Author: Shahuraj H Kadam, Siddarth Apartment A, Sinhagad road, Pune. shahurajk@gmail.com
Introduction
Medicinal plants and traditional medicine have been used by tribal communities and ancient civilizations for thousands of years. Recent, modern medicine has taken a look back at medicinal plants and herbs for healing. No one knows exactly how many different plants are used in the world today, but we do know that medicinal plants are enormously important in both traditional and Western medicine. Ethnobotany, the study of traditional plant use, is a field of growing interest to research studies and pharmaceutical companies looking to develop new and more effective drugs.
Analyzing the phytochemicals in medicinal plants provides scientist with insight into how effective plants are medicinally, and understanding how and why they are effective can lead to the development of new medicines.
History
People have used medicinal plants throughout human history and long before good records were kept about plant use. There is evidence that humans have been using medicinal plants not just for centuries, but for thousand of years. Otzi the “Ice-man,” a 5000-year-old man found preserved in the retreating glaciers of Europe, was carrying a pouch of mushrooms that have phytochemicals known to fight intestinal parasites, and analysis showed Otzi did indeed have intestinal parasites when he died from injuries. Texts from ancient India and China also contain descriptions of countless plant-derived medicines.
Natural products chemistry actually began with the work of Serturner who first isolated Morphine from opium poppy (Papaver somniferum) in 1803 [1]. Subsequent conversion into heroin was reported by Wright in 1874[2]. In 1817 Emetine was isolated from Ipecacuanha [3]. Further other alkaloids such as Strychnine (Strychnos nux vomica)[4], Quinine (Cinchona officinalis)[5], etc were isolated. No historical perspective of natural products derived drugs would be complete without discussion of Aspirin (acetyl salicylic acid). Mac lagain in 1876 introduced the salicin from extract of Salix or Spirae ulmaria[6]. Bergmann reported first antiviral agent Spongouridine and Spongothymidine from sponge[7]. The first antibiotic derived from natural products is the serendipitous discovery of Penicillin from Penicillium notatum (fungus) by Alexander Fleming in 1928[8].
Scope
Phytochemical analysis of medicinal plants has shown that numerous compounds in plants traditionally used for medicinal purposes have chemical properties effective at treating illness. In the book, “Modern Phytomedicine: Turning Medicinal Plants into Drugs,” the authors state that phytochemicals extracted from medicinal plants include alkaloids, tannins, flavonoids, sterols and numerous other chemicals. Tannins, flavonoids and alkaloids are chemicals that are known to have anti-bacterial properties. In the Jan. 5, 2009 issue of “Africal Journal of Biotechnology,” researcher’s report that the medicinal plant Lasienthera africanum, which is a medicinal plant used to fight bacterial infections, does indeed contain antibacterial phytochemicals that were effective in the laboratory against the bacteria E.coli, Sal. Typhi and K. pneumoniae, More than a quarter of all pharmaceutical drugs used in the United States are derived from the phytochemicals in rainforest plant species. Seventy percent of plants identified by the National Cancer Institute as having anti-cancer properties come from the world’s rainforest, but only a tiny fraction of rainforest have yet been chemically analyzed.
Medicinal chemistry is the application of chemical research techniques to the synthesis of pharmaceuticals. During the early stages of medicinal chemistry development, scientists were primarily concerned with the isolation of medicinal agents found in plants. Today, scientists in this field are also equally concerned with the creation of new synthetic drug compounds. Medicinal chemistry is almost always geared toward drug discovery and development. The laboratory synthesis of these biologically active compounds will be very interesting aspect and these compounds will be used to cure the diseases that are curse to mankind.
SLUMPED OF NATURAL PRODUCTS
Despite the success of the natural products approach in drug discovery process, in recent years it has slumped particulary within pharmaceutical industry due to some factors. These factors include:-
- Incompatibility of crude extracts with high throughput assay procedures
- Lack of reproducible results
- High cost of collection of natural product sample
- Presence of artefacts in some extract
- Long resupply time for active extracts
- Difficulty in isolating active compound from extract
- Problems with large scale supply if a drug emerges from natural resources
- Slow growth and sparsely distribution of the species
- Difficulty of complying with Rio Treaty or Biodiversity
- Diversion of resources of combinational chemical approaches to drug discovery
- Despite of all these slumped of natural products in pharmaceuticals, still natural products play a vital role in drug discovery process [9-13]
Some of the examples are as below.
Representative examples of drugs based on natural products[14]
Why Natural Products as Drug targets?
1. Natural products are very large in numbers with an excellent chemical diversity.
2. Natural products are “naturally bioactive”. They come from life organisms and have been tailored to play a biological role.
3. Long term history of usage.
4. Wider public acceptance.
5. Limitations of original molecule can be overcome if the natural resources serve as starting point, as it has a bilateral promise of delivering the original isolate as a candidate or a semi-synthetic molecule development.
References
1.Derosne JF. Natural Product Chemistry for Drug Discovery. Ann Chim 1803;92:225.
2.Seguin MA. Natural Product Chemistry for Drug Discovery. Ann Chim 1814:92:225.
3.Derg Marderosian, A Beutler, J A. The Review of Natural Products. 2nd edn. Facts and comparision, Seattle, WA, USA, 2002; pp 13-43.
4.Caventou JB, Pelletier PJ. The contributions of Henri Victor Regnault in the context of organic chemistry of the first half of the nineteenth century. Ann ChimPhys 1820;15:2893.
5. Robiquet P J. Natural Product Chemistry for Drug Discovery. Ann ChimPhys 1832;51:2809.
6. Maclagan T. Drug Discovery: A History.Lancet. 1876; 107: 342.
7. Bergmann W, Feenly RJ. Natural Product Chemistry for Drug Discovery. Ann ChemSoc 1950;72:2809.
8. Daniel A. Dias, Sylvia Urban, UTE Roessner. A Historical Overview of Natural Products in Drug Discvoery. Metabolites 2012;2:303-336.
9. Mishra BB, Tiwari VK. Natural products: An evolving role in future drug discovery. Eur J MedChem 2011;46: 4769-4807.
10. Baker DD et al. The value of natural products to future pharmaceutical discovery. Nat Prod Rep2007;24: 1225-1244.
11. McChesney JD. Plant natural products: back to the future or into extinction?
Phytochemistry 2007; 68: 2015-2022.
12. Rishton G M Natural products as a robust source of new drugs and drug leads: past successes and present day issues. Am J Cardinol 2008; 101 (Suppl.): 43D-49D.
13. Ortholand J Y, Ganesan A. Natural producs and combinatorial chemistryl back to the future. CurrOpinChemBiol 2004; 8: 271-280.
