07-08-2012, 02:41 PM
EXTRACTION OF ALKALOIDS FROM-Leonotis nepotifolia- PLANT FOR ITS MEDICINAL VALUE TO TREAT MALARIA
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ABSTRACT
The majority of people in Africa use plant based traditional medicines for their care. This has renewed interest in plant antimicrobials since microbes are becoming resistant to the presently available antibiotics. Leonotisnepetifoliaplant is used medicinally by the Kisii community as a fever remedy and its roots,in the treatment of influenza.
Leonotisnepetifolia plant was chosen for this study, whose main objective was to determine the antimicrobial activity of its solvent extracts. The powdered sample was subjected to solvent extraction and chemical tests done on the extracts. Antimicrobial activities were done on two different types of identified microbes on the basis of their relevance to public health. They includedEscherichia coli and Staphylococcus aureus. Some activity was observed and also some chemical tests were done on the plant whereby some revealed bioactive compounds like tannins, steroids, saponins and flavonoids etc
INTRODUCTION
Plant materials remain an important resource to combat serious diseases in the world. The traditional medicinal methods, especially the use of medicinal plants, still play a vital role to cover the basic health needs in the developing countries. The medicinal value of these plants lies in some chemical active substances that produce a definite physiological action on the human body. The most important of these bioactive constituents of plants are alkaloids, tannin, flavonoid and phenolic compounds
Within the recent years, infections have increased to a great extent and antibiotics resistance effects become an ever-increasing therapeutic problem. Natural products of higher plants may possess a new source of antimicrobial agents with possibly novel mechanisms of action. They are effective in the treatment of infectious diseases while simultaneously mitigating many of the side effects that are often associated with synthetic antimicrobials. Therefore, it is of great interest to carry out screening of these plants in order to validate their use in folk medicine and to reveal the active principle by isolation and characterisation of their constituents. Systematic screening of them may result in the discovery of novel active compounds.
STATEMENT OF THE PROBLEM
Kenya’s cases of malaria have increased slightly in the last three years, a government survey shows. The disease now affects about 8 per cent of all children under five years and pregnant women (are especially vulnerable), compared with 3 per cent in 2007. In Kenya, the region hit hardest by malaria is Nyanza, where 38 per cent of children suffer from the disease at any one time compared with 17 per cent in 2007.
Precise statistics are unknown because many cases occur in rural areas where people do not have access to hospitals or the means to afford health care. As a consequence, the majority of cases are undocumented.
The protozoan that causes malaria disease undergoes mutation which renders malaria treatment and control a bigger challenge over the years. This has made most of the discovered medicine useless.
This has prompted a continuous study of the disease in order to manufacture the most effective medicine to eradicate malaria. The extracts from Leontis nepetifolia plant has offered an alternative treatment to malaria, this can help to curb the high death rates in sub-Saharan Africa.
COLLECTION AND IDENTIFICATION
Methods
The leaves of the plant leonotis nepetifolialeaves were collected from Botanic garden at Egerton University, and shade dried. Dried leaves were ground into fine powder using mortar and pestle in the laboratory as described.
The plant was identified by Dr. S T.Kariuki of the Biological sciences Department, Egerton University.
Extraction
40g of ground material were weighed and extracted using 100ml of methanol solvent. Extracts were filtered through active charcoal using a glass funnel fitted with a wet filter paper. The filtrate were dried using anhydrous sodium sulphate. The solvents was then removed using rotor evaporator. The residue was then weighed and subjected to various chemical and phytochemical tests. Finally, the materials were preserved in a dessicator ready for antimicrobial activity.
Thin Layer Chromatography (TLC)
Before conducting a column chromatography, I had to identify the correct solvent to be used. Determining the best solvent required a degree of trial and error. I started witha ration of 1:1 hexane:ethyl acetatesolvent. Varying the ratio can have a pronounced effect of Rf. Rf values ranged from 0 to 1- 0 meaning that the solvent polarity was very low and 1 meant that the solvent polarity wass very high.
The best solvent system was found to be, ration of 7:3 ethyl acetate:methanol solvent.
Performing a TLC analysis consisted of a number of steps: preparing a spotting capillary; marking the TLC plate; spotting the TLC plate; developing the TLC plate; drying the plate; visualizing the substance spots, and measuring the Rf values