CHAPTER ONEINTRODUCTION1.1 Background of the studyHealth is the most precious of all things and it is the foundation of all happiness. Traditional medicine has developed in various communities in Nigeria in response to the health needs of the people. Many communities have, therefore, since creation, developed various traditional systems using locally available resources for the alleviation of their health problems. As once noted some 13 years ago (Tella, 1986), traditional medicine is as old as the hills in Nigeria. The development of traditional medicine in Nigeria has led to various categories of healers, the various healing methods, strategies, and medicines or remedies now known. The use of herbal medicines in Asia represents a long history of human interactions with the environment. Plants used for traditional medicine contain a wide range of substances that can be used to treat chronic as well as infectious diseases (Duraipandiyan et al., 2006). Due to the development of adverse effects and microbial resistance to chemically synthesized drugs, the population has turned to the use of plants for treatments. They found literally thousands of phytochemicals from plants as safe and broadly effective alternatives with fewer adverse effects. Much beneficial biological activity such as anticancer, antimicrobial, antioxidant, antidiarrhoeal, analgesic, and wound healing activities were reported. In many cases, people claim the good benefit of certain natural or herbal products. However, clinical trials are necessary to demonstrate the effectiveness of a bioactive compound to verify this traditional claim. Clinical trials directed towards understanding the pharmacokinetics, bioavailability, efficacy, safety, and drug interactions of newly developed bioactive compounds and their formulations (extracts) require a careful evaluation. Clinical trials are carefully planned to safeguard the health of the participants as well as answer specific research questions by evaluating for both immediate and long-term side effects and their outcomes are measured before the drug is widely applied to patients. Due to the fact that plant extracts usually occur as a combination of various types of bioactive compounds or phytochemicals with different polarities, their separation still remains a big challenge for the process of identification and characterization of bioactive compounds. It is a common practice in isolation of these bioactive compounds that a number of different separation techniques such as TLC, column chromatography, flash chromatography, Sephadex chromatography, and HPLC, should be used to obtain pure compounds. The pure compounds are then used for the determination of structure and biological activity. Besides that, non-chromatographic techniques such as immunoassay, which uses monoclonal antibodies (MAbs), phytochemical screening assay, Fourier-transform infrared spectroscopy (FTIR), can also be used to obtain and facilitate the identification of the bioactive compounds (Sasidharan et al., 2011).Phytochemicals are chemicals derived from plants and the term is often used to describe the large number of secondary metabolic compounds found in plants. Phytochemical screening assay is a simple, quick, and inexpensive procedure that gives the researcher a quick answer to the various types of phytochemicals in a mixture and an important tool in bioactive compound analyses (Sasidharan et al., 2011). Depression (Major depressive disorder) is a common and serious medical illness that negatively affects how a person feels, the way they think, and how they act. Depression causes feelings of sadness and/or a loss of interest in activities once enjoyed. The occurrence of depression is associated with factors such as age, marital status, social class, and social conditions. Individuals who are separated or divorced have significantly higher rates of major depression than the currently married and the prevalence of major depression generally goes down with age. (Andrade et al., 2003). This evidence, however, comes primarily from studies conducted in Western countries. The sparse data available from low-middle income countries suggest that the age pattern might either be non-monotonic or reversed compared to other countries, with depression increasing with age (Murray et al., 2010). Major depression is a chronic illness with a high prevalence and is a major component of disease burden. The prevalence of major depression is higher in women than in men; in 2008, its global annual prevalence was 5.5% and 3.2%, respectively, representing a 1.7-fold greater incidence in women. (Stotland et al., 2010). Some risk factors associated with depression are Family history, early childhood experience, stress, marital status, work status, physical illness, medication, gender, age, tobacco, etc. The major treatment for depression is a drug treatment and there are quite a lot of drugs used in this treatment. But these drugs have limitations in terms of side effects, cost, availability, presence of toxic chemicals and heavy metals which makes them less effective. And so, there is an ever-increasing effort at discovering a newer treatment that could be blessed toxic, cheaper, and readily available. Plant sources, because of their less toxicity and side effects, happen to be an area where the search line is focused. Plant (herbal medicine) is made from all-natural ingredients, they are much safer than laboratory-made drugs. Studies show that manufactured items including synthetic drugs are not effective than natural items such as herbal medicine (Duraipandiyan et al., 2006).