CHAPTER ONE
- Introduction
Extracts of several plants are highly effective against parasitic as well as saprophytic microbes. It is well estimated that around 70,000 plant species, from lichens of tress, have been used at one or the other time for medical purpose (Purohit et al., 2004). The demands of medical plants modern pharmaceutical industries has also increased manifold (Ashiraf et al., 2006). The medicinal plants occupy a significant place in modern medicine for some important drugs, although synthetic drugs and antibiotics brought about a revolution in controlling different diseases (Huynh et al., 2001). The anti-infectional compounds show broad-spectrum bioactivity against bacteria, fungi, protocists, protozoans, viruses, yeasts, etc. (Conlon et al., 2003).
Medicinal plants have been identified and used throughout human history. Plants have the ability to synthesize a wide variety of chemical compounds that are used to perform important biological functions, and to defend against attack from predators such as insects, fungi and herbivorous mammals. At least 12,000 such compounds have been isolated so far; a number estimated to be less than 10% of the total (Tapsell et at., 2006; Lai et al., 2004). Chemical compounds in plants medicate their effects on the human body through processes identical to those already well understood for the chemical compounds in conventional drugs; thus herbal medicines do not differ greatly from conventional drugs in terms of how they work. This enables herbal medicines to be as effective as conventional medicine, but also gives them the same potential to cause harmful side effect (Tapsul et al., 2006; La et al., 2004). The use of plants as medicines predates written human history. Ethnobotany (the use of traditional human uses of plants) is recognized as an effective way to discover future medicines.
In 2001, researchers identified 122 compounds used in modern medicine which were derived from “ethnomedical” plant sources; 80% of these have had an ethnomedical use identical or related to the current use of the active elements of the plant (Fabricant et al., 2001)
Many of the pharmaceutical currently available to physicians have a long history of use as herbal remedies, including aspirin, digitalis, quinine, and opium (Swain and Tony, 1968). The use of herbs to treat disease is almost universal among non-industrialized societies, and is often more affordable than purchasing expensive modern pharmaceuticals. The World Health Organization (WHO) estimates that 80% of the population of some Asian and African countries presently use herbal medicine for some aspect of primary health care.
Studies in the United States and Europe have shown that their use is less common in clinical settings, but has become increasingly more in recent years as scientific evidence about the effectiveness of herbal medicine has become more widely available. The annual global export value of pharmaceutical plants in 2011 accounted for over US $2.2 billion (http://www.traffic.org/medicalplants/).
The Nigerian climate favours a wide variety of plants with vast antimicrobial and medicinal potentials some of which have been used traditionally for decades without any references to their phytochemical constituent (Abdullah et at., 2011). The most important of these bioactive compound research based on ethnopharmacological information is generally considered on effective approach in the discovery of new anti-infective agents from higher plants (Duraipandiyan et al., 2006).
Numerous plants or their phytochemical constituents have been proven by rigorous science or approved by regulatory agencies such as the United States food and drug administration or European food safety authority to have medicinal value of which Waltheria indica is inclusive (Timothy et al., 2008; Philip et al., 2005).
Waltheria indica also known as Uhaloa (Hawaiian name) is used medically for asthma, neuralgia, and pain killer when mixed with other plants (David, 2011). Leaves were pounded and used for filling in cracks on canoes instead of pitch (Joseph et al., 2011).
Medically, in the Hawaiian Islands “uhaloa” (Waltheria Indica) is still used even if other traditional plants are not in use (Isabella, 2011). When mixed with certain other plants Waltheria indica (sleepy morning plant/Uhaloa) is used for sore throats, bronchial infections, and asthma (David, and Marie, 2011). The bitter roots are used much like aspirin is today (Marie, 2001).
Waltheria indica is used throughout the Americans. One reference source outlines the importance of Waltheria indica; “A tropical shrub, the whole plant (roots, leaves, buds and flowers) is used against chronic asthma. This plant has anti-inflammatory and antifungal properties. Other uses include: cortex (root bark); chewed as a very effective natural medicine for sore throat. Internally for arthritis, neuralgia, common cold, cough, bronchial phlegm or mucous, diarrhea, eyebaths, fatigue; used as a bitter tonic”. (http://www.tropilab.com/waltheriatincture.html).
1.1 Statement of the Problem
Modern pharmaceutical drugs are typically based on single chemical with active properties (Cunha, 2001). Many drugs have been discovered through research into the physiological effects of chemicals found in plants. Some of these drugs are still derived directly from plants (e.g. digitalin from foxglove digitals) while others are now synthesized (e.g. aspirin inspired by the medicinal properties of the back of the willow, Salix alba). Chemicals in some plants are extracted and transformed, providing the building blocks of drugs (e.g. progesterone, synthesized from chemicals found in some species of Dioscorea, the wild yam (Murty et al., 2000).
It is believed that the use of herbal medicines of properly tested efficacy would be of great advantage in developing countries like Nigeria which is blessed with bountiful plant resources. The idea is to keep people healthy by treating illnesses at an early stage instead of resorting to treatment when the disease is already at an advanced stage.
Herbal plants offer alternative remedies with tremendous opportunities. They do not only provide access and affordable medicine to poor people, they can also generate income, employment and foreign exchange for developing countries, for instance, people who live in rural areas of the Asian pacific are familiar with the medicinal properties of plants, growing close to their homes, in the open fields, water margins, waste lands, both inside and outside the nearby forest areas and under different growth conditions. Most of the plant materials collected are fresh, either to obtain the extract from the whole plant or parts, whether they are leaves, root, flowers or fruits. One of the most popular and important procedure for drug discovery involves the fractionation of active extracts and fractions until pure active ingredients are produced (Vlientinck et al., 2005).
1.2 Significance of Study
Many antibiotics currently in use are either too expensive or possesses undesirable side effect while some are not more effective due to bacterial resistance (Sydney et al., 1980).
Despite the remarkable progress in synthetic organic chemistry of the twentieth century, over 25% of prescribed medicines in industrialized countries are derived directly or indirectly from plants (Newman et al., 2000). Human disease management in Nigerian history also provides evidence of the relationship of plants and medicine (Ayandele and Adebiyi, 2007).
1.3 Aims and Objectives
This study is aimed at analyzing the phytochemical properties and to evaluate the antimicrobial activity of Waltheria indica. The objectives of the study are:
- to identify some phytochemical substance present in the leaves of Waltheria indica.
- to determine the antibacterial effect of the leaves extracts on test organisms.
- To compose the activity of aqueous and methanolic extracts of
1.4 Scope and limitation of study
The study was limited to the antibacterial effect of Waltheria indica (sleepy morning flower/Uhaloa) leaves as well as some phytochemical screening of the leaves.
The determination of the chemical constituents was qualitative. The qualitative analysis was for chemical constituents like alkaloids, flavanoids, saponins, tannins, steroids, glycosides, terpenoids, volatile oils, flavotanins, reducing sugars, anthraquinones.
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