Antimicrobial and brine shrimp activity of Acanthus pubescens root extracts

Abstract

The root dichloromethane and ethyl acetate extracts of Acanthus puberscens (Oliv.) Engl (ACANTHACEAE) exhibited weak antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Bacillus anthracis, Salmonella typhi, Streptococcus faecalis, Streptococcus agalactiae and Pseudomonas aeruginosa, with MIC values ranging from 1.6-6.25 mg/ml. The two extracts also exhibited weak antifungal activity against Candida albicans (MIC 6.25 mg/ml). Using the brine shrimps lethality test ethanol, ethyl acetate and aqueous extracts were virtually non-toxic to brine shrimp larvae, but the dichloromethane extract (LC₅₀ 38.9 µg/ml) was mildly toxic. These results support the use of the plant in traditional medicine to treat gonorrhea, syphilis, gastroenteritis and pneumonia. Since the plant is used in combination with other plants it is difficult to make any final conclusions regarding safety and efficacy. Further work is needed to evaluate the activity of an extract made from a combination of the six plants.