172
All dabai fruits exhibited high DPPH free radicals
scavenging activities of more than 88 percent, indi-
cating good potential as free radicals scavengers.
The hierarchy of dabai fruits with respect to their
abilities to scavenge DPPH free radicals was red
dabai fruits>purple dabai fruits from Kanowit>
purple dabai fruits from Kapit >purple dabai fruits
from Song. Cooking of fruits at 60°C for 3–5 min-
utes also resulted in increases of DPPH free radi-
cals scavenging activity (Table 10). Interestingly, red
dabai fruits from Sarikei with lowest TEAC and
FRAP value demonstrated the greatest DPPH free
radicals scavenging activity.
Purple dabai fruits from Kapit that were found to
possess significantly the highest TPC, TFC and TAC
exhibited significantly the greatest TEAC and FRAP.
Similarly, significantly the lowest TEAC and FRAP
were observed in red dabai fruits from Sarikei
which had significantly the least TPC, TFC and TAC.
These data suggest that phenolic compounds (in-
cluding flavonoids and anthocyanins) in dabai
fruits provide substantial antioxidant activities. It
is strongly believed that the antioxidant properties
of purple dabai fruits from Kapit are intimately re-
lated to the geographical location of Kapit. It is a
remote division of Sarawak, with less exposure to
pollutants which could have a positive effect on the
phytochemical properties of dabai fruits cultivated
in Kapit.Further data analysis indicated very strong linear
correlations between TPC and TEAC (r = 0.958), and
between TPC and FRAP (r = 0.999). Similarly, very
strong linear correlations between TFC and TEAC
(r = 0.991), and between TFC and FRAP (r = 0.983)
were noted. Strong linear correlations between TAC
and TEAC (r = 0.870), and between TAC and FRAP
(r = 0.906) were also observed. Due to the lower
correlations of TAC with TEAC and FRAP values, we
could say that anthocyanins did not play a major
role in antioxidant mechanisms with these tests.
Moderate to strong negative correlations were
found between TPC and DPPH (r = -0.898), between
TFC and DPPH (r = -0.794) and between TAC and
DPPH (r = -0.912).8. Phenolic compounds
In the present study, the chromatographic profiles
of phenolic acids and flavonoids in dabai fruits were
qualitatively similar for the two varieties (purple and
red dabai fruits). However, they differed in the
amount of phenolic compounds identified. The chro-
matographic profile of anthocyanidins and antho-
cyanins in dabai fruits revealed marked differences
between varieties, with more phenolics in purple
dabai fruits. Anthocyanidins and anthocyanins were
relatively more abundant in purple dabai fruits.
Catechin was the major phenolic compound in dabai
fruits. Catechin in red dabai fruits (0.33 mg/g DW)Table 1 0 .DPPH radicals scavenging activity of dabai fruits from different growing areas.Purple dabai fruits Red dabai fruits
DPPH Kanowit¥ Kapit¥ Song¥ SarikeiCooked fruit 89.45±0.50a,b 88.14±1.21b 88.12±1.09b 90.96±0.22a
(88.85–90.08) (85.84–89.57) (85.80–88.94) (90.80–91.21)Uncooked fruit 71.22±3.34b 58.96±7.89c 64.59±8.30b,c 91.03±0.03a
(66.74–74.84) (51.44–70.91) (49.27–72.35) (91.01–91. 0
DPPH, DPPH radicals scavenging activity expressed as percentage of inhibition. Results are expressed in mean±SD and (range).
Values with different letters are significantly different at p < 0.05 within the same row.
¥ indicates significantly different at p < 0.05 within the same column.