Abstract:
2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical has been widely used to evaluate the free
radical scavenging activity of natural antioxidants. Antioxidants react with DPPH radical,
which is a stable free radical and convert it to 2,2-diphenyl-1-picryl hydrazine. The
degree of discoloration indicates the scavenging activity of antioxidant extracts. In the
present study, phenolic compounds of coconut cake were extracted using methanol :
water (80 : 20 v/v) and the radical scavenging activities of the phenolic extracts and
butylhydoxytolucne (BHT) against DPPH radical were determined
spectrophotometrically in order to compare the antioxidant potential of the phenolic
extracts of coconut cake. The change in color from deep violet to light yellow was
measured at 515 nm using a UV /Visible spectrophotometer. Radical scavenging activity
of the phenolic extracts was expressed as the percentage inhibition with respect to a
control with no added phenolic extract.
Total phenol concentrations of the phenolic extracts measured by Folin-Denis
colorimetric method were adjusted to a range of concentrations by suitable dilutions of
the extracts with the methanol water solvent system. A similar concentration series was
also prepared by suitable dilutions of BHT. Figure 1 compares the DPPH radical
scavenging activity of the phenolic extracts of coconut cake with that of BHT.
Figure 1.
100-
90 ~
80 "
70
5 so
"' ~ 50
.5
;f. 40
30
20 '
10'
0 ;
DPPH radical scavenging activities of the phenolic
extracts of coconut cake and BHT
-.-Coconut cake extract
25 50 75 100
Concentration of the extract or BHT (mg/ L)
There is lot of interest in recent times about the suitable alternatives for synthetic
antioxidants. The above results indicate that the phenolic extracts of coconut cake are
potential candidates for nontoxic natural antioxidants.
