Ethnobotanical Survey and Some Biological Activities of Ageratum conyzoides Collected in Southern-Benin

Aims: Ageratum conyzoides L. is a small annual herbaceous highly odorous plant use in traditional medicine. The aim of this study is to evaluate in vitro antioxidant potential, toxicity and antimicrobial activity of aerial part extracts of A. conyzoides on strains potentially involved in vaginal infections.

Methodology: An ethnobotanical survey has been carried out on A. conyzoides among ethnobotanists and traditional therapists in fifteen markets in the communes of Abomey- Calavi, Cotonou, Zogbodomey, Bohicon and Abomey in Southern Benin. The phytochemical screening was a qualitative analysis based on staining and precipitation reactions. Antimicrobial activity of A. conyzoides aqueous and ethanolic extracts was evaluated on reference and clinical strains of Staphylococcus aureus, Candida albicans and Escherichia coli using micro dilutions method in wells from. The toxicity of A. conyzoides extracts was determine using Artemia salina larvae, whereas the antiradical activity was evaluated using the Ferric Reducing Antioxidant Power (FRAP) method.

Results: The survey showed that the population of Southern-Benin uses A. conyzoides according to different modes of preparation. Also, the administration in the treatment of a variety of pathologies affecting the female reproductive system. The phytochemical screening revealed the presence of flavonoids, tannins, anthocyanins, triterpenes and C- heterosides. The yield of 6.18% for the aqueous extract and 4.32% for the ethanolic extract as recorded. The highest inhibition diameter (24.05 ± 0.5 mm) was obtained using aqueous extract against the clinical S. aureus strain. In contrast, the lowest inhibition diameter (10±0 mm) was obtained against the S. aureus ATCC29213 with the same extract. The Minimum Inhibitory Concentration varied from 2.5 to 5 mg/ml. Both extracts show a bactericidal and fungicidal effect on the different strains studied but the sensitivity of the strains to the aqueous extract is better compared to the ethanolic extract. In addition, the aqueous extracts showed higher antioxidant power compared to the ethanolic extract. No toxicity is revealed for both extracts.

Conclusion: The results obtained show that the aqueous and ethanolic extracts of the aerial part of A. conyzoides have antioxidant and antimicrobial properties on strains involved in vaginal infections and do not present a toxicity.