In vitro Antibacterial, Antioxidant and Anti-Inflammatory Effects of Senecio asperulus and Gunnera perpensa from Mohale's Hoek, Lesotho

Background: Traditional medicinal plants have been widely used to treat or manage various ailments for centuries in Lesotho. With an increase in multi drug resistance and undesired adverse events to current drugs challenges, there is a need for alternative drugs. Aim: In this study we aimed at the investigation of antibacterial, antioxidant and anti-inflammatory effects of Senecio asperulus and Gunnera perpensa roots extracted in three solvents of different polarities. Materials and Methods: Antibacterial activity was determined using the disc diffusion method, while antioxidant activity was determined using free radical scavenging of 2,2-diphenyl-1-picrylhydrazyl and the ferric reducing antioxidant power assay. The Lipopolysaccharide (LPS) stimulated RAW 264.7 mouse macrophage in vitro model was used to evaluate the anti-inflammatory activity of both plants. Resveratrol was used as a positive control. Results: Methanol extracts of Senecio asperulus inhibited microbial growth even at the lowest concentration of 50 μg/ml. Senecio asperulus dichloromethane extract was active on most bacteria with MIC’s between 50 μg/ml and 500 μg/ml. However, the water and methanol extracts of Gunnera perpensa had no activity against all organisms tested. Aqueous extracts of Senecio asperulus and Gunnera perpensa showed free radical scavenging activity yielding EC₅₀ values of 100 μg/ml and 25 μg/ml, respectively. The aqueous extracts of Senecio asperulus showed moderate anti-inflammatory activity from 50 to 200 μg/ml. while the methanol extract was at 200 μg/ml and with no cytotoxicity. No anti-inflammatory activity was observed from all Gunnera perpensa extracts using LPS-induced macrophages, this suggests that this species may be using other mechanisms for anti-inflammatory activity. Conclusion: The antibacterial, antioxidant and anti-inflammatory activities observed from water extracts of Senecio asperulus support its ethnomedicinal use for the management of inflammation related diseases.