Evaluation of Antibacterial and Antioxidant Activities of Root and Aerial Extracts of Imperata Cylindrica

Yap, Shwu Tyng (2018) Evaluation of Antibacterial and Antioxidant Activities of Root and Aerial Extracts of Imperata Cylindrica. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Lalang grass, (cogongrass, Imperata cylindrica).is a notoriously problematic invasive species which colonizes land by forming a network of rootstocks resistant to fire, flood and drought. Although it is one of the worst weeds in the world, it has numerous uses, from edible to medicinal properties. The first objective of the study is to investigate the antibacterial activity of methanolic aerial and root extracts of Imperata cylindrica against common gram-positive and gram-negative bacteria. The antibacterial activity was performed under sterile conditions using well diffusion method in Muller Hinton agar media. Three concentrations (1%, 5% and 10%) of the macerated methanolic extracts were prepared. Gram-positive bacteria (Staphylococcus aureus and Bacillus. Sp) and Gram-negative bacteria, E. coli and Salmonella. Sp were tested. Plates were incubated at 37C for 18-24 hours. Extracts of the aerial part showed better antibacterial activity than the root part. Both extracts have shown no antibacterial properties towards Bacillus. Sp. The second objective is to investigate the scavenging ability of the methanolic aerial and root extracts of Imperata cylindrica to reduce hydrogen peroxide and nitric oxide using spectrophotometric methods. Ascorbic acid was used as standards for both methods. The results of hydrogen peroxide scavenging assay showed that root had a scavenging percentage of (88.01±0.029%), and aerial (77.01±0.656%). Nitric Oxide scavenging assay was performed using Griess’ reagent and the absorbance was measured at 546nm. The results of nitric oxide scavenging assay showed that a highest scavenging % in the root (66.13±0.227%) than the aerial (33.40±0.656%). The extracts were then subjected to qualitative phytochemicals screenings. Both aerial and root extracts showed the presence of flavonoid, phenol, tannin and the absence in alkaloid. Saponin and terpenoid were present only in aerial extracts. The quantitative screenings were carried out to determine the total phenol and flavonoid compounds. The total phenolic compound of aerial and root extracts were 41.111±0.667ppm and 56.311±0.340ppm. The total flavonoids compound of aerial and root extracts were 7.062±0.130ppm and 9.547±0.095ppm.