25-08-2017, 09:32 PM
ANALYTICAL BIOCHEMICAL TECHNIQUES IN THE STUDIES OF MEDICINAL PLANTS USED IN SOME AILMENTS
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INTRODUCTION
HISTORY OF MEDICINAL PLANT
In all countries of the world, earliest type of medicine in most cultures was the use of plants(herbalism) and animal plants. While it is impossible to know exactly when early man first started using herbs and plants for medicinal purposes, archaeological remains from early civilization have revealed that plants were used in burials and other rituals. The earliest written account of herbal remedies comes from china and dates back to 2800 BC. In 2735 BC, the Chinese emperor Shen Nong wrote an authoritative treatise on herbs that is still in use today. Herbal medicine have had a chequered history ever since, in and out of favour with the great and the common man. But throughout the 5000 or so years, it has continued to develop until today, when in the light of growing concern about the efficacy and side effects of many synthetic drugs, herbal medicines are once again providing a safe and natural alternative for many everyday complaints.
Around 400 BC, Hippocrates, a Greek referred to as father of medicine, developed principles of diet, exercise and happiness as the cornerstone of health and his book, material medica, which consists of herbal recipes of complication of about 400 simple remedies was published. Theophrastus, another famous Greek, who was a biologist-botanist, produced historia planetarium which became the standard botanical textbook in his time and for years after death. Discorides in 60AD, produced De materia medica which was referred to as the standard reference work in Europe because it contains the description of about 600 medicinal plants (Le Strange, 1977). The search continued by the Arabian Physicians who after translating the work of the Greek into Arabic, added their own drugs and observation.
Medicinal plants in general use in health
Traditional medicine is widely used, however, there is no uniform system of traditional medicine in the country but there are wide variations with each variant being strongly bound to the local culture and beliefs; the local health authorities shall, where applicable seek the collaboration of the traditional practitioners in promoting their health programs such as nutrition, environmental sanitation, personal hygiene, family planning and immunization. Traditional health practitioners should be trained to improve their skills and to ensure their cooperation in making use of the referral system in dealing with high risk patients. Government of the Federation shall seek to gaina better understanding of traditional health practices, and support research activities to evaluate them. Primary health care recognises the importance of complimentary, alternative and traditional medicine. There is a major assignment for our elders and leaders to re-orientate our people.
Analytical Biochemical Techniques
Published monographs in a pharmacopeia are the most practical approach forquality control of herbal drugs and there are many available. When pharmacopeia monographs areunavailable, development and validationof analytical procedures have to be carried out by the manufacturer. The best strategy is to follow closely the pharmacopeia definitions of identity, purity, and content or assay. Valuable sources for general analytical procedures are included in the pharmacopeias, in guidelines published by the WHO. Additional information, especially on chromatographic and/or spectroscopic methods can be found in the general scientific literature. The plant or plant extract can be evaluated by various biological methods to determine pharmacological activity, potency, and toxicity. A simple chromatographic technique such as TLC may provide valuable additional information to establish the identity of the plant material. This is especially important for those species that contain different active constituents. Qualitative and quantitative information can be gathered concerning the presence or absence of metabolites or breakdown products. TLC fingerprinting is of key importance for herbal drugs made up of essential oils, resins, and gums, which are complex mixtures of constituents that no longer have any organic structure.
Medicinal Plants
“Let your food be your first medicine” (Hippocrates, 377 BC) was probably the first time that the link was made between nutrition and well-being which emphasizes theimportance of functional foods (Carbone 2005). In addition, the practice of medicinal plants is very well known for treating the diseases from ancient times. Even today because of the belief that medicinal plants are safe and effective most of the plant products are being used in local traditional systems of medicine (Dhawan 2003). In developing countries, a report of WHO survey indicates that 80% of the populations rely on mostly traditional medicine for their primary health care needs (Goyal, et al. 2007). Besides, scientific validations of medicinal plants have been ensured by various phytopharmacologicalstudies which evaluate active plant constituents. So today, plants are the important raw materials for pharmacological research and drug developing (Mendonça 2006), and they are also being increasingly used as the complementary or alternative medicine in industrialized countries.Medicinal plants have considerable importance in international trade and their clinical, pharmaceutical, and economic value is still growing, although this varies widely between countries. Based on current research and financial investments, medicinal plants will, seemingly, continue to play an important role as an health aid. Use of herbal medicines in Asia represents a long history with several applications against various diseases (Draipandiyan, et al. 2006). The practice of traditional medicine is widespread in China, India, Japan, Pakistan, Sri Lanka and Thailand
Processing of Medicinal Plants
The increasing demand and consumption of medicinal plants induced the large scale production and processing of plant products as raw materials for several industries. Processing of medicinal plant products need to follow a standardized quality arrangement. Quality here refers to the product in terms of technical specifications and to the organization of the production process and the continuity of service. The knowhow and control of the production process and the coordination of all links are essential for good quality. Monitoring should be done at selected steps in production process (Groot and Roest 2006).
Medicinal Plant Extraction
Extraction, as the term is used pharmaceutically, involves the separation of medicinally active portions of plant or animal tissues fromthe inactive or inert components by using selective solvents in standard extraction procedures. The products so obtained from plants are relatively impure liquids, semisolids or powders intended only for oral or external use. These include classes of preparations known as decoctions, infusions, fluid extracts, tinctures, pilular (semisolid) extracts and powdered extracts. Such preparations popularly have been called galenicals, named after Galen, the second century Greek physician. The purposes of standardized extraction procedures for crude drugs are to attain the therapeutically desired portion and to eliminate the inert material by treatment with a selective solvent known as menstruum. The extract thus obtained may be ready for use as a medicinal agent in the form of tinctures and fluid extracts, it may be further processed to be incorporatedin any dosage form such as tablets or capsules, or it may be fractionated to isolate individual chemical entities such as ajmalicine, hyoscine and vincristine, which are modem drugs.
Pressurized solvent extraction
Pressurized solvent extraction, also called ‘‘accelerated solvent extraction,’’ employs temperatures that are higher than those used in other methods of extraction, and requires high pressures to maintain the solvent in a liquid state at high temperatures. It is best suited for the rapid and reproducible initial extraction of a number of samples. The powdered plant material is loaded into an extraction cell, which is placed in an oven. The solvent is then pumped from a reservoir to fill the cell, which is heated and pressurized at programmed levels for a set period of time. The cell is flushed with nitrogen gas, and the extract, which is automatically filtered, is collected in a flask. Fresh solvent is used to rinse the cell and to solubilize the remaining components. A final purge with nitrogen gas is performed to dry the material. High temperatures and pressures increase the penetration of solvent into the material and improve metabolite solubilization, enhancing extraction speed and yield.