THE ANTIBACTERIAL AND ANTIOXIDATIVE STRESS ACTIVITIES AND CHARACTERISATION OF ASPARAGUS LARICINUS AQUEOUS EXTRACT

Abstract

Background: Research indicates an increase in drug resistance to pathogenic human bacteria, despite the increase in synthetic antimicrobial drugs. As a result, medicinal plants are proving to be rich resources of constituents which can be used in drug development and synthesis of antimicrobial agents and/or their derivatives. Many of therapeutic drugs e.g. antimicrobial, anti-cancer and antioxidants have compounds extracted from plants as their primary active ingredients or molecules of plant origin serve as blue prints for synthetic or partially synthetic drugs. Methods: The antimicrobial activity of the Asparagus laricinus aqueous extract was evaluated by determination of minimum inhibitory concentration against laboratory strains of both gram-positive ( Bacillus subtilis , Streptococcus pneumonia and Staphylococcus aureus ) and gram-negative bacteria ( Pseudomonas aeruginosa , Escherichia coli and Proteus vulgaris ). The micro-plate assays based on iodo-nitrotetrazolium violet indicator was used to evaluate cell viability. Antioxidative stress activity of the extract was determined using Saccharomyces cerevisiae (BY4742) as the model eukaryotic system, while constitutes of the plant extract were profiled using LC/MS. Results: This study reports on the anti-bacterial and antioxidative stress activity of Asparagus laricinus . It was observed that 50µg/ml of the plant extract was the (MIC) for the gram-positive bacteria Bacillus subtilis , Streptococcus pneumonia and Staphylococcus aureus . While100µg/ml that was required for other gram-negative strains, Pseudomonas aeruginosa , Escherichia coli and Proteus vulgaris and Staphylococcus aureus was inhibited by 25µg/ml of the plant extract. The plant extract protected Saccharomycescerevisiae (BY4742) cells from oxidative stress when the cells were incubated with 10mM (H 2 O 2 ) for 1.5 hours. The phyto constituents of the plant extract were profiled using LC/MS and four major peaks were assigned chemical formulae. Conclusions: Asparagus laricinus water extract showed antimicrobial and antioxidative stress activities. LC/MS profile of major constituents of the plant extract revealed the presence of an alkaloid similar to 4-thiazolidinones, known to have important biological activities.