Purpose: To evaluate the influence of extraction method and solvent type on extractable polyphenols
and flavonoids in Doum
Hyphaene Thebaica
L Mart (
Arecaceae) fruit, as well as to examine the
antioxidant and antibacterial activities of the fruit extracts.
Methods: The extraction procedures were performed separately in an ultrasonic bath or shaking water
bath for 30 min (70 °C for ethanol and 60 °C for methanol) at agitation speed of 50 Hz and 70 rpm,
respectively. The antioxidant potential of the extracts was investigated using β-carotene bleaching, 2,2-
diphenylpicrylhydrazyl (DPPH) and reducing power ability assays.
In vitro antibacterial activity of the
extracts against
Staphylococcus aureus
,
Listeria monocytogenes
,
Escherichia coli
, and
Salmonella typhi
was assessed using agar disc diffusion assay.
Results: Total polyphenol content (TPC) and total flavonoid content (TFC), as well as antioxidant
capacity were maximized using methanol as the extraction solvent, particularly with the ultrasonic
method. The half maximal inhibitory concentration (IC
50) values of the methanol/ultrasonic (MU),
methanol/water bath (MW), ethanol/ultrasonic (EU), and ethanol/water bath (EW) extracts in the DPPH
assay were 107.6 126.7, 172.7, and 196.3 μg/mL, respectively. The extracts showed strong
antibacterial activity against
Staphylococcus aureus and
Salmonella typhi, while MU extract inhibited the
growth of all pathogenic bacteria used in this study.
Conclusion: The antioxidant and antibacterial activities of Doum fruit extracts are significantly affected
by the type of extracting solvent and equipment used. The findings further demonstrate that MU extract
had stronger antioxidant and antibacterial activity than the other extracts.
