycosides of Carissa Species.- IX. Peruvoside.- F. Miscellaneous.- I. Curcumine.- II. Arnebin.- III. Diospyrol.- IV. Steroidal Constituents of Commiphora mukul.- References.- Chemistry of Neolignans with Potential Biological Activity.- A. Introduct…