Discovery and resupply of plant derived bioactive natural products
Background: There is increasing awareness of the use of Traditional medicine in today’s medical practices. This is a known fact that over 80% of the world population depends on herbal medicines and product for healthy living. The disappointment appears due to adulteration in the drugs, which is critical side for herbal manufacturers. Hence there is a need to develop validation techniques to prevent health, consumer’s faith as also for economic productivity. Medhya Rasayanas are a group of medicinal plants described in Ayurveda (Indian system of medicine) with multi-fold benefits, specifically to improve memory and intellect by Prabhava (specific action). Medha means intellect / retention and Rasayana means therapeutic procedure that on regular practice will boost nourishment, health, memory, intellect and immunity.
Objective: To increase the awareness of use of medhyarasayan plants in nuerological disorders by giving light of research updates.
Method: The research updates of Four Medhyarasayan plant spp namely Withania somnífera, Bacopa monnerie, Nardostachys jatamansi, Centell asiatica is mentioned in the present review covering the preclinical research aspact as also with mentioning their active principals.
Results and Conclusion: The present review deals with a study of modern techniques/bioassays useful in validation of some Medhyarasayan plants. On the other hand, they are beneficial to understand metabolomics, physiology, biochemistry and proteomics of living being and also play a vital role in drug discovery.
Key words: Traditional Medicine; Medhyarasayan; validation; Techniques; Bioassays
Ayurveda is a Sanskrit word, which means “the scripture for longevity”. It represents an ancient system of traditional medicine prevalent in India and in several other south Asian countries. It is based on a holistic view of treatment which is believed to cure human diseases through establishment of equilibrium in the different elements of human life, the body, the mind, the intellect and the soul1. Ayurveda relates to the period of the Indus Valley civilization (about 3000 B.C) and has been passed on through generations of oral tradition, like the other four sacred texts (Rigveda, Yajurveda, Samaveda and Atharvanaveda) which were composed between 12th and 7th century B.C ’ . Charaka and Shushrutha, who composed the basic texts of their trade, the Samhitas. By this time, ayurveda had already developed eight different subspecialties of medical treatment, named Ashtanga, which included surgery, internal medicine, pediatrics, toxicology, health and longevity, and spiritual healing4. Ayurveda medicine was mainly composed of herbal preparations which were occasionally combined with different levels of other compounds, as supplements5.
The practices and public interest in natural therapies and Traditional Medicine have increased dramatically. This(TM) has increased international trade in herbal medicine and attracted number of pharmaceutical companies. A few years ago, only small companies had interest in the marketing of TM, now multinational companies have started showing interest in commercializing herbal drugs6.
In traditional systems of medicine, the medicinal plants play a major role and constitute their backbone. Indian Materia Medica includes about 2000 drugs of natural origin almost all of which are derived from different traditional systems and folklore practices . According to WHO reports the populations in developing countries like India (70%), Rwanda (70%), Uganda (60%), Tanzania (60%), Benin (80%) and Ethiopia(90%) use traditional and alternative medicines for health care. In developed countries like Belgium (31%), USA (42%), Australia (48%), France (49%), Canada (70%), a significant percentage of the population has used traditional and alternative remedies for healthcare .
Many traditional medicines are made by crushing leaves or bark, and the resulting mixture can contain hundreds of potentially active molecules. Identifying these is hard enough, and testing each one for safety and effectiveness is practically impossible. Unlike many modern pharmaceuticals, the quality of material for traditional medicines varies enormously between, and even within, source countries and plants. This is both because of genetic differences and other factors such as environmental conditions, harvesting, transport and storage. Dosage is similarly varied. Modern medicine demands dosages that are standardized based on factors such as bodyweight or disease severity. Traditional healers are more likely to give patients a unique dosage or combination of medicines that is decided during the consultation. So when modern evaluations of traditional drugs give poor results, it may be due to many factors. Through a slow process of clinical trial and error, each culture developed a local, natural resource-based tradition of healing. These systems of TM, today, provide the basis of drug supply for an estimated 4.6 billion people worldwide9
Though herbal products have become increasingly popular throughout the world, one of the weaknesses in its acceptance is the lack of standard quality control profile, hence following some assays, validation and standardization of herbal drugs can be carried out.
1. Macro and microscopic examination: For Identification of right variety and search of adulterants.
2. Foreign organic matter: This involves removal of matter other than source plant to get the drug in pure form.
3. Ash values: These are criteria to judge the identity and purity of crude drug - Total ash, sulphated ash, water soluble ash and acid insoluble ash etc.
4. Moisture content: Checking moisture content helps reduce errors in the estimation of the actual weight of drug material. Low moisture suggests better stability against degradation of product.
5. Extractive values: These are indicative weights of the extractable chemical constituents of crude drug under different solvents environment.
6. Crude fibers: This helps to determine the woody material component, and it is a standard for judging purity.
7. Qualitative chemical evaluation: This covers identification and characterization of crude drug with respect to phyto-chemical constituents. It employs different analytical technique to detect and isolate the active constituents. Phytochemical screening techniques involve botanical identification, extraction with suitable solvents, purification, and characterization of the active constituents of pharmaceutical importance.
8. Quantitative chemical evaluation: To estimate the amount of the major classes of constituents.
9. Toxicological studies: This helps to determine the pesticide residues, potentially toxic elements, safety studies in animals like LD50 and Microbial assay to establish the absence or presence of potentially harmful microorganisms10.
10. Quality Assurance (QA) is the thrust area for traditional formulations in TM like Churnas (herb powder), Bhasmas (calcined metallic ashes), Kwath (liquid orals) and Lehas (oral supplements)11.
11. Chromatographic examination: Include identification of crude drug based on the use of major chemical constituents as markers Chromatographic finger printing and marker compound analysis are getting momentum for the standardization of traditional medicinal formulations. This technique helps not only in establishing the correct botanical identity but also helps in regulating the chemical profile of the herbs12 (Fig.1). Under the Ministry of AYUSH, there are 5 research councils, 1 board, 8 educational institutions, 2 statutory organizations, 1 drug manufacturing unit, 2 laboratories, and 11 national institutes established at national level for promoting current research, clinical practices and related aspects13.Various sectors of Ministry of AYUSH, Govt. of India for promotion and development of TM are given (Table 1.).
Tablel. Various sectors of Ministry of AYUSH, Govt. of India for exploration and development of TM Ministry of AYUSH, Govt. of India13.
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Today, the World Health Organization (WHO) estimates that 80 percent of the world's population still uses traditional remedies, including plants, as their primary health care tools. Meanwhile, the majority of new drugs (70 percent) introduced in the US are derived from natural products, primarily plants. (Tab.2)
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Tab 2.Traditional herbal medicines used for different purposes