RESUMEN
Background: Bacterial pathogens have evolved numerous defense mechanisms against commercial antimicrobial agents, and their resistance to most of the available antimicrobials is increasing. Medicinal plants are a potential source of antimicrobial agents during the spread and emergence of infectious disease caused by resistant microorganisms. The aim of this study was thus to investigate the antimicrobial activity and acute toxicity of 80% methanol extracts of leaves of Artemisia absinthium, seeds of Datura stramonium, and fruit of Solanum anguivi. Materials and Methods: The 80% methanol extracts were prepared by cold maceration. Antimicrobial activity was evaluated against five bacterial species using agar-well diffusion at concentrations of 125, 250, and 500 mg/mL in the presence of positive and negative controls. Minimum inhibitory concentration was determined by broth dilution. The acute toxicity study was done following OECD guidelines. Results: The 80% methanol extract of the fruit of S. anguivi exhibited better activity against most of the bacterial strains, of which Salmonella enterica serovar Typhimurium was found to be the most susceptible, with minimum inhibitory concentration and minimum bactericidal concentration of 1.3 mg/mL and 1.95 mg/mL, respectively, while the seed extract of D. stramonium showed the least activity against most test organisms. The acute toxicity study showed that all three plants had an LD50 >2,000 mg/kg body weight, and were thus safe. Conclusion: The results of this study revealed that the methanol extracts of the three plants (A. absinthium, D. stramonium, and S. anguivi) had different degrees of antibacterial activity against the selected pathogenic bacteria and were safe at higher doses, thus being of great potential to be developed as antibacterial agents. The study also provided scientific evidence to support the continued traditional use of these medicinal plants by communities in different parts of Ethiopia to treat infectious diseases.
RESUMEN
Epizootic lymphangitis is prevalent in equines in Ethiopia, causing remarkable economic and welfare impacts but often neglected. Lack of effective treatment contributed to its continued occurrence, and hence, search for an effective treatment should be considered a priority area to minimize its impacts. Previous ethnobotanical studies have reported that Curcuma longa, Phytolacca dodecandra, and Datura stramonium were used to treat cutaneous fungal infections and reduce their incidence. The treatment effects of these plants against epizootic lymphangitis should be studied. The in vitro growth inhibitory effects of methanol extracts of the root of C. longa, berry of P. dodecandra, and leaf of D. stramonium were evaluated. Histoplasma capsulatum var farciminosum was isolated from clinical cases of epizootic lymphangitis in carthorses in central Ethiopia. The nested polymerase chain reaction was used to confirm the identity of the isolates. Serial twofold dilutions of the extract of berries of P. dodecandra and leaves of D. stramonium were done in sterile water, whereas dilution of the extract of roots of C. longa was done in dimethylsulphoxide. The effects of the plants on the growth of Histoplasma capsulatum var farciminosum were assessed by agar dilution assay. Culture media with no antifungal agent and media containing ketoconazole served as negative and positive control, respectively. The methanol extract of C. longa showed inhibitory effects at concentrations ranging from 0.07 to 5 mg/mL. Similarly, the methanol extract of P. dodecandra showed growth inhibitory effects at concentrations ranging from 0.156 to 5 mg/mL. That is, the growth inhibitory concentration of C. longa was 0.07 mg/mL, whereas that of P. dodecandra was 0.156 mg/mL. In contrast, D. stramonium showed no inhibitory effect. This preliminary observation showed that methanol extracts of C. longa and P. dodecandra showed inhibitory effects on the growth of Histoplasma capsulatum var farciminosum requiring further repeated in vitro evaluation so as to generate adequate evidence, which would justify in vivo trials.