Medicinal properties of plants predominantly used for ethno-veterinary purposes in the highland grasslands of the Free State province, South Africa, and Lesotho

Abstract

The use of medicinal plants to maintain animal health in most parts of the world is well-known. It is also common for ethnoveterinary knowledge to be orally passed from generation to generation. However, this knowledge can easily be lost or distorted if not properly documented. The present study, therefore, aimed to identify and document the commonly used medicinal plants for ethnoveterinary practices in the QwaQwa and Thaba ‘Nchu areas of the Free State province in South Africa and Maseru and Mokhotlong towns of Lesotho. Furthermore, the most predominantly used plants were tested for phytochemical constituents, antimicrobial, cytotoxicity, and anthelmintic activities. Semi-structured interviews for ethnobotanical information were held with 69 randomly selected respondents, consisting of subsistence livestock farmers, traditional healers and other traditional knowledge holders. Data on the plants used, their common names, methods of preparation and administration and livestock ailments treated were collected. The relative citation frequency (RFC) index determined the most predominantly used plant species. The most frequently reared livestock in the study areas were cattle (62) > sheep (37) >goats (25)> horses (10) > pigs (6) > donkeys (6) > poultry (2). Fifty-one plant species belonging to 35 families were reported to have ethnoveterinary uses. The RFC values indicate that Rhamnus prinoides (0.45), Aloe striatula (0.38), Monsonia burkeana (0.29) and Leucosidea sericea (0.25) were the most frequently mentioned and important plants of the study. Digestive anomalies or liver malfunction (excess bile) was the most mentioned (56.5%) disease. Black quarter (15%) and intestinal parasites (8%) were also frequently reported. Tannins, saponins, flavonoids, cardiac glycosides, phenols, and steroids were detected in R. prinoides, A. striatula, M. burkeana and L. sericea while alkaloids were absent. Total phenolic content of R. prinoides was the highest at 5.102 mg/ml, followed by the aqueous extract of M. burkeana at 3.991 mg/ml, while the lowest (1.846 mg/ml) was observed from the aqueous extract of L. sericea. The total tannin content was highest in the aqueous extract of A. striatula (2.242 mg/ml) followed by the acetone extract of R. prinoides (1.47 mg/ml), while the lowest (0.242 mg/ml) was observed from the methanol extract of R. prinoides. The ethanolic extract of L. sericea had antibacterial activity with MIC ranging from ≤0.098 mg/ml to 0.78 mg/ml, and the MBC ranged from 0.195 mg/ml to 1.56 mg/ml. However, the aqueous extract of L. sericea was not active against all tested fungal strains. The methanolic extract of M. burkeana MIC ranged from ≤0.098 mg/ml to 1.56 mg/ml, while the MBC ranged from 1.56 mg/ml to 3.125 mg/ml. The acetone extract of A. striatula displayed high MIC values ranging from 0.78 mg/ml to >12.5 mg/ml and a high MBC ranging from 6.25 mg/ml to >12.5 mg/ml, but was inactive against the bacterial strains. The acetone extract of A. striatula was also fungicidal at 0.049 mg/ml. The acetone extract of L. sericea and the water extract of M. burkeana had some toxicity at 200 μg/mL. The methanol extract of M. burkeana was the most cytotoxic against Vero cells, exhibiting nearly 50 % cell death at 100 μg/mL. In contrast, the water extract of L. sericea) had no cytotoxic effects. All the extracts showed some level of larval development inhibition. Total inhibition (100 %) was recorded for the positive control at 50 μg/ml and L. sericea acetone extract at 25 μg/ml. The least inhibition was 22.95 μg/ml for the M. burkeana methanol extract, which showed generally lower inhibition than the rest of the other treatments. L. sericea water extract and L. sericea acetone extract showed higher egg hatch inhibition than M. burkeana methanol extract, water extract and positive control. M. burkeana methanol extract recorded the least (9.57 μg/ml) under higher concentrations. The present study observed that most plants used in the highland grasslands of the Free State province of South Africa and Lesotho can treat multiple animal diseases thus validating the use of medicinal plants in traditional medicine. Further comprehensive studies are recommended to investigate their bioactive compounds and potential development of plant-derived medicinal products.