Antimicrobial activities of medicinal plants used by indigenous people of Mogalakwena and Mookgopong municipalities in the Waterberg District Limpopo Province South Africa for the treatment of food-borne pathogens

Abstract

Food-borne diseases (FBD) are a main concern globally, around 250 different FBD having been described to date and bacteria contributing to two third of FBD outbreaks. Among the leading bacteria involved in FBD are Salmonella typhi and Escherichia coli, which are accountable for majority of global deaths of FBD. In Africa the condition is worse, about 70% of mortality is caused by food related bacterial diarrhoea. Symptoms of FBD vary widely, however diarrhoea and vomiting are the most common symptoms. It is estimated that 43 000 South Africans die of diarrhoeal disease every year, while private and public health care spend over R73 million per annum due to diarrhoea. However, in the rural communities of Southern Africa dependence on medicinal plants as remedies for diarrhoea and vomiting is still on the rise. Almost 80% of the South African population use medicinal plants to meet their primary health care needs; however, few medicinal plants in South Africa have been scientifically tested. Medicinal plants can inhibit the growth of wide range of pathogenic microorganisms. About fifty percent (50%) of all drugs in clinical use in the world are derived from natural products. There are large number of plant species that are of medicinal use that have not been tested for antimicrobial activities. Some bacteria’s have developed resistance against antibiotics currently in use, making it difficult to treat patients successfully. Medicinal plant extracts offer great potential in developing new drugs which might be effective in treating infections currently difficult to treat. The use of medicinal plants in dates back to over 4000 years ago, the knowledge acquired since then is through trial and errors. Every community in South Africa have different medicinal plants used to treat the same disease. Hence, it is important to work with the experienced traditional healers to acquire information on medicinal plants used to treat diarrhoeal pathogens. A questionnaire was used to collect the data, the antimicrobial activities of the five species with the highest frequency were evaluated against Salmonella typhi and Escherichia coli. They were further subjected to phytochemical tests. The study revealed 19 plants species belonging to 12 families were used to treat diarrhoeal food borne pathogens in the study area. Poulzozia mixta, Sclerocarya birrea, Psidium guajava, Ozoroa reticulata and Punica granatum were the most mentioned plant species. Dried ground plant materials were each extracted using distilled water and 70% ethanol. Distilled water extract had higher percentage yield over the ethanol extract. Ethanol extract showed higher antimicrobial activities over the aqueous extract. Punica granatum fruitpeels was the most effective medicinal plant against Escherichia coli on both aqueous and ethanol extract, when using agar disc diffusion method. However, it also exhibited antimicrobial activities against Salmonella typhi. During phytochemical test Punica granatum fruitpeels had positive results for saponins and tannins. Saponins are known to have anti-inflammatory, antiviral and antimicrobial activities. Pharmaceuticals use tannins as antidiarrheal, diuretics, stomach pain, anti-inflammatory, antiseptic and antioxidant. In their antidiarrheal activity, tannins are responsible for increasing colonic water and electrolyte reabsorption. The results obtained points to the value of untested medicinal plants which can have significant contribution to the pharmaceutical industry.