Phytochmical analysis and antibacterial property assessment of helencha (Enhydra fluctuans; Family: Asteraceae) extracts

Abstract

This communication stands for the phytochemical analysis, and antibacterial activity of Enhydra fluctuans, alone and in combination with some antibiotics, against gram-negative and gram-positive bacteria. Following disc diffusion, the methanolic extract of E. fluctuans (MEE) had antibacterial activity against gram-positive (B. cereus and L. monocytogenes) and gram-negative (A. baumannii and P. aeruginosa) clinical as well as standard (E. coli ATCC 25922 and L. monocytogenes MTCC 657) bacterial strains, displaying ZDI (zone of the diameter of inhibition) values 12 – 24 mm. The aqueous extract of E. fluctuans (AEE) showed no activity against P. aeruginosa; however, for the other test bacterial isolates AEE had ZDIs of 13 – 21 mm (for gram-negative bacteria) and 10 – 17 mm (for gram-positive bacteria). The MIC (minimum inhibitory concentration) values of MEE, for both gram-negative and gram-positive bacteria, ranged from 2.5 to 10 mg/ml, by agar dilution method. The extracts (AEE and MEE) were screened qualitatively to contain bioactive components: flavonoids, glycosides, steroids, terpenoids, phenols, quinone and saponins, while cardiac glycoside was detected in AEE only. The HPLC chromatogram showed the presence of 14 detectable compounds, within the retention time of 1.53 - 5.69 min, in MEE. The growth inhibitory indices of 0.59 – 1.08, from the antibiotic-MEE combined action, demonstrated synergism against the test bacterial strains. The E. fluctuans, alone or in combination with antibiotics, might be useful in combating infections caused by both gram-negative and gram-positive bacteria.