Abstract

The present study was aimed at screening the phytochemical contents and antimicrobial activities of different solvent extracts as well as partial identification of the bioactive constituents from leaf, root, wood and bark of Ceriops decandra, a mangrove plant from Sundarban estuary, India. Phytochemical analysis revealed the presence of high phenolics (GAE 42.33 - 163.44 mg/g), flavonoids (QE 39.16 - 582.22 mg/g), tannins (TAE 16.71 - 134.77 mg/g), alkaloids (34.04 - 150.50 mg/g) and saponins (16 - 38 mg/g). Antimicrobial activities of different tissue extracts were screened by disc diffusion method using two Gram-positive (Bacillus subtilis and Bacillus coagulans), two Gram-negative (Escherichia coli and Proteus vulgaris) bacteria and two fungi (Saccharomyces cerevisiae andAspergillus niger). The extracts exhibited significant antimicrobial activities against all the microorganisms tested except A. niger. Selected plant extracts, when subjected to pH (3.0, 6.0 and 9.0) and heat (40, 60, 80 and 100°C) treatments, retained their antimicrobial activities in these extreme conditions thus demonstrating the stability of these compounds. The phytochemical components in each of the selected tissue extracts were also separated using thin layer chromatography (TLC); the antimicrobial constituents’ positions on TLC-plates were determined by TLC-bioautography, followed by partial identification of the nature of active phytochemical constituents exhibiting these antimicrobial activities. This study suggests the plant as a potential source of stable antimicrobial compounds for use as phytotherapeutic agents and in food-processing industries.

Key words: Ceriops decandra, phytochemicals, antimicrobials, Sundarban, mangroves, TLC-bioautography, TLC-fingerprinting.