CHAPTER ONE
INTRODUCTION
1.1 General Introduction
The history of the use of herbs dates back to the time of the early man who used herbs to keep fit (Kafaru, 1994). The earliest evidence of humans’ use of plants for healing dates back to the Neanderthal period (Kleiner, 1995). This made botanic medicine one of the oldest practiced professions by mankind (Kambizi and Afolayan, 2001).
Herbal medicine practice flourished until the 17th century when more “scientific pharmacological remedies were favoured (Trevelyan, 1993). In the early 19th century, scientific methods became more advanced and preferred, and the practice of botanical healing was dismissed as quackery (Aiyegoro et al., 2010). Before then the plant kingdom had served as an inexhaustible source of useful drugs, foods, additives, flavouring agents, lubricants, colouring agents and gums from time immemorial (Parikh et al., 2005). Different medicinal plants have different medicinal properties and no one herb is found to be used for just one purpose (Kafaru, 1994).
Recently, researchers’ interest on the role of complementary and alternative medicines for the treatment of various acute and chronic diseases is on the increase (Schafer and Wink, 2009). Presently, it is estimated that over 80% of the developing world’s population still depend on herbal medicines, while half of the population in the industrialized countries, also use herbal formulations for health care (Akerele, 1993;WHO, 1998).
Plants’ vegetables and spices used in folk and traditional medicine have gained wide acceptance as one of the main sources of prophylactic and chemo-preventive drug discovery and development (Schafer and Wink, 2009). Worldwide, herbal use again became popular and in 1974 the World Health Organization (WHO, Geneva, Switzerland) encouraged developing countries to use traditional plant medicines to “fulfil a need unmet by modern systems” (Trevelyan, 1993). Hence, the practice of herbalism has become main stream throughout the world within the last century. Moreover, in spite of the great advances observed in modern medicine, plants still make an important contribution to health care and it is estimated that about 30% of the drugs in the modern pharmacopeia were derived from plants and many others, which are synthetic analogues, were built on prototype compounds isolated from plants (Farnsworth, NR et al., 1985; De Silva, 2005; Kim, 2005) and over the years there have been increasing interests in the use of herbal therapeutics worldwide. This is due in part to the recognition of the value of traditional medical systems, particularly of Asian origin, and the identification of medicinal plants from indigenous pharmacopoeias, which have significant healing power. Medicinal plants are distributed worldwide, but they are most abundant in tropical countries (Calixto 2000, Lewis 2001). In Brazil, around 80,000 species of higher plants were described, which offer enormous prospects for discovering new compounds with therapeutic properties. There has recently been a renewed interest in the antimicrobial effects of natural compounds which were commonly used as health remedies in the Western world until the advent of antibiotic drugs in the 1940s and 50s.
1.1.1 Justification for the renewed interest in herbal medicine
After the emergence of antibiotics many previously fatal infections and infectious diseases were brought under control and millions of lives were saved. Due to the dramatic effect of the new synthetic drugs, some health professionals even believed that the threat to mankind of pathogenic microorganisms had finally been eliminated (Halldor, 2011).
The success of antibiotic drugs is due to the fact that our knowledge of their actions is based on a solid scientific ground. Their actions are in most cases predictable and their side effects known, because they have undergone a thorough scientific scrutiny, for both safety and activity, before being applied to the general public. In contrast, the use of natural health remedies was for a long time mainly based on anecdotal evidence and on accumulated experience of their beneficial effects obtained over centuries. The knowledge was mostly empirical. However,recently, and mostly during the past few decades, the antimicrobial actions of the natural compounds, which originate in both the animal and the plant kingdom, have been studied by modern scientific methods similar to those applied in the study of synthetic drugs (Halldor, 2011).
The great success of chemotherapy, using synthetic antibiotics against bacterial and fungal infections and nucleoside analogues against viral infections, discouraged researchers and the pharmaceutical industry from making serious efforts to develop drugs containing simple natural compounds. Recently, there is an increased attention on extracts and biologically active compounds isolated from plant species used in herbal medicine due to the side effects and the resistance that pathogenic micro-organisms build against conventional antibiotics (Essawi and Srour, 1999). The primary benefits of using plant-derived medicines are that they are relatively safer than synthetic alternatives, offering profound therapeutic benefits and more affordable treatment (Van Wyk and Gericke, 2000). Eloff (1999) stated that the antimicrobial compounds from plants may inhibit bacteria by a different mechanism than the presently used antibiotics and may have clinical value in the treatment of resistant microbial strains.
The clinically useful antibiotics now in use have major setbacks. Apart from the narrow spectrum of antimicrobial activity many of them have been found to be neurotoxic, nephrotoxic, ototoxic or hypertensive and few others cause severe damage to the liver and cause bone marrow depression (Chong and Pagano, 1997) and importantly; infectious pathogens have developed resistance to all known antibiotics (Aiyegoro and Okoh, 2009).
1.1.2 Justification for the use of plants in Combination Therapy
Several reasons have been advanced to justify the use of combination of two or more antibiotics in treatment (Esimone et al., 2006; Ibezim et al., 2006).
As certain antibiotic treatments lead to the development of multi resistant organisms, it is now a standard clinical practice to use a combination of two or more antibiotics with different mechanisms of action in an attempt to prevent the early development of antibiotic resistance and improve the outcome of therapy (Beringer, 1999). Combination therapy can be used to expand the antimicrobial spectrum, to prevent the emergence of resistant mutants, to minimize toxicity and to obtain synergistic antimicrobial activity, it could be an alternative to monotherapy for patients with invasive infections that are difficult to treat, such as those due to multi-resistant species and for those who fail to respond to standard treatment (Kamatou et al., 2006).
