Phytochemical screening, antibacterial and anti-oxidant activities of Aspara-

The aim of this study was to investigate anti-oxidant activities, antibacterial activities and a phytochemical constituent of Asparagus laricinus stem and leaf extracts. Determination of antibacterial activity of extracts was assessed by agar dilution method and anti-oxidant properties by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The minimum inhibitory concentration (MIC) of the leaf was at a concentration of 0.125 mg/mL against S. saprophyticus and E. cloacae, and at a concentration of 1 mg/mL against S. aureus and B. subtilis. There was no MIC of the stem extract at any concentration. The leaf extract showed effective free radical scavenging activity (72.1%), while stem extract had low activity. Qualitative phytochemical analysis of these plant extracts revealed the presence of tannins, saponins, flavonoids and phlobatannins. The leaf extract further confirmed the presence of glycosides, steroids, ternoids and carbohydrates. Our results indicate that, A. laricinus leaf extracts have potential antimicrobial and anti-oxidant activities. Article Info Received: 11 November 2013 Accepted: 15 December 2013 Available Online: 7 January 2014 DOI: 10.3329/bjp.v9i1. 16967 Cite this article: Ntsoelinyane PMAH, Mashele S. Phytochemical screening, antibacterial and anti-oxidant activities of asparagus laricinus leaf and stem extracts. Bangladesh J Pharmacol. 2014; 9: 1014. This work is licensed under a Creative Commons Attribution 3.0 License. You are free to copy, distribute and perform the work. You must attribute the work in the manner specified by the author or licensor. Phytochemical screening, antibacterial and anti-oxidant activities of Asparagus laricinus leaf and stem extracts Polo-Ma-Abiele Hildah Ntsoelinyane and Samson Mashele Central University of Technology, Free State, South Africa. Extraction methods Plant material (10 g of the dried leaf and stem) was weighed and soaked with purified water for 72 hours with occasional stirring. The extracts were filtered and lyophilized. Microorganisms Clinical isolates of Staphylococcus aureus (ATCC29213), Staphylococcus saprophyticus (ATCC 15305), Escherichia cloacae (ATCC13047) and Bacillus subtilis (ATCC11774) were used in this study. Antibacterial activity test (MIC determination) Antibac-terial activity was assessed using the agardilution method as described elsewhere (Madamombe and Afolayan, 2003). Staphylococcus aureus (ATCC 29213), Staphylococcus saprophyticus (ATCC15305), Escherichia cloacae (ATCC13047) and Bacillus subtilis (ATCC11774) were cultured and maintained on nutrient broth. Different volumes of extracts (51.9; 25.9; 12.9; 6.4; 3.2 μL) were added to nutrient agar respectively, mixed to obtain different concentrations (2; 1; 0.5; 0.25; 0.125 mg/mL), and dishes were allowed to set. Using a sterile swab, microorganisms were streaked on diluted nutrient agars. Dilutions of chloramphenicol served as a positive control while broth without plant extract was used as a negative control. Plates were covered and incubated for 24 hours at 37°C. Bacterial growth was determined by visual looking at the plates and results were recorded as growth or no growth. Since the activity of the antibacterial depends frequently on its concentration, the minimum inhibitory concentration of the A. laricinus extracts were determined. Scavenging ability towards 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical The (DPPH) assay was performed as described by Shirwaikar et al. (2006). 100 μL of various concentrations of each sample was added to 2 mL solution of 0.1 mM DPPH. 100 μL of methanol and 2 mL DPPH served as control. After 60 min of incubation at 25°C in the dark, the absorbance was recorded at 517 nm. The experiment was performed in triplicates. The DPPH radical scavenging activity was calculated according to the following equation: % DPPH radical scavenging activity = 1 [Asample/ Acontrol] x 100 where Asample and Acontrol are absorbance of sample and control respectively. The SC50 (concentration of sam -ple required to scavenge 50% of DPPH radicals) values were determined. The decrease of absorbance of DPPH solution indicates an increase of the DPPH radical scavenging activity. The anti-oxidant activity was expre -ssed as the number of equivalents of ascorbic acid. Phytochemical screening of the plant extract A small portion of the dry extract was used for the phytochemical tests for compounds which include tannins, flavonoids, alkaloids, saponins, and steroids in accordance with the methods with little modifications (Trease and Evans, 1989; Harborne, 1998). Total phenolic content Total phenolic content in the obtained extracts were estimated by a colorimetric assay based on procedures described elsewhere (Singleton and Rossi, 1965) with some modifications. Briefly, 1 mL of sample was mixed with 1 mL of Folin and Ciocalteu’s phenol reagent. After 3 min, 1 mL of saturated sodium carbonate solution was added to the mixture and adjusted to 10 mL with distilled water. The reaction was kept in the dark for 90 min, after which the absorbance was read at 725 nm. Gallic acid was used for constructing the standard curve. The results were expressed as mg of gallic acid equivalents/g of extract (GAEs). Statistical analysis Tests were carried out in triplicates. MIC of test samples was compared with that of positive and negative control. The mean values were calculated from the triplicate values. Values were expressed as the Mean ± SD (n = 3) and differences between groups were considered to be statistically significant if p<0.05. Data from the test groups were compared with SC50 value of the standard which is the concentration of sample, required to scavenge 50% of DPPH free radicals.