Anti-bacterial, free radical scavenging activity and cytotoxicity of  acetone extracts of Grewia flava.

Stella Makgabo Lamol, Jean Paul Dzoyem, Francien Botha, Candice van Wyk
1. Phytomedicine Programme, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of
Pretoria, Private Bag X04, Onderstepoort 0110, Pretoria, South Africa.
2. Department of Biochemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon
3. Department of Community Dentistry, Faculty ofHealth Sciences, University of Pretoria, Pretoria, P. O. Box
1266, Pretoria 0001, South Africa

Abstract
Background:Bacterial infections of the gastrointestinal tract (GIT) cause vomiting, diarrhoea and even systemic disease. There
is a need for the development of natural products into alternative and safer medicines.

Objectives: This study evaluated the anti-microbial activity of extracts prepared from berries, leaves,bark and roots of the edible plant Grewia flava.

Methods: The anti-bacterial activity was evaluated by the broth microdilution method. Anti-oxidant activity of the most active  extracts was performed by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay. The cytotoxicity of the extracts was determined using  the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

Results: The acetone extracts of the leaves and roots showed the best activity with MIC values as low as 0.03 mg/mL against Staphylococcus aureus and Salmonella typhimuriumand 0.07 mg/mL against Bacillus cereus, Escherichia coli and Staphylococcus aureus.
Quantitative analysis of the scavenging ability showed that acetone extracts exhibited good free radical scavenging activity in a
dose-dependent manner. The berries extract had the highest LC 50 (lowest toxicity) of 551.68 68 µg/mL.

Conclusion: Acetone extract of leaves and roots of Grewia flavacontain anti-microbial and anti-oxidant compounds and could  therefore be used as a natural product with little toxicity to host cells.

Keywords: Extracts, anti-microbial, cytotoxicity, enteric pathogens, Grewia flava.