Somali Chattopadhyay, Shohini Chakraborty and Sukanta Majumdar

Microbiology and Microbial Biotechnology Laboratory, Department of Botany, University of Gour Banga, Malda-732103 (India)

ABSTRACT

In present study we evaluated the antioxidant activity and anti quorum sensing activity of ethanolic extracts of Nasturtium officinale R.Br (Brassicaceae) and Amaranthus spinosus L. (Amaranthaceae). The experiments conducted on the basis of the QS-I (quorum sensing inhibition) activity of plant extract against the MTCC2656 Chromobacterium violaceum. Extractive value of ethanolic plant extracts were 85.0% in case of A. spinosus and 18.5 % in case of N. officinale. The anti-biofilm activity of plant sample was done by the three different ways such as agar well diffusion method, flask incubation assay and bioassay for quorum sensing inhibition by TLC. In flask incubation assay, inhibition percentage (%) of violacein production by A. Spinosus and N. officinale were 87% and 82% respectively. In the thin layer directed (TLC) bio autography, zone of inhibition determined by the help of Rf values that showed two unique spots likes 0.49 and 0.51 which were responsible for the anti QS activity in N. officinale, A. spinosus respectively. On the basis of phytochemical studies, the result revealed that both the samples consists of carbohydrate, protein, glycosides but in A. spinosus phenol was absent, where as flavonoids and tannin were present. Similarly, in N. officinale phenol was present but flavonoids and tannin were absent. Some nutritional factors present in both plant extract such as A. spinosus consist of 348.27 μg/ml of total protein, 37.6 μg/ml of total soluble sugar and 63.1 μg/ml of total reducing sugar as well as N. officinale consist of 536.19 μg/ml of total protein, 83 μg/ml of total soluble sugar and 19.7 μg/ml of total reducing sugar. Antioxidant activity of plant sample was checked by DPPH free radical scavenging activity at 517 nm. A dose dependent DPPH scavenging activity was observed in case of both the plants. TLC showed that coumarin and saponins were present in both the sample, but the presence of tannin and flavonoid was recorded only in A. spinosus.

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