Antioxidant and antimicrobial activities of Sonneratia albain vitro and In vivo : comparative study with Rhizophora mucronata and Bruguiera gymnorrhiza / Md. Imdadul Haq
The present study evaluated the antioxidant and antimicrobial potential of three mangrove
species namely, Sonneratial alba, Rhizophora mucronat and Bruguiera gymnorrhiza. The
bioactivities of methanol, ethanol and chloroform extracts of in vivo and in vitro explants
of S. alba and in vivo explants of R. mucronata and B. gymnorrhiza were evaluated. The
effects of growth regulators on seed germination of S. alba, to obtain the in vitro explants,
were also studied. In the first part of bioactivity study, total phenolic contents were detected
by using the Folin-ciocalteu assay. Ethanol extract of leaves of R. mucronata had the
highest result for total phenolic content as 358.6 ± 0.53 mg of GAE/g of dry sample. Both
enzymatic and non-enzymatic antioxidant assays were used to examine the potential of
antioxidant activities of all tested samples. Ethanol and methanol extracts of barks showed
better antioxidant activities compared to the leaves. Chloroform extracts in both leaf and
bark samples exhibited poor antioxidant activities for all selected mangrove plants.
Disc diffusion method was used to detect the antimicrobial activity of the extracts of all
three plants. Two gram positive (Bacillus cereus and Staphylococcus aureus) and two gram
negative (Escherichia coli and Pseudomonas aeruginosa) bacterial pathogens were used to
evaluate antimicrobial activity. Methanol and ethanol extracts of leaves and barks showed
promising antimicrobial activities when tested for all four abovementioned bacterial
pathogens. Nevertheless, chloroform extracts exhibited poor or no antimicrobial activities
against all tested microbial.
Ethanol extract of barks of S. alba was fractionated into water and ethyl acetate fraction,
and their antioxidant and antimicrobial activities were assessed. Water fraction exhibited
better bioactive potential compared with ethyl acetate fraction. Liquid chromatography tandem mass spectrometry (LCMS/MS) analysis was also carried out with water fraction to obtain the nominal mass of the major active components in the water fraction
