Abstract

Methanol and water extracts from Gunnera perpensa rhizomes and Heteromorpha arborescens roots were investigated for their in vitro antimicrobial activities. These plants are implicated in the treatment of dysmenorrhoea in the Eastern Cape, South Africa. Ten bacterial strains (5 Gram positive and 5 Gram negative) and four fungal strains were selected for the antimicrobial assays. Both plant species were active against the Gram positive bacteria, with G. perpensa being more effective than H. arborescens. The antifungal assays showed all extracts significantly inhibiting the growth of four strains and Candida albicans not inhibited by all. The LC₅₀ values ranged from 0.07 to 3.81 for all the extracts. Albeit the fact that most of the fungal species used in the investigation are not directly implicated as human pathogens, it was important to assess the extracts activity against them. These may give rise to fungicides that can be employed in therapy.

Key words: Gunnera perpensa, Heteromorpha arborescens, antimicrobial activity, bacteria and fungi.