ETHNOBOTANICAL SURVEY AND ANTIBACTERIAL ACTIVITY OF SELECTED MEICINAL PLANTS IN DAMOT WOYDE DISTRICT, WOLAITA ZONE, ETHIOPIA

Abstract

Traditional medicine in Ethiopia has a long history of using medicinal plants to treat both human and animal diseases. However, the antibacterial properties and bioactive compounds of many of these plants remain underexplored. This study aimed to investigate the ethnobotanical knowledge and antibacterial activities of selected medicinal plants in the Damot Woyde district of Wolaita Zone. Ethnobotanical data were collected from August 2014 to February 2015 using semi-structured interviews, and field observations with the involvement of 40 traditional healers purposefully based on their traditional medicinal knowledge. Based on preference ranking and use value, three most preferred and most commonly used plants [Artemisia absinthium L., Leucas abyssinica (Benth.) Briq. and Ocimum gratissimum L.] were selected for further analysis. Dried leaf powders of these plants were successively extracted using three solvents. Antibacterial activity was evaluated using the agar well diffusion method against Staphylococcus aurous and Escherichia coli. Kanamycin (30 µg) and 5% dimethyl sulfoxide (DMSO) served as positive and negative controls, respectively. Phytochemical screening was conducted to determine the presence of secondary metabolites. Descriptive statistics were used to analyze ethnobotanical data and inhibition zones using Microsoft Excel 2016, while solvent significance was tested via one-way ANOVA. A total of 65 medicinal plant species belonging to 29 families were recorded, with Lamiaceae being the most represented family. Among them, 52.3% were cultivated, and herbs (33.8%) were the most frequently used growth form. Leaves were the most commonly used plant part and oral administration (55.4%) was the predominant route. Among the selected plants, the chloroform extract of A. absinthium leaves showed the highest zone of inhibition against S. aurous (17.17 ± 0.76 mm), compared to ethyl acetate (15.7 ± 0.79 mm) and aqueous extract (9.67 ± 0.58 mm). Phytochemicals such as terpenoids, phenolics, tannins, glycosides, anthraquinones, alkaloids, and flavonoids were detected. This study concludes that the area is rich in medicinal plant diversity, and the selected species exhibit promising antibacterial activity due to their phytochemical content. The study recommends conservation of medicinal plants and advises against the use of A. absinthium in pregnant women due to potential toxicity at high doses.