Antioxidant and Antimicrobial Potential of Hydroethanolic Extracts of Padina tetrastromatica from North-west Coast of India
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Keywords:
Padina sp., polyphenols, alkaloids, hydroalcoholic extractAbstract
Brown seaweeds are rich sources of several biologically
active compounds, particularly polyphenols.
The present study investigates the efficiency of
hydroalcoholic solvent to extract bioactive molecules
from the brown seaweed P. tetrastromatica. Six
different combinations of ethanol in water (0, 20, 40,
60, 80 and 100% v/v) mixture were employed to
extract the bioactives with an objective to study their
antioxidant and antimicrobial activity. The antioxidant
potential of different extracts was assessed by
Total Phenolic Content (TPC), Ferric-reducing antioxidant
power (FRAP) assay, 1,1-diphenyl-2-
picrylhydrazyl (DPPH) radical scavenging activity,
2, 2'-azino-bis 3-ethylbenzothiazoline-6-sulphonic
acid (ABTS) radical cation scavenging and Total
antioxidant activity assays. 100% ethanolic extract
was found to have the highest TPC and exhibited
significantly higher antioxidant activity for all tests
done while aqueous extract contained the highest
extractive yield. The antimicrobial activity of the
extracts were also evaluated against food spoilage
and pathogenic bacteria using disc diffusion assay.
100% extracts significantly (p<0.05) inhibited the
growth of gram-negative bacteria while 60% extract
also exhibited the best inhibitory effects against
gram-positive bacteria. HR-LCMS analysis of the
extracts revealed that 100% ethanolic extract contained
a higher number of alkaloid compounds than
phenolic compounds whereas aqueous extracts
contained more phenolic compounds. It was observed
that as the polarity decreases, the efficiency of a hydroethanolic solvent to extract active alkaloid compounds along with polyphenols increases, which in turn contributes to the higher bioactivity of the extract.