Manufacturing of herbal drugs
It cannot be emphasized strongly enough that herbs in their medicinal sense are drugs. Certain special interest groups continually emphasize their point of view that medicinal herbs are foods or dietary supplements, but scientifically, although not legally under current law, that is not the case. If they are used in the treatment (cure or mitigation) of disease or improvement of health (diagnosis or prevention of disease), they conform to the definition of the word drug (Foster and Tyler, 1999).
Restrictions on the collection of certain wild plants, and limit availability of plant resources, can increase the cost of production. Countries are forced to specialize in producing only certain types of phytomedicinal resources. Factors such as age, environmental conditions, temperature, rainfall, length of daylight, altitude, atmosphere, and soil, can affect the quality and concentration of active plant constituents. Drying the plant parts can take very long (depending on the technique of drying), and preventive measurements must ensure that the plant parts are thoroughly cleaned from any infestations before dried. To minimise microbial contamination, proper storage and preservation have to be in place to ensure quality of the product until the crude drug undergoes various processes before being transformed into a herbal pharmaceutical (Fetrow and Avila, 2001).
Plant parts that can be used, includes the following: the roots, bulbs, scales, rhizomes, tubers, bark, leaves, stems, flowers, fruit, and seeds. Gums and nectars can also be used. The method and form into which the plant will be prepared is also important. The different forms include: enemas, extracts, infusions, inhalations, linctuses, liniments, lotions, mixtures, nasal drops, ointments, tinctures and snuffs.
The most common methods of administering plant medicines are orally, sublingually, rectally, topically, nasally, smoking, steaming and bathing (Van Wyk et al., 2009).
In 1995 the United States Pharmacopoeia (USP) commissioned an advisory panel on natural products; their goal was to establish standards and to develop information concerning herbal and dietary supplements. The National Nutritional Foods Association (NNFA) of the United States is an organization of representatives from several thousand manufacturers, retailers, suppliers, and distributors of natural products, health foods, and dietary supplements. The NNFA has accreditation programs that inspect members with manufacturing facilities to determine whether they meet NNFA-specified standards of good manufacturing practices (GMP). From 1999 the NNFA seal appeared on some dietary supplement products. The time-tested and labour-intensive process of investigation and development of any new pharmaceutical entity should never fall short of determining its risk-versus-benefit profile (Fetrow and Avila, 2001).
Registration of medicines in South Africa is regulated by Act 101 of 1965 (Medicines and Related Substances Act), that stipulates all medicines should be safe (non-toxic), efficacious and of good quality. However, some of the plants used as food or for medicinal purposes are potentially toxic, mutagenic and carcinogenic (Schimmer et al., 1988; Higashimoto et al., 1993; Kassie et al., 1996).
It would appear that a clear link between herbal medicines and toxic incidents applied to less than 0.1 percent of toxicity cases (Wolpert, 2001); however misidentification of the plant species, poor quality of the preparations, prolonged usage and the addition of toxic substances to plant derived remedies contribute significantly to the toxicity associated with plant extracts (Stewart and Steenkamp, 2000; Wolpert, 2001; Fennell et al., 2004).
Candidiasis has become a major public health problem as an opportunistic infection in patients being treated with chemotherapy and radiotherapy for cancer, and in patients who are immuno-compromised because of HIV infection and AIDS. C. albicans is the most common fungal pathogen and has developed an extensive array of putative virulent mechanisms that allows successful colonization and infection of the host under suitable predisposing conditions (Runyoro et al., 2006; Ship et al., 2007).
Treatment of candidiasis is complicated by the emergence of strains of Candida that are resistant to the currently used antifungal agents (Perea et al., 2001; Khan et al., 2003). Patients are treated with the membrane-active polyenes nyastatin and amphotericin B, usually administered as a suspension or lozenges, while the ergosterol biosynthesis inhibitors (imidazoles and triazoles) are administered as tablets (miconazole, ketoconazole, and fluconazole), as a gel (miconazole), or as troches (clotrimazole) (Budtz-Jörgensen, 1990; Martin, 1990; Cannon et al., 1995).
These currently used antifungal agents are not only limited in number, but, many are in addition toxic (Mehta et al., 2002; Ship et al., 2007) and very costly (Salie et al., 1996; Mehta et al., 2002). Further, the social stigma associated with the HIV disease in many developing regions in Africa and Asia appears to modify the therapeutic strategies and management of fungal infections (Samaranayake et al., 2002). Relapse of Candida infections is also very common and this increases the burden of managing this opportunistic infection (Debruyne, 1997). These factors prompt the need for development of new antifungal agents in order to widen the spectrum of activities against Candida species and combat strains expressing resistance to the available antifungals.
CHAPTER 1: INTRODUCTION
CHAPTER 2: AIM AND OBJECTIVES
CHAPTER 3: LITERATURE REVIEW
3.1 Adhesion of Candida albicans in the oral cavity
3.2 History of herbal medicine
3.3 Some compounds isolated from plants
3.4 Manufacturing of herbal drugs
3.5 Drugs discovered from ethnobotanical leads
3.6 Treatment of oral candidiasis
CHAPTER 4: PRELIMINARY SCREENING OF SELECTED PLANT SPECIES
4.1 Plant species used in this study
4.3 Materials and Methods
4.4 Results and Discussion
CHAPTER 5: BIOAUTOGRAPHY
5.3 Bioautography procedure
5.4 Results and Discussion
CHAPTER 6: ANTIOXIDANT ACTIVITY
6.3 Materials and Methods
6.4 Results and Discussion
CHAPTER 7: CYTOTOXICITY
7.3 Material and Methods
7.4 Results and Discussion
CHAPTER 8: BIOASSAY-GUIDED FRACTIONATION OF Ptaeroxylon obliquum (Thunb.) Radlk. ACETONE LEAF EXTRACT
8.3 Materials and Methods
8.4 Results and Discussion
CHAPTER 9: BIOASSAY-GUIDED ISOLATION OF THE ANTIFUNGAL COMPOUNDS FROM THE CHLOROFORM-FRACTION OBTAINED FROM P. obliquum (Thunb.) Radlk. ACETONE LEAF EXTRACT
9.3 Materials and Methods
9.4 Results and Discussion
CHAPTER 10: BIOLOGICAL ACTIVITY OF THE ISOLATED COMPOUNDS AND STRUCTURE ELUCIDATION
10.3 Materials and Methods
10.4 Results and Discussion
CHAPTER 11: ADHESION OF Candida albicans TO HUMAN BUCCAL EPITHELIAL CELLS (HBEC) IN THE PRESENCE OF Ptaeroxylon obliquum ACETONE LEAF EXTRACT
11.3 Materials and Methods
11.4 Results and Discussion
CHAPTER 12: GENERAL DISCUSSION AND CONCLUSION
12.2 Recommendations for future work
CHAPTER 13: REFERENCES